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Zhang Q, Wang H, Liu L, Zhai T, Zhang X. Multiple isotopes reveal the driving mechanism of high NO 3- level and key processes of nitrogen cycling in the lower reaches of Yellow River. J Environ Sci (China) 2024; 138:597-606. [PMID: 38135423 DOI: 10.1016/j.jes.2023.05.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/02/2023] [Accepted: 05/02/2023] [Indexed: 12/24/2023]
Abstract
The continuous increase of nitrate (NO3-) level in rivers is a hot issue in the world. However, the driving mechanism of high NO3- level in large rivers is still lacking, which has limited the use of river water and increased the cost of water treatment. In this study, multiple isotopes and source resolution models are applied to identify the driving mechanism of high NO3- level and key processes of nitrogen cycling in the lower reaches of the Yellow River (LRYR). The major sources of NO3- were sewage and manure (SAM) in the low-flow season and soil nitrogen (SN) and chemical fertilizer (CF) in the high-flow season. Nitrification was the most key process of nitrogen cycling in the LRYR. However, in the biological removal processes, denitrification may not occur significantly. The temporal variation of contributions of NO3- sources were estimated by a source resolution model in the LRYR. The proportional contributions of SAM and CF to NO3- in the low-flow and high-flow season were 32.5%-52.3%, 44.2%-46.2% and 36.0%-40.8%, 54.9%-56.9%, respectively. The driving mechanisms of high NO3- level were unreasonable sewage discharge, intensity rainfall runoff, nitrification and lack of nitrate removal capacity. To control the NO3- concentration, targeted measures should be implemented to improve the capacity of sewage and wastewater treatment, increase the utilization efficiency of nitrogen fertilizer and construct ecological engineering. This study deepens the understanding of the driving mechanism of high nitrate level and provides a vital reference for nitrogen pollution control in rivers to other area of the world.
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Affiliation(s)
- Qianqian Zhang
- Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Hebei 050061, China; Hebei Provincial Laboratory of Water Environmental Science, Hebei 050037, China; Hebei Provincial Academy of Ecological Environmental Science, Hebei 050037, China
| | - Huiwei Wang
- Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Hebei 050061, China
| | - Lu Liu
- Geo-Environmental Monitoring Institute of Hebei Province, Hebei 050011, China
| | - Tianlun Zhai
- Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Hebei 050061, China
| | - Xueqing Zhang
- Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Hebei 050061, China.
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2
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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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Yang S, Deng Y, Shu J, Luo X, Peng X, Pan K, Jiang H. Nitrate budget of a terrestrial-to-marine continuum in South China: Insights from isotopes and a Markov chain Monte Carlo model. MARINE POLLUTION BULLETIN 2024; 199:116000. [PMID: 38171166 DOI: 10.1016/j.marpolbul.2023.116000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 12/25/2023] [Accepted: 12/26/2023] [Indexed: 01/05/2024]
Abstract
Anthropogenic nitrate (NO3-) production has been increasing and is exported to the ocean via river networks, causing eutrophication and ecological damage. While studies have focused on river NO3- pollution, what has been lacking is the quantification of the sources of NO3- in coastal rivers. This study applied the dual isotopes (δ15N/δ18O-NO3-) to quantify the sources and their fluxes of NO3- in two inflow rivers of the Qinzhou Bay. By adding our results to the NO3- source apportionment in Qinzhou Bay, we, for the first time, established the NO3- budgets of the terrestrial-to-marine continuum in both high- and low-flow seasons. We quantitatively showed the direct and indirect roles (e.g., the stimulation of nitrification by sewage ammonium-NH4+) of terrestrial sources in driving the high NO3- loading in the estuary. The results highlighted the necessity to consider coastal rivers and estuary as a whole, which could shed light on the effective reduction of NO3- pollution in coastal environments.
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Affiliation(s)
- Shaomei Yang
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Yan Deng
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Junlin Shu
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Xin Luo
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Xiaoyan Peng
- Beibu Gulf Marine Ecological Environment Field Observation and Research Station of Guangxi, Marine Environmental Monitoring Centre of Guangxi, Beihai 536000, China
| | - Ke Pan
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, The Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China; Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China.
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Lv S, Zheng F, Wang Z, Hayat K, Veiga MC, Kennes C, Chen J. Unveiling novel pathways and key contributors in the nitrogen cycle: Validation of enrichment and taxonomic characterization of oxygenic denitrifying microorganisms in environmental samples. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 908:168339. [PMID: 37931816 DOI: 10.1016/j.scitotenv.2023.168339] [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: 09/05/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/08/2023]
Abstract
Microorganisms play a crucial role in both the nitrogen cycle and greenhouse gas emissions. A recent discovery has unveiled a new denitrification pathway called oxygenic denitrification, entailing the enzymatic reduction of nitrite to nitric oxide (NO) by a putative nitric oxide dismutase (nod) enzyme. In this study, the presence of the nod gene was detected and subsequently enriched in anaerobic-activated sludge, farmland soil, and paddy soil samples. After 150 days, the enriched samples exhibited significant denitrification, and concomitant oxygen production. The removal efficiency of nitrite ranged from 64.6 % to 79.0 %, while the oxygen production rate was between 15.4 μL/min and 18.6 μL/min when exposed to a sole nitrogen source of 80 mg/L sodium nitrite. Additionally, batch experiments and kinetic analyses revealed the intricate pathways and underlying mechanisms governing the oxygenic denitrification reaction by using CARBOXY-PTIO, 18O-labelled water, and acetylene to unravel the intricacies of the reaction. The quantitative polymerase chain reaction (qPCR) results indicated a significant surge in the abundance of nod genes, escalating from 7.59 to 10.12-fold. Moreover, analysis of 16S ribosomal DNA (rDNA) amplicons revealed Proteobacteria as the dominant phylum and Thauera as the main genus, with the presumed affiliation. In this study, a new nitrogen conversion pathway, oxygenic denitrification, was discovered in environmental samples. This process provides the possibility for the control of nitrous oxide in the treatment of nitrogenous wastewater.
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Affiliation(s)
- Sini Lv
- College of Environment, Zhejiang University of Technology, Hangzhou 310014, China
| | - Fengzhen Zheng
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - Zeyu Wang
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - Kashif Hayat
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN group, University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN group, University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Jun Chen
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China.
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5
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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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6
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Li R, Ren C, Wu L, Zhang X, Mao X, Fan Z, Cui W, Zhang W, Wei G, Shu D. Fertilizing-induced alterations of microbial functional profiles in soil nitrogen cycling closely associate with crop yield. ENVIRONMENTAL RESEARCH 2023; 231:116194. [PMID: 37217131 DOI: 10.1016/j.envres.2023.116194] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 05/08/2023] [Accepted: 05/16/2023] [Indexed: 05/24/2023]
Abstract
Fertilization and rhizosphere selection are key regulators for soil nitrogen (N) cycling and microbiome. Thus, clarifying how the overall N cycling processes and soil microbiome respond to these factors is a prerequisite for understanding the consequences of high inputs of fertilizers, enhancing crop yields, and formulating reasonable nitrogen management strategies under agricultural intensification scenarios. To do this, we applied shotgun metagenomics sequencing to reconstruct N cycling pathways on the basis of abundance and distribution of related gene families, as well as explored the microbial diversity and interaction via high throughput sequencing based on a two-decade fertilization experiment in Loess Plateau of China semiarid area. We found that bacteria and fungi respond divergent to fertilization regimes and rhizosphere selection, in terms of community diversity, niche breadth, and microbial co-occurrence networks. Moreover, organic fertilization decreased the complexity of bacterial networks but increased the complexity and stability of fungal networks. Most importantly, rhizosphere selection exerted more strongly influences on the soil overall nitrogen cycling than the application of fertilizers, accompanied by the increase in the abundance of nifH, NIT-6, and narI genes and the decrease in the abundance of amoC, norC, and gdhA genes in the rhizosphere soil. Furthermore, keystone families screening from soil microbiome (e.g., Sphingomonadaceae, Sporichthyaceae, and Mortierellaceae), which were affected by the edaphic variables, contributed greatly to crop yield. Collectively, our findings emphasize the pivotal roles of rhizosphere selection interacting with fertilization regimes in sustaining soil nitrogen cycling processes in response to decades-long fertilization, as well as the potential importance of keystone taxa in maintaining crop yield. These findings significantly facilitate our understanding of nitrogen cycling in diverse agricultural soils and lay a foundation for manipulating specific microorganisms to regulate N cycling and promote agroecosystem sustainability.
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Affiliation(s)
- Ruochen Li
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China
| | - Chengyao Ren
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China
| | - Likun Wu
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China
| | - Xinxin Zhang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China
| | - Xinyi Mao
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China
| | - Zhen Fan
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China
| | - Weili Cui
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China
| | - Wu Zhang
- Heihe Branch, Heilongjiang Academy of Agricultural Sciences, Heihe, Heilongjiang, 150086, China
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China.
| | - Duntao Shu
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, Yangling, Shaanxi, 712100, China.
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7
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Han R, Liu W, Zhang J, Zhao T, Sun H, Xu Z. Hydrogeochemical characteristics and recharge sources identification based on isotopic tracing of alpine rivers in the Tibetan Plateau. ENVIRONMENTAL RESEARCH 2023; 229:115981. [PMID: 37100365 DOI: 10.1016/j.envres.2023.115981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 04/17/2023] [Accepted: 04/22/2023] [Indexed: 05/21/2023]
Abstract
Alpine rivers originating from the Tibetan Plateau (TP) contain large amounts of water resources with high environmental sensitivity and eco-fragility. To clarify the variability and controlling factors of hydrochemistry on the headwater of the Yarlung Tsangpo River (YTR), the large river basin with the highest altitude in the world, water samples from the Chaiqu watershed were collected in 2018, and major ions, δ2H and δ18O of river water were analyzed. The values of δ2H (mean: -141.4‰) and δ18O (mean: -18.6‰) were lower than those in most Tibetan rivers, which followed the relationship: δ2H = 4.79*δ18O-52.2. Most river deuterium excess (d-excess) values were lower than 10‰ and positively correlated with altitude controlled by regional evaporation. The SO42- in the upstream, the HCO3- in the downstream, and the Ca2+ and Mg2+ were the controlling ions (accounting for >50% of the total anions/cations) in the Chaiqu watershed. Stoichiometry and principal component analysis (PCA) results revealed that sulfuric acid stimulated the weathering of carbonates and silicates to produce riverine solutes. This study promotes understanding water source dynamics to inform water quality and environmental management in alpine regions.
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Affiliation(s)
- Ruiyin Han
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wenjing Liu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China
| | - Jiangyi Zhang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China
| | - Tong Zhao
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China
| | - Huiguo Sun
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China
| | - Zhifang Xu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; University of Chinese Academy of Sciences, Beijing, 100049, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing, 100044, China.
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8
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Zhang W, Jiang H, Guo W, Li S, Zhang Q. Unexpectedly high nitrate levels in a pristine forest river on the Southeastern Qinghai-Tibet Plateau. JOURNAL OF HAZARDOUS MATERIALS 2023; 458:132047. [PMID: 37453353 DOI: 10.1016/j.jhazmat.2023.132047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 06/30/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
River nitrate (NO3-) pollution is a global environmental issue. Recently, high NO3- levels in some pristine or minimally-disturbed rivers were reported, but their drivers remain unclear. This study integrated river isotopes (δ18O/δ15N-NO3- and δD/18O-H2O), 15N pairing experiments, and qPCR to reveal the processes driving the high NO3- levels in a nearly pristine forest river on the Qinghai-Tibet Plateau. The river isotopes suggested that, at the catchment scale, NO3- removal was prevalent in summer, but weak in winter. The pristine forest soils contributed more than 90 % of the riverine NO3-, indicating the high NO3- backgrounds. The release of soil NO3- to the river was "transport-limited" in both seasons, i.e., the NO3- production/stock in the soils exceeded the capacity of hydrological NO3- leaching. In summer, this regime and the NO3--plentiful conditions in the soils associated with the strong NO3- nitrification led to the high riverine NO3- levels. While the in-soil nitrification was weak in winter, the leaching of legacy NO3- resulted in the consistently high NO3- levels. This study provides insights into the reasons for high NO3- levels in pristine or minimally-disturbed rivers worldwide and highlights the necessity to consider NO3- backgrounds when evaluating anthropogenic NO3- pollution in rivers.
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Affiliation(s)
- Wenshi Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China.
| | - Wenjing Guo
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Shen Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Quanfa Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, China
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9
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Li S, Jiang H, Guo W, Zhang W, Zhang Q. From Soil to River: Revealing the Mechanisms Underlying the High Riverine Nitrate Levels in a Forest Dominated Catchment. WATER RESEARCH 2023; 241:120155. [PMID: 37270954 DOI: 10.1016/j.watres.2023.120155] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 05/04/2023] [Accepted: 05/30/2023] [Indexed: 06/06/2023]
Abstract
Elevated riverine nitrate (NO3-) levels have led to increased eutrophication and other ecological implications. While high riverine NO3- levels were generally ascribed to anthropogenic activities, high NO3- levels in some pristine or minimally disturbed rivers were reported. The drivers of these unexpectedly high NO3- levels remain unclear. This study combined natural abundance isotopes, 15N-labeling techniques, and molecular techniques to reveal the processes driving the high NO3- levels in a sparsely populated forest river. The natural abundance isotopes revealed that the NO3- was mainly from soil sources and that NO3- removal processes were insignificant. The 15N-labeling experiments also quantitatively showed that the biological NO3- removal processes, i.e., denitrification, dissimilatory NO3- reduction to ammonium (DNRA), and anaerobic ammonia oxidation (anammox), in the soils and sediments were weak relative to nitrification in summer. While nitrification was minor in winter, the NO3- removal was insignificant relative to the large NO3- stock in the catchment. Stepwise multiple regression analyses and structural equation models revealed that in summer, nitrification in the soils was regulated by the amoA-AOB gene abundances and NH4+-N contents. Low temperature constrained nitrification in winter. Denitrification was largely controlled by moisture content in both seasons, and anammox and DNRA could be explained by the competition with nitrification and denitrification on their substrate (nitrite-NO2-). We also revealed the strong hydrological control on the transport of soil NO3- to the river. This study effectively revealed the mechanisms underlying the high NO3- levels in a nearly pristine river, which has implications for the understanding of riverine NO3- levels worldwide.
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Affiliation(s)
- Shen Li
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, PR China.
| | - Wenjing Guo
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Wenshi Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Quanfa Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430074, PR China
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Li X, Xu YJ, Ni M, Wang C, Li S. Riverine nitrate source and transformation as affected by land use and land cover. ENVIRONMENTAL RESEARCH 2023; 222:115380. [PMID: 36716803 DOI: 10.1016/j.envres.2023.115380] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
A mixed land use/land cover (LULC) catchment increases the complexity of sources and transformations of nitrate in rivers. Spatial paucity of sampling particularly low-resolution sampling in tributaries can result in a bias for identifying nitrate sources and transformations. In this study, high spatial resolution sampling campaigns covering mainstream and tributaries in combination with hydro-chemical parameters and dual isotopes of nitrate were performed to reveal spatio-temporal variations of nitrate sources and transformations in a river draining a mixed LULC catchment. This study suggested that point sources dominated the nitrate in the summer and winter, while non-point sources dominated the nitrate in the spring and autumn. A positive correlation was observed between proportions from sewage and land use index (LUI). However, negative correlations between soil nitrogen/nitrogen fertilizer and LUI were observed. With an increase of urban areas, the increased contribution from domestic sewage resulted in an increase of NO3- concentrations in rivers. Both urban and agricultural inputs should be considered in nitrate pollution management in a mixed LULC catchment. We concluded that the seasonal variations of nitrate sources were mainly affected by flow velocity conditions and agricultural activities, while spatial variations were mainly affected by LULC. In addition, we found a novel underestimation of dominated sources from Bayesian model because of mixing effect of isotope values from the tributaries to mainstream, however, high spatial resolution sampling can make up for this shortcoming. δ15N and δ18O values of nitrate indicated that nitrate originated from nitrification in soils. The nitrate concentrations and correlation between δ15N and 1/[NO3-] suggested little contribution of nitrate removal by denitrification. Thus, the nitrate reduction in the Yuehe River basin needs to be strengthened. The study provides new implications for estimation of nitrate sources and transformations and basis for nitrate reduction in the river with mixed LULC catchment.
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Affiliation(s)
- Xing Li
- Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Y Jun Xu
- School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA; Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Maofei Ni
- College of Eco-environmental Engineering, Guizhou Minzu University, Guiyang, China
| | - Chunlin Wang
- Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, 430205, China
| | - Siyue Li
- Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, 430205, China.
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11
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Jeong YJ, Park HJ, Baek N, Seo BS, Lee KS, Kwak JH, Choi SK, Lee SM, Yoon KS, Lim SS, Choi WJ. Assessment of sources variability of riverine particulate organic matter with land use and rainfall changes using a three-indicator (δ 13C, δ 15N, and C/N) Bayesian mixing model. ENVIRONMENTAL RESEARCH 2023; 216:114653. [PMID: 36328228 DOI: 10.1016/j.envres.2022.114653] [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: 09/07/2022] [Revised: 10/12/2022] [Accepted: 10/22/2022] [Indexed: 06/16/2023]
Abstract
In intensive agricultural watersheds, riverine particulate organic matter (POM) may be transported from many sources such as rice paddies, crop uplands, forests, and livestock farming areas during rainy seasons. However, the impacts of land-use and rainfall changes on the POM sources are not well understood. In this study, changes in the sources of riverine POM were investigated in an agricultural area of Korea between 2014 and 2020/21. During this period, land-use and rainfall patterns changed dramatically. The δ13C, δ15N, and C/N of the POM sources as well as those of riverine POM were analyzed, and a stable isotope analysis in R (SIAR) model was utilized for source apportionment. There were differences in δ13C, δ15N, and C/N among the sources. For example, manure had higher δ13C (-22.6 ± 3.3‰) and δ15N (+10.6 ± 5.9‰) than soils (from -28.0 ± 0.8‰ to -25.1 ± 1.2‰ for δ13C and +3.6 ± 1.7‰ to +9.8 ± 1.4‰ for δ15N). For soils, the δ13C and δ15N were higher for upland soils, while C/N was greater for forest soils than for others. For riverine POM, the δ15N marginally changed; however, the δ13C and C/N increased from -26.1 ± 0.9‰ to -20.8 ± 5.3‰ and from +7.7 ± 1.7 to +18.8 ± 8.3 between 2014 and 2020/21, respectively. The SIAR model showed that the contributions of paddy (from 41.0% to 14.9%) and upland fields (from 48.1% to 23.7%) to riverine POM decreased between the periods due to decreased paddy area and the implementation of best management practice on upland fields, respectively. However, the contribution of forests (from 3.5% to 28.0%) and manure (from 7.4% to 33.5%) increased probably due to improper management of forest clear-cutting sites and livestock manure storage sites. The contributions of agricultural soils to riverine POM decreased in drier years. Our study suggests that land management rather than land-use area is critical in riverine POM management, particularly in wetter years.
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Affiliation(s)
- Young-Jae Jeong
- Department of Rural and Bio-systems Engineering (BK 21), Chonnam National University, Gwangju, 61186, Republic of Korea; National Institute of Agricultural Sciences, Wanju, Jeollabuk-do, 55365, Republic of Korea
| | - Hyun-Jin Park
- Department of Rural and Bio-systems Engineering (BK 21), Chonnam National University, Gwangju, 61186, Republic of Korea; AgriBio Institute of Climate Change Management, Chonnam National University, Gwangju, 61186, Republic of Korea.
| | - Nuri Baek
- Department of Rural and Bio-systems Engineering (BK 21), Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Bo-Seong Seo
- Department of Rural and Bio-systems Engineering (BK 21), Chonnam National University, Gwangju, 61186, Republic of Korea; National Institute of Crop Sciences, Wanju, Jeollabuk-do, 55365, Republic of Korea
| | - Kwang-Seung Lee
- National Institute of Crop Sciences, Wanju, Jeollabuk-do, 55365, Republic of Korea
| | - Jin-Hyeob Kwak
- Department of Rural Construction Engineering, Jeonbuk National University, Jeonju, Jeollabuk-do, 57896, Republic of Korea
| | - Soon-Kun Choi
- National Institute of Agricultural Sciences, Wanju, Jeollabuk-do, 55365, Republic of Korea
| | - Sang-Mo Lee
- National Instrumentation Center for Environmental Management, Seoul National University, Seoul, 08826, Republic of Korea
| | - Kwang-Sik Yoon
- Department of Rural and Bio-systems Engineering (BK 21), Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Sang-Sun Lim
- Bio R&D Center, CJ Cheiljedang, Suwon, Gyeonggi-do, 16495, Republic of Korea
| | - Woo-Jung Choi
- Department of Rural and Bio-systems Engineering (BK 21), Chonnam National University, Gwangju, 61186, Republic of Korea; AgriBio Institute of Climate Change Management, Chonnam National University, Gwangju, 61186, Republic of Korea.
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12
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Zhang Q, Zhang J, Wang H, Zhai T, Liu L, Li G, Xu Z. Spatial patterns in water quality and source apportionment in a typical cascade development river southwestern China using PMF modeling and multivariate statistical techniques. CHEMOSPHERE 2023; 311:137139. [PMID: 36347353 DOI: 10.1016/j.chemosphere.2022.137139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 11/01/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
River cascade development is one of the human activities that have the most significant impact on the water environment. However, the mechanism of cascade development affecting river hydrochemical components still needs to be further studied. In this study, water quality index(WQI), positive matrix factorization(PMF) model and multivariate statistical techniques were used to identify the mechanism of cascade development affecting river hydrochemical components in an typical cascade development Rivers, Lancang River, China. The results showed that the water quality of Lancang River is relatively good due to less affected by human activity. The spatial variation of river hydrochemistry is affected by the development of cascade reservoirs, and shows three patterns: irregular variation (pH and DO), fluctuating decreasing (Na+, Cl-, SO42- and HCO3-) and multi-peak variation (TN, TDN, NO3--N and NH4+-N). It's worth noting that the concentration of the most hydrochemical parameters is higher in the upper reaches (less human activities) than that in the middle and lower reaches of river due to the retention effect of the reservoir on the chemical composition. The PMF model outputs revealed that the rock weathering and internal source, sewage and soil nitrogen, and chemical fertilizer were primary material sources of Lancang River. Compared with the natural channel zone (41.0%), the interaction of water-rock has more influence on chemical component in the reservoir area (56.3%), while the contribution of fertilizer (11.2%) to the river hydrochemistry is less. The sites of downstream of the reservoir dam were affected by the retention of the reservoir and the disturbance of the bottom drainage, which leads to the weakening of the influence of the sewage (44.7%) on the river material and the increase of the contribution of fertilizer (25.0%). These results could provide valuable information in controlling the eutrophication of cascade reservoirs and the scientific construction of river cascade reservoirs.
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Affiliation(s)
- Qianqian Zhang
- Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China; Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing, China
| | - Jiangyi Zhang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China
| | - Huiwei Wang
- Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China
| | - Tianlun Zhai
- Hebei and China Geological Survey Key Laboratory of Groundwater Remediation, Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China
| | - Lu Liu
- Geo-Environmental Monitoring Institute of Hebei Province, Shijiazhuang, 050011, China
| | - Gan Li
- College of Forestry, Southwest Forestry University, Kunming, 650233, China
| | - Zhifang Xu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China; Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
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13
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Zhang A, Lei K, Lang Q, Li Y. Identification of nitrogen sources and cycling along freshwater river to estuarine water continuum using multiple stable isotopes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:158136. [PMID: 35987221 DOI: 10.1016/j.scitotenv.2022.158136] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 08/04/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
Nitrogen (N) transport from terrene to river water is a major source of N in estuarine water, contributing to eutrophication, harmful algal blooms and hypoxia. However, there is a lack of holistic and systematic research on N sources and transformation in the freshwater river-estuarine water continuum. In this study, multiple stable isotope signatures of nitrate (δ15N-NO3-, δ18O-NO3-), ammonium (δ15N-NH4+), and suspended particulate nitrogen (δ15N-PN) were employed to differentiate the sources and transformations of N and calculate the proportional contribution of NO3- sources by Bayesian model in Qiantang River (QTR)-Hangzhou Bay (HZB) during the dry season. The results showed that: (1) Evidences from isotopic signatures suggested the occurrence of N transformation instead of conservation mixing. (2) Negative correlations between the δ15N-NO3- and δ15N-NH4+, the relationships between δ15N-NO3- and NO3--N concentrations, and smaller δ18O-NO3- values were found in almost all surface water, indicating that nitrification was the dominant N transformation. (3) In addition to the nitrification evidence, significant correlations between δ15N-PN and δ15N-NH4+ revealed that assimilation and nitrification jointly affected the N transformation in the QTR's upstream, midstream and lower tributaries, which are unaffected or less affected by tides. (4) The lack of a relationship between δ15N-NO3- and δ18O-NO3- or ln(NO3-) indicated that denitrification was weakened in all surface waters. (5) Qualitative identification of N pollution sources and quantitative calculation of NO3--N potential sources revealed that sewage was the dominant source of N in the QTR and the HZB, while the internal nitrification was also important factor in determining N levels. This study provided evidence to further understand the sources, transport, and transformation of N in the river-estuary continuum, which deepens the understanding of the land-ocean integrated management of N contaminant.
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Affiliation(s)
- Anqi Zhang
- 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; 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
| | - Qi Lang
- 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.
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Liu W, Jiang H, Guo X, Li Y, Xu Z. Time-series monitoring of river hydrochemistry and multiple isotope signals in the Yarlung Tsangpo River reveals a hydrological domination of fluvial nitrate fluxes in the Tibetan Plateau. WATER RESEARCH 2022; 225:119098. [PMID: 36126428 DOI: 10.1016/j.watres.2022.119098] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 06/15/2023]
Abstract
Nutrient element cycling in the Tibetan Plateau, the highest and largest plateau in the world, is sensitive to anthropogenic disturbances and climate change. Studying the spatiotemporal dynamics of reactive nitrogen (N) - predominantly in the form of nitrate (NO3-) - in the plateau is crucial to understand the regional and global N cycles and their feedbacks with climate change. We conducted the first weekly frequency hydro-geochemical monitoring (i.e., discharge, water chemistry, and multiple isotopes) from the upper to the lower reaches of the Yarlung Tsangpo River, the largest river in the plateau, in pronounced wet/dry cycles to reveal the biogeochemical transformations and fluvial fluxes of NO3- response to hydrologic condition. Relative stable NO3- concentration and significant linear correlations between the fluvial NO3- fluxes and the discharge were observed, suggesting that a significant potential NO3- source counterbalanced the diluting effects during the rainy season. The negative correlations between δ15N-NO3- and discharge/NO3- fluxes suggested that the increasing NO3- flux respond to the increasing discharge was mainly from water leaching of 15N-depleted soil sources, rather than 15N-enriched sewage. The isotopic mixing model calculation showed that NO3- fluxes were largely generated in the relatively densely populated middle reaches (56%), of which 74% were from soil sources. The fluxes of the soil sources showed large seasonal variation and peaked in August, with hydrological condition as the primary driver. Based on the critical findings, we put forward a NO3- export conceptual model that integrated anthropogenic and climatic forcings and classified NO3- export mechanisms in river basins into transport-limited and generation-limited regimes. In a transport-limited regime that characterized most river basins in the Tibetan Plateau, fluvial NO3- flux presented a linearly relationship in response to runoff variation. In contrast, in a generation-limited regime, the flux would be largely dependent on the thermodynamic of nitrification.
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Affiliation(s)
- Wenjing Liu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hao Jiang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing 100049, China; Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Xiao Guo
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanchuan Li
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhifang Xu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Li S, Jiang H, Xu Z, Zhang Q. Backgrounds as a potentially important component of riverine nitrate loads. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:155999. [PMID: 35597340 DOI: 10.1016/j.scitotenv.2022.155999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/25/2022] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
Nitrate (NO3-) is a major trigger for river eutrophication. While efforts have been made to understand the anthropogenic NO3- pollution in rivers, the role of background NO3- in determining NO3- loads remains to be studied. In this study, we used dual-isotopes (δ15N/δ18O-NO3-) and an isotope-mixing model to reveal the natural and anthropogenic processes regulating the NO3- loads in a forest river that acts as a headwater source for the China's South to North Water Transfer Project. Even though the basin is sparsely populated, the mean NO3--N concentration (0.6 ± 0.2 mg/L) was much higher than the median concentration of global rivers (0.3 ± 0.2 mg/L). Meanwhile, the δ15N-NO3- was extremely depleted (as low as -14.4‰). The correlations between the NO3- concentrations and isotopes indicate that the nitrification of different sources (i.e., soil organic nitrogen, chemical fertilizer, manure, and sewage) dominates the NO3- loads. Soil organic nitrogen accounted for c.a. 60% of the riverine NO3- in the high-flow season, which alone exceeds China's national standard. This finding clearly shows that high NO3- loads in rivers could not all be ascribed to direct anthropogenic inputs, and background NO3- could be critical triggers. Therefore, when evaluating the NO3- pollution of rivers, the background NO3- concentrations must be considered along with the actual NO3- loads. In the low-flow season, the contribution from manure and sewage (c.a. 34%) increases. This study highlights the potentially important role of background NO3- in regulating riverine NO3- loads, providing important implications for understanding high riverine NO3- loads worldwide.
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Affiliation(s)
- Siyue Li
- Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430205, China
| | - Hao Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan 430074, China.
| | - Zhifang Xu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
| | - Quanfa Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan 430074, China.
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16
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Zhang S, Han G, Zeng J, Liu M, Li X, Liu J. Multi-isotopes revealing the coastal river anthropogenic pollutants and natural material flux to ocean: Sr, C, N, S, and O isotope study. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:61397-61411. [PMID: 35441999 DOI: 10.1007/s11356-022-20223-z] [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: 06/30/2021] [Accepted: 04/08/2022] [Indexed: 06/14/2023]
Abstract
Coastal river exports massive terrestrial materials to the adjacent marine environment with information about chemical weathering, providing critical insights on riverine flux and the potential impact on marine ecosystem. In this study, the preliminary data of dissolved strontium (Sr) and 87Sr/86Sr in a typical coastal river in southeastern China were collected along with hydrochemistry and C, N, S, and O isotopes to discriminate the source of terrestrial weathering and the riverine flux. Sr concentrations exhibited a range of 0.084 ~ 1.307 μmol L-1, and 87Sr/86Sr values ranged 0.7089 ~ 0.7164. The total cationic charge (TZ+) ranged 0.2 ~ 11.7 meq L-1 with the predominant Ca2+ which accounted for > 50% of TZ+, while the anions were dominated by HCO3-. The extremely high Na+ and Cl- near the estuary indicated seawater mixing in such a coastal river. δ13C-DIC, δ15N-NO3-, δ18O-NO3-, and δ34S-SO42- of river water ranged - 24.1‰ ~ - 9.2‰, 0.3‰ ~ 22.7‰, - 2.1‰ ~ 21.4‰, and - 9.3‰ ~ 18.0‰, respectively. δ13C enhanced correspondingly to decreased δ34S, confirming the attendance of H2SO4 in carbonate weathering. Most δ18O values exhibited within ± 10‰, indicating the dominant nitrification process. δ15N presented slightly negative relationship with δ13C and no obvious correlation with δ34S, indicating relatively limited impact of denitrification. The depleted δ13C and δ15N may be attributed to carbonate dissolution with nitric acids and the oxidation of organic matters into C and N pools. Quantitative analysis revealed that silicate weathering accounts for 79% of total dissolved Sr, indicating the dominant weathering process. The estimated monthly flux of dissolved Sr to the East China Sea was 138.1 tons, demonstrating an potential impact on seawater Sr isotope evolution. Overall, the investigations of multi-isotopes revealed the enhancement of weathering rates and the consequently depleted CO2 consumption, which further proved the involvement of strong acids (H2SO4 and HNO3). This study provides scientific insight in terrestrial weathering and anthropogenic impact of a typical coastal watershed and may orient the management of environmental issues related to coastal ecosystems.
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Affiliation(s)
- Shitong Zhang
- Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing, 100083, China
| | - Guilin Han
- Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing, 100083, China.
| | - Jie Zeng
- Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing, 100083, China
| | - Man Liu
- Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing, 100083, China
| | - Xiaoqiang Li
- Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing, 100083, China
| | - Jinke Liu
- Institute of Earth Sciences, China University of Geosciences (Beijing), Beijing, 100083, China
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Jiang H, Liu W, Li Y, Zhang J, Xu Z. Multiple Isotopes Reveal a Hydrology Dominated Control on the Nitrogen Cycling in the Nujiang River Basin, the Last Undammed Large River Basin on the Tibetan Plateau. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:4610-4619. [PMID: 35294176 DOI: 10.1021/acs.est.1c07102] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The Tibetan Plateau is sensitive to climate change, but the feedbacks of nitrogen (N) cycling to climate conditions on this plateau are not well-understood, especially under varying degrees of anthropogenic disturbances. The Nujiang River Basin, the last undammed large river basin on the Tibetan Plateau, provides an opportunity to reveal the feedbacks at a broad river basin scale. The isotopic compositions revealed that the conservative mixing of multiple sources controlled the nitrate (NO3-) loadings during the low-flow season, while biological removal processes (assimilation and denitrification) occurred in the high-flow season. During the high-flow season, soil sources, sewage, and atmospheric precipitation contributed 76.3%, 15.6%, and 8.1% to the riverine NO3-. In the low-flow season, the contribution of soil sources decreased while that of sewage increased. The relationship between d-excess and δ15N-NO3- suggests that the hydrological conditions largely controlled the N cycling dynamics in the basin, causing the high spatiotemporal heterogeneity of the riverine NO3- sources and transformation mechanisms. During the high-flow season, the precipitation and evaporation patterns controlled the in-soil processes and soil leaching. In contrast, in-stream nitrification became more evident during the low-flow season, which was related to the long water residence time. This study illustrates hydrology dominated control on N cycling over a large basin scale, which has implications for understanding the N cycling dynamics in the Tibetan Plateau.
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Affiliation(s)
- Hao Jiang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenjing Liu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanchuan Li
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiangyi Zhang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhifang Xu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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Niu C, Zhai T, Zhang Q, Wang H, Xiao L. Research Advances in the Analysis of Nitrate Pollution Sources in a Freshwater Environment Using δ 15N-NO 3- and δ 18O-NO 3. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph182211805. [PMID: 34831560 PMCID: PMC8623930 DOI: 10.3390/ijerph182211805] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 11/02/2021] [Accepted: 11/03/2021] [Indexed: 11/16/2022]
Abstract
Nitrate is usually the main pollution factor in the river water and groundwater environment because it has the characteristics of stable properties, high solubility and easy migration. In order to ensure the safety of water supply and effectively control nitrate pollution, it is very important to accurately identify the pollution sources of nitrate in freshwater environment. At present, as the most accurate source analysis method, isotope technology is widely used to identify the pollution sources of nitrate in water environment. However, the complexity of nitrate pollution sources and nitrogen migration and transformation in the water environment, coupled with the isotopic fractionation, has changed the nitrogen and oxygen isotopic values of nitrate in the initial water body, resulting in certain limitations in the application of this technology. This review systematically summarized the typical δ15N and δ18O-NO3- ranges of NO3- sources, described the progress in the application of isotope technique to identify nitrate pollution sources in water environment, analyzed the application of isotope technique in identifying the migration and transformation of nitrogen in water environment, and introduced the method of quantitative source apportionment. Lastly, we discussed the deficiency of isotope technique in nitrate pollution source identification and described the future development direction of the pollution source apportionment of nitrate in water environment.
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Affiliation(s)
- Chao Niu
- College of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710054, China; (C.N.); (L.X.)
| | - Tianlun Zhai
- Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China;
| | - Qianqian Zhang
- Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China;
- Correspondence: (Q.Z.); (H.W.)
| | - Huiwei Wang
- Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang 050061, China;
- Correspondence: (Q.Z.); (H.W.)
| | - Lele Xiao
- College of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710054, China; (C.N.); (L.X.)
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