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Shi H, Du Y, Xiong Y, Deng Y, Li Q. Source-oriented health risk assessment of groundwater nitrate by using EMMTE coupled with HHRA model. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 934:173283. [PMID: 38759927 DOI: 10.1016/j.scitotenv.2024.173283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 04/20/2024] [Accepted: 05/13/2024] [Indexed: 05/19/2024]
Abstract
Conventional concentration-oriented approaches for nitrate risk diagnosis only provide overall risk levels without identifying risk values of individual sources or sources accountable for potential health risks. Therefore, a hybrid model combining the end-member mixing model tool on Excel™ (EMMTE) with human health risk assessment (HHRA) was developed to assess the source-oriented health risks for groundwater nitrate, particularly in the Poyang Lake Plain (PLP) region. The results indicated that the EMMTE and the Bayesian stable isotope mixing model (MixSIAR) exhibited remarkable consistency in source apportionment of groundwater nitrate. The source contribution of groundwater nitrate in PLP was related to land use types, hydrogeological conditions, and soil properties. Notably, manure and sewage sources, contributing up to 53.4 %, represented the largest nitrate pollution sources, with a significant contribution of soil nitrogen and nitrogen fertilizers. The non-carcinogenic risk for four potential sources was below the acceptable threshold of 1. Given the factors including rainfall dilution and economic development, attention should be directed towards mitigating the health risks posed by manure and sewage. This study can verify the efficacy of EMMTE in source apportionment and offer valuable insights for decision-makers to regulate the largest sources of nitrate contamination and enhance groundwater management efficiency.
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Affiliation(s)
- Huanhuan Shi
- MOE Key Laboratory of Groundwater Quality and Health, China University of Geosciences, Wuhan, 430078, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China
| | - Yao Du
- MOE Key Laboratory of Groundwater Quality and Health, China University of Geosciences, Wuhan, 430078, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China.
| | - Yaojin Xiong
- MOE Key Laboratory of Groundwater Quality and Health, China University of Geosciences, Wuhan, 430078, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China
| | - Yamin Deng
- MOE Key Laboratory of Groundwater Quality and Health, China University of Geosciences, Wuhan, 430078, China; State Environmental Protection Key Laboratory of Source Apportionment and Control of Aquatic Pollution, China University of Geosciences, Wuhan, 430078, China; School of Environmental Studies, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430078, China
| | - Qinghua Li
- Wuhan Center of China Geological Survey, Wuhan 430205, China.
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2
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Kang P, Xu J, Wang F, Zhang H, Zhao H. Characterizing the impact of reservoir storage and discharge on nitrogen dynamics in an upstream wetland using a δ 15N and δ 18O dual-isotope approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 931:172923. [PMID: 38701929 DOI: 10.1016/j.scitotenv.2024.172923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/08/2024] [Accepted: 04/29/2024] [Indexed: 05/05/2024]
Abstract
The identification of nitrate sources in reservoir water is important for watershed-scale surface pollution management. Significant fluctuations in river water levels arising from reservoir storage and discharge influence nitrate sources and transport processes. The Sanmenxia Reservoir, in the middle reaches of the Yellow River in China, undergoes significant water level changes (290-316 m), altering the composition of the nitrogen sources. This study employed a δ15N and δ18O dual-isotope method and MixSIAR modeling to quantify the contributions of nitrate sources. This reveals the impact of reservoir water impoundment and discharge on nitrogen dynamics in the upstream region of the wetland and the model sensitivity for each nitrate source. The results showed that the average concentrations of nitrate‑nitrogen (NO- 3-N) were elevated during the impoundment period compared to the discharge period. Nitrogen sources exhibited varying proportions in surface water, groundwater, and soil water during both the impoundment and discharge periods. The predominant sources include manure and sewage (MS), with a maximum proportion of 57.4 % in surface water. Soil nitrogen (SN) accounted for 25.8 % of groundwater nitrogen and 32.1 % of soil water nitrogen during the impoundment period, whereas, during the discharge period, soil nitrogen made up 41.4 % of surface water nitrogen, manure and sewage contributed 44.8 % of groundwater nitrogen, and manure and sewage dominated with 56.7 % of soil water nitrogen. Sensitivity analysis of the MixSIAR model revealed that the isotopic composition of the manure and sewage primary source most significantly influenced the apportionment results of the riverine nitrate source. Reservoir discharge facilitates the dissimilatory nitrate reduction to ammonium (DNRA). The migration of NO- 3 from surface water to soil water and groundwater occurred from the impoundment period to the discharge period.
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Affiliation(s)
- Pingping Kang
- North China University of Water Resources and Electric Power, Zhengzhou 450046, Henan, China; Henan Key Laboratory of Water Resources Conservation and Intensive Utilization in the Yellow River Basin, Zhengzhou 450046, Henan, China
| | - Jie Xu
- North China University of Water Resources and Electric Power, Zhengzhou 450046, Henan, China
| | - Fuqiang Wang
- North China University of Water Resources and Electric Power, Zhengzhou 450046, Henan, China; Henan Key Laboratory of Water Resources Conservation and Intensive Utilization in the Yellow River Basin, Zhengzhou 450046, Henan, China.
| | - Honglu Zhang
- North China University of Water Resources and Electric Power, Zhengzhou 450046, Henan, China
| | - Heng Zhao
- North China University of Water Resources and Electric Power, Zhengzhou 450046, Henan, China; Henan Key Laboratory of Water Resources Conservation and Intensive Utilization in the Yellow River Basin, Zhengzhou 450046, Henan, China
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3
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Li J, Liu H, Pei H, Liu W, Yang G, Xie Y, Cao S, Wang J, Ma L, Zhang H. Coupled processes involving ammonium inputs, microbial nitrification, and calcite dissolution control riverine nitrate pollution in the piedmont zone (Qingshui River, China). THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 931:172970. [PMID: 38705293 DOI: 10.1016/j.scitotenv.2024.172970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 04/30/2024] [Accepted: 05/01/2024] [Indexed: 05/07/2024]
Abstract
Rivers in agricultural countries widely suffer from diffuse nitrate (NO3-) pollution. Although pollution sources and fates of riverine NO3- have been reported worldwide, the driving mechanisms of riverine NO3- pollution associated with mineral dissolution in piedmont zones remain unclear. This study combined hydrogeochemical compositions, stable isotopes (δ18O-NO3-, δ15N-NO3-, δ18O-H2O, and δ2H-H2O), and molecular bioinformation to determine the pollution sources, biogeochemical evolution, and natural attenuation of riverine NO3- in a typical piedmont zone (Qingshui River). High NO3- concentration (37.5 ± 9.44 mg/L) was mainly observed in the agricultural reaches of the river, with ~15.38 % of the samples exceeding the acceptable limit for drinking purpose (44 mg/L as NO3-) set by the World Health Organization. Ammonium inputs, microbial nitrification, and HNO3-induced calcite dissolution were the dominant driving factors that control riverine NO3- contamination in the piedmont zone. Approximately 99.4 % of riverine NO3- contents were derived from NH4+-containing pollutants, consisted of manure & domestic sewage (74.0 % ± 13.0 %), NH4+-synthetic fertilizer (16.1 % ± 8.99 %), and soil organic nitrogen (9.35 % ± 4.49 %). These NH4+-containing pollutants were converted to HNO3 (37.2 ± 9.38 mg/L) by nitrifying bacteria, and then the produced HNO3 preferentially participated in the carbonate (mainly calcite) dissolution, which accounted for 40.0 % ± 12.1 % of the total riverine Ca2+ + Mg2+, also resulting in the rapid release of NO3- into the river water. Thus, microbial nitrification could be a new and non-negligible contributor of riverine NO3- pollution, whereas the involvement of HNO3 in calcite dissolution acted as an accelerator of riverine NO3- pollution. However, denitrification had lesser contribution to natural attenuation for high NO3- pollution. The obtained results indicated that the mitigation of riverine NO3- pollution should focus on the management of ammonium discharges, and the HNO3-induced carbonate dissolution needs to be considered in comprehensively understanding riverine NO3- pollution in piedmont zones.
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Affiliation(s)
- Jun Li
- Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources, Hebei University of Architecture, Zhangjiakou 075000, China
| | - Haoyang Liu
- Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources, Hebei University of Architecture, Zhangjiakou 075000, China
| | - Hongwei Pei
- Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources, Hebei University of Architecture, Zhangjiakou 075000, China
| | - Wei Liu
- Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources, Hebei University of Architecture, Zhangjiakou 075000, China
| | - Guoli Yang
- Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources, Hebei University of Architecture, Zhangjiakou 075000, China
| | - Yincai Xie
- Key Laboratory of Karst Dynamics, MNR&GZAR, Institute of Karst Geology, CAGS, Guilin 541004, China
| | - Shengwei Cao
- Institute of Hydrogeology and Environmental Geology, CAGS, Shijiazhuang 050061, China
| | - Jiawei Wang
- Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources, Hebei University of Architecture, Zhangjiakou 075000, China
| | - Lishan Ma
- Hebei Key Laboratory of Water Quality Engineering and Comprehensive Utilization of Water Resources, Hebei University of Architecture, Zhangjiakou 075000, China
| | - Hengxing Zhang
- Institute of Hydrogeology and Environmental Geology, CAGS, Shijiazhuang 050061, China.
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Zhang C, Rao W, Wu Z, Zheng F, Li T, Li C, Lei X, Xie H, Xiaodong Chu. Anthropogenic impacts and quantitative sources of nitrate in a rural-urban canal using a combined PMF, δ 15N/δ 18O-NO 3-, and MixSIAR approach. ENVIRONMENTAL RESEARCH 2024; 251:118587. [PMID: 38437903 DOI: 10.1016/j.envres.2024.118587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 02/23/2024] [Accepted: 02/27/2024] [Indexed: 03/06/2024]
Abstract
Nitrate (NO3-) pollution in irrigation canals is of great concern because it threatens canal water use; however, little is known about it at present. Herein, a combination of positive matrix factorization (PMF), isotope tracers, and Mixing Stable Isotope Analysis in R (MixSIAR) was developed to identify anthropogenic impacts and quantitative sources of NO3- in a rural-urban canal in China. The NO3- concentration (0.99-1.93 mg/L) of canal water increased along the flow direction and was higher than the internationally recognized eutrophication risk value in autumn and spring. The inputs of the Fuhe River, NH4+ fertilizer, soil nitrogen, manure & sewage, and rainfall were the main driving factors of canal water NO3- based on principal component analysis and PMF, which was supported by evidence from δ15N/δ18O-NO3-. According to the chemical and isotopic analyses, nitrogen transformation was weak, highlighting the potential of δ15N/δ18O-NO3- to trace NO3- sources in canal water. The MixSIAR and PMF results with a <15% divergence emphasized the predominance of the Fuhe River (contributing >50%) and anthropogenic impacts (NH4+ fertilizer plus manure & sewage, >37%) on NO3- in the entire canal, reflecting the effectiveness of the model analysis. According to the MixSIAR model, (1) higher NO3- concentration in canal water was caused by the general enhancement of human activities in spring and (2) NO3- source contributions were associated with land-use patterns. The high contributions of NH4+ fertilizer and manure & sewage showed inverse spatial variations, suggesting the necessity of reducing excessive fertilizer use in the agricultural area and controlling blind wastewater release in the urban area. These findings provide valuable insights into NO3- dynamics and fate for sustainable management of canal water resources. Nevertheless, long-term chemical and isotopic monitoring with alternative modeling should be strengthened for the accurate evaluation of canal NO3- pollution in future studies.
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Affiliation(s)
- Chi Zhang
- College of Earth Sciences and Engineering, Jiangning Campus of Hohai University, No. 8, Fochengxi Road, Jiangning District, Nanjing 211100, China
| | - Wenbo Rao
- College of Earth Sciences and Engineering, Jiangning Campus of Hohai University, No. 8, Fochengxi Road, Jiangning District, Nanjing 211100, China.
| | - Zhihua Wu
- Jiangxi Authority of Water Conservancy Project of the Ganfu Plain, No. 2, Fazhan Road, High-Tech Development District, Nanchang 330096, China
| | - Fangwen Zheng
- School of Hydraulic and Ecological Engineering, Nanchang Institute of Technology, Qingshanhu District, No. 59, Beijingdong Road, Nanchang 330099, China
| | - Tianning Li
- College of Earth Sciences and Engineering, Jiangning Campus of Hohai University, No. 8, Fochengxi Road, Jiangning District, Nanjing 211100, China
| | - Chao Li
- College of Earth Sciences and Engineering, Jiangning Campus of Hohai University, No. 8, Fochengxi Road, Jiangning District, Nanjing 211100, China
| | - Xiang Lei
- College of Earth Sciences and Engineering, Jiangning Campus of Hohai University, No. 8, Fochengxi Road, Jiangning District, Nanjing 211100, China
| | - Hengwang Xie
- Jiangxi Authority of Water Conservancy Project of the Ganfu Plain, No. 2, Fazhan Road, High-Tech Development District, Nanchang 330096, China
| | - Xiaodong Chu
- Jiangxi Institute of Geo-Environment Monitoring, Nanchang 330095, China
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5
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Kypritidou Z, Kelepertzis E, Kritikos I, Kapaj E, Skoulika I, Kostakis M, Vassilakis E, Karavoltsos S, Boeckx P, Matiatos I. Geochemistry and origin of inorganic contaminants in soil, river sediment and surface water in a heavily urbanized river basin. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 927:172250. [PMID: 38599404 DOI: 10.1016/j.scitotenv.2024.172250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Revised: 04/03/2024] [Accepted: 04/03/2024] [Indexed: 04/12/2024]
Abstract
Understanding the geochemistry and contamination of rivers affected by anthropogenic activities is paramount to water resources management. The Asopos river basin in central Greece is facing environmental quality deterioration threats due to industrial, urban and agricultural activities. Here, the geochemistry of river sediments and adjacent soil in terms of major and trace elements (Al, Ca, Mg, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) and the geochemical composition of surface water in terms of major ions, trace elements and nutrients along the Asopos river basin were determined. In addition, this study characterized potential nitrate sources through the analysis of stable isotope composition of NO3- (δ15Ν-ΝΟ3- and δ18Ο-ΝΟ3-). Results indicated that specific chemical constituents including nutrients (NO2-, NH4+, PO43-) and major ions (Na+, Cl-) were highest in the urban, industrialized and downstream areas. On the other hand, nitrate (NO3-) concentration in river water (median 7.9 mg/L) showed a decreasing trend from the upstream agricultural sites to the urban area and even more in the downstream of the urban area sites. Ionic ratios (NO3-/Cl-) and δ15Ν-ΝΟ3- values (range from +10.2 ‰ to +15.7 ‰), complemented with a Bayesian isotope mixing model, clearly showed the influence of organic wastes from septic systems and industries operating in the urban area on river nitrate geochemistry. The interpretation of geochemical data of soil and river sediment samples demonstrated the strong influence of local geology on Cr, Fe, Mn and Ni content, with isolated samples showing elevated concentrations of Cd, Cu, Pb and Zn, mostly within the industrialized urban environment. The calculation of enrichment factors based on the national background concentrations provided limited insights into the origin of geogenic metals. Overall, this study highlighted the need for a more holistic approach to assess the impact of the geological background and anthropogenic activities on river waters and sediments.
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Affiliation(s)
- Zacharenia Kypritidou
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784 Athens, Greece
| | - Efstratios Kelepertzis
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784 Athens, Greece.
| | - Ioannis Kritikos
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784 Athens, Greece
| | - Emanuela Kapaj
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784 Athens, Greece
| | - Iro Skoulika
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784 Athens, Greece
| | - Marios Kostakis
- Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 157 84 Athens, Greece
| | - Emmanuel Vassilakis
- Department of Geology and Geoenvironment, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 15784 Athens, Greece
| | - Sotirios Karavoltsos
- Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zographou, 157 84 Athens, Greece
| | - Pascal Boeckx
- Isotope Bioscience Laboratory-ISOFYS, Department of Green Chemistry and Technology, Ghent University, Belgium
| | - Ioannis Matiatos
- Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 46.7 km of Athens-Sounio Ave., 19013 Anavissos, Attikis, Greece
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Zhang W, Wu F, Luo X, Song L, Wang X, Zhang Y, Wu J, Xiao Z, Cao F, Bi X, Feng Y. Quantification of NO x sources contribution to ambient nitrate aerosol, uncertainty analysis and sensitivity analysis in a megacity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 926:171583. [PMID: 38461977 DOI: 10.1016/j.scitotenv.2024.171583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Revised: 02/06/2024] [Accepted: 03/06/2024] [Indexed: 03/12/2024]
Abstract
Dual isotopes of nitrogen and oxygen of NO3- are crucial tools for quantifying the formation pathways and precursor NOx sources contributing to atmospheric nitrate. However, further research is needed to reduce the uncertainty associated with NOx proportional contributions. The acquisition of nitrogen isotopic composition from NOx emission sources lacks regulation, and its impact on the accuracy of contribution results remains unexplored. This study identifies key influencing factors of source isotopic composition through statistical methods, based on a detailed summary of δ15N-NOx values from various sources. NOx emission sources are classified considering these factors, and representative means, standard deviations, and 95 % confidence intervals are determined using the bootstrap method. During the sampling period in Tianjin in 2022, the proportional nitrate formation pathways varied between sites. For suburban and coastal sites, the ranking was [Formula: see text] (NO2 + OH radical) > [Formula: see text] (N2O5 + H2O) > [Formula: see text] (NO3 + DMS/HC), while the rural site exhibited similar fractional contributions from all three formation pathways. Fossil fuel NOx sources consistently contributed more than non-fossil NOx sources in each season among three sites. The uncertainties in proportional contributions varied among different sources, with coal combustion and biogenic soil emission showing lower uncertainties, suggesting more stable proportional contributions than other sources. The sensitivity analysis clearly identifies that the isotopic composition of 15N-enriched and 15N-reduced sources significantly influences source contribution results, emphasizing the importance of accurately characterizing the localized and time-efficient nitrogen isotopic composition of NOx emission sources. In conclusion, this research sheds light on the importance of addressing uncertainties in NOx proportional contributions and emphasizes the need for further exploration of nitrogen isotopic composition from NOx emission sources for accurate atmospheric nitrate studies.
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Affiliation(s)
- Wenhui Zhang
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Fuliang Wu
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Xi Luo
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Lilai Song
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Xuehan Wang
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yufen Zhang
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Jianhui Wu
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhimei Xiao
- Tianjin Eco-Environmental Monitoring Center, Tianjin 300191, China
| | - Fang Cao
- Yale-NUIST Center on Atmospheric Environment, International Joint Laboratory on Climate and Environment Change, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Xiaohui Bi
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
| | - Yinchang Feng
- State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China; China Meteorological Administration-Nankai University (CMA-NKU) Cooperative Laboratory for Atmospheric Environment-Health Research, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
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7
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Chen W, Zhang X, Wu N, Yuan C, Liu Y, Yang Y, Chen Z, Dahlgren RA, Zhang M, Ji X. Sources and transformations of riverine nitrogen across a coastal-plain river network of eastern China: New insights from multiple stable isotopes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 924:171671. [PMID: 38479520 DOI: 10.1016/j.scitotenv.2024.171671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/10/2024] [Accepted: 03/10/2024] [Indexed: 03/18/2024]
Abstract
Riverine nitrogen pollution is ubiquitous and attracts considerable global attention. Nitrate is commonly the dominant total nitrogen (TN) constituent in surface and ground waters; thus, stable isotopes of nitrate (δ15N/δ18O-NO3-) are widely used to differentiate nitrate sources. However, δ15N/δ18O-NO3- approach fails to present a holistic perspective of nitrogen pollution for many coastal-plain river networks because diverse nitrogen species contribute to high TN loads. In this study, multiple isotopes, namely, δ15N/δ18O-NO3-, δ18O-H2O, δ15N-NH4+, δ15N-PN, and δ15Nbulk/δ18O/SP-N2O in the Wen-Rui Tang River, a typical coastal-plain river network of Eastern China, were investigated to identify transformation processes and sources of nitrogen. Then, a stable isotope analysis in R (SIAR) model-TN source apportionment method was developed to quantify the contributions of different nitrogen sources to riverine TN loads. Results showed that nitrogen pollution in the river network was serious with TN concentrations ranging from 1.71 to 8.09 mg/L (mean ± SD: 3.77 ± 1.39 mg/L). Ammonium, nitrate, and suspended particulate nitrogen were the most prominent nitrogen components during the study period, constituting 45.4 %, 28.9 %, and 19.9 % of TN, respectively. Multiple hydrochemical and isotopic analysis identified nitrification as the dominant N cycling process. Biological assimilation and denitrification were minor N cycling processes, whereas ammonia volatilization was deemed negligible. Isotopic evidence and SIAR modeling revealed municipal sewage was the dominant contributor to nitrogen pollution. Based on quantitative estimates from the SIAR model, nitrogen source contributions to the Wen-Rui Tang River watershed followed: municipal sewage (40.6 %) ≈ soil nitrogen (39.5 %) > nitrogen fertilizer (9.7 %) > atmospheric deposition (2.8 %) during wet season; and municipal sewage (59.1 %) > soil nitrogen (30.4 %) > nitrogen fertilizer (4.1 %) > atmospheric deposition (1.0 %) during dry season. This study provides a deeper understanding of nitrogen dynamics in eutrophic coastal-plain river networks, which informs strategies for efficient control and remediation of riverine nitrogen pollution.
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Affiliation(s)
- Wenli Chen
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Xiaohan Zhang
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Nianting Wu
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Can Yuan
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Yinli Liu
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Yue Yang
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China; Southern Zhejiang Water Research Institute, Wenzhou 325035, China
| | - Zheng Chen
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Randy A Dahlgren
- Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA
| | - Minghua Zhang
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China; Southern Zhejiang Water Research Institute, Wenzhou 325035, China; Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA
| | - Xiaoliang Ji
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China.
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8
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Shu L, Chen W, Liu Y, Shang X, Yang Y, Dahlgren RA, Chen Z, Zhang M, Ji X. Riverine nitrate source identification combining δ 15N/δ 18O-NO 3- with Δ 17O-NO 3- and a nitrification 15N-enrichment factor in a drinking water source region. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170617. [PMID: 38311089 DOI: 10.1016/j.scitotenv.2024.170617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 01/15/2024] [Accepted: 01/30/2024] [Indexed: 02/06/2024]
Abstract
Dual nitrate isotopes (δ15N/δ18O-NO3-) are an effective tool for tracing nitrate sources in freshwater systems worldwide. However, the initial δ15N/δ18O values of different nitrate sources might be altered by isotopic fractionation during nitrification, thereby limiting the efficiency of source apportionment results. This study integrated hydrochemical parameters, site-specific isotopic compositions of potential nitrate sources, multiple stable isotopes (δD/δ18O-H2O, δ15N/δ18O-NO3- and Δ17O-NO3-), soil incubation experiments assessing the nitrification 15N-enrichment factor (εN), and a Bayesian mixing model (MixSIAR) to reduce/eliminate the influence of 15N/18O-fractionations on nitrate source apportionment. Surface water samples from a typical drinking water source region were collected quarterly (June 2021 to March 2022). Nitrate concentrations ranged from 0.35 to 3.06 mg/L (mean = 0.78 ± 0.46 mg/L), constituting ∼70 % of total nitrogen. A MixSIAR model was developed based on δ15N/δ18O-NO3- values of surface waters and the incorporation of a nitrification εN (-6.9 ± 1.8 ‰). Model source apportionment followed: manure/sewage (46.2 ± 10.7 %) > soil organic nitrogen (32.3 ± 18.5 %) > nitrogen fertilizer (19.7 ± 13.1 %) > atmospheric deposition (1.8 ± 1.6 %). An additional MixSIAR model coupling δ15N/δ18O-NO3- with Δ17O-NO3- and εN was constructed to estimate the potential nitrate source contributions for the June 2021 water samples. Results revealed similar nitrate source contributions (manure/sewage = 43.4 ± 14.1 %, soil organic nitrogen = 29.3 ± 19.4 %, nitrogen fertilizer = 19.8 ± 13.8 %, atmospheric deposition = 7.5 ± 1.6 %) to the original MixSIAR model based on εN and δ15N/δ18O-NO3-. Finally, an uncertainty analysis indicated the MixSIAR model coupling δ15N/δ18O-NO3- with Δ17O-NO3- and εN performed better as it generated lower uncertainties with uncertainty index (UI90) of 0.435 compared with the MixSIAR model based on δ15N/δ18O-NO3- (UI90 = 0.522) and the MixSIAR model based on δ15N/δ18O-NO3- and εN (UI90 = 0.442).
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Affiliation(s)
- Lielin Shu
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Wenli Chen
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Yinli Liu
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Xu Shang
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China; Southern Zhejiang Water Research Institute (iWATER), Wenzhou 325035, China
| | - Yue Yang
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China; Southern Zhejiang Water Research Institute (iWATER), Wenzhou 325035, China
| | - Randy A Dahlgren
- Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA
| | - Zheng Chen
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China.
| | - Minghua Zhang
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China; Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA
| | - Xiaoliang Ji
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China.
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Mu J, Ding S, Liu SM, Song G, Ning X, Zhang X, Xu W, Zhang H. Multiple isotopes decipher the nitrogen cycle in the cascade reservoirs and downstream in the middle and lower Yellow River: Insight for reservoir drainage period. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170625. [PMID: 38320705 DOI: 10.1016/j.scitotenv.2024.170625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/13/2024]
Abstract
Intensive anthropogenic activities, such as excessive nitrogen input and dam construction, have altered the nitrogen cycle in the global river system. However, the focus on the source, transformation and fate of nitrogen in the Yellow River is still scarce. In this study, the multiple isotopes (δ15N-NO3-, δ18O-NO3-, δ15N-NH4+ and δ15N-PN) were deciphered to explore the nitrogen cycling processes and the driving factors in the thermally stratified cascade reservoirs (Sanmenxia Reservoir: SMXR and Xiaolangdi Reservoir: XLDR) and Lower Yellow River (LYR) during the drainage period of the XLDR. In the SMXR, algal bloom triggered the assimilation process in the upper layer before the SMX Dam, followed by remineralization and subsequent nitrification processes in the lower water layers. The nitrification reaction in the XLDR progressively increased along both longitudinal and vertical directions to the lower layer of the XLD Dam, which was linked to the variation in the water residence time of riverine, transition and lentic zones. The robust nitrification rates in the lower layer of the lentic zone coincided with the substantial depletion of nitrate isotopic composition and enrichment of both δ15N-PN and δ15N-NH4+, indicating the longer water residence time not only promoted the growth of the nitrifying population but also facilitated the remineralization to enhance NH4+ availability. In the LYR, the slight nitrate assimilation, as indicated by nitrate isotopic composition and fractionation models, was the predominant nitrogen transformation process. The Bayesian isotope mixing model results showed that manure and sewage was the dominant nitrate source (50 %) in the middle and lower Yellow River. Notably, the in-reservoir nitrification was a significant nitrate source (27 %) in the XLDR and LYR. Our study deepens the understanding of anthropogenic activities impacting the nitrogen cycle in the river-reservoir system, providing valuable insight into water quality management and nitrogen cycle mechanisms in the Yellow River.
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Affiliation(s)
- Jinglong Mu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Shuai Ding
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Su Mei Liu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
| | - Guodong Song
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xiaoyan Ning
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xiaotong Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Wenqi Xu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Hongmei Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
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10
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Xia Y, Xiao J, Wang W, Li Z. Nitrate dynamics in the streamwater-groundwater interaction system: Sources, fate, and controls. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 918:170574. [PMID: 38311085 DOI: 10.1016/j.scitotenv.2024.170574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 01/07/2024] [Accepted: 01/28/2024] [Indexed: 02/06/2024]
Abstract
Nitrate (NO3-) pollution has attracted widespread attention as a threat to human health and aquatic ecosystems; however, elucidating the controlling factors behind nitrate dynamics under the context of changeable hydrological processes, particularly the interactions between streamwater and groundwater (SW-GW), presents significant challenges. A multi-tracer approach, integrating physicochemical and isotopic tracers (Cl-, δ2H-H2O, δ18O-H2O, δ15N-NO3- and δ18O-NO3-), was employed to identify the response of nitrate dynamics to SW-GW interaction in the Fen River Basin. The streamwater and groundwater NO3- concentrations varied greatly with space and time. Sewage and manure (28 %-73 %), fertilizer (14 %-36 %) and soil organic nitrogen (12 %-28 %) were the main NO3- sources in water bodies. Despite the control of land use type on streamwater nitrate dynamics in losing sections, SW-GW interactions drove NO3- dynamics in both streamwater and groundwater under most circumstances. In gaining streams, streamwater nitrate dynamics were influenced either by groundwater dilution or microbial nitrification, depending on whether groundwater discharge ratios exceeded or fell below 25 %, respectively. In losing streams, groundwater nitrate content increased with streamwater infiltration time, but the influence was mainly limited within 3 km from the river channel. This study provides a scientific basis for the effective management of water nitrate pollution at the watershed scale.
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Affiliation(s)
- Yun Xia
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Jun Xiao
- State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, Shaanxi 710061, China
| | - Wanzhou Wang
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Zhi Li
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
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11
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Zaryab A, Alijani F, Knoeller K, Minet E, Musavi SF, Ostadhashemi Z. Identification of groundwater nitrate sources in an urban aquifer (Alborz Province, Iran) using a multi-parameter approach. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2024; 46:100. [PMID: 38407701 DOI: 10.1007/s10653-024-01872-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 01/12/2024] [Indexed: 02/27/2024]
Abstract
High concentrations of NO3̄ in water resources are detrimental to both human health and aquatic ecosystems. Identification of NO3̄ sources and biogeochemical processes is a crucial step in managing and controlling NO3̄ pollution. In this study, land use, hydrochemical data, dual stable isotopic ratios and Bayesian Stable Isotope Mixing Models (BSIMM) were integrated to identify NO3̄ sources and estimate their proportional contributions to the contamination of the Karaj Urban Aquifer (Iran). Elevated NO3̄ concentrations indicated a severe NO3̄ pollution, with 39 and 52% of groundwater (GW) samples displaying the concentrations of NO3̄ in exceedance of the World Health Organization (WHO) standard of 50 mg NO3̄ L-1 in the rainy and dry seasons, respectively. Dual stable isotopes inferred that urban sewage is the main NO3̄ source in the Karaj Plain. The diagram of NO3̄/Cl‾ versus Cl‾ confirmed that municipal sewage is the major source of NO3̄. Results also showed that biogeochemical nitrogen dynamics are mainly influenced by nitrification, while denitrification is minimal. The BSIMM model suggested that NO3̄ originated predominantly from urban sewage (78.2%), followed by soil organic nitrogen (12.2%), and chemical fertilizer (9.5%) in the dry season. In the wet season, the relative contributions of urban sewage, soil nitrogen and chemical fertilizer were 87.5, 6.7, and 5.5%, respectively. The sensitivity analysis for the BSIMM modeling indicates that the isotopic signatures of sewage had the major impact on the overall GW NO3̄ source apportionment. The findings provide important insights for local authorities to support effective and sustainable GW resources management in the Karaj Urban Aquifer. It also demonstrates that employing Bayesian models combined with multi-parameters can improve the accuracy of NO3̄ source identification.
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Affiliation(s)
- Abdulhalim Zaryab
- Engineering Geology and Hydrogeology, Faculty of Geology and Mines, Kabul Polytechnic University, District 5, Kabul, Afghanistan
| | - Farshad Alijani
- Department of Minerals and Groundwater Resources, Faculty of Earth Sciences, Shahid Beheshti University, Evin Ave, Tehran, Iran.
| | - Kay Knoeller
- Department Catchment Hydrology Helmholtz-Centre for Environmental Research-UFZ, 06120, Halle, Germany
| | - Eddy Minet
- Environmental Protection Agency (EPA), Dublin, Ireland
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12
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Chen X, Ren M, Li G, Zhang J, Xie F, Zheng L. Identification of nitrate accumulation mechanism of surface water in a mining-rural-urban agglomeration area based on multiple isotopic evidence. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169123. [PMID: 38070569 DOI: 10.1016/j.scitotenv.2023.169123] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 11/28/2023] [Accepted: 12/03/2023] [Indexed: 01/18/2024]
Abstract
The accumulation of nitrate (NO3-) in surface waters resulting from mining activities and rapid urbanization has raised widespread concerns. Therefore, it is crucial to develop a nitrate transformation information system to elucidate the nitrogen cycle and ensure sustainable water quality management. In this study, we focused on the main river and subsidence area of the Huaibei mining region to monitor the temporal and spatial variations in the NO3- content. Multiple isotopes (δD, δ18O-H2O, δ15N-NO3-, δ18O-NO3-, and δ15N-NH4+) along with water chemistry indicators were employed to identify the key mechanisms responsible for nitrate accumulation (e.g., nitrification and denitrification). The NO3- concentrations in surface water ranged from 0.28 to 7.50 mg/L, with NO3- being the predominant form of nitrogen pollution. Moreover, the average NO3- levels were higher during the dry season than during the wet season. Nitrification was identified as the primary process driving NO3- accumulation in rivers and subsidence areas, which was further supported by the linear relationship between δ15N-NO3- and δ15N-NH4+. The redox conditions and the relationship between δ15N-NO3- and δ18O-NO3-, and lower isotope enrichment factor of denitrification indicated that denitrification was weakened. Phytoplankton preferentially utilized available NH4+ sources while inhibiting NO3- assimilation because of their abundance. These findings provide direct evidence regarding the mechanism underlying nitrate accumulation in mining areas, while aiding in formulating improved measures for effectively managing water environments to prevent further deterioration.
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Affiliation(s)
- Xing Chen
- School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Anhui University, Hefei 230601, China
| | - Mengxi Ren
- School of Biological and Environmental Engineering, Chaohu University, Chaohu 238000, China; Anhui Province Engineering Laboratory for Mine Ecological Remediation, Anhui University, Hefei 230601, China
| | - Guolian Li
- School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Jiamei Zhang
- School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Fazhi Xie
- School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China.
| | - Liugen Zheng
- Anhui Province Engineering Laboratory for Mine Ecological Remediation, Anhui University, Hefei 230601, China.
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13
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Xie F, Cai G, Li G, Li H, Chen X, Liu Y, Zhang W, Zhang J, Zhao X, Tang Z. Basin-wide tracking of nitrate cycling in Yangtze River through dual isotope and machine learning. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169656. [PMID: 38157890 DOI: 10.1016/j.scitotenv.2023.169656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 12/19/2023] [Accepted: 12/22/2023] [Indexed: 01/03/2024]
Abstract
The nitrate (NO3-) input has adversely affected the water quality and ecological function in the whole basin of the Yangtze River. The protection of water sources and implementation of "great protection of Yangtze River" policy require large-scale information on water contamination. In this study, dual isotope and Bayesian mixing model were used to research the transformation and sources of nitrate. Chemical fertilizers contribute 76 % of the nitrate sources in the upstream, while chemical fertilizers were also dominant in the midstream (39 %) and downstream (39 %) of Yangtze River. In addition, nitrification process occurred in the whole basin. Four machine learning models were used to relate nitrate concentrations to explanatory variables describing influence factors to predict nitrate concentrations in the whole basin of Yangtze River. The anthropogenic and natural factors, such as rainfall, GDP and population were chosen to take as predictor variables. The eXtreme Gradient Boosting (XGBoost) model for nitrate has a better predictive performance with an R2 of 0.74. The predictive models of nitrate concentrations will help identify the nitrate distribution and transport in the whole Yangtze River basin. Overall, this study represents the first basin-wide data-driven assessment of the nitrate cycling in the Yangtze River basin.
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Affiliation(s)
- Fazhi Xie
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230031, Anhui, China
| | - Gege Cai
- School of Materials and Chemical Engineering, Anhui Jianzhu University, Hefei 230031, Anhui, China
| | - Guolian Li
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230031, Anhui, China
| | - Haibin Li
- School of Materials and Chemical Engineering, Anhui Jianzhu University, Hefei 230031, Anhui, China
| | - Xing Chen
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230031, Anhui, China
| | - Yun Liu
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230031, Anhui, China
| | - Wei Zhang
- Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei 230031, Anhui, China
| | - Jiamei Zhang
- School of Environmental and Energy Engineering, Anhui Jianzhu University, Hefei 230031, Anhui, China.
| | - Xiaoli Zhao
- Chinese Research Academy of Environmental Sciences, Beijing 100000, China
| | - Zhi Tang
- Chinese Research Academy of Environmental Sciences, Beijing 100000, China
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Ren X, Yue FJ, Tang J, Li C, Li SL. Nitrate transformation and source tracking of rivers draining into the Bohai Sea using a multi-tracer approach combined with an optimized Bayesian stable isotope mixing model. JOURNAL OF HAZARDOUS MATERIALS 2024; 463:132901. [PMID: 37931340 DOI: 10.1016/j.jhazmat.2023.132901] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 10/26/2023] [Accepted: 10/29/2023] [Indexed: 11/08/2023]
Abstract
Excessive levels of NO3- can result in multiple eco-environmental issues due to potential toxicity, especially in coastal areas. Accurate source tracing is crucial for effective pollutant control and policy development. Bayesian models have been widely employed to trace NO3- sources, while limited studies have utilized optimized Bayesian models for NO3- tracing in the coastal rivers. The Bohai Rim is highly susceptible to ecological disturbances, particularly N pollution, and has emerged as a critical area. Therefore, identification the N fate and understanding their sources contribution is urgent for pollution mitigation efforts. In addition, understanding the influenced key driven factors to source dynamic in the past ten years is also implication to environmental management. In this study, water samples were collected from 36 major river estuaries that drain into the Bohai Sea of North China. The main transformation processes were analyzed and quantified the sources of NO3- using a Bayesian stable isotope mixing model (MixSIAR) with isotopic approach (δ15N-NO3- and δ18O-NO3-). The overall isotopic composition of δ15N-NO3- and δ18O-NO3- in estuary waters ranged from -0.8-19.3‰ (9.3 ± 4.6‰) and from -7.1-10.5‰ (5.0 ± 4.3‰), respectively. The main sources of nitrate in most river estuaries were manure & sewage, and chemical fertilizer, while weak denitrification and mixed processes were observed in Bohai Rim region. A temporal decrease in the nitrogen load entering the Bohai Sea indicates an improvement in water quality in recent years. By incorporating informative priors and utilizing the calculated coefficients, the accuracy of sourcing results was significantly improved. This study highlighted the optimized MixSIAR model enhanced its accuracy for sourcing analysis and providing valuable insights for policy formulation. Future efforts should focus on improving management strategies to reduce nitrogen into the bay.
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Affiliation(s)
- Xinwei Ren
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China
| | - Fu-Jun Yue
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; Tianjin Bohai Rim Coastal Earth Critical Zone National Observation and Research Station, Tianjin University, Tianjin 300072, China; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China.
| | - Jianhui Tang
- Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Cai Li
- School of Urban and Environment Science, Huaiyin Normal University, Huaian 223300, China
| | - Si-Liang Li
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; Tianjin Bohai Rim Coastal Earth Critical Zone National Observation and Research Station, Tianjin University, Tianjin 300072, China; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China; Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China.
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Yang S, Deng Y, Shu J, Luo X, Peng X, Pan K, Jiang H. Nitrate budget of a terrestrial-to-marine continuum in South China: Insights from isotopes and a Markov chain Monte Carlo model. MARINE POLLUTION BULLETIN 2024; 199:116000. [PMID: 38171166 DOI: 10.1016/j.marpolbul.2023.116000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/25/2023] [Accepted: 12/26/2023] [Indexed: 01/05/2024]
Abstract
Anthropogenic nitrate (NO3-) production has been increasing and is exported to the ocean via river networks, causing eutrophication and ecological damage. While studies have focused on river NO3- pollution, what has been lacking is the quantification of the sources of NO3- in coastal rivers. This study applied the dual isotopes (δ15N/δ18O-NO3-) to quantify the sources and their fluxes of NO3- in two inflow rivers of the Qinzhou Bay. By adding our results to the NO3- source apportionment in Qinzhou Bay, we, for the first time, established the NO3- budgets of the terrestrial-to-marine continuum in both high- and low-flow seasons. We quantitatively showed the direct and indirect roles (e.g., the stimulation of nitrification by sewage ammonium-NH4+) of terrestrial sources in driving the high NO3- loading in the estuary. The results highlighted the necessity to consider coastal rivers and estuary as a whole, which could shed light on the effective reduction of NO3- pollution in coastal environments.
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Affiliation(s)
- Shaomei Yang
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Yan Deng
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Junlin Shu
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Xin Luo
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Xiaoyan Peng
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Ke Pan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, The Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China; Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China.
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16
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Li H, Wu J, Huang Q, Lin L, Yuan B, Wang Q, Lu H, Liu J, Hong H, Yan C. Combined use of positive matrix factorization and 13C 15N stable isotopes to trace organic matter-bound potential toxic metals in the urban mangrove sediments. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 904:166684. [PMID: 37652389 DOI: 10.1016/j.scitotenv.2023.166684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 08/25/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
Coastal sediments act as sinks of sediment organic matter (SOM) and metals because of their special land-sea location and depositional properties. However, there are few reports on the correlation between the sources of organic matter (OM) and associated potential toxic metals (PTMs). In this study, we combined CN stable isotope analysis and positive matrix factorization to identify the matter and metal sources of OM and glomalin-related soil protein (GRSP) in an estuary under several decades of urbanization. The results of the positive matrix factorization (PMF) reveal a correlation between the sources of total sediment metals and the sources of OM-related metals. The sources of both SOM-bound PTMs and GRSP-bound PTMs are significantly related to the sources of total PTMs. OM sources were elucidated through 13C-15 N stable isotopes, and the potential sources of different types of OM differed. In addition, there is a significant correlation between OM-associated PTMs and organic matter sources. Interestingly, the functional groups of SOM were mainly influenced by multiple PTM sources but no OM source, while the functional groups of GRSP were regulated by a single metal source and OM source. This study deepened the understanding of the coupling between PTMs and SOM. The possibility of combined use of positive matrix factorization and 13C-15 N stable isotope tracing of metals as well as the sources of each metal fractions has been evaluated, which will provide new insights for the transportation of PTMs.
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Affiliation(s)
- Hanyi Li
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Jiajia Wu
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Qian Huang
- Institute of Geosciences, University of Mainz, Johann-Joachim-Becher-Weg 21, Mainz 55128, Germany.
| | - Lujian Lin
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Bo Yuan
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Qiang Wang
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agricultural Science and Technology, Lanzhou University, Lanzhou 730020, China.
| | - Haoliang Lu
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Jingchun Liu
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Hualong Hong
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
| | - Chonglin Yan
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, Xiamen University, Xiamen 361102, China.
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Matiatos I, Lazogiannis K, Papadopoulos A, Skoulikidis NT, Boeckx P, Dimitriou E. Stable isotopes reveal organic nitrogen pollution and cycling from point and non-point sources in a heavily cultivated (agricultural) Mediterranean river basin. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 901:166455. [PMID: 37607634 DOI: 10.1016/j.scitotenv.2023.166455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 08/18/2023] [Accepted: 08/18/2023] [Indexed: 08/24/2023]
Abstract
The Pinios River Basin (PRB) is the most intensively cultivated area in Greece, which hosts numerous industries and other anthropogenic activities. The analysis of water samples collected monthly for ∼1 ½ years in eight monitoring sites in the PRB revealed nitrate pollution of organic origin extending from upstream to downstream and occurring throughout the year, masking the signal from the application of synthetic fertilizers. Nitrate concentrations reached up to 3.6 mg/l as NO3--N, without exceeding the drinking water threshold of ∼11.0 mg/l (as NO3--N). However, the water quality status was "poor" or "bad" in ∼50 % of the samples based on a local index, which considers the potential impact of nitrate on aquatic biological communities. The δ15Ν-ΝΟ3- and δ18O-NO3- values ranged from +4.4 ‰ to +20.3 ‰ and from -0.5 ‰ to +14.4 ‰, respectively. The application of a Bayesian model showed that the proportional contribution of organic pollution from industries, animal breeding facilities and manure fertilizers exceeded 70 % in most river sites with an overall uncertainty of ∼0.3 (UI90 index). The δ18O-NO3- and its relationship with δ18O-H2O revealed N-cycling and mixing processes, which were difficult to identify apart from the uptake of nutrients by phytoplankton during the growing season and metabolic activities. The strong correlation of δ15Ν-ΝΟ3- values with a Land Use Index (LUI) and a Point Source Index (PSI) highlighted not only the role of non-point nitrate sources but also of point sources of nitrate pollution on water quality degradation, which are usually overlooked. The nitrification of organic wastes is the dominant nitrate source in most rivers in Europe. The systematic monitoring of rivers for nitrate isotopes will help improve the understanding of N-cycling and the impact of these pollutants on ecosystems and better inform policies for protection measures so to achieve good ecological status.
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Affiliation(s)
- Ioannis Matiatos
- Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece.
| | - Konstantinos Lazogiannis
- Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece
| | - Anastasios Papadopoulos
- Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece
| | - Nikolaos Th Skoulikidis
- Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece
| | - Pascal Boeckx
- Isotope Bioscience Laboratory-ISOFYS, Department of Green Chemistry and Technology, Ghent University, Belgium
| | - Elias Dimitriou
- Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, 19013 Anavissos Attikis, Greece
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18
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Zaryab A, Farahmand A, Mack TJ. Identification and apportionment of groundwater nitrate sources in Chakari Plain (Afghanistan). ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2023; 45:7813-7827. [PMID: 37462844 DOI: 10.1007/s10653-023-01684-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 07/06/2023] [Indexed: 10/29/2023]
Abstract
The Chakari alluvial aquifer is the primary source of water for human, animal, and irrigation applications. In this study, the geochemistry of major ions and stable isotope ratios (δ2H-H2O, δ18O-H2O, δ15N-NO3̄, and δ18O-NO3̄) of groundwater and river water samples from the Chakari Plain were analyzed to better understand characteristics of nitrate. Herein, we employed nitrate isotopic ratios and BSIMM modeling to quantify the proportional contributions of major sources of nitrate pollution in the Chakari Plain. The cross-plot diagram of δ15N-NO3̄ against δ18O-NO3̄ suggests that manure and sewage are the main source of nitrate in the plain. Nitrification is the primary biogeochemical process, whereas denitrification did not have a significant influence on biogeochemical nitrogen dynamics in the plain. The results of this study revealed that the natural attenuation of nitrate in groundwater of Chakari aquifer is negligible. The BSIMM results indicate that nitrate originated mainly from sewage and manure (S&M, 75‰), followed by soil nitrogen (SN, 13‰), and chemical fertilizers (CF, 9.5‰). Large uncertainties were shown in the UI90 values for S&M (0.6) and SN (0.47), whereas moderate uncertainty was exhibited in the UI90 value for CF (0.29). The findings provide useful insights for decision makers to verify groundwater pollution and develop a sustainable groundwater management strategy.
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Affiliation(s)
- Abdulhalim Zaryab
- Engineering Geology and Hydrogeology, Faculty of Geology and Mines, Kabul Polytechnic University, Kabul, Afghanistan.
- Highland Groundwater Research Group, Kabul, Afghanistan.
| | - Asadullah Farahmand
- Department of Hydrogeology, Ministry of Energy and Water, Kabul, Afghanistan
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19
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Zhao G, Sun T, Wang D, Chen S, Ding Y, Li Y, Shi G, Sun H, Wu S, Li Y, Wu C, Li Y, Yu Z, Chen Z. Treated wastewater and weak removal mechanisms enhance nitrate pollution in metropolitan rivers. ENVIRONMENTAL RESEARCH 2023; 231:116182. [PMID: 37201708 DOI: 10.1016/j.envres.2023.116182] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 05/07/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023]
Abstract
The focus of urban water environment renovation has shifted to high nitrate (NO3-) load. Nitrate input and nitrogen conversion are responsible for the continuous increase in nitrate levels in urban rivers. This study utilized nitrate stable isotopes (δ15N-NO3- and δ18O-NO3-) to investigate NO3- sources and transformation processes in Suzhou Creek, located in Shanghai. The results demonstrated that NO3- was the most common form of dissolved inorganic nitrogen (DIN), accounting for 66 ± 14% of total DIN with a mean value of 1.86 ± 0.85 mg L-1. The δ15N-NO3- and δ18O-NO3- values ranged from 5.72 to 12.42‰ (mean value: 8.38 ± 1.54‰) and -5.01 to 10.39‰ (mean value: 0.58 ± 1.76‰), respectively. Based on isotopic evidence, the river received a significant amount of nitrate through direct exogenous input and sewage ammonium nitrification, while nitrate removal (denitrification) was insignificant, resulting in nitrate accumulation. Analysis using the MixSIAR model revealed that treated wastewater (68.3 ± 9.7%), soil nitrogen (15.7 ± 4.8%) and nitrogen fertilizer (15.5 ± 4.9%) were the main sources of NO3- in rivers. Despite the fact that Shanghai's urban domestic sewage recovery rate has reached 92%, reducing nitrate concentrations in treated wastewater is crucial for addressing nitrogen pollution in urban rivers. Additional efforts are needed to upgrade urban sewage treatment during low flow periods and/or in the main stream, and to control non-point sources of nitrate, such as soil nitrogen and nitrogen fertilizer, during high flow periods and/or tributaries. This research provides insights into NO3- sources and transformations, and serves as a scientific basis for controlling NO3- in urban rivers.
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Affiliation(s)
- Guanghui Zhao
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Taihu Sun
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Dongqi Wang
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China; Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, Shanghai, 200241, China.
| | - Shu Chen
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China; College of Smart Energy, Shanghai Jiao Tong University, Shanghai, 200240, China; Research Institute of Carbon Neutrality, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yan Ding
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Yilan Li
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Guitao Shi
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Hechen Sun
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Shengnan Wu
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Yizhe Li
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Chenyang Wu
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Yufang Li
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China
| | - Zhongjie Yu
- Department of Natural Resources and Environmental Sciences, University of Illinois Urbana-Champaign, Urbana, 61801, IL, USA
| | - Zhenlou Chen
- School of Geographical Sciences, Key Laboratory of Geographic Information Science (Ministry of Education), East China Normal University, Shanghai, 200241, China.
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20
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Zhang W, Jiang H, Guo W, Li S, Zhang Q. Unexpectedly high nitrate levels in a pristine forest river on the Southeastern Qinghai-Tibet Plateau. JOURNAL OF HAZARDOUS MATERIALS 2023; 458:132047. [PMID: 37453353 DOI: 10.1016/j.jhazmat.2023.132047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 06/30/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
River nitrate (NO3-) pollution is a global environmental issue. Recently, high NO3- levels in some pristine or minimally-disturbed rivers were reported, but their drivers remain unclear. This study integrated river isotopes (δ18O/δ15N-NO3- and δD/18O-H2O), 15N pairing experiments, and qPCR to reveal the processes driving the high NO3- levels in a nearly pristine forest river on the Qinghai-Tibet Plateau. The river isotopes suggested that, at the catchment scale, NO3- removal was prevalent in summer, but weak in winter. The pristine forest soils contributed more than 90 % of the riverine NO3-, indicating the high NO3- backgrounds. The release of soil NO3- to the river was "transport-limited" in both seasons, i.e., the NO3- production/stock in the soils exceeded the capacity of hydrological NO3- leaching. In summer, this regime and the NO3--plentiful conditions in the soils associated with the strong NO3- nitrification led to the high riverine NO3- levels. While the in-soil nitrification was weak in winter, the leaching of legacy NO3- resulted in the consistently high NO3- levels. This study provides insights into the reasons for high NO3- levels in pristine or minimally-disturbed rivers worldwide and highlights the necessity to consider NO3- backgrounds when evaluating anthropogenic NO3- pollution in rivers.
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Affiliation(s)
- Wenshi Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China.
| | - Wenjing Guo
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Shen Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Quanfa Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China
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21
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Liu D, Li X, Zhang Y, Qiao Q, Bai L. Using a Multi-isotope Approach and Isotope Mixing Models to Trace and Quantify Phosphorus Sources in the Tuojiang River, Southwest China. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:7328-7335. [PMID: 36920429 DOI: 10.1021/acs.est.2c07216] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Identifying phosphorus (P) sources is critical for solving eutrophication and controlling P in aquatic environments. Phosphate oxygen isotopes (δ18Op) have been used to trace P sources. However, the application of this method has been greatly restricted due to δ18OP values from the potential source having wide and overlapping ranges. In this research, P sources were traced by combining δ18Op with multiple stable isotopes of nitrogen (δ15N), hydrogen (δD), and dissolved inorganic carbon (δ13C). Then, a Bayesian-based Stable Isotope Analysis in R (SIAR) model and IsoSource model were used to estimate the proportional contributions of the potential sources in the Tuojiang River. δ18Op was not in equilibrium with ambient water, and statistically significant differences in the δ18Op values were found between the potential sources, indicating that δ18Op can be used to trace the P sources. δ15N, δD, and δ13C could assist δ18Op in identifying the main sources of P. The SIAR and IsoSource models suggested that industrial and domestic sewage was the largest contributor, followed by phosphate rock and phosphogypsum and agricultural sewage. The uncertainty of the calculation results of the SIAR model was lower than that of the IsoSource model. These findings provide new insights into tracing P sources using multiple stable isotopes in watersheds.
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Affiliation(s)
- Dandan Liu
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- SEPA Key Laboratory of Eco-Industry, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Xueying Li
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- SEPA Key Laboratory of Eco-Industry, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Yue Zhang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- SEPA Key Laboratory of Eco-Industry, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Qi Qiao
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- SEPA Key Laboratory of Eco-Industry, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Lu Bai
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
- SEPA Key Laboratory of Eco-Industry, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
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22
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Wang Y, Cao X, Yu H, Xu Y, Peng J, Qu J. Nitrate with enriched heavy oxygen isotope linked to changes in nitrogen source and transformation as groundwater table rises. JOURNAL OF HAZARDOUS MATERIALS 2023; 455:131527. [PMID: 37163892 DOI: 10.1016/j.jhazmat.2023.131527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 04/19/2023] [Accepted: 04/26/2023] [Indexed: 05/12/2023]
Abstract
Nitrate is a significant constituent of the total nitrogen pool in shallow aquifers and poses an escalating threat to groundwater resources, making it crucial to comprehend the source, conversion, and elimination of nitrogen using appropriate techniques. Although dual-isotope dynamics in nitrate have been widely used, uncertainties remain regarding the asynchronously temporal changes in δ18O-NO3- and δ15N-NO3- observed in hypoxic aquifers. This study aimed to investigate changes in nitrogen sources and transformations using temporal changes in field-based NO3- isotopic composition, hydro-chemical variables, and environmental DNA profiling, as the groundwater table varied. The results showed that the larger enrichment in δ18O-NO3- (+13‰) compared with δ15N-NO3- (-2‰) on average during groundwater table rise was due to a combination of factors, including high 18O-based atmospheric N deposition, canopies nitrification, and soil nitrification transported vertically by rainfalls, and 18O-enriched O2 produced through microbial and root respiration within denitrification. The strong association between functional gene abundance and nitrogen-related indicators suggests that anammox was actively processed with nitrification but in small bacterial population during groundwater table rise. Furthermore, bacterial species associated with nitrogen-associated gradients provided insight into subsurface nitrogen transformation, with Burkholderiaceae species and Pseudorhodobacter potentially serving as bioindicators of denitrification, while Candidatus Nitrotogn represents soil nitrification. Fluctuating groundwater tables can cause shifts in hydro-chemical and isotopic composition, which in turn can indicate changes in nitrogen sources and transformations. These changes can be used to improve input sources for mixture models and aid in microbial remediation of nitrate.
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Affiliation(s)
- Yajun Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, and State Environmental Protection Key Laboratory of Simulation and Control of Groundwater Pollution, Chinese Research Academy of Environmental Sciences, Beijing 100012, China; Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Xiaofeng Cao
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Hongwei Yu
- State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yan Xu
- College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China
| | - Jianfeng Peng
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Jiuhui Qu
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
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23
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Chen R, Hu Q, Shen W, Guo J, Yang L, Yuan Q, Lu X, Wang L. Identification of nitrate sources of groundwater and rivers in complex urban environments based on isotopic and hydro-chemical evidence. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 871:162026. [PMID: 36754334 DOI: 10.1016/j.scitotenv.2023.162026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 01/18/2023] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
Groundwater and rivers in Chinese cities suffer from severe nitrate pollution. The accurate identification of nitrate sources throughout aquatic systems is key to the water nitrate pollution management. This study investigated nitrogen components of groundwater for twelve years and analyzed the sources of nitrate in the aquatic system based on dual isotopes (δ15N-NO3- and δ18O-NO3-) in the city of Nanjing, a core city of the Yangtze River Delta region, China. Our results showed that the ratio of nitrate to the sum of ammonia and nitrate in groundwater show an increasing trend during 2010-2021. The nitrate concentration was positively correlated with the proportion of cultivated land and negatively correlated with the proportion of forest land in the buffer zone. The relationship between Cl- and NO3-/ Cl- showed that agriculture and sewage sources increased during 2010-2015, sewage sources increased during 2016-2018, agriculture sources increased during 2019-2021. Manure and sewage were the primary sources of groundwater nitrate (72 %). There was no significant difference between the developed land (78 %), cultivated land (69 %), and aquaculture area (72 %). This indicates that dense population and intensive aquaculture in the suburbs have a significant impact on nitrate pollution. The contributions of manure and sewage to the fluvial nitrate sources in the lower reaches of the Qinhuai River Basin were 61 %. The non-point sources, including groundwater N (39 %) and soil N (35 %), were 74 % over the upper reaches. This study highlights the necessity of developing different N pollution management strategies for different parts of highly urbanized watersheds and considers groundwater restoration and soil nitrogen management as momentous, long-term tasks.
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Affiliation(s)
- Ruidong Chen
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province 210023, China
| | - Qihang Hu
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province 210023, China
| | - Wanqi Shen
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province 210023, China
| | - Jiaxun Guo
- Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Long Yang
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province 210023, China
| | - Qiqi Yuan
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province 210023, China
| | - Xiaoming Lu
- Jiangsu Province Hydrology and Water Resources Investigation Bureau, Nanjing, Jiangsu province 210029, China
| | - Lachun Wang
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province 210023, China.
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Guo W, Zhang D, Zhang W, Li S, Pan K, Jiang H, Zhang Q. Anthropogenic impacts on the nitrate pollution in an urban river: Insights from a combination of natural-abundance and paired isotopes. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 333:117458. [PMID: 36758410 DOI: 10.1016/j.jenvman.2023.117458] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 01/31/2023] [Accepted: 02/02/2023] [Indexed: 06/18/2023]
Abstract
Urban rivers are often characterized by high nitrate (NO3-) loadings. High NO3- loadings cause water quality and ecological damages, which undermines the sustainable development of cities. To date, the drivers of these high NO3- loadings remain unclear. This study, for the first time, integrated natural-abundance isotopes (δ15 N/δ18O-NO3- and δD/δ18O-H2O) and 15N-pairing techniques to comprehensively reveal the anthropogenic impacts on the NO3- pollution in an urban river. Natural-abundance isotopes suggested that in both the wet and dry seasons, the NO3- was predominantly from the conservative mixing of different sources, and biological NO3- removal was minor. The 15N-pairing experiments supported the natural-abundance isotope data, quantitatively showing that in-soil nitrification was prevailing, while NO3- removal processes (denitrification, anammox, and dissimilatory NO3- reduction to ammonium) were weak. A Bayesian isotope-mixing model showed that soil sources (soil organic nitrogen and chemical fertilizer) dominated the NO3- in the upper reaches, while in the lower reaches, the impermeable riparian zone short-circuited the access of soils to the river. Here, the wastewater treatment plants became a significant source of NO3-. This study quantitatively revealed the drivers of high NO3- loadings in an urban river, and generated important clues for effective NO3- pollution control and remediation in urban rivers.
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Affiliation(s)
- Wenjing Guo
- School of Resource and Environment, Henan Polytechnic University, Jiaozuo, 454000, China; Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China
| | - Dong Zhang
- School of Resource and Environment, Henan Polytechnic University, Jiaozuo, 454000, China
| | - Wenshi Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shen Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ke Pan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan, 430074, China.
| | - Quanfa Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan, 430074, China
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25
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Li X, Xu YJ, Ni M, Wang C, Li S. Riverine nitrate source and transformation as affected by land use and land cover. ENVIRONMENTAL RESEARCH 2023; 222:115380. [PMID: 36716803 DOI: 10.1016/j.envres.2023.115380] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
A mixed land use/land cover (LULC) catchment increases the complexity of sources and transformations of nitrate in rivers. Spatial paucity of sampling particularly low-resolution sampling in tributaries can result in a bias for identifying nitrate sources and transformations. In this study, high spatial resolution sampling campaigns covering mainstream and tributaries in combination with hydro-chemical parameters and dual isotopes of nitrate were performed to reveal spatio-temporal variations of nitrate sources and transformations in a river draining a mixed LULC catchment. This study suggested that point sources dominated the nitrate in the summer and winter, while non-point sources dominated the nitrate in the spring and autumn. A positive correlation was observed between proportions from sewage and land use index (LUI). However, negative correlations between soil nitrogen/nitrogen fertilizer and LUI were observed. With an increase of urban areas, the increased contribution from domestic sewage resulted in an increase of NO3- concentrations in rivers. Both urban and agricultural inputs should be considered in nitrate pollution management in a mixed LULC catchment. We concluded that the seasonal variations of nitrate sources were mainly affected by flow velocity conditions and agricultural activities, while spatial variations were mainly affected by LULC. In addition, we found a novel underestimation of dominated sources from Bayesian model because of mixing effect of isotope values from the tributaries to mainstream, however, high spatial resolution sampling can make up for this shortcoming. δ15N and δ18O values of nitrate indicated that nitrate originated from nitrification in soils. The nitrate concentrations and correlation between δ15N and 1/[NO3-] suggested little contribution of nitrate removal by denitrification. Thus, the nitrate reduction in the Yuehe River basin needs to be strengthened. The study provides new implications for estimation of nitrate sources and transformations and basis for nitrate reduction in the river with mixed LULC catchment.
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Affiliation(s)
- Xing Li
- Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Y Jun Xu
- School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA; Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Maofei Ni
- College of Eco-environmental Engineering, Guizhou Minzu University, Guiyang, China
| | - Chunlin Wang
- Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Siyue Li
- Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, 430205, China.
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Kaown D, Koh DC, Mayer B, Mahlknecht J, Ju Y, Rhee SK, Kim JH, Park DK, Park I, Lee HL, Yoon YY, Lee KK. Estimation of nutrient sources and fate in groundwater near a large weir-regulated river using multiple isotopes and microbial signatures. JOURNAL OF HAZARDOUS MATERIALS 2023; 446:130703. [PMID: 36587594 DOI: 10.1016/j.jhazmat.2022.130703] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
The excessive input of nutrients into groundwater can accelerate eutrophication in associated surface water systems. This study combined hydrogeochemistry, multi isotope tracers, and microbiological data to estimate nutrient sources and the effects of groundwater-surface water interactions on the spatiotemporal variation of nutrients in groundwater connected to a large weir-regulated river in South Korea. δ11B and δ15N-NO3- values, in combination with a Bayesian mixing model, revealed that manure and sewage contributed 40 % and 25 % respectively to groundwater nitrate, and 42 % and 27 % to nitrate in surface water during the wet season. In the dry season, the source apportionment was similar for groundwater while the sewage contribution increased to 52 % of nitrate in river water. River water displayed a high correlation between NO3- concentration and cyanobacteria (Microcystis and Prochlorococcus) in the wet season. The mixing model using multiple isotopes indicated that manure-derived nutrients delivered with increased contributions of groundwater to the river during the wet season governed the occurrence of cyanobacterial blooms in the river. We postulate that the integrated approach using multi-isotopic and microbiological data is highly effective for evaluating nutrient sources and for delineating hydrological interactions between groundwater and surface water, as well as for investigating surface water quality including eutrophication in riverine and other surface water systems.
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Affiliation(s)
- Dugin Kaown
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, the Republic of Korea.
| | - Dong-Chan Koh
- Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, the Republic of Korea; University of Science and Technology, Daejeon 34113, the Republic of Korea.
| | - Bernhard Mayer
- Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
| | - Jürgen Mahlknecht
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterey, Eugenio Garza Sada 2501, Monterrey 64149, Nuevo León, Mexico.
| | - YeoJin Ju
- Radioactive Waste Disposal Research Division, Korea Atomic Energy Research Institute, Daejeon 34057, the Republic of Korea.
| | - Sung-Keun Rhee
- Department of Biological Sciences and Biotechnology, Chungbuk National University, Cheongju 28644, the Republic of Korea.
| | - Ji-Hoon Kim
- Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, the Republic of Korea.
| | - Dong Kyu Park
- Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, the Republic of Korea.
| | - Inwoo Park
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, the Republic of Korea.
| | - Hye-Lim Lee
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, the Republic of Korea.
| | - Yoon-Yeol Yoon
- Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, the Republic of Korea.
| | - Kang-Kun Lee
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, the Republic of Korea.
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Mao H, Wang G, Liao F, Shi Z, Zhang H, Chen X, Qiao Z, Li B, Bai Y. Spatial variability of source contributions to nitrate in regional groundwater based on the positive matrix factorization and Bayesian model. JOURNAL OF HAZARDOUS MATERIALS 2023; 445:130569. [PMID: 37055948 DOI: 10.1016/j.jhazmat.2022.130569] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 06/19/2023]
Abstract
Groundwater nitrate (NO3-) pollution has attracted widespread attention; however, accurately evaluating the sources of NO3- and their contribution patterns in regional groundwater is difficult in areas with multiple sources and complex hydrogeological conditions. In this study, 161 groundwater samples were collected from the Poyang Lake Basin for hydrochemical and dual NO3- isotope analyses to explore the sources of NO3- and their spatial contribution using the Positive Matrix Factorization (PMF) and Bayesian stable isotope mixing (MixSIAR) models. The results revealed that the enrichment of NO3- in groundwater was primarily attributed to sewage/manure (SM), which accounted for more than 50 %. The contributions of nitrogen fertilizer and soil organic nitrogen should also be considered. Groundwater NO3- sources showed obvious spatial differences in contributions. Regions with large contributions of SM (>90 %) were located in the southeastern part of the study area and downstream of Nanchang, which are areas with relatively high population density. Nitrogen fertilizer and soil organic nitrogen showed concentrated contributions in paddy soil in the lower reaches of the Gan and Rao Rivers, and these accumulations were mainly driven by the soil type, land use type, and topography. This study provides insight into groundwater NO3- contamination on a regional scale.
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Affiliation(s)
- Hairu Mao
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Guangcai Wang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China.
| | - Fu Liao
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Zheming Shi
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Hongyu Zhang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Xianglong Chen
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Zhiyuan Qiao
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Bo Li
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
| | - Yunfei Bai
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing 100083, China; School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
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28
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Yang F, Guo J, Qi R, Yan C. Isotopic and hydrochemical analyses reveal nitrogen source variation and enhanced nitrification in a managed peri-urban watershed. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 316:120534. [PMID: 36341828 DOI: 10.1016/j.envpol.2022.120534] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 10/15/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Watershed management practices (WMPs) alter the sources and transformation of reactive nitrogen (N) in peri-urban watersheds, but a precise description of how WMPs impact N cycling is still lacking. In this study, four sampling campaigns were conducted in the wet and dry seasons of 2019 (before WMPs) and 2020 (after WMPs) to determine the spatiotemporal variations in nitrate isotopes (15N-NO3- and 18O-NO3-) and hydrochemical compositions in the Muli River watershed. The results showed that the WMPs could significantly reduce the N load in the middle and lower reaches, but substantial improvements were not observed in 2020. Manure and sewage (M&S, 36.2 ± 15.8-55.0 ± 19.4%) was the major source of nitrate (NO3-) in the stream water, followed by smaller-scale wastewater treatment plants (WWTPs, 14.0 ± 10.9-25.6 ± 11.5%). The WMPs were effective in controlling M&S, resulting in an approximately 16.7% (p < 0.01) lower M&S contribution during the dry season in 2020 compared to that in 2019. However, the smaller-scale WWTP input increased by approximately 5.4% (p < 0.01) after the WMPs. During the study period, the assimilation of NO3- by phytoplankton was important for NO3- loss, but the WMPs promoted nitrification in the watershed because of the elevated redox potential (Eh). Overall, the present study provides a better estimate of the variations in nitrogen sources and transformation in a peri-urban watershed after WMPs and provides an approach for developing timely nitrogen management solutions.
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Affiliation(s)
- Fan Yang
- Key Laboratory of Urban Environment and Health, Fujian Key Laboratory of Watershed Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Jianhua Guo
- Yellow River Institute of Hydraulic Research, Zhengzhou, 450003, China
| | - Ran Qi
- Key Laboratory of Urban Environment and Health, Fujian Key Laboratory of Watershed Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Changzhou Yan
- Key Laboratory of Urban Environment and Health, Fujian Key Laboratory of Watershed Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
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