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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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Xie R, Lin L, Shi C, Zhang P, Rao P, Li J, Izabel-Shen D. Elucidating the links between N 2O dynamics and changes in microbial communities following saltwater intrusions. ENVIRONMENTAL RESEARCH 2024; 245:118021. [PMID: 38147917 DOI: 10.1016/j.envres.2023.118021] [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: 11/16/2023] [Revised: 12/18/2023] [Accepted: 12/22/2023] [Indexed: 12/28/2023]
Abstract
Saltwater intrusion in estuarine ecosystems alters microbial communities as well as biogeochemical cycling processes and has become a worldwide problem. However, the impact of salinity intrusion on the dynamics of nitrous oxide (N2O) and associated microbial community are understudied. Here, we conducted field microcosms in a tidal estuary during different months (December, April and August) using dialysis bags, and microbes inside the bags encountered a change in salinity in natural setting. We then compared N2O dynamics in the microcosms with that in natural water. Regardless of incubation environment, saltwater intrusion altered the dissolved N2O depending on the initial saturation rates of N2O. While the impact of saltwater intrusion on N2O dynamics was consistent across months, the dissolved N2O was higher in summer than in winter. The N-related microbial communities following saltwater intrusion were dominated by denitrifers, with fewer nitrifiers and bacterial taxa involved in dissimilatory nitrate reduction to ammonium. While denitrification was a significant driver of N2O dynamics in the studied estuary, nitrifier-involved denitrification contributed to the additional production of N2O, evidenced by the strong associations with amoA genes and the abundance of Nitrospira. Higher N2O concentrations in the field microcosms than in natural water limited N2O consumption in the former, given the lack of an association with nosZ gene abundance. The differences in the N2O dynamics observed between the microcosms and natural water could be that the latter comprised not only indigenous microbes but also those accompanied with saltwater intrusion, and that immigrants might be functionally rich individuals and able to perform N transformation in multiple pathways. Our work provides the first quantitative assessment of in situ N2O concentrations in an estuary subjected to a saltwater intrusion. The results highlight the importance of ecosystem size and microbial connectivity in the source-sink dynamics of N2O in changing environments.
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Affiliation(s)
- Rongrong Xie
- College of Environmental and Resource Science, Fujian Normal University, Fuzhou, 350117, China; Key Laboratory of Pollution Control and Resource Recycling of Fujian Province, Fujian Normal University, Fuzhou, 350117, China; Leibniz Institute for Baltic Sea Research, Warnemünde, Rostock, 18119, Germany.
| | - Laichang Lin
- College of Environmental and Resource Science, Fujian Normal University, Fuzhou, 350117, China
| | - Chengchun Shi
- Fujian Research Academy of Environmental Sciences, Fuzhou, 350013, China
| | - Peng Zhang
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, China
| | - Peiyuan Rao
- College of Environmental and Resource Science, Fujian Normal University, Fuzhou, 350117, China
| | - Jiabing Li
- College of Environmental and Resource Science, Fujian Normal University, Fuzhou, 350117, China; Key Laboratory of Pollution Control and Resource Recycling of Fujian Province, Fujian Normal University, Fuzhou, 350117, China
| | - Dandan Izabel-Shen
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Oldenburg, 26129, Germany; Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, 27570, Germany.
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3
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Shu W, Zhang Q, Audet J, Li Z, Leng P, Qiao Y, Tian C, Chen G, Zhao J, Cheng H, Li F. Non-negligible N 2O emission hotspots: Rivers impacted by ion-adsorption rare earth mining. WATER RESEARCH 2024; 251:121124. [PMID: 38237464 DOI: 10.1016/j.watres.2024.121124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Revised: 12/06/2023] [Accepted: 01/08/2024] [Indexed: 02/12/2024]
Abstract
Rare earth mining causes severe riverine nitrogen pollution, but its effect on nitrous oxide (N2O) emissions and the associated nitrogen transformation processes remain unclear. Here, we characterized N2O fluxes from China's largest ion-adsorption rare earth mining watershed and elucidated the mechanisms that drove N2O production and consumption using advanced isotope mapping and molecular biology techniques. Compared to the undisturbed river, the mining-affected river exhibited higher N2O fluxes (7.96 ± 10.18 mmol m-2d-1 vs. 2.88 ± 8.27 mmol m-2d-1, P = 0.002), confirming that mining-affected rivers are N2O emission hotspots. Flux variations scaled with high nitrogen supply (resulting from mining activities), and were mainly attributed to changes in water chemistry (i.e., pH, and metal concentrations), sediment property (i.e., particle size), and hydrogeomorphic factors (e.g., river order and slope). Coupled nitrification-denitrification and N2O reduction were the dominant processes controlling the N2O dynamics. Of these, the contribution of incomplete denitrification to N2O production was greater than that of nitrification, especially in the heavily mining-affected reaches. Co-occurrence network analysis identified Thiomonas and Rhodanobacter as the key genus closely associated with N2O production, suggesting their potential roles for denitrification. This is the first study to elucidate N2O emission and influential mechanisms in mining-affected rivers using combined isotopic and molecular techniques. The discovery of this study enhances our understanding of the distinctive processes driving N2O production and consumption in highly anthropogenically disturbed aquatic systems, and also provides the foundation for accurate assessment of N2O emissions from mining-affected rivers on regional and global scales.
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Affiliation(s)
- Wang Shu
- Shandong Yucheng Agro-Ecosystem National Observation and Research Station, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College of University of Chinese Academy of Sciences, Beijing 101408, China; Sino-Danish Centre for Education and Research, Beijing 101408, China
| | - Qiuying Zhang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
| | - Joachim Audet
- Department of Ecoscience, Aarhus University, C.F. Møllers Allé, Aarhus 8000, Denmark
| | - Zhao Li
- Shandong Yucheng Agro-Ecosystem National Observation and Research Station, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Peifang Leng
- Shandong Yucheng Agro-Ecosystem National Observation and Research Station, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Yunfeng Qiao
- Shandong Yucheng Agro-Ecosystem National Observation and Research Station, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Chao Tian
- Shandong Yucheng Agro-Ecosystem National Observation and Research Station, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
| | - Gang Chen
- Department of Civil and Environmental Engineering, Florida A&M University (FAMU)-Florida State University (FSU) Joint College of Engineering, 32310, United States
| | - Jun Zhao
- School of Geography and Ocean Science, Nanjing University, Nanjing 210023, China
| | - Hefa Cheng
- MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
| | - Fadong Li
- Shandong Yucheng Agro-Ecosystem National Observation and Research Station, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; Sino-Danish College of University of Chinese Academy of Sciences, Beijing 101408, China.
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Wang Z, Ruan X, Li R, Zhang Y. Microbial interaction patterns and nitrogen cycling regularities in lake sediments under different trophic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:167926. [PMID: 37863216 DOI: 10.1016/j.scitotenv.2023.167926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 10/05/2023] [Accepted: 10/16/2023] [Indexed: 10/22/2023]
Abstract
Exploring how nitrogen (N) cycling microbes interact in eutrophic lake sediments and how biogenic elements influence the nitrogen cycle is crucial for understanding biogeochemical cycles and nitrogen accumulation mechanisms. In this study, sediment samples were collected from various areas of Taihu Lake with different trophic conditions in all four seasons from 2015 to 2017. Using high-throughput sequencing and molecular ecological network analysis, we investigated the microbial interaction patterns and the role of nitrogen cycling in sediments from lakes with different trophic conditions. The results showed distinct structures of sediment microbial networks between lake areas with different trophic conditions. In the more eutrophic region, network indices indicate higher transfer efficiency of energy, material, and information, more significant competition, and weaker niche differentiation of the microbial community. The sedimentary environment in the moderately eutrophic area exhibited greater potential for denitrification, nitrification, and anammox compared to the mesotrophic area, but the inhibition between N functional microbes and limitations in N removal processes were also more likely to occur. The topological structure of the networks showed that the carbon (C), sulfur (S), and iron (Fe) cycles had a strong influence on the nitrogen cycle in both lake areas. In the moderately eutrophic lake area, C- and S-cycling functional bacteria facilitated a closed cycle of the coupled N fixation-nitrification-DNRA (dissimilatory nitrate reduction to ammonium) process and reduced N removal. In the mesotrophic lake area, C- and S-cycling functional bacteria promoted both N fixation and mineralization, and Fe-cycling functional bacteria coupled with denitrifiers enhanced the nitrogen removal process of products from nitrogen fixation and mineralization. This study improved the understanding of the nitrogen cycling mechanism in lake sediments under different trophic conditions.
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Affiliation(s)
- Ziwei Wang
- Department of Hydrosciences, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China; MOE Key Laboratory of Surficial Geochemistry, Nanjing University, Nanjing 210023, China
| | - Xiaohong Ruan
- Department of Hydrosciences, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China; MOE Key Laboratory of Surficial Geochemistry, Nanjing University, Nanjing 210023, China.
| | - Rongfu Li
- Department of Hydrosciences, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China; MOE Key Laboratory of Surficial Geochemistry, Nanjing University, Nanjing 210023, China
| | - Yaping Zhang
- Department of Hydrosciences, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China; MOE Key Laboratory of Surficial Geochemistry, Nanjing University, Nanjing 210023, China
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5
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Yang X, Mazarji M, Li M, Li A, Li R, Zhang Z, Pan J. Mechanism of magnetite-assisted aerobic composting on the nitrogen cycle in pig manure. BIORESOURCE TECHNOLOGY 2024; 391:129985. [PMID: 37931761 DOI: 10.1016/j.biortech.2023.129985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/26/2023] [Accepted: 11/03/2023] [Indexed: 11/08/2023]
Abstract
Magnetite affects nitrogen cycle of pig manure (PM) biostabilisation was investigated. Various doses of magnetite (0 % (T1); 2.5 % (T2); 5 % (T3); 7.5 % (T4)) were homogeneously added into PM and wolfberry branch fillings (BF) mixture for a 50-day composting. Compared to T1, total nitrogen (TN) loss in gaseous form increased remarkably by 17.51 %, 56.31 %, and 24.91 %, respectively, in T2-T4. In particular, T3 dramatically increased the cumulative N2O emission but decreased NH3 emissions. However, T2 and T3 enhanced the total nitrogen contents by 7.24 % and 3.09 %. Structural equation models (SEM) analysis indicated that magnetite addition increased the direct and indirect pathways of N2O emission. Further analysis revealed that Ruminofilibacter and N2O emission were significantly correlated, and Pseudomonas played a vital role in nitrogen preservation. Although using 2 % magnetite as an additive could increase the TN content, the obvious increase of N2O emission should be considered in engineering practice.
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Affiliation(s)
- Xu Yang
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China; College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Mahmoud Mazarji
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Mengtong Li
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Aohua Li
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Ronghua Li
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Zengqiang Zhang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Junting Pan
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
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Qiao Z, Sheng Y, Wang G, Chen X, Liao F, Mao H, Zhang H, He J, Liu Y, Lin Y, Yang Y. Deterministic factors modulating assembly of groundwater microbial community in a nitrogen-contaminated and hydraulically-connected river-lake-floodplain ecosystem. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 347:119210. [PMID: 37801950 DOI: 10.1016/j.jenvman.2023.119210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/25/2023] [Accepted: 09/30/2023] [Indexed: 10/08/2023]
Abstract
The river-lake-floodplain system (RLFS) undergoes intensive surface-groundwater mass and energy exchanges. Some freshwater lakes are groundwater flow-through systems, serving as sinks for nitrogen (N) entering the lake. Despite the threat of cross-nitrogen contamination, the assembly of the microbial communities in the RLFS was poorly understood. Herein, the distribution, co-occurrence, and assembly pattern of microbial community were investigated in a nitrogen-contaminated and hydraulically-connected RLFS. The results showed that nitrate was widely distributed with greater accumulation on the south than on the north side, and ammonia was accumulated in the groundwater discharge area (estuary and lakeshore). The heterotrophic nitrifying bacteria and aerobic denitrifying bacteria were distributed across the entire area. In estuary and lakeshore with low levels of oxidation-reduction potential (ORP) and high levels of total organic carbon (TOC) and ammonia, dissimilatory nitrate reduction to ammonium (DNRA) bacteria were enriched. The bacterial community had close cooperative relationships, and keystone taxa harbored nitrate reduction potentials. Combined with multivariable statistics and self-organizing map (SOM) results, ammonia, TOC, and ORP acted as drivers in the spatial evolution of the bacterial community, coincidence with the predominant deterministic processes and unique niche breadth for microbial assembly. This study provides novel insight into the traits and assembly of bacterial communities and potential nitrogen cycling capacities in RLFS groundwater.
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Affiliation(s)
- Zhiyuan Qiao
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Yizhi Sheng
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China.
| | - Guangcai Wang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China.
| | - Xianglong Chen
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Fu Liao
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Hairu Mao
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Hongyu Zhang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Jiahui He
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Yingxue Liu
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Yilun Lin
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Ying Yang
- State Key Laboratory of Biogeology and Environmental Geology & MOE Key Laboratory of Groundwater Circulation and Environment Evolution, China University of Geosciences, Beijing, 100083, PR China; School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
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Liang J, Ding J, Zhu Z, Gao X, Li S, Li X, Yan M, Zhou Q, Tang N, Lu L, Li X. Decoupling the heterogeneity of sediment microbial communities along the urbanization gradients: A Bayesian-based approach. ENVIRONMENTAL RESEARCH 2023; 238:117255. [PMID: 37775011 DOI: 10.1016/j.envres.2023.117255] [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: 06/23/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/01/2023]
Abstract
Comprehending the response of microbial communities in rivers along urbanization gradients to hydrologic characteristics and pollution sources is critical for effective watershed management. However, the effects of complex factors on riverine microbial communities remain poorly understood. Thus, we established a bacteria-based index of biotic integrity (Ba-IBI) to evaluate the microbial community heterogeneity of rivers along an urbanization gradient. To examine the response of Ba-IBI to multiple stressors, we employed a Bayesian network based on structural equation modeling (SEM-BN) and revealed the key control factors influencing Ba-IBI at different levels of urbanization. Our findings highlight that waterborne nutrients have the most significant direct impact on Ba-IBI (r = -0.563), with a particular emphasis on ammonia nitrogen, which emerged as the primary driver of microbial community heterogeneity in the Liuyang River basin. In addition, our study confirmed the substantial adverse effects of urbanization on river ecology, as urban land use had the greatest indirect effect on Ba-IBI (r = -0.460). Specifically, the discharge load from wastewater treatment plants (WWTP) was found to significantly negatively affect the Ba-IBI of the entire watershed. In the low urbanized watersheds, rice cultivation (RC) and concentrated animal feeding operations (CAFO) are key control factors, and an increase in their emissions can lead to a sharp decrease in Ba-IBI. In moderately urbanized watersheds, the Ba-IBI tended to decrease as the level of RC emissions increased, while in those with moderate RC emissions, an increase in point source emissions mitigated the negative impact of RC on Ba-IBI. In highly urbanized watersheds, Ba-IBI was not sensitive to changes in stressors. Overall, our study presents a novel approach by integrating Ba-IBI with multi-scenario analysis tools to assess the effects of multiple stressors on microbial communities in river sediments, providing valuable insights for more refined environmental decision-making.
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Affiliation(s)
- Jie Liang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China.
| | - Junjie Ding
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Ziqian Zhu
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Xiang Gao
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Shuai Li
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Xin Li
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Min Yan
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Qinxue Zhou
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Ning Tang
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Lan Lu
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
| | - Xiaodong Li
- College of Environmental Science and Engineering, Hunan University and Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, 41082, PR China
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Shang J, Zhang W, Gao Y, Li Y, Wu H. Dam-induced flow alternations drive the regime shift towards a cyanobacteria-dominated microbiota state in the Yangtze River. WATER RESEARCH 2023; 244:120527. [PMID: 37651866 DOI: 10.1016/j.watres.2023.120527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 07/25/2023] [Accepted: 08/24/2023] [Indexed: 09/02/2023]
Abstract
While satisfying the demands of social and economic development, dams act as physical barriers affecting both abiotic and biotic factors in large rivers. These altered factors can interact with each other and gradually reshape the local ecosystem state. The reshaped state may spread downstream and affect ecosystem states on a large scale. However, the spread extent and characteristics of ecosystem states along large rivers remain understudied. To address this problem, alternative microbiota states and their responses to environmental conditions in the Yangtze River were investigated, considering the preponderance of alternative stable states theory in explaining the response of ecosystem states as well as the role of benthic microorganisms in indicating ecosystem states. In this study, flow discharge was identified as the main hydrological factor that clustered benthic microbiota into two types, and these two microbiota types were bistable and characterized by differential enrichment of the Cyanobacteria phylum. Potential analysis demonstrated that reducing flow discharge beneath a threshold (i.e., flow discharge < 12,900 m3/s) could shift benthic microbiotas to a state where benthic cyanobacteria would become the dominant species (the Microbiota State B). In the bistable region (i.e., 12,900 < flow discharge < 28,000 m3/s), both the ecological resilience and the contribution of deterministic process were found weak by relative potential depth calculations and neutral community modeling, suggesting that this region is susceptible to the microbiota state of its upstream and thus deserves more scientific attention to prevent the unfavorable state from spreading downstream. In addition, high denitrification potential at sites of the Microbiota State B was likely responsible for the low N:P ratio, further benefiting the dominance of N-fixing cyanobacteria. This study empirically showed the response of alternative microbiota states to flow gradients, and explored the distribution and characteristics of the microbiota states along the mainstream of the Yangtze River, therefore providing insights into environmental flow design and reservoir regulation of large rivers.
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Affiliation(s)
- Jiahui Shang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xikang Road #1, Nanjing 210098, PR China
| | - Wenlong Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xikang Road #1, Nanjing 210098, PR China.
| | - Yu Gao
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xikang Road #1, Nanjing 210098, PR China
| | - Yi Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Xikang Road #1, Nanjing 210098, PR China.
| | - Hainan Wu
- College of Environmental Science and Engineering, Yangzhou University, Huayang West Road #196, Yangzhou 225009, PR China
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9
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Zhang W, Liu B, Sun Z, Wang T, Tan S, Fan X, Zou D, Zhuang Y, Liu X, Wang Y, Li Y, Mai K, Ye C. Comparision of nitrogen removal characteristic and microbial community in freshwater and marine recirculating aquaculture systems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 878:162870. [PMID: 36933726 DOI: 10.1016/j.scitotenv.2023.162870] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/27/2023] [Accepted: 03/10/2023] [Indexed: 05/13/2023]
Abstract
Recirculating aquaculture system (RAS) has a good prospect in aquaculture, but its nitrogen removal characteristics and microbial community changes in freshwater and marine water remain unclear. In this study, six RAS were designed and divided into freshwater group and marine water group with salinity of 0‰ and 32‰, respectively, and operated for 54 days to test changes in nitrogen (NH4+-N, NO2--N, NO3--N), extracellular polymeric substances and microbial communities. The results showed that ammonia nitrogen was rapidly reduced and almost converted to nitrate nitrogen in the freshwater RAS but to nitrite nitrogen in marine RAS. Compared with freshwater RAS, marine RAS had lower tightly bound extracellular polymeric substances and worse stability and settleability condition. 16S rRNA amplicon sequencing reflected significantly lower bacterial diversity and richness in marine RAS. Microbial community structure at phylum level showed lower relative abundance of Proteobacteria, Actinobacteria, Firmicutes, Nitrospirae, but higher abundance of Bacteroidetes under a salinity of 32‰. High salinity decreased the abundance of funtional genera (Nitrosospira, Nitrospira, Pseudomonas, Rhodococcus, Comamonas, Acidovorax, f_Comamonadaceae), which may account for nitrite accumulation and low nitrogen removal capacity in marine RAS. These findings could provide theoretical and practical basis for improving the start-up speed of high-salinity nitrification biofilm.
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Affiliation(s)
- Wenqian Zhang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Bo Liu
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Zhenzhu Sun
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Tingyu Wang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Simin Tan
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Xin Fan
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Danyang Zou
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Yutong Zhuang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Xinting Liu
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Yizhu Wang
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Yanyu Li
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Kangsen Mai
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China
| | - Chaoxia Ye
- Guangzhou Key Laboratory of Subtropical Biodiversity and Biomonitoring, Institute of Modern Aquaculture Science and Engineering, Guangdong Provincial Key Laboratory for Healthy and Safe Aquaculture, School of Life Science, South China Normal University, Guangzhou 510631, People's Republic of China.
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10
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Shang J, Zhang W, Li Y, Zheng J, Ma X, Wang L, Niu L. How nutrient loading leads to alternative stable states in microbially mediated N-cycle pathways: A new insight into bioavailable nitrogen removal in urban rivers. WATER RESEARCH 2023; 236:119938. [PMID: 37054605 DOI: 10.1016/j.watres.2023.119938] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/14/2023] [Accepted: 04/02/2023] [Indexed: 06/19/2023]
Abstract
Excessive nutrients have disrupted pathways of microbial-mediated nitrogen (N) cycle in urban rivers and caused bioavailable N to accumulate in sediments, while remedial actions sometimes fail to recover degraded river ecosystems even when environmental quality has been improved. It is not sufficient to revert the ecosystem to its original healthy state by restoring the pre-degradation environmental conditions, as explained by alternative stable states theory. Understanding the recovery of disrupted N-cycle pathways from the perspective of alternative stable states theory can benefit effective river remediation. Previous studies have found alternative microbiota states in rivers; however, the existence and implications of alternative stable states in microbial-mediated N-cycle pathway remain unclear. Here, high-throughput sequencing and N-related enzyme activities measurement were combined in the field investigation to provide empirical evidence for the bi-stability in microbially mediated N-cycle pathways. According to the behavior of bistable ecosystems, the existence of alternative stable states in microbial-mediated N-cycle pathway have been shown, and nutrient loading, mainly total nitrogen and total phosphorus, were identified as key driver of regime shifts. In addition, potential analysis revealed that reducing nutrient loading shifted the N-cycle pathway to a desirable state characterized by high ammonification and nitrification, probably avoiding the accumulation of ammonia and organic N. It should be noted that the improvement of microbiota status can facilitate the recovery of the desirable pathway state according to the relationship between microbiota states and N-cycle pathway states. Keystone species, including Rhizobiales and Sphingomonadales, were discerned by network analysis, and the increase in their relative abundance may facilitate the improvement of microbiota status. The obtained results suggested that the nutrient reduction should be combined with microbiota management to benefit the bioavailable N removal in urban rivers, therefore providing a new insight into alleviating adverse effects of the nutrient loading on urban rivers.
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Affiliation(s)
- Jiahui Shang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China; Research Institute of Mulan Ecological River, Putian 351100, PR China
| | - Wenlong Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China.
| | - Yi Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China; Research Institute of Mulan Ecological River, Putian 351100, PR China.
| | - Jinhai Zheng
- College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, PR China; Research Institute of Mulan Ecological River, Putian 351100, PR China
| | - Xin Ma
- College of Hydrology and Water Resources, Hohai University, Nanjing 210098, PR China; Research Institute of Mulan Ecological River, Putian 351100, PR China
| | - Longfei Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China; Research Institute of Mulan Ecological River, Putian 351100, PR China
| | - Lihua Niu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, PR China; Research Institute of Mulan Ecological River, Putian 351100, PR China
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11
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Yan R, Wang F, Wang Y, Chen N. Pollution abatement reducing the river N 2O emissions although it is partially offset by a warming climate: Insights from an urbanized watershed study. WATER RESEARCH 2023; 236:119934. [PMID: 37043873 DOI: 10.1016/j.watres.2023.119934] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 03/15/2023] [Accepted: 03/31/2023] [Indexed: 06/19/2023]
Abstract
Global nitrogen (N) pollution has resulted in increased river nitrous oxide (N2O) emissions, which contribute to climate change. However, little is known about how pollution abatement conversely reduces river N2O production in a warming climate. Here, field observations and microcosmic experiments were conducted in a coastal urbanized watershed (S.E. China) to explore the interactive effect of changing nitrate and temperature on river sediment denitrification (DNF) and N2O production. The results showed that urban river reaches (UR) with higher organic carbon content and denitrifying gene abundance in sediments have a greater DNF rate, nitrate removal efficiency (NRE), and N2O concentration than agricultural river reaches (AR). Microcosmic incubation suggested that the DNF rate and associated N2O production decreased under low nitrate addition, wherein the NRE increased. The scenario simulation illustrated a nonlinear response of N2O production to nitrate removal (i.e., ΔN2O/ΔNO3-N) from both UR and AR sediments at a given temperature, and the DNF rate and N2O production increased with increasing temperature. An increase in temperature by 1 degree Celsius would offset 18.75% of the N2O reduction by nitrate removal via DNF. These findings implied that watershed pollution abatement undoubtedly contributes to the reduction in global river N2O emissions although it is partially offset by extra N2O production caused by global warming.
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Affiliation(s)
- Ruifeng Yan
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China
| | - Fenfang Wang
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen, 361102, China
| | - Yao Wang
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China
| | - Nengwang Chen
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen, 361102, China.
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12
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Yang F, Guo J, Qi R, Yan C. Isotopic and hydrochemical analyses reveal nitrogen source variation and enhanced nitrification in a managed peri-urban watershed. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 316:120534. [PMID: 36341828 DOI: 10.1016/j.envpol.2022.120534] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 10/15/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Watershed management practices (WMPs) alter the sources and transformation of reactive nitrogen (N) in peri-urban watersheds, but a precise description of how WMPs impact N cycling is still lacking. In this study, four sampling campaigns were conducted in the wet and dry seasons of 2019 (before WMPs) and 2020 (after WMPs) to determine the spatiotemporal variations in nitrate isotopes (15N-NO3- and 18O-NO3-) and hydrochemical compositions in the Muli River watershed. The results showed that the WMPs could significantly reduce the N load in the middle and lower reaches, but substantial improvements were not observed in 2020. Manure and sewage (M&S, 36.2 ± 15.8-55.0 ± 19.4%) was the major source of nitrate (NO3-) in the stream water, followed by smaller-scale wastewater treatment plants (WWTPs, 14.0 ± 10.9-25.6 ± 11.5%). The WMPs were effective in controlling M&S, resulting in an approximately 16.7% (p < 0.01) lower M&S contribution during the dry season in 2020 compared to that in 2019. However, the smaller-scale WWTP input increased by approximately 5.4% (p < 0.01) after the WMPs. During the study period, the assimilation of NO3- by phytoplankton was important for NO3- loss, but the WMPs promoted nitrification in the watershed because of the elevated redox potential (Eh). Overall, the present study provides a better estimate of the variations in nitrogen sources and transformation in a peri-urban watershed after WMPs and provides an approach for developing timely nitrogen management solutions.
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Affiliation(s)
- Fan Yang
- Key Laboratory of Urban Environment and Health, Fujian Key Laboratory of Watershed Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Jianhua Guo
- Yellow River Institute of Hydraulic Research, Zhengzhou, 450003, China
| | - Ran Qi
- Key Laboratory of Urban Environment and Health, Fujian Key Laboratory of Watershed Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Changzhou Yan
- Key Laboratory of Urban Environment and Health, Fujian Key Laboratory of Watershed Ecology, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
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Hao Z, Dong Z, Han S, Zhang A. Effects of biochar and arbuscular mycorrhizal fungi on winter wheat growth and soil N 2O emissions in different phosphorus environments. FRONTIERS IN PLANT SCIENCE 2022; 13:1069627. [PMID: 36589067 PMCID: PMC9795251 DOI: 10.3389/fpls.2022.1069627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 11/23/2022] [Indexed: 06/17/2023]
Abstract
INTRODUCTION Promoting crop growth and regulating denitrification process are two main ways to reduce soil N2O emissions in agricultural systems. However, how biochar and arbuscular mycorrhizal fungi (AMF) can regulate crop growth and denitrification in soils with different phosphorus (P) supplies to influence N2O emission remains largely unknown. METHOD Here, an eight-week greenhouse and one-year field experiments biochar and/or AMF (only in greenhouse experiment) additions under low and high P environments were conducted to characterize the effects on wheat (Triticum aestivum L.) growth and N2O emission. RESULTS With low P supply, AMF addition decreased leaf Mn concentration (indicates carboxylate-releasing P-acquisition strategies), whereas biochar addition increased leaf Mn concentration, suggesting biochar and AMF addition regulated root morphological and physiological traits to capture P. Compared with low P supply, the high P significantly promoted wheat growth (by 16-34%), nutrient content (by 33-218%) and yield (by 33-41%), but suppressed soil N2O emissions (by 32-95%). Biochar and/or AMF addition exhibited either no or negative effects on wheat biomass and nutrient content in greenhouse, and biochar addition promoted wheat yield only under high P environment in field. However, biochar and/or AMF addition decreased soil N2O emissions by 24-93% and 32% in greenhouse and field experiments, respectively. This decrease was associated mainly with the diminished abundance of N2O-producing denitrifiers (nirK and nirS types, by 17-59%, respectively) and the increased abundance of N2O-consuming denitrifiers (nosZ type, by 35-65%), and also with the increased wheat nutrient content, yield and leaf Mn concentration. DISCUSSION These findings suggest that strengthening the plant-soil-microbe interactions can mitigate soil N2O emissions via manipulating plant nutrient acquisition and soil denitrification.
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