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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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Liu H, Zeng W, Zhan M, Li J. Revealing the ammonia oxidation process and shortcut nitrification performance using nitrogen and oxygen isotope fractionation effect. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169322. [PMID: 38103601 DOI: 10.1016/j.scitotenv.2023.169322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 11/21/2023] [Accepted: 12/10/2023] [Indexed: 12/19/2023]
Abstract
Natural abundance isotope fractionation properties have become the most effective way to explore nitrogen transformations of biological nitrogen removal from wastewater. The migration and transformation characteristics of N and O elements in the shortcut nitrification were analyzed using the N and O dual isotopic fractionation technique. The effects of dissolved oxygen (DO) and temperature changes on the performance of shortcut nitrification and isotopic fractionation were investigated. The fractionation characteristics of N and O elements during shortcut nitrification were explored by adjusting DO concentration (0.2-0.4, 1-1.2 and 3-4 mg/L) and temperature (33 ± 1 °C, 25 ± 1 °C and 18 ± 1 °C). Both δ15NNO2 and δ18ONO2 showed a gradually increasing trend with the accumulation of NO2--N, and the fractionation effects induced by temperature were significantly higher than those by DO. The higher the temperature, the more significant the increase in δ15NNO2; the higher the DO, the more remarkable the increase in δ18ONO2, while δ15NNO2: δ18ONO2 was maintained at 0.77-6.45. The 18O-labeled H2O was successfully transferred to NO2--N, and the replacement of O element was as high as 100 %, indicating that DO and H2O simultaneously participated in the shortcut nitrification process. The dynamic changes in isotope fractionation effects can be successfully applied to reveal the performance and mechanism of shortcut nitrification.
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Affiliation(s)
- Hong Liu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Wei Zeng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China.
| | - Mengjia Zhan
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Jianmin Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
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Liu H, Chen Y, Li W, Zhang Y. Analysis of full nitrification performance and optimization of reaction properties using N and O isotope fractionation. CHEMOSPHERE 2024; 349:140808. [PMID: 38042418 DOI: 10.1016/j.chemosphere.2023.140808] [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: 10/07/2023] [Revised: 11/09/2023] [Accepted: 11/23/2023] [Indexed: 12/04/2023]
Abstract
Isotopic fractionation properties have been successfully applied to identify the distribution and fate of nitrogen in ecosystems, revealing the dynamic response of N and O elements during nitrogen transport and transformation. However, only a few studies used the dual isotope technology in activated sludge treatment of domestic wastewater and many aspects of the process are unclear. Here, we use the dual isotope techniques to increase the understanding of the substrates required for nitrification reactions, nitrification performance, and process operation. Mixed sludge was successfully enriched with nitrifying bacteria in a continuous culture, and three dissolved oxygen (DO; 0.2-0.4, 3-4, and 7-8 mg/L) and three temperature levels (18 ± 1, 25 ± 1, and 33±1 °C) were tested for efficiency of nitrate nitrogen accumulation. Both δ15NNO3 and δ18ONO3 showed a gradual increase with an increase in DO or temperature, the increase in DO slowed down the fractionation effect of isotopes, and the increase in temperature reduced the variability in N and O utilization. The slope of δ15NNO3:δ18ONO3 gradually approached 1 with the increase in DO (<7 mg/L) or in temperature, and the optimal range of DO and temperature were accurately judged to strengthen the denitrification performance of nitrifying bacteria. δ18OH2O was successfully taken up to form NO2--N and NO3--N with 74 and 91% replacement rates, respectively, indicating that DO and H2O jointly completed the formation of nitrate nitrogen during the long nitrification process. In summary, the in situ dual isotope technology can help optimize the influence of environmental factors on nitrification performance to guide the long-term stable operation of nitrification reactions in sludge treatment and provide a reliable basis for complex activated sludge nitrification systems.
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Affiliation(s)
- Hong Liu
- Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; Technical Center of Sewage Treatment Industry in Gansu Province, Lanzhou, 730070, Gansu, China
| | - Yongzhi Chen
- Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; Technical Center of Sewage Treatment Industry in Gansu Province, Lanzhou, 730070, Gansu, China.
| | - Weiwei Li
- Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; Technical Center of Sewage Treatment Industry in Gansu Province, Lanzhou, 730070, Gansu, China
| | - Yonghui Zhang
- Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; School of Environmental and Municipal Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, Gansu, China; Technical Center of Sewage Treatment Industry in Gansu Province, Lanzhou, 730070, Gansu, China
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Wang S, Lyu T, Li S, Jiang Z, Dang Z, Zhu X, Hu W, Yue FJ, Ji G. Unignorable enzyme-specific isotope fractionation for nitrate source identification in aquatic ecosystem. CHEMOSPHERE 2024; 348:140771. [PMID: 38000558 DOI: 10.1016/j.chemosphere.2023.140771] [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: 10/07/2023] [Revised: 11/14/2023] [Accepted: 11/18/2023] [Indexed: 11/26/2023]
Abstract
Nitrate contamination in aquatic systems is a widespread problem across the world. The isotopic composition (δ15N, δ18O) of nitrate and their isotope effect (15ε, 18ε) can facilitate the identification of the source and transformation of nitrate. Although previous researches claimed the isotope fractionations may change the original δ15N/δ18O values and further bias identification of nitrate sources, isotope effect was often ignored due to its complexity. To fill the gap between the understanding and application, it is crucial to develop a deep understanding of isotopic fractionation based on available evidence. In this regard, this study summarized the available methods to determine isotope effects, thereby systematically comparing the magnitude of isotope effects (15ε and 18ε) in nitrification, denitrification and anammox. We found that the enzymatic reaction plays the key role in isotope fractionations, which is significantly affected by the difference in the affinity, substrate channel properties and redox potential of active site. Due to the overlapping of microbial processes and accumulation of uncertainties, the significant isotope effects at small scales inevitably decrease in large-scale ecosystems. However, the proportionality of N and O isotope fractionation (δ18O/δ15N; 18ε/15ε) associated with nitrate reduction generally follows enzyme-specific proportionalities (i.e., Nar, 0.95; Nap, 0.57; eukNR, 0.98) in aquatic ecosystems, providing enzyme-specific constant factors for the identification of nitrate transformation. With these results, this study finally discussed feasible source portioning methods when considering the isotope effect and aimed to improve the accuracy in nitrate source identification.
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Affiliation(s)
- Shuo Wang
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China
| | - Tao Lyu
- School of Water, Energy and Environment, Cranfield University, College Road, Cranfield, Bedfordshire, MK43 0AL, UK
| | - Shengjie Li
- Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, 28359, Bremen, Germany
| | - Zhuo Jiang
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China
| | - Zhengzhu Dang
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China
| | - Xianfang Zhu
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China
| | - Wei Hu
- 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
| | - Guodong Ji
- Key Laboratory of Water and Sediment Sciences, Ministry of Education, Department of Environmental Engineering, Peking University, Beijing, 100871, China.
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Wang F, Liu L, Xu W, Li Y, Ruan Q, Cao W. Multiple stable isotopic approaches for tracing nitrate contamination sources: Implications for nitrogen management in complex watersheds. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 269:115822. [PMID: 38091679 DOI: 10.1016/j.ecoenv.2023.115822] [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: 09/09/2023] [Revised: 12/07/2023] [Accepted: 12/10/2023] [Indexed: 01/12/2024]
Abstract
Nitrate (NO3-) contamination of surface water is a global environmental problem that has serious consequences for watershed ecosystems and endangers human health. It is crucial to identify influences of different sources of NO3-, especially the incoming water from upper reaches. A combination of hydrochemistry and multi-isotope tracers (δ11B, δ15N-NO3-, and δ18O-NO3-) were used to determine NO3- sources and their transformation the North Jiulong River (NJLR), Southeast China. The findings revealed that NO3-, which accounted for an average of 87.1% of dissolved inorganic nitrogen (DIN), was the main chemical form of nitrogen species. The integration of dual stable isotopes of NO3-, δ11B, and hydrochemistry showed that NO3- was primarily contributed by sewage, soil nitrogen (SN), and ammonium (NH4+) via precipitation or fertilizers. The contributions from the sewage and soil nitrate source were almost equivalent and much higher than those from other sources in the NJLR watershed. The contributions from diverse sources varied seasonally and spatially. Manure and sewage (M&S) were the leading sources in the summer and autumn, accounting for 60.9 ± 8.5% and 47.3 ± 7.9%, respectively. However, NO3- fertilizers were the predominant source in the spring and winter. The NO3- inflow from upper reaches was proposed as an additional end-member to identify its contribution in the midstream and downstream in this study. The contributions of NO3- from the upper reaches were significant sources in the midstream and downstream, accounting for 27.2 ± 17.8% and 42.9 ± 21.9%, respectively. The obvious decline in local NO3-contribution shares from midstream to downstream implied structural changes in pollutant sources and regional environmental responsibility. Therefore, tracing nitrate sources and quantifying their contributions is critical for clarifying environmental responsibilities for precise local nitrogen management in watersheds.
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Affiliation(s)
- Feifei Wang
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
| | - Lihua Liu
- Fujian Xiamen Environmental Monitoring Central Station, Xiamen, Fujian 361022, China
| | - Wenfeng Xu
- Fujian Xiamen Environmental Monitoring Central Station, Xiamen, Fujian 361022, China
| | - Yasong Li
- Fujian Provincial Key Laboratory of Water Cycling and EcoGeological Processes, Xiamen 361021, China; Key Laboratory of Groundwater Contamination and Remediation of Hebei Province and China Geological Survey, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China
| | - Qizhen Ruan
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
| | - Wenzhi Cao
- Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China.
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6
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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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Roberts K, Grace M, Cook P, Erler D, Wong WW. Stable isotopes of nitrate (δ 15N and δ 18O) as functional indicators of nitrogen processing in constructed wetlands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 899:165246. [PMID: 37419364 DOI: 10.1016/j.scitotenv.2023.165246] [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: 07/28/2022] [Revised: 06/26/2023] [Accepted: 06/29/2023] [Indexed: 07/09/2023]
Abstract
The effectiveness of nitrogen removal in wetlands relies heavily on the biological processes that control its removal. Here, we used δ15N and δ18O of nitrate (NO3-) to assess the presence and the dominance of transformation processes of nitrogen in two urban water treatment wetlands in Victoria, Australia over two rainfall events. Laboratory incubation experiments were undertaken in both light and dark to measure the isotopic fractionation factor of nitrogen assimilation (by periphyton and algae) and benthic denitrification (using bare sediment). Highest isotopic fractionations were observed for nitrogen assimilation by algae and periphyton in the light, 15ε = -14.6 to -25 ‰ while the 15ε = -1.5 ‰ in bare sediment, consistent with that of benthic denitrification. Transect water samplings of the wetlands showed different rainfall patterns (discrete versus continuous) affect the removal capability of the wetlands. During the discrete event sampling, the observed 15ε of NO3- (an average of 3.0 to 4.3 ‰) within the wetland falls between the experimental 15ε of benthic denitrification and assimilation; coinciding with the decrease in NO3- concentrations, suggesting that both denitrification and assimilation were important removal pathways. Depletion of δ15N-NO3- throughout the whole wetland system also suggested the influence of water column nitrification during this time. In contrast, during continuous rain events, no fractionation effect was observed within the wetland and was consistent with limited NO3- removal. The difference in fractionation factors within the wetland during different sampling conditions suggested that nitrate removal was highly likely limited by changes in overall nutrient inputs, residence time and water temperature which impeded biological uptake or removal. These highlight that consideration of sampling condition is crucial when assessing the efficacy of a wetland in removing nitrogen.
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Affiliation(s)
- Keryn Roberts
- Water Studies, Monash University, Wellington, Clayton, Victoria 3800, Australia
| | - Michael Grace
- Water Studies, Monash University, Wellington, Clayton, Victoria 3800, Australia
| | - Perran Cook
- Water Studies, Monash University, Wellington, Clayton, Victoria 3800, Australia
| | - Dirk Erler
- Faculty of Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia
| | - Wei Wen Wong
- Water Studies, Monash University, Wellington, Clayton, Victoria 3800, Australia.
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Jung H, Kim YS, Yoo J, Han SJ, Lee J. Identification of nitrate sources in tap water sources across South Korea using multiple stable isotopes: Implications for land use and water management. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 864:161026. [PMID: 36549543 DOI: 10.1016/j.scitotenv.2022.161026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/26/2022] [Accepted: 12/14/2022] [Indexed: 06/17/2023]
Abstract
Stable nitrate isotopes (δ15N-NO3 and δ18O-NO3) in conjunction with stable water isotopes (δ18O-H2O and δD-H2O) were used to identify nitrogen (N) sources and N-biogeochemical transformation in tap water sources sampled from 11 water purification plants across South Korea. The raw water sources are taken from rivers within the water supply basins, which indicates the quality of tap water is highly dependent on surrounding the land use type. We estimated the proportional contribution of the various N sources (AD: atmospheric deposition; SN: soil nitrogen; CF: chemical fertilizer; M&S: manure/sewage) using Bayesian Mixing Model. As a result, the contribution of N sources exhibited large seasonal and spatial differences, which were related to the type of land use in the water supply basins. Commonly, the M&S and SN were the dominant N source during the dry and wet seasons in almost regions, respectively. However, in the regions with high N loading ratios from urban and industrial sources, the M&S was the dominant N source during both the wet and dry seasons. In addition, the regions were characterized by high NO3- concentrations due to the decreased dilution effect of precipitation during the dry seasons. In contrast, the SN was the dominant N source in the regions with high N loading ratios from agricultural areas during both the wet and dry seasons. The NO3--N concentration during the wet season was significantly higher than those during the dry season in these regions due to the input of non-point sources with high concentrations. Meanwhile, denitrification and nitrification were observed in the watersheds. It is important to understand the isotope fractionation due to N-biogeochemical transformation for considering the potential misinterpretations of the origin and fate NO3-. Collectively, our findings provide a basis on N source control strategies to ensure tap water quality in complex land use areas.
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Affiliation(s)
- Hyejung Jung
- Department of Science Education, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Yun S Kim
- Water Quality & Safety Management Center, K-water, Daejeon 34350, Republic of Korea.
| | - Jisu Yoo
- Water Quality & Safety Management Center, K-water, Daejeon 34350, Republic of Korea; Environmental Measurement & Analysis Center, Fundamental Environmental Research Department, National Institute of Environmental Research (NIER), Incheon 22689, Republic of Korea
| | - So Jeong Han
- Water Quality & Safety Management Center, K-water, Daejeon 34350, Republic of Korea
| | - Jeonghoon Lee
- Department of Science Education, Ewha Womans University, Seoul 03760, Republic of Korea.
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9
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Matiatos I, Araguás-Araguás L, Wassenaar LI, Monteiro LR, Harjung A, Douence C, Kralik M. Nitrate isotopes reveal N-cycled waters in a spring-fed agricultural catchment. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2023; 59:27-47. [PMID: 36562699 DOI: 10.1080/10256016.2022.2157412] [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: 06/24/2022] [Accepted: 11/09/2022] [Indexed: 06/17/2023]
Abstract
Nitrate stable isotopes provide information about nitrate contamination and cycling by microbial processes. The Fischa-Dagnitz (Austria) spring and river system in the agricultural catchment of the Vienna basin shows minor annual variance in nitrate concentrations. We measured nitrate isotopes (δ15N, δ18O) in the source spring and river up to the confluence with the Danube River (2019-2020) with chemical and water isotopes to assess mixing and nitrate transformation processes. The Fischa-Dagnitz spring showed almost stable nitrate concentration (3.3 ± 1.0 mg/l as NO3--N) year-round but surprisingly variable δ15N, δ18O-NO3- values ranging from +5.5 to +11.1‰ and from +0.5 to +8.1‰, respectively. The higher nitrate isotope values in summer were attributed to release of older denitrified water from the spring whose isotope signal was dampened downstream by mixing. A mixing model suggested denitrified groundwater contributed > 50 % of spring discharge at baseflow conditions. The isotopic composition of NO3- in the gaining streams was partly controlled by nitrification during autumn and winter months and assimilation during the growing season resulting in low and high δ15N-NO3- values, respectively. NO3- isotope variation helped disentangle denitrified groundwater inputs and biochemical cycling processes despite minor variation of NO3- concentration.
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Affiliation(s)
- Ioannis Matiatos
- Hellenic Centre for Marine Research, Institute of Marine Biological Resources and Inland Waters, Anavissos Attikis, Greece
| | - Luis Araguás-Araguás
- International Atomic Energy Agency, Isotope Hydrology Section, Vienna International Centre, Vienna, Austria
| | | | - Lucilena Rebelo Monteiro
- Instituto de Pesquisas Energéticas e Nucleares, IPEN/CNEN - Cidade Universitária, São Paulo, Brazil
| | - Astrid Harjung
- International Atomic Energy Agency, Isotope Hydrology Section, Vienna International Centre, Vienna, Austria
| | - Cedric Douence
- International Atomic Energy Agency, Isotope Hydrology Section, Vienna International Centre, Vienna, Austria
| | - Martin Kralik
- Division of Environmental Geosciences (EDGE), Center for Microbiology and Environmental Systems Science (CMESS), University of Vienna, Vienna, Austria
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Rempfert KR, Nothaft DB, Kraus EA, Asamoto CK, Evans RD, Spear JR, Matter JM, Kopf SH, Templeton AS. Subsurface biogeochemical cycling of nitrogen in the actively serpentinizing Samail Ophiolite, Oman. Front Microbiol 2023; 14:1139633. [PMID: 37152731 PMCID: PMC10160414 DOI: 10.3389/fmicb.2023.1139633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Accepted: 03/15/2023] [Indexed: 05/09/2023] Open
Abstract
Nitrogen (N) is an essential element for life. N compounds such as ammonium ( NH 4 + ) may act as electron donors, while nitrate ( NO 3 - ) and nitrite ( NO 2 - ) may serve as electron acceptors to support energy metabolism. However, little is known regarding the availability and forms of N in subsurface ecosystems, particularly in serpentinite-hosted settings where hydrogen (H2) generated through water-rock reactions promotes habitable conditions for microbial life. Here, we analyzed N and oxygen (O) isotope composition to investigate the source, abundance, and cycling of N species within the Samail Ophiolite of Oman. The dominant dissolved N species was dependent on the fluid type, with Mg2+- HCO 3 - type fluids comprised mostly of NO 3 - , and Ca2+-OH- fluids comprised primarily of ammonia (NH3). We infer that fixed N is introduced to the serpentinite aquifer as NO 3 - . High concentrations of NO 3 - (>100 μM) with a relict meteoric oxygen isotopic composition (δ18O ~ 22‰, Δ17O ~ 6‰) were observed in shallow aquifer fluids, indicative of NO 3 - sourced from atmospheric deposition (rainwater NO 3 - : δ18O of 53.7‰, Δ17O of 16.8‰) mixed with NO 3 - produced in situ through nitrification (estimated endmember δ18O and Δ17O of ~0‰). Conversely, highly reacted hyperalkaline fluids had high concentrations of NH3 (>100 μM) with little NO 3 - detectable. We interpret that NH3 in hyperalkaline fluids is a product of NO 3 - reduction. The proportionality of the O and N isotope fractionation (18ε / 15ε) measured in Samail Ophiolite NO 3 - was close to unity (18ε / 15ε ~ 1), which is consistent with dissimilatory NO 3 - reduction with a membrane-bound reductase (NarG); however, abiotic reduction processes may also be occurring. The presence of genes commonly involved in N reduction processes (narG, napA, nrfA) in the metagenomes of biomass sourced from aquifer fluids supports potential biological involvement in the consumption of NO 3 - . Production of NH 4 + as the end-product of NO 3 - reduction via dissimilatory nitrate reduction to ammonium (DNRA) could retain N in the subsurface and fuel nitrification in the oxygenated near surface. Elevated bioavailable N in all sampled fluids indicates that N is not likely limiting as a nutrient in serpentinites of the Samail Ophiolite.
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Affiliation(s)
- Kaitlin R. Rempfert
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
- *Correspondence: Kaitlin R. Rempfert
| | - Daniel B. Nothaft
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - Emily A. Kraus
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
| | - Ciara K. Asamoto
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - R. Dave Evans
- School of Biological Sciences, Washington State University, Pullman, WA, United States
| | - John R. Spear
- Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, United States
- Quantitative Biosciences and Engineering, Colorado School of Mines, Golden, CO, United States
| | - Juerg M. Matter
- National Oceanography Centre, University of Southampton, Southampton, United Kingdom
| | - Sebastian H. Kopf
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
| | - Alexis S. Templeton
- Department of Geological Sciences, University of Colorado, Boulder, CO, United States
- Alexis S. Templeton
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11
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Feng Y, Han L, Sun H, Zhu D, Xue L, Jiang ZT, Poinern GEJ, Lu Q, Feng Y, Xing B. Every coin has two sides: Continuous and substantial reduction of ammonia volatilization under the coexistence of microplastics and biochar in an annual observation of rice-wheat rotation system. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 847:157635. [PMID: 35905962 DOI: 10.1016/j.scitotenv.2022.157635] [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: 04/10/2022] [Revised: 07/06/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
Microplastics (MPs) are verified to affect the fate of ammonia (NH3) in agricultural soils. However, the impacts and mechanisms of MPs coupled with biochar (BC), a widely used agricultural conditioner, on NH3 losses are mostly untapped. The aim of this study was to investigate the mechanisms of common MPs (i.e., polyethylene, polyester, and polyacrylonitrile) and straw-derived BC on NH3 volatilization in rice-wheat rotation soils. Results showed that BC alone and MPs with BC (MPs + BC) reduced 5.5 % and 11.2-26.6 % cumulative NH3 volatilization than the control (CK), respectively, in the rice season. The increased nitrate concentration and soil cation exchange capacity were dominant contributors to the reduced soil NH3 volatilization in the rice season. BC and MPs + BC persistently reduced 44.5 % and 60.0-62.6 % NH3 losses than CK in the wheat season as influenced by pH and nitrate concentration. Moreover, BC and MPs + BC increased humic acid-like substances in soil dissolved organic matter by an average of 159.1 % and 179.6 % than CK, respectively, in rice and wheat seasons. The increased adsorption of soil NH4+ and the promotion of crop root growth were the main mechanisms of NH3 reduction. Our findings partially revealed the mechanisms of the coexistence of MPs and BC on NH3 mitigation in rice-wheat rotational ecosystems.
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Affiliation(s)
- Yuanyuan Feng
- Key Laboratory of Agro-Environment in Downstream of Yangtze Plain, National Agricultural Experiment Station for Agricultural Environment (Liuhe), Key Laboratory for Combined Farming and Raising, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China; Murdoch Applied Innovation Nanotechnology Research Group/Surface Analysis and Materials Engineering Research Group, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA 5150, Australia
| | - Lanfang Han
- Guangdong Provincial Key Laboratory of Water Quality Improvement and Ecological Restoration for Watersheds, Institute of Environmental and Ecological Engineering, Guangdong University of Technology, Guangzhou 510006, China
| | - Haijun Sun
- Co-Innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
| | - Dong Zhu
- State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China
| | - Lihong Xue
- Key Laboratory of Agro-Environment in Downstream of Yangtze Plain, National Agricultural Experiment Station for Agricultural Environment (Liuhe), Key Laboratory for Combined Farming and Raising, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
| | - Zhong-Tao Jiang
- Murdoch Applied Innovation Nanotechnology Research Group/Surface Analysis and Materials Engineering Research Group, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA 5150, Australia
| | - Gerrard Eddy Jai Poinern
- Murdoch Applied Innovation Nanotechnology Research Group/Surface Analysis and Materials Engineering Research Group, College of Science, Health, Engineering and Education, Murdoch University, Perth, WA 5150, Australia
| | - Qianwen Lu
- University of Connecticut, Department of Plant Sciences and Landscape Architecture, Storrs, CT 06269, United States of America
| | - Yanfang Feng
- Key Laboratory of Agro-Environment in Downstream of Yangtze Plain, National Agricultural Experiment Station for Agricultural Environment (Liuhe), Key Laboratory for Combined Farming and Raising, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.
| | - Baoshan Xing
- Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States of America
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12
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Hong Y, Tu Q, Cheng H, Huangfu X, Chen Z, He Q. Chronic high-dose silver nanoparticle exposure stimulates N 2O emissions by constructing anaerobic micro-environment. WATER RESEARCH 2022; 225:119104. [PMID: 36155009 DOI: 10.1016/j.watres.2022.119104] [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: 05/20/2022] [Revised: 09/05/2022] [Accepted: 09/10/2022] [Indexed: 06/16/2023]
Abstract
Silver nanoparticles (Ag-NPs) were found to be responsible for nitrous oxide (N2O) generation; however, the mechanism of Ag-NP induced N2O production remains controversial and needs to be elucidated. In this study, chronic Ag-NP exposure experiments were conducted in five independent sequencing batch biofilm reactors to systematically assess the effects of Ag-NPs on N2O emission. The results indicated that a low dose of Ag-NPs (< 1 mg/L) slightly suppressed N2O generation by less than 22.99% compared with the no-Ag-NP control method. In contrast, a high dose (5 mg/L) of Ag-NPs stimulated N2O emission by 67.54%. ICP-MS and SEM-EDS together revealed that high Ag-NP content accumulated on the biofilm surface when exposed to 5 mg/L Ag-NPs. N2O and DO microelectrodes, as well as N2O isotopic composition analyses, further demonstrated that the accumulated Ag-NPs construct the anaerobic zone in the biofilm, which is the primary factor for the stimulation of the nitrite reduction pathway to release N2O. A metagenomic analysis further attributed the higher N2O emissions under exposure to a high dose of Ag-NPs to the higher relative abundance of narB and nirK genes (i.e. 1.52- and 1.29-fold higher, respectively). These findings collectively suggest that chronic exposure to high doses of Ag-NPs could enhance N2O emissions by forming anaerobic micro-environments in biofilms.
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Affiliation(s)
- Yiyihui Hong
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Qianqian Tu
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China; China TieGong Investment & Construction Group Co., Ltd, Beijing 101300, China
| | - Hong Cheng
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China.
| | - Xiaoliu Huangfu
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Ziwei Chen
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Qiang He
- Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, College of Environment and Ecology, Chongqing University, Chongqing 400044, China
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13
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Xuan Y, Mai Y, Xu Y, Zheng J, He Z, Shu L, Cao Y. Enhanced microbial nitrification-denitrification processes in a subtropical metropolitan river network. WATER RESEARCH 2022; 222:118857. [PMID: 35868099 DOI: 10.1016/j.watres.2022.118857] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 06/15/2023]
Abstract
Urban rivers are hotspots of regional nitrogen (N) pollution and N transformations. Previous studies have reported that the microbial community of urban rivers was different from that of natural rivers. However, how microbial community affects N transformations in the urban rivers is still unclear. In this study, we employed N nutrients-related isotope technology (includes natural-abundance isotopes survey and isotope-labeling method) and bioinformatics methods (includes 16S rRNA high-throughput sequencing and quantitative PCR analysis) to investigate the major N transformations, microbial communities as well as functional gene abundances in a metropolitan river network. Our results suggested that the bacterial community structure in the highly urbanized rivers was characterized by higher richness, less complexity and increased abundances of nitrification and denitrifying bacterium compared to those in the suburban rivers. These differences were mainly caused by high sewage discharge and N loadings. In addition, the abundances of nitrifier gene (amoA) and denitrifier genes (nirK and nirS) were significantly higher in the highly urbanized rivers (2.36 × 103, 7.43 × 107 and 2.28 × 107 copies·mL-1) than that in the suburban rivers (0.43 × 103, 2.18 × 107 and 0.99 × 107 copies·mL-1). These changes in microbes have accelerated nitrification-denitrification processes in the highly urbanized rivers as compared to those in the suburban rivers, which was evidenced by environmental isotopes and the rates of nitrification (10.52 vs. 0.03 nmol·L-1·h-1) and denitrification (83.31 vs. 22.49 nmol·g-1·h-1). Overall, this study concluded that the excess exogenous N has significantly shaped the specific aquatic bacterial communities, which had a potential for enhancing nitrification-denitrification processes in the highly urbanized river network. This study provides a further understanding of microbial N cycling in urban river ecosystems and expands the combined application of isotopic technology and bioinformatics methods in studying biogeochemical cycling.
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Affiliation(s)
- Yingxue Xuan
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China
| | - Yingwen Mai
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China
| | - Yunqiu Xu
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China
| | - Jianyi Zheng
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China
| | - Zhili He
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China
| | - Longfei Shu
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China.
| | - Yingjie Cao
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China.
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14
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Su F, Wu J, Wang D, Zhao H, Wang Y, He X. Moisture movement, soil salt migration, and nitrogen transformation under different irrigation conditions: Field experimental research. CHEMOSPHERE 2022; 300:134569. [PMID: 35421440 DOI: 10.1016/j.chemosphere.2022.134569] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/19/2022] [Accepted: 04/06/2022] [Indexed: 06/14/2023]
Abstract
Irrigation and fertilizer application can lead to significant changes in groundwater quality. In this study, a field irrigation experiment was carried out from April 9 to 23, 2021 under irrigation and fertigation conditions to understand the mechanisms of moisture movement, soil salt migration, and nitrogen transformation in the soil profile. Continuous in-situ monitoring and sampling of soil and irrigation water, as well as stable isotopes, chemical parameters, and soluble salt analyses, were performed in this research. The results showed that the time cost by the irrigation water in the vadose zone was about 5 h. The infiltrated irrigation water was accompanied by high concentrations of soluble salts, leached from the soil layers of 20-80 cm and 100-150 cm, which is associated with the leaching of Na+, Cl-, SO42-, and Ca2+ and the dissolution of minerals such as gypsum and halite. Furthermore, the variations in nitrogen concentrations (NH4+ and NO3-) in the soil profile suggested that fertilizer application was the main source of NO3- in the soil and groundwater, while irrigation was the biggest driving force for nitrogen transport and transformation in soil. The application of urea fertilizer can increase the content of ammonium nitrogen at the soil layer of 0-80 cm. This nitrogen form can be subsequently transformed to nitrate nitrogen during the water transport to the groundwater. The current study provides a strong scientific basis for the protection and management of groundwater and soil quality in agricultural areas.
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Affiliation(s)
- Fengmei Su
- School of Water and Environmental Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China
| | - Jianhua Wu
- School of Water and Environmental Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China.
| | - Dan Wang
- School of Water and Environmental Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China
| | - Hanghang Zhao
- School of Water and Environmental Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China
| | - Yuanhang Wang
- School of Water and Environmental Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China
| | - Xiaodong He
- School of Water and Environmental Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China
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15
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Aharoni I, Dahan O, Siebner H. Continuous monitoring of dissolved inorganic nitrogen (DIN) transformations along the waste-vadose zone - groundwater path of an uncontrolled landfill, using multiple N-species isotopic analysis. WATER RESEARCH 2022; 219:118508. [PMID: 35533620 DOI: 10.1016/j.watres.2022.118508] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 03/22/2022] [Accepted: 04/21/2022] [Indexed: 06/14/2023]
Abstract
Landfill leachates contain a heavy load of dissolved inorganic nitrogen (DIN), posing a threat to water resources. Therefore, it is highly important to understand the processes that control its evolution (speciation, accumulation, or attenuation) during the percolation of leachates through the unsaturated zone, finally affecting the groundwater. However, tracking DIN transformations in this complex and inaccessible environment is challenging, and knowledge concerning this important topic under field conditions is scarce. The presented study used a unique monitoring system that allows sampling of repetitive samples from within the waste and the unsaturated zone. An array of 8 wells penetrating the underlying aquifer completed the spatial observation. Multiple N-species isotopic approach was applied to discern the dominating N-involving processes over the continuum - from the waste mound through the unsaturated zone and the underlying aquifer. Despite the considerable heterogeneity observed throughout the profile, the results provided a cohesive and valuable reflection of the evolution of the inorganic nitrogen pool in this highly contaminated environment. Leachates inside the waste had reducing characteristics with high accumulation of ammonium (up to 360 mg/l NH4+-N), and a distinct δ15N-NH4+ range (-3‰ to +10‰). The upper layers of the unsaturated zone underneath the landfill margins found to be aerated, promoting N oxidation which resulted in the accumulation of nitrate in the leachates (up to 490 mg/l NO3-N). Exceptionally high concentrations of nitrite (up to 126 mg/l NO2-N) were found as oxygen levels decreased in deeper sections of the vadose zone. Enrichment of δ15N-NO2- compared to δ15N-NO3- indicated the significance of autotropic nitrite reduction, controlling the DIN composition, correlated with NO2- accumulation and net DIN attenuation. The δ15N: δ18O ratio implied co-occurrence of denitrification in the leachates, even in the more oxidized sections, further contributing to N-attenuation in the unsaturated zone. In the aquifer, δ15N-NH4+ values and δ15N: δ18O ratio linked N contamination to the leachates source. The encounter with the oxidized groundwater promoted intensive nitrification. δ15N-NO2- values in the groundwater were lighter than both δ15N-NH4+ and δ15N-NO3- by 22‰ to 62‰, implying the co-occurrence of nitrification-denitrification processes. The effect of denitrification grew with decreasing dissolved oxygen (DO) levels below 0.5 mg/l towards the center of the plume, contributing to net DIN attenuation in the plume. The findings are significant for any consideration of the risk posed by DIN, as well as remediation measures, in a landfill environment and other sites with a heavy load of degrading organic matter.
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Affiliation(s)
- Imri Aharoni
- Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 8499000, Israel.
| | - Ofer Dahan
- Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 8499000, Israel
| | - Hagar Siebner
- Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion 8499000, Israel.
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16
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Kaushal R, Hsueh YH, Chen CL, Lan YP, Wu PY, Chen YC, Liang MC. Isotopic assessment of soil N 2O emission from a sub-tropical agricultural soil under varying N-inputs. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 827:154311. [PMID: 35257756 DOI: 10.1016/j.scitotenv.2022.154311] [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: 10/02/2021] [Revised: 02/12/2022] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Nitrogen fertilizers result in high crop productivity but also enhance the emission of N2O, an environmentally harmful greenhouse gas. Only approximately a half of the applied nitrogen is utilized by crops and the rest is either vaporized, leached, or lost as NO, N2O and N2 via soil microbial activity. Thus, improving the nitrogen use efficiency of cropping systems has become a global concern. Factors such as types and rates of fertilizer application, soil texture, moisture level, pH, and microbial activity/diversity play important roles in N2O production. Here, we report the results of N2O production from a set of chamber experiments on an acidic sandy-loam agricultural soil under varying levels of an inorganic N-fertilizer, urea. Stable isotope technique was employed to determine the effect of increasing N-fertilizer levels on N2O emissions and identify the microbial processes involved in fertilizer N-transformation that give rise to N2O. We monitored the isotopic changes in both substrate (ammonium and nitrate) and the product N2O during the entire course of the incubation experiments. Peak N2O emissions of 122 ± 98 μg N2O-N m-2 h-1, 338 ± 49 μg N2O-N m-2 h-1 and 739 ± 296 μg N2O-N m-2 h-1 were observed for urea application rate of 40, 80, and 120 μg N g-1. The duration of emissions also increased with urea levels. The concentration and isotopic compositions of the substrates and product showed time-bound variation. Combining the observations of isotopic effects in δ15N, δ18O, and 15N site preference, we inferred co-occurrence of several microbial N2O production pathways with nitrification and/or fungal denitrification as the dominant processes responsible for N2O emissions. Besides this, dominant signatures of bacterial denitrification were observed in a second N2O emission pulse in intermediate urea-N levels. Signature of N2O consumption by reduction could be traced during declining emissions in treatment with high urea level.
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Affiliation(s)
- Ritika Kaushal
- Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
| | - Yu-Hsin Hsueh
- Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan; Taiwan International Graduate Program-Earth Systems Science, Academia Sinica, Taipei, Taiwan
| | - Chi-Ling Chen
- Agricultural Chemistry Division, Taiwan Agricultural Research Institute, Taichung, Taiwan
| | - Yi-Ping Lan
- Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
| | - Ping-Yu Wu
- Agricultural Chemistry Division, Taiwan Agricultural Research Institute, Taichung, Taiwan
| | - Yi-Chun Chen
- Agricultural Chemistry Division, Taiwan Agricultural Research Institute, Taichung, Taiwan
| | - Mao-Chang Liang
- Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan.
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17
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Liu H, Zeng W, Zhan M, Li J, Fan Z, Peng Y. Analysis of nitrite oxidation process and nitrification performance by nitrogen and oxygen isotope fractionation effect. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 814:152511. [PMID: 34990690 DOI: 10.1016/j.scitotenv.2021.152511] [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: 10/19/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
The N and O isotope fractionation effects in NO2--N oxidation and nitrification performance of an activated sludge system treating municipal wastewater are unknown. The nitrifying sludge was cultured under different temperature (33 ± 1 °C, 25 ± 1 °C,and 18 ± 1 °C) and dissolved oxygen (DO: 0.5-1 mg/L, 3-4 mg/L, and 7-8 mg/L). The inverse kinetic isotope effects of N and O (15εNO2 and 18εNO2) were -0.62‰ to -7.08‰ and -0.87‰ to -1.68‰ in the process of NO2--N oxidation, respectively. 15εNO3 gradually increased with increasing of temperature (15εNO3-33°C (14.49‰) > 15εNO3-25°C (10.43‰) > 15εNO3-18°C (7.3‰)), while the 15εNO3:18εNO3 was maintained at 1.02-5.32. The increase of temperature improved the nitrification activity, which promoted the fractionation effect, but the change of DO did not highlight this difference. The exchange of NO2--N and H2O (XNOB) was 32.5 ± 1.5%, and the kinetic isotope effect of H2O participating in the reaction (18εk, H2O, 2) was 22.57 ± 1.79‰, indicating that H2O was involved in the NO2--N oxidation rather than DO. In summary, the elevated temperature enhanced the fractionation effect of NO2--N oxidation. This study provides a new perspective to reveal the mechanism of NO2--N oxidation, optimize the process of nitrogen removal from wastewater and further control water eutrophication.
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Affiliation(s)
- Hong Liu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Wei Zeng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China.
| | - Mengjia Zhan
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Jianmin Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Zhiwei Fan
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Yongzhen Peng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
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18
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Zhou M, Granger J, Chang BX. Influence of sample volume on nitrate N and O isotope ratio analyses with the denitrifier method. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2022; 36:e9224. [PMID: 34787344 DOI: 10.1002/rcm.9224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 09/15/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE Analyses of the isotope ratios of nitrogen (15 N/14 N) and oxygen (18 O/16 O) in nitrate (NO3 - ) with the denitrifier method require relatively high sample volumes at low concentrations (≤1 μM) to afford sufficient analyte for mass spectrometry, resulting in isotopic offsets compared to more concentrated samples of the same isotopic composition. METHODS To uncover the origins of isotopic offsets, we analyzed the N and O isotope ratios of NO3 - reference materials spanning concentrations of 0.5-20 μM. We substantiated the incidence of volume-dependent isotopic offsets, then investigated whether they resulted from (a) incomplete sample recovery during N2 O sparging, (b) blanks - bacterial, atmospheric, or in reference material solutions - and (c) oxygen atom exchange with water during the bacterial conversion of NO3 - to N2 O. RESULTS Larger sample volumes resulted in modest offsets in δ15 N, but substantial offsets in δ18 O. N2 O recovery from sparging was less complete at higher volumes, resulting in decreases in δ15 N and δ18 O due to associated isotope fractionation. Blanks increased detectably with volume, whereas oxygen atom exchange with water remained constant within batch analyses, being sensitive to neither sample volume nor salinity. The sizeable offsets in δ18 O with volume are only partially explained by the factors considered in our analysis. CONCLUSIONS Our observations argue for bracketing of NO3 - samples with reference materials that emulate sample volumes (concentrations) to achieve improved measurement accuracy and foster inter-comparability.
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Affiliation(s)
- Mengyang Zhou
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - Julie Granger
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - Bonnie X Chang
- Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA, USA
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Liu H, Zeng W, Zhan M, Fan Z, Li J, Peng Y. Nitrogen removal performance of sulfur autotrophic denitrification under different S 2O 32- additions using isotopic fractionation of nitrogen and oxygen. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 794:148794. [PMID: 34323755 DOI: 10.1016/j.scitotenv.2021.148794] [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: 04/08/2021] [Revised: 06/15/2021] [Accepted: 06/28/2021] [Indexed: 06/13/2023]
Abstract
The dual isotope fractionation of nitrogen (N) and oxygen (O) is an effective way to track the transformation of NO3--N in biological denitrification process. The Sulfur autotrophic denitrification combined with the different concentrations of S2O32- was investigated using the dual isotope fractionation of nitrogen (N) and oxygen (O) to reveal the nitrogen removal mechanism of the activated sludge. Based on successful autotrophic denitrification incubation, the modified Logistic model responded to the short-term effects of S2O32- addition on NO3--N removal and SO42- generation. Under the S2O32- addition of 0.5, 1, 2 and 4 times of the incubation stage (49.29 mg/L-394.32 mg/L), the fractionation effect of N in NO3--N (15εNO3) decreased from 8.74 ± 1.81‰ to 2.08 ± 0.06‰, and the fractionation effect of O in NO3--N (18εNO3) declined from 11.34 ± 0.46‰ to 5.48 ± 0.46‰. The 15εNO3/18εNO3 was maintained at 0.46-0.94, indicating a negative correlation between addition amount and isotope effect, and the addition of high concentrations of S2O32- was not suitable for system stabilization. Moreover, the 18O-labeled H2O (δ18OH2O) tests significantly proved the presence of O exchange between NO2--N/NO3--N and H2O (67%/97%) during the nitrogen removal process, while the reoxidation of NO2--N was explored in the autotrophic denitrification. The kinetic models coupled with isotope fractionation effectively revealed the nitrogen removal characteristics in the autotrophic denitrification systems, and verified the difference between the activated sludge-based wastewater treatment process and the natural ecosystem.
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Affiliation(s)
- Hong Liu
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Wei Zeng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China.
| | - Mengjia Zhan
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Zhiwei Fan
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Jianmin Li
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
| | - Yongzhen Peng
- National Engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology, Department of Environmental Engineering, Beijing University of Technology, Beijing 100124, China
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20
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Webster AJ, Douglas TA, Regier P, Scheuerell MD, Harms TK. Multi-Scale Temporal Patterns in Stream Biogeochemistry Indicate Linked Permafrost and Ecological Dynamics of Boreal Catchments. Ecosystems 2021. [DOI: 10.1007/s10021-021-00709-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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21
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Torres-Martínez JA, Mora A, Mahlknecht J, Kaown D, Barceló D. Determining nitrate and sulfate pollution sources and transformations in a coastal aquifer impacted by seawater intrusion-A multi-isotopic approach combined with self-organizing maps and a Bayesian mixing model. JOURNAL OF HAZARDOUS MATERIALS 2021; 417:126103. [PMID: 34229392 DOI: 10.1016/j.jhazmat.2021.126103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/17/2021] [Accepted: 05/06/2021] [Indexed: 06/13/2023]
Abstract
Over the past few decades, the La Paz aquifer system in Baja California Sur, Mexico, has been under severe pressure due to overexploitation for urban water supply and agriculture; this has caused seawater intrusion and deterioration in groundwater quality. Previous studies on the La Paz aquifer have focused mainly on seawater intrusion, resulting in limited information on nitrate and sulfate pollution. Therefore, pollution sources have not yet been identified sufficiently. In this study, an approach combining hydrochemical tools, multi-isotopes (δ2HH2O, δ18OH2O, δ15NNO3, δ18ONO3, δ34SSO4, δ18OSO4), and a Bayesian isotope mixing model was used to estimate the contribution of different nitrate and sulfate sources to groundwater. Results from the MixSIAR model revealed that seawater intrusion and soil-derived sulfates were the predominant sources of groundwater sulfate, with contributions of ~43.0% (UI90 = 0.29) and ~42.0% (UI90 = 0.38), respectively. Similarly, soil organic nitrogen (~81.5%, UI90 = 0.41) and urban sewage (~12.1%, UI90 = 0.25) were the primary contributors of nitrate pollution in groundwater. The dominant biogeochemical transformation for NO3- was nitrification. Denitrification and sulfate reduction were discarded due to the aerobic conditions in the study area. These results indicate that dual-isotope sulfate analysis combined with MixSIAR models is a powerful tool for estimating the contributions of sulfate sources (including seawater-derived sulfate) in the groundwater of coastal aquifer systems affected by seawater intrusion.
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Affiliation(s)
- Juan Antonio Torres-Martínez
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterey, Eugenio Garza Sada 2501, Monterrey 64149, Nuevo León, México
| | - Abrahan Mora
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Puebla, Atlixcáyotl 5718, Puebla de Zaragoza 72453, Puebla, México
| | - Jürgen Mahlknecht
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Campus Monterey, Eugenio Garza Sada 2501, Monterrey 64149, Nuevo León, México.
| | - Dugin Kaown
- School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, South Korea
| | - Damia Barceló
- Department of Environmental Chemistry, IIQAB, 08034 Barcelona, Spain
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22
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Yu J, Zhang W, Tan Y, Zong Z, Hao Q, Tian C, Zhang H, Li J, Fang Y, Zhang G. Dual-isotope-based source apportionment of nitrate in 30 rivers draining into the Bohai Sea, north China. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 283:117112. [PMID: 33862341 DOI: 10.1016/j.envpol.2021.117112] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 04/02/2021] [Accepted: 04/05/2021] [Indexed: 06/12/2023]
Abstract
Excessive nitrate (NO3-) in rivers can lead to water quality deterioration, and can also be directly input into estuaries and oceans, thus posing a serious threat to the stability of their ecosystems. In this study, the concentration, isotopes and sources of NO3- in 30 rivers discharging into the Bohai Sea were comprehensively investigated. The mean concentration of NO3--N was 2.24 ± 2.11 mg L-1, with obvious seasonal and spatial variations. In total, 104.24 kt of NO3--N was discharged into the Bohai Sea annually, to which the Yellow River Basin and Liao River Basin made the largest contributions. The range of δ15N-NO3- was -1.1‰ to +33.2‰ (mean value, +11.4 ± 5.0‰), with no significant seasonal or spatial differences; the mean value of δ18O-NO3- was +9.4 ± 7.2‰, with much higher values seen in June. Based on the MixSIAR model, manure (24.3 ± 7.5%) and sewage (19.1 ± 14.5%) were the primary sources of NO3- in the 30 rivers, followed by NO3- fertilizers (16.3 ± 12.5%), soil N (15.5 ± 11.9%), atmospheric deposition of NO3- (13.5 ± 5.7%) and NH4+ fertilizers (11.4 ± 8.9%). This finding highlights the vital roles of sewage and manure management in riverine NO3-. Using a mathematical method, the contributions of various sources to each river were simulated. The results indicated that management of the Yellow River, Daliao River, Liao River, and Xiaoqing River is more urgently needed than that of other rivers to control Bohai NO3- pollution. We believe that this finding will provide guidance for scientific management of NO3- pollution in these 30 rivers and the Bohai Sea.
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Affiliation(s)
- Jing Yu
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong, 264003, PR China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, PR China
| | - Wei Zhang
- School of Environmental and Material Engineering, Yantai University, Yantai, Shandong, 264005, PR China
| | - Yang Tan
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong, 264003, PR China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, PR China
| | - Zheng Zong
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong, 264003, PR China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, PR China.
| | - Qinqin Hao
- National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou, 510650, PR China
| | - Chongguo Tian
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong, 264003, PR China; Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, PR China
| | - Hua Zhang
- CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai, Shandong, 264003, PR China
| | - Jun Li
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
| | - Yunting Fang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, Liaoning, 110164, PR China
| | - Gan Zhang
- State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, 510640, PR China
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23
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Guo J, Zuo P, Yang L, Pan Y, Wang L. Quantitative identification of non-point sources of nitrate in urban channels based on dense in-situ samplings and nitrate isotope composition. CHEMOSPHERE 2021; 263:128219. [PMID: 33297176 DOI: 10.1016/j.chemosphere.2020.128219] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/16/2020] [Accepted: 08/30/2020] [Indexed: 06/12/2023]
Abstract
Quantitative identification of non-point sources of nitrate in urban channels plays a critical role in effective nutrient management in urban regions. This is an emerging issue due to fast urbanization and the resultant complicated hydrological and hydraulic conditions in urban areas. In this study, we examine spatial-temporal characteristics of nitrogen concentration in urban channels based on dense in-situ samplings during a one-year period over a small urban catchment in China. We quantitatively identify nitrate sources into urban channels based on dual-isotope analyses and Bayesian isotope mixing model. Results show that nitrogen concentration peaks in winter as well as in urban channels and land surfaces in the urban core region. Sewage (47%) is the dominate contributor to NO3--N in urban channels, followed by NH4+ in fertilizer (30%) as the second contributor. Sewage (NH4+ in fertilizer) contributes more NO3--N to channels in winter (summer) with the proportion of 65% (44%), and more NO3--N to urban core (suburban) channels with the proportion of 59% (42%). The rainfall and distribution of rainwater drains explain the monthly and spatial variations of contribution of NO3--N sources well, respectively. In addition, less NO3--N in the urban channels derives from nitrification, which is consistent with the results of high properties of NH4+-N/TN in this region. Our results highlight the key roles of land use types and rainfall in NO3--N source apportionment, and provide support for the nitrogen management practices in urbanized regions.
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Affiliation(s)
- Jiaxun Guo
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province, 210023, China
| | - Ping Zuo
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province, 210023, China
| | - Long Yang
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province, 210023, China
| | - Ye Pan
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province, 210023, China
| | - Lachun Wang
- School of Geography and Ocean Science, Nanjing University, Nanjing, Jiangsu province, 210023, China.
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24
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Yue FJ, Li SL, Waldron S, Wang ZJ, Oliver DM, Chen X, Liu CQ. Rainfall and conduit drainage combine to accelerate nitrate loss from a karst agroecosystem: Insights from stable isotope tracing and high-frequency nitrate sensing. WATER RESEARCH 2020; 186:116388. [PMID: 32916623 DOI: 10.1016/j.watres.2020.116388] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/29/2020] [Accepted: 09/02/2020] [Indexed: 06/11/2023]
Abstract
Understanding where nitrate is mobilized from and under what conditions is required to reduce nitrate loss and protect water quality. Low frequency sampling may inadequately capture hydrological and biogeochemical processes that will influence nitrate behavior. We used high-frequency isotope sampling and in-situ nitrate sensing to explore nitrate export and transformation in a karst critical zone. Nitrate was mobilised during light rainfall, and transferred from soil layers to the karst matrix, where some nitrate was retained and denitrified. Nitrate isotopic composition changed rapidly during the rising limb of events and slowly during the falling limb. The main nitrate source was synthetic fertiliser (up to 80% during event flow), transported by conduit flow following high rainfall events, and this contribution increased significantly as discharge increased. Soil organic nitrogen contribution remained constant indicating at baseflow this is the primary source. Isotope source appointment of nitrate export revealed that synthetic fertilizer accounted for more than half of the total nitrate export, which is double that of the secondary source (soil organic nitrogen), providing valuable information to inform catchment management to reduce nitrate losses and fluvial loading. Careful land management and fertilizer use are necessary to avoid nitrate pollution in the karst agroecosystem, for example by timing fertilizer applications to allow for plant uptake of nitrate before rainfall can flush it from the soils into the karst and ultimately into catchment drainage.
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Affiliation(s)
- Fu-Jun Yue
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
| | - Si-Liang Li
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China.
| | - Susan Waldron
- School of Geographical and Earth Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Zhong-Jun Wang
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China
| | - David M Oliver
- Biological & Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, United Kingdom
| | - Xi Chen
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
| | - Cong-Qiang Liu
- Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China; Tianjin Key Laboratory of Earth Critical Zone Science and Sustainable Development in Bohai Rim, Tianjin University, Tianjin 300072, China
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25
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Zhao H, Xiao Q, Miao Y, Wang Z, Wang Q. Sources and transformations of nitrate constrained by nitrate isotopes and Bayesian model in karst surface water, Guilin, Southwest China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:21299-21310. [PMID: 32266624 DOI: 10.1007/s11356-020-08612-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 03/26/2020] [Indexed: 06/11/2023]
Abstract
Surface water suffering from nitrate (NO3-) contamination in karst area is not only harmful to human health as drinking water but can also affect the process of carbonate rock weathering, so it is crucial to trace the sources and transformations of NO3- in karst surface water. In this study, an investigation of water chemical data and NO3- isotopes (δ15N and δ18O) was used to elucidate the transformations of NO3- and quantify a proportional apportionment of NO3- sources of individual potential sources (incl. soil organic nitrogen (SON), atmospheric precipitation (AP), manure and sewage wastes (M&S), and chemical fertilizer (CF)) in the Lijiang River (typical karst surface water), Guilin, Southwest China. δ15N-NO3- and δ18O-NO3- values of water samples from the Lijiang River range from 2.14 to 13.50‰ (mean, 6.59‰) and from - 2.44 to 6.97‰ (mean, 3.76‰), respectively. A positive correlation between Cl- and NO3- but no correlations between NO3- and δ15N-NO3- or δ18O-NO3- are found and the δ18O-NO3- values fitted the theoretical δ18O-NO3- values produced from nitrification, suggesting that the genesis of NO3- in waters of the Lijiang River is affected by nitrification processes and the mixing process has a major effect on NO3- transportation. Results of the Bayesian stable isotope mixing model show that the M&S and SON are the main NO3- source through the whole year (accounting for ~ 61% and 65% of the total NO3- in the wet and dry season, respectively), followed by CF (~ 29%). Furthermore, we find that nitrification of nitrogen in fertilizers, soil, and manure and sewage can promote the carbonate rock weathering. The estimated contribution of such nitrification to the weathering of carbonate rocks accounts for about 11% of the total carbonate rock weathering flux (calculated by HCO3-) in the Lijiang River. This finding indicates that the weathering of carbonate rock is probably affected by nitrogen nitrification processes in karst catchment.
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Affiliation(s)
- Haijuan Zhao
- Chongqing Key Laboratory of Karst Environment, School of Geographical Sciences, Southwest University, Chongqing, 400715, China
- Key Laboratory of Karst Dynamics, MLR & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin, 541004, China
| | - Qiong Xiao
- Key Laboratory of Karst Dynamics, MLR & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin, 541004, China.
| | - Ying Miao
- Key Laboratory of Karst Dynamics, MLR & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin, 541004, China
| | - Zhijun Wang
- Key Laboratory of Karst Dynamics, MLR & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin, 541004, China
| | - Qigang Wang
- Key Laboratory of Karst Dynamics, MLR & Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin, 541004, China
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26
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Bratek A, Emeis KC, Sanders T, Wankel SD, Struck U, Möbius J, Dähnke K. Nitrate sources and the effect of land cover on the isotopic composition of nitrate in the catchment of the Rhône River. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2020; 56:14-35. [PMID: 32098505 DOI: 10.1080/10256016.2020.1723580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
The Rhône River originates in the high Alps and drains an intensely cultivated and industrialised catchment before it discharges to the Gulf of Lion. We investigated the interaction of catchment geomorphology with nitrate sources (atmosphere, agriculture, and nitrification of soil organic matter) and removal processes in large and diverse watersheds on the basis of dual nitrate isotope signatures in river water.In March 2015, we took surface water samples along the Rhône River, including its main tributaries, and measured nutrient concentrations and the stable isotopic composition of nitrate (δ15N, δ18O and Δ17O), and water (δ18O-H2O).Results show that high altitude regions are dominated by nitrate from nitrification in pristine soils and atmospheric deposition, while nitrate in the downstream Rhône River originates mainly from nitrification of agricultural/urban sources. Parallel increases in δ15N and δ18O reflect the influence of primary production. Previous studies suggested robust correlations between land use and [Formula: see text]. Based on our observation that nitrate δ15N values at higher altitudes are lower than expected, we assume that lower nitrate δ15N values likely reflect limited nitrate consumption and lower soil nitrogen turnover rates. We propose that correlation between land use and nitrate δ15N is sensitive to slope and geomorphology.
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Affiliation(s)
- Alexander Bratek
- Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, Geesthacht, Germany
- Institute for Geology, University of Hamburg, Hamburg, Germany
| | - Kay-Christian Emeis
- Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, Geesthacht, Germany
- Institute for Geology, University of Hamburg, Hamburg, Germany
| | - Tina Sanders
- Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, Geesthacht, Germany
| | - Scott D Wankel
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Ulrich Struck
- Museum für Naturkunde, Leibnitz Institute for Evolution and Biodiversity Science, Berlin, Germany
- Department of Earth Sciences, Freie Universität Berlin, Berlin, Germany
| | - Jürgen Möbius
- Institute for Geology, University of Hamburg, Hamburg, Germany
| | - Kirstin Dähnke
- Helmholtz-Zentrum Geesthacht, Institute for Coastal Research, Geesthacht, Germany
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27
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Skoyles A, Chaganti SR, Mundle SOC, Weisener CG. 'Nitrification kinetics and microbial community dynamics of attached biofilm in wastewater treatment'. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 81:891-905. [PMID: 32541108 DOI: 10.2166/wst.2020.170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
A comparative bench-scale and field site analysis of BioCord was conducted to investigate seasonal microbial community dynamics and its impact on nitrogen removal in wastewater. This was assessed using metabolite (NO3 -) stable isotope analysis, high-throughput sequencing of the 16S rRNA gene, and RT-qPCR of key genes in biological treatment representing nitrification, anammox, and denitrification. Bench-scale experiments showed an increase in nitrifiers with increasing ammonia loading resulting in an ammonia removal efficiency up to 98 ± 0.14%. Stable isotope analysis showed that 15ɛ and δ18ONO3 could be used in monitoring the efficiency of the enhanced biological nitrification. In the lagoon field trials, an increase in total nitrogen promoted three principle nitrifying genera (Nitrosomonas, Nitrospira, Candidatus Nitrotoga) and enhanced the expression of denitrification genes (nirK, norB, and nosZ). Further, anaerobic ammonia oxidizers were active within BioCord biofilm. Even at lower temperatures (2-6°C) the nitrifying bacteria remained active on the BioCord.
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Affiliation(s)
- Adam Skoyles
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada E-mail:
| | - Subba Rao Chaganti
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada E-mail: ; Present address: Cooperative Institute for Great Lakes Research, University of Michigan, 4840 South State Rd, Ann Arbor, MI 48108, USA
| | - Scott O C Mundle
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada E-mail:
| | - Chris G Weisener
- Great Lakes Institute for Environmental Science, University of Windsor, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada E-mail:
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28
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Granger J, Boshers DS, Böhlke JK, Yu D, Chen N, Tobias CR. The influence of sample matrix on the accuracy of nitrite N and O isotope ratio analyses with the azide method. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8569. [PMID: 31472482 DOI: 10.1002/rcm.8569] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/23/2019] [Accepted: 08/24/2019] [Indexed: 06/10/2023]
Abstract
RATIONALE The isotope ratios of nitrogen (15 N/14 N) and oxygen (18 O/16 O) in nitrite (NO2 - ) can be measured by conversion of the nitrite into nitrous oxide (N2 O) with azide, followed by mass spectrometric analysis of N2 O by gas chromatography isotope ratio mass spectrometry (GC/IRMS). While applying this method to brackish samples, we noticed that the N and O isotope ratio measurements of NO2 - are highly sensitive to sample salinity and to the pH at which samples are preserved. METHODS We investigated the influence of sample salinity and sample preservation pH on the N and O isotope ratios of the N2 O produced from the reaction of NO2 - with azide. The N2 O isotope ratios were measured by GC/IRMS. RESULTS Under the experimental reaction conditions, the conversion of NO2 - into N2 O was less complete in lower salinity solutions, resulting in respective N and O isotopic offsets of +2.5‰ and -14.0‰ compared with seawater solutions. Differences in salinity were also associated with differences in the fraction of O atoms exchanged between NO2 - and water during the reaction. Similarly, aqueous NO2 - samples preserved at elevated pH values resulted in the incomplete conversion of NO2 - into N2 O by azide, and consequent pH-dependent isotopic offsets, as well as differences in the fraction of O atoms exchanged with water. The addition of sodium chloride to the reaction matrix of samples and standards largely mitigated salinity-dependent isotopic offsets in the N2 O product, and nearly homogenized the fraction of O atom exchange among samples of different salinity. A test of the hypobromite-azide method to measure N isotope ratios of ammonium by conversion into NO2 - then N2 O revealed no influence of sample salinity on the N isotope ratios of the N2 O product. CONCLUSIONS We outline recommendations to mitigate potential matrix effects among samples and standards, to improve the accuracy of N and O isotope ratios in NO2 - measured with the azide method.
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Affiliation(s)
- Julie Granger
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - Danielle S Boshers
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | | | - Dan Yu
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Nengwang Chen
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Craig R Tobias
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
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Sebestyen SD, Ross DS, Shanley JB, Elliott EM, Kendall C, Campbell JL, Dail DB, Fernandez IJ, Goodale CL, Lawrence GB, Lovett GM, McHale PJ, Mitchell MJ, Nelson SJ, Shattuck MD, Wickman TR, Barnes RT, Bostic JT, Buda AR, Burns DA, Eshleman KN, Finlay JC, Nelson DM, Ohte N, Pardo LH, Rose LA, Sabo RD, Schiff SL, Spoelstra J, Williard KWJ. Unprocessed Atmospheric Nitrate in Waters of the Northern Forest Region in the U.S. and Canada. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3620-3633. [PMID: 30830765 DOI: 10.1021/acs.est.9b01276] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Little is known about the regional extent and variability of nitrate from atmospheric deposition that is transported to streams without biological processing in forests. We measured water chemistry and isotopic tracers (δ18O and δ15N) of nitrate sources across the Northern Forest Region of the U.S. and Canada and reanalyzed data from other studies to determine when, where, and how unprocessed atmospheric nitrate was transported in catchments. These inputs were more widespread and numerous than commonly recognized, but with high spatial and temporal variability. Only 6 of 32 streams had high fractions (>20%) of unprocessed atmospheric nitrate during baseflow. Seventeen had high fractions during stormflow or snowmelt, which corresponded to large fractions in near-surface soil waters or groundwaters, but not deep groundwater. The remaining 10 streams occasionally had some (<20%) unprocessed atmospheric nitrate during stormflow or baseflow. Large, sporadic events may continue to be cryptic due to atmospheric deposition variation among storms and a near complete lack of monitoring for these events. A general lack of observance may bias perceptions of occurrence; sustained monitoring of chronic nitrogen pollution effects on forests with nitrate source apportionments may offer insights needed to advance the science as well as assess regulatory and management schemes.
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Affiliation(s)
- Stephen D Sebestyen
- USDA Forest Service , Northern Research Station , 1831 Highway 169 E , Grand Rapids , Minnesota 55744-3399 , United States
| | - Donald S Ross
- University of Vermont , Dept. of Plant and Soil Science , Burlington , Vermont 05405-1737 , United States
| | - James B Shanley
- U.S. Geological Survey (USGS) , New England Water Science Center , Montpelier , Vermont 05602 , United States
| | - Emily M Elliott
- University of Pittsburgh , Dept. of Geology and Environmental Science , Pittsburgh , Pennsylvania 15260-3332 , United States
| | - Carol Kendall
- USGS , Menlo Park , California 94025 , United States
| | - John L Campbell
- USDA Forest Service , Northern Research Station , Durham , New Hampshire 03824 , United States
| | - D Bryan Dail
- University of Maine , Department of Plant, Soil, and Environmental Science , Orono , Maine 04469 , United States
| | - Ivan J Fernandez
- University of Maine , School of Forest Resources , Orono , Maine 04469 , United States
| | - Christine L Goodale
- Cornell University , Ecology and Evolutionary Biology , Ithaca , New York 14850 , United States
| | | | - Gary M Lovett
- Cary Institute of Ecosystem Studies , Millbrook , New York 12545 , United States
| | - Patrick J McHale
- State University of New York College of Environmental Science and Forestry , Department of Environmental and Forest Biology , Syracuse , New York 13210 , United States
| | - Myron J Mitchell
- State University of New York College of Environmental Science and Forestry , Department of Environmental and Forest Biology , Syracuse , New York 13210 , United States
| | - Sarah J Nelson
- University of Maine , School of Forest Resources , Orono , Maine 04469 , United States
| | - Michelle D Shattuck
- University of New Hampshire , Dept. of Natural Resources and the Environment , Durham , New Hampshire 03824 , United States
| | - Trent R Wickman
- USDA Forest Service , National Forest System - Eastern Region , Duluth , Minnesota 55808 , United States
| | - Rebecca T Barnes
- Colorado College , Environmental Program , Colorado Springs , Colorado 80903 , United States
| | - Joel T Bostic
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Anthony R Buda
- USDA Agricultural Research Service , Pasture Systems and Watershed Management Research Unit , University Park , Pennsylvania 16802-3702 , United States
| | - Douglas A Burns
- USGS , NY Water Science Center , Troy , New York 12180 , United States
| | - Keith N Eshleman
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Jacques C Finlay
- University of Minnesota , Ecology, Evolution, and Behavior , St. Paul , Minnesota 55108 , United States
| | - David M Nelson
- University of Maryland Center for Environmental Science , Appalachian Laboratory , Frostburg , Maryland 21532 , United States
| | - Nobuhito Ohte
- Kyoto University , Department of Social Informatics , Kyoto , Kyoto Prefecture 6068501 , Japan
| | - Linda H Pardo
- USDA Forest Service , Northern Research Station , Burlington , Vermont 05405 , United States
| | - Lucy A Rose
- University of Minnesota , Department of Forest Resources , St. Paul , Minnesota 55108 , United States
| | - Robert D Sabo
- USDA Forest Service , Northern Research Station , Burlington , Vermont 05405 , United States
| | - Sherry L Schiff
- University of Waterloo , Department of Earth and Environmental Sciences , Waterloo , Ontario N2L 3G1 , Canada
| | - John Spoelstra
- Environment and Climate Change Canada , Canada Center for Inland Waters , Burlington , Ontario L7S 1A1 , Canada
| | - Karl W J Williard
- Southern Illinois University , Forestry Center for Ecology , Carbondale , Illinois 62901 , United States
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