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Chen W, Zhang X, Wu N, Yuan C, Liu Y, Yang Y, Chen Z, Dahlgren RA, Zhang M, Ji X. Sources and transformations of riverine nitrogen across a coastal-plain river network of eastern China: New insights from multiple stable isotopes. Sci Total Environ 2024; 924:171671. [PMID: 38479520 DOI: 10.1016/j.scitotenv.2024.171671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/10/2024] [Accepted: 03/10/2024] [Indexed: 03/18/2024]
Abstract
Riverine nitrogen pollution is ubiquitous and attracts considerable global attention. Nitrate is commonly the dominant total nitrogen (TN) constituent in surface and ground waters; thus, stable isotopes of nitrate (δ15N/δ18O-NO3-) are widely used to differentiate nitrate sources. However, δ15N/δ18O-NO3- approach fails to present a holistic perspective of nitrogen pollution for many coastal-plain river networks because diverse nitrogen species contribute to high TN loads. In this study, multiple isotopes, namely, δ15N/δ18O-NO3-, δ18O-H2O, δ15N-NH4+, δ15N-PN, and δ15Nbulk/δ18O/SP-N2O in the Wen-Rui Tang River, a typical coastal-plain river network of Eastern China, were investigated to identify transformation processes and sources of nitrogen. Then, a stable isotope analysis in R (SIAR) model-TN source apportionment method was developed to quantify the contributions of different nitrogen sources to riverine TN loads. Results showed that nitrogen pollution in the river network was serious with TN concentrations ranging from 1.71 to 8.09 mg/L (mean ± SD: 3.77 ± 1.39 mg/L). Ammonium, nitrate, and suspended particulate nitrogen were the most prominent nitrogen components during the study period, constituting 45.4 %, 28.9 %, and 19.9 % of TN, respectively. Multiple hydrochemical and isotopic analysis identified nitrification as the dominant N cycling process. Biological assimilation and denitrification were minor N cycling processes, whereas ammonia volatilization was deemed negligible. Isotopic evidence and SIAR modeling revealed municipal sewage was the dominant contributor to nitrogen pollution. Based on quantitative estimates from the SIAR model, nitrogen source contributions to the Wen-Rui Tang River watershed followed: municipal sewage (40.6 %) ≈ soil nitrogen (39.5 %) > nitrogen fertilizer (9.7 %) > atmospheric deposition (2.8 %) during wet season; and municipal sewage (59.1 %) > soil nitrogen (30.4 %) > nitrogen fertilizer (4.1 %) > atmospheric deposition (1.0 %) during dry season. This study provides a deeper understanding of nitrogen dynamics in eutrophic coastal-plain river networks, which informs strategies for efficient control and remediation of riverine nitrogen pollution.
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Affiliation(s)
- Wenli Chen
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Xiaohan Zhang
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Nianting Wu
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Can Yuan
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
| | - Yinli Liu
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Yue Yang
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China; Southern Zhejiang Water Research Institute, Wenzhou 325035, China
| | - Zheng Chen
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China
| | - Randy A Dahlgren
- Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA
| | - Minghua Zhang
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China; Southern Zhejiang Water Research Institute, Wenzhou 325035, China; Department of Land, Air and Water Resources, University of California, Davis, California 95616, USA
| | - Xiaoliang Ji
- Key Laboratory of Watershed Science and Health of Zhejiang Province, School of Public Health and Management, Wenzhou Medical University, Wenzhou 325035, China.
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Pelletier M, Oczkowski A, Hagy J. Deciphering patterns in whole fish nitrogen isotopes on a continental scale. Sci Total Environ 2024; 931:172684. [PMID: 38663629 DOI: 10.1016/j.scitotenv.2024.172684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 04/02/2024] [Accepted: 04/20/2024] [Indexed: 05/06/2024]
Abstract
Nitrogen isotopes (δ15N) have been used as an indicator of anthropogenic nitrogen loading at local and regional scales. We examined δ15N in fish from estuaries across the continental United States. In the summer of 2015, the U.S. Environmental Protection Agency's National Coastal Condition Assessment (NCCA) collected fish in 136 coastal waterbodies throughout the United States. Whole fish were analyzed by NCCA for metals, organic contaminants, and lipids. For this study, we also analyzed these fish for isotopes of nitrogen (N). NCCA collected water quality, nutrients, chlorophyll a, and sediment chemistry at each site. We used these data, along with fish life history and watershed land use, to examine how whole fish δ15N was related to these environmental variables using random forest regression models at national and ecoregional scales. At the national scale, fish δ15N were negatively related to total N:total phosphorous (P) ratios (TN:TP) in surface water and reflected differences between the P-limited, δ15N depleted sites in the Floridian ecoregion to sites in other regions. δ15N was lower on the Atlantic relative to the Pacific coast. When considered by region, TN:TP was an important predictor of fish δ15N in 4 of 9 ecoregions, with higher δ15N observed with increasing N limitation (lower TN:TP) Fish life history was also an important predictor of fish δ15N at both the national and ecoregional scale. Whole fish δ15N was positively associated with bioaccumulative contaminants such as PCBs and mercury. Although land use was related to δ15N in fish, it was location specific. This study showed that N stable isotopes reflected ecological conditions at both regional and continental scales.
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Affiliation(s)
- Marguerite Pelletier
- Atlantic Coastal Environmental Sciences Division, Center for Environmental Measurement and Modeling, US Environmental Protection Agency, United States of America.
| | - Autumn Oczkowski
- Atlantic Coastal Environmental Sciences Division, Center for Environmental Measurement and Modeling, US Environmental Protection Agency, United States of America
| | - James Hagy
- Atlantic Coastal Environmental Sciences Division, Center for Environmental Measurement and Modeling, US Environmental Protection Agency, United States of America
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Mu J, Ding S, Liu SM, Song G, Ning X, Zhang X, Xu W, Zhang H. Multiple isotopes decipher the nitrogen cycle in the cascade reservoirs and downstream in the middle and lower Yellow River: Insight for reservoir drainage period. Sci Total Environ 2024; 918:170625. [PMID: 38320705 DOI: 10.1016/j.scitotenv.2024.170625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/13/2024]
Abstract
Intensive anthropogenic activities, such as excessive nitrogen input and dam construction, have altered the nitrogen cycle in the global river system. However, the focus on the source, transformation and fate of nitrogen in the Yellow River is still scarce. In this study, the multiple isotopes (δ15N-NO3-, δ18O-NO3-, δ15N-NH4+ and δ15N-PN) were deciphered to explore the nitrogen cycling processes and the driving factors in the thermally stratified cascade reservoirs (Sanmenxia Reservoir: SMXR and Xiaolangdi Reservoir: XLDR) and Lower Yellow River (LYR) during the drainage period of the XLDR. In the SMXR, algal bloom triggered the assimilation process in the upper layer before the SMX Dam, followed by remineralization and subsequent nitrification processes in the lower water layers. The nitrification reaction in the XLDR progressively increased along both longitudinal and vertical directions to the lower layer of the XLD Dam, which was linked to the variation in the water residence time of riverine, transition and lentic zones. The robust nitrification rates in the lower layer of the lentic zone coincided with the substantial depletion of nitrate isotopic composition and enrichment of both δ15N-PN and δ15N-NH4+, indicating the longer water residence time not only promoted the growth of the nitrifying population but also facilitated the remineralization to enhance NH4+ availability. In the LYR, the slight nitrate assimilation, as indicated by nitrate isotopic composition and fractionation models, was the predominant nitrogen transformation process. The Bayesian isotope mixing model results showed that manure and sewage was the dominant nitrate source (50 %) in the middle and lower Yellow River. Notably, the in-reservoir nitrification was a significant nitrate source (27 %) in the XLDR and LYR. Our study deepens the understanding of anthropogenic activities impacting the nitrogen cycle in the river-reservoir system, providing valuable insight into water quality management and nitrogen cycle mechanisms in the Yellow River.
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Affiliation(s)
- Jinglong Mu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Shuai Ding
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Chinese Research Academy of Environmental Sciences, Beijing 100012, China
| | - Su Mei Liu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China.
| | - Guodong Song
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xiaoyan Ning
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China; Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
| | - Xiaotong Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Wenqi Xu
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Hongmei Zhang
- Frontiers Science Center for Deep Ocean Multispheres and Earth System, Key Laboratory of Marine Chemistry Theory and Technology Ministry of Education, Ocean University of China, Qingdao 266100, China
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Zhang A, Wang Y, Li Y, Tan Y, Liu P, Lv X, Lei K. Multiple isotopes reveal the driving forces of nitrogen cycling from freshwater to brackish water. Sci Total Environ 2023; 897:165396. [PMID: 37437639 DOI: 10.1016/j.scitotenv.2023.165396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 07/05/2023] [Accepted: 07/06/2023] [Indexed: 07/14/2023]
Abstract
Rivers play a crucial role in global nitrogen (N) cycling, but revealing the driving mechanism of N cycling remains challenging because of the complex natural background gradients. The Qiantang River Basin provides an opportunity to elucidate the driving mechanism due to the complex climatic and hydrological conditions. In this study, the multiple stable isotopes suggested that the conservative mixing of two end members was insufficient to explain the complex behavior of N in both seasons. In-soil processes were the primary N cycling processes that controlled riverine N loading during the wet season, whereas in-stream N biological transformation processes (nitrification and assimilation) were more prevalent during the dry season. The results of MixSIAR revealed that soil sources (soil N and N fertilizer) contributed the most to NO3- during the wet season, accounting for 64.3 %, followed by manure and sewage (31.6 %) and atmospheric precipitation (4.1 %). During the dry season, manure and sewage were the predominant contributors to NO3- (52.1 %), followed by soil N (26.6 %), N fertilizer (18.8 %), and atmospheric precipitation (2.5 %). The relationships between d-excess and δ15N-NH4+ or δ15N-NO3- suggested that both climatic and hydrological conditions would be the driving forces regulating the N transportation and transformation in this basin, leading to the high spatiotemporal heterogeneity in N loading and isotopic compositions. In the wet season, precipitation patterns served as the primary driving forces regulating in-soil biological processes and soil leaching. While the hydrological conditions, especially water residence time, were the crucial factors controlling in-stream biological processes during the dry season. This study elucidates N sources, biotransformation processes, and their driving forces from freshwater to brackish water, which has applications for understanding the N fate from terrene to ocean.
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Affiliation(s)
- Anqi Zhang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China; Key Lab of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, PR China
| | - Yan Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China
| | - Yi Li
- Key Lab of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling 712100, PR China
| | - Yingyu Tan
- Key Laboratory of Environmental Pollution Control Technology of Zhejiang Province, Eco-Environmental Science Research & Design Institute of Zhejiang Province, Hangzhou, Zhejiang 310007, PR China
| | - Pengxia Liu
- Ecology and Environment Monitoring and Scientific Research Center of Taihu Basin & East China Sea Ecology and Environment Supervision Authority, Ministry of Ecology and Environment, Shanghai 200120, China
| | - Xubo Lv
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China
| | - Kun Lei
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, PR China.
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Zhang W, Jiang H, Guo W, Li S, Zhang Q. Unexpectedly high nitrate levels in a pristine forest river on the Southeastern Qinghai-Tibet Plateau. J Hazard Mater 2023; 458:132047. [PMID: 37453353 DOI: 10.1016/j.jhazmat.2023.132047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 06/30/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
River nitrate (NO3-) pollution is a global environmental issue. Recently, high NO3- levels in some pristine or minimally-disturbed rivers were reported, but their drivers remain unclear. This study integrated river isotopes (δ18O/δ15N-NO3- and δD/18O-H2O), 15N pairing experiments, and qPCR to reveal the processes driving the high NO3- levels in a nearly pristine forest river on the Qinghai-Tibet Plateau. The river isotopes suggested that, at the catchment scale, NO3- removal was prevalent in summer, but weak in winter. The pristine forest soils contributed more than 90 % of the riverine NO3-, indicating the high NO3- backgrounds. The release of soil NO3- to the river was "transport-limited" in both seasons, i.e., the NO3- production/stock in the soils exceeded the capacity of hydrological NO3- leaching. In summer, this regime and the NO3--plentiful conditions in the soils associated with the strong NO3- nitrification led to the high riverine NO3- levels. While the in-soil nitrification was weak in winter, the leaching of legacy NO3- resulted in the consistently high NO3- levels. This study provides insights into the reasons for high NO3- levels in pristine or minimally-disturbed rivers worldwide and highlights the necessity to consider NO3- backgrounds when evaluating anthropogenic NO3- pollution in rivers.
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Affiliation(s)
- Wenshi Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China.
| | - Wenjing Guo
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Shen Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Quanfa Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China
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Wang C, Zhou Z, Li Y, Kong J, Dong H. Effects of changes in land use structure on nitrogen input in the Pingzhai Reservoir watershed, a karst mountain region. Heliyon 2023; 9:e16262. [PMID: 37251895 PMCID: PMC10208923 DOI: 10.1016/j.heliyon.2023.e16262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 04/28/2023] [Accepted: 05/11/2023] [Indexed: 05/31/2023] Open
Abstract
Optimizing land use composition to control nitrogen input into water bodies is one way to address surface source pollution in karst mountain regions. In this study, changes in land use, N sources, and spatial and temporal changes of N migration in the Pingzhai Reservoir watershed were evaluated from 2015 to 2021, and the relationship between land use composition and N input was elucidated. N was the main pollution in the water of the watershed; NO3- was the dominant form of N, and it did not react during migration. N came from soil, livestock manure or domestic sewage, and atmospheric deposition. Isolating the fractionation effects of source nitrogen is crucial to improve the accuracy of nitrogen and oxygen isotope traceability in the Pingzhai Reservoir. From 2015 to 2021, the grassland area in the Pingzhai Reservoir increased by 5.52%, the woodland area increased by 2.01%, the water area increased by 1.44%, the cropland decreased by 5.8%, unused land decreased by 3.18%, and construction land remained unchanged. Policies and reservoir construction were the main drivers of changes in land-use type in the catchment. Changes in land use structure affected nitrogen input patterns, with unused land having a highly significant positive correlation with inputs of NH3-N, NO2-, and TN, and construction land having a significant positive correlation with the input of NO2-. The inhibitory effect of forest and grassland on nitrogen input in the basin was offset by the promoting effect of cropland and construction land on nitrogen input, with unused land becoming a new focus area for nitrogen emissions due to a lack of environmental management. Modifying the area of different land use types in the watershed can effectively control nitrogen input to the watershed.
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Affiliation(s)
- Cui Wang
- State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, Guiyang 550001, China
- School of Geography and Environment, Guizhou Normal University, Guiyang 550001, China
| | - Zhongfa Zhou
- School of Karst Science, Guizhou Normal University, Guiyang 550001, China
- State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, Guiyang 550001, China
- School of Geography and Environment, Guizhou Normal University, Guiyang 550001, China
| | - Yongliu Li
- School of Karst Science, Guizhou Normal University, Guiyang 550001, China
- School of Geography and Environment, Guizhou Normal University, Guiyang 550001, China
| | - Jie Kong
- State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, Guiyang 550001, China
- School of Geography and Environment, Guizhou Normal University, Guiyang 550001, China
| | - Hui Dong
- School of Karst Science, Guizhou Normal University, Guiyang 550001, China
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