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Zhang T, Xu Q, Liu X, Lei Q, Luo J, An M, Du X, Qiu W, Zhang X, Wang F, Liu H. Sources, fate and influencing factors of nitrate in farmland drainage ditches of the irrigation area. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 367:122113. [PMID: 39111010 DOI: 10.1016/j.jenvman.2024.122113] [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: 02/21/2024] [Revised: 05/29/2024] [Accepted: 08/03/2024] [Indexed: 08/15/2024]
Abstract
Global irrigation areas face the contradictory challenges of controlling nitrate inputs and ensuring food-safe production. To prevent and control nitrate pollution in irrigation areas, the study using the Yellow River basin (Ningxia section) of China as a case study, employed nitrogen and oxygen dual isotope tracing and extensive field investigations to analyze the sources, fate, and influencing factors of nitrate in agricultural drainage ditches. The results of source tracing of nitrate showed that annual proportions of nitrate sources entering the Yellow River in the ditches are as follows: for manure & sewage, fertilizer, and natural sources, the ratios are 33%, 35%, and 32% overall. The results of nitrate fate showed that nitrates derived from nitrate fertilizer exhibit a lower residual rate in drainage ditches (ecological ditches) compared to ammonium fertilizer, which can undergo self-ecological restoration within one year. The results of influencing factors showed that crops with high water and nutrient requirements, such as vegetables, the nitrate pollution and environmental harm resulting from "exploitative cultivation" are five times more than normal cultivation practices in dryland and paddy fields, especially winter irrigation without crop interception exacerbates the leaching of nitrate from the soil. Therefore, nitrate management in irrigation areas should focus on preventing and controlling "exploitative cultivation" and losses during winter irrigation, while appropriately adjusting the application ratio of ammonium nitrogen fertilizers. The results of the study can guide strategies to mitigate nitrate pollution in irrigated areas such as livestock farming, fertilizer application, irrigation management, ditch optimization, and crop cultivation.
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Affiliation(s)
- Tianpeng Zhang
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Qiyu Xu
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Xiaotong Liu
- Institute of Agricultural Resources and Environment, Ningxia Academy of Agriculture and Forestry Sciences, Yinchuan, 750002, China
| | - Qiuliang Lei
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Jiafa Luo
- AgResearch Ruakura, Hamilton, 3240, New Zealand
| | - Miaoying An
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
| | - Xinzhong Du
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
| | - Weiwen Qiu
- The New Zealand Institute for Plant and Food Research Limited Private Bag 3230, Hamilton, 3240, New Zealand
| | - Xuejun Zhang
- Institute of Agricultural Resources and Environment, Ningxia Academy of Agriculture and Forestry Sciences, Yinchuan, 750002, China
| | - Fengzhi Wang
- Analysis and Testing Center of Ningxia, North Minzu University, Yinchuan, 750021, China
| | - Hongbin Liu
- State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, Key Laboratory of Non-point Source Pollution Control, Ministry of Agriculture and Rural Affairs, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, China
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Li Y, Zhang M, Liu X, Zhang L, Chen F. Trophic homogeneity due to seasonal variation in nitrogen in shallow subtropical lakes. WATER RESEARCH 2024; 266:122321. [PMID: 39217645 DOI: 10.1016/j.watres.2024.122321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 07/22/2024] [Accepted: 08/23/2024] [Indexed: 09/04/2024]
Abstract
Lakes play a crucial role in the nitrogen (N) cycle, and eutrophication disrupts the balance of the nitrogen cycle within lakes, including both the N removal process and the N supplement process. However, the mechanisms by which different nutrient levels affect seasonal nitrogen variations in the water columns are not clear, especially for long-term and large- scale studies. In this study, we used 206 independent spatial samples from a total of 108 subtropical shallow lakes from four surveys in the middle and lower reaches of the Yangtze River, as well as time-case study data from Lake Taihu and Lake Donghu of up to 23 and 14 years, respectively, to analyze the changes in summer TN compared to spring (delta TN). Delta TN was significantly negatively correlated with initial spring TN concentrations, with similar trends observed in both space and time. Furthermore, the slopes of spring TN vs. delta TN varied little across lakes in both time and space, suggesting a consistent relationship between initial spring TN and summer TN changes. When initial TN or TN: TP ratio was low, N fixation by algae played a significant role in compensating for summer N removal, thus mitigating summer N reductions; when TN was high or TN: TP ratio was high, ammonia stress reduced the compensatory effect of algae and denitrification played a significant role in summer N removal, thus increasing summer N reductions. Our study suggested that no matter what the initial conditions are, lakes tend to evolve towards a common nutrient status through biological regulation.
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Affiliation(s)
- Yun Li
- Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Min Zhang
- Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Xia Liu
- Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Lu Zhang
- Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Feizhou Chen
- Key Laboratory of Lake and Watershed Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
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Bu H, Fry B, Burford MA. Effects of macrophytes and environmental factors on sediment denitrification in a subtropical reservoir. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 303:119118. [PMID: 35278586 DOI: 10.1016/j.envpol.2022.119118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/03/2022] [Accepted: 03/05/2022] [Indexed: 06/14/2023]
Abstract
Sediment denitrification plays an important role in nitrogen removal in aquatic systems. However, the importance in nitrogen removal in reservoirs, with a focus on seasonal differences of conditions such as macrophyte beds and environmental factors, is less well understood. This study examined sediment denitrification rate (Dn), and their potential controlling factors were determined in both macrophyte beds and deeper waters in the subtropical reservoir. The mean Dn in the reservoir annually was 18.0 ± 6.3 (mean ± S.E.) mmol N m-2 d-1, with significant seasonal variation (p < 0.01), i.e. 43.2 ± 12.8, 6.7 ± 6.3, and 4.0 ± 2.2 mmol N m-2 d-1 in winter, spring and summer respectively. There were no statistical differences in Dn between shallow waters with macrophyte beds and deeper waters without macrophyte beds, although macrophyte beds had higher denitrification rates in summer. The Dn rates were significantly correlated with temperature, conductivity, dissolved oxygen, pH, nitrate-nitrogen concentration (NO3--N) (p < 0.01) and turbidity (p < 0.05). Linear regression models demonstrated environmental variables explained between 36% and 76% of the variation in Dn. The correlation with NO3--N concentrations suggests that it may be a limited factor for Dn. Annual nitrogen removal of the reservoir by a combination of sediment and water denitrification was totally estimated to be 370 t N with an annual removal efficiency of approximately 11%. Nitrogen removal was much higher in winter than other seasons, with about 305 t N removed, accounting for 12% of the total nitrogen inputs. Therefore, denitrification appears to play a minor role throughout much of the year, but in winter months when nitrate accumulates, it may play a more major role.
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Affiliation(s)
- Hongmei Bu
- Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Brian Fry
- Australian Rivers Institute and School of Environment and Science, Griffith University, Nathan, QLD, 4111, Australia
| | - Michele A Burford
- Australian Rivers Institute and School of Environment and Science, Griffith University, Nathan, QLD, 4111, Australia
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Zhihao W, Xia J, Shuhang W, Li Z, Lixin J, Junyi C, Qing C, Kun W, Cheng Y. Mobilization and geochemistry of nutrients in sediment evaluated by diffusive gradients in thin films: Significance for lake management. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 292:112770. [PMID: 34020304 DOI: 10.1016/j.jenvman.2021.112770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 04/29/2021] [Accepted: 05/04/2021] [Indexed: 06/12/2023]
Abstract
Investigation of in-situ mobilization of both nitrogen (N) and phosphate (PO43-) in sediment is important for lake management strategy. In this paper, diffusion gradients in thin films (DGT) and DGT induced flux in sediments (DIFS) model are newly designed for in-situ measurement of iron (Fe), PO43-, nitrate (NO3-N) and ammonium (NH4-N), and nutrients' mobility in sediment in Lake Nanhu (China). According to DGT profiles together with physicochemical properties in sediment, (I) PO43- is released from (i) Fe-bound P plus loosely sorbed P in anoxic sediment and (ii) the loosely sorbed P in oxic sediment; (II) anoxic sediment inhibits nitrification and NO3-N release, but it favors denitrification and dissimilatory nitrate reduction to ammonium (DNRA), leading to NH4-N release; (III) Eh and organic matter are two key influence factors on mobility of PO43-, NO3-N and NH4-N. According to DIFS calculation, the dynamics of desorption and diffusion at two sites belong to (i) slow rate of resupply and (ii) fast resupply cases, respectively. Internal loadings are estimated to be 92.74 (PO43-), 268.1 (NH4-N) and -2466 kg a-1 (NO3-N), which reflects sediment mainly acts as a source for PO43- and NH4-N, and a sink for NO3-N in water. Based on sediment P release risk index (SPRRI), P release risks in lake sediments are estimated, ranging from light to relative high level. DGT and SPRRI aid choice of restoration methods for sediment, including sediment dredging, phytoremediation and in-situ inactivation.
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Affiliation(s)
- Wu Zhihao
- National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China; State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China
| | - Jiang Xia
- National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China; State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China
| | - Wang Shuhang
- National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China; State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China.
| | - Zhao Li
- State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China
| | - Jiao Lixin
- State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China
| | - Chen Junyi
- State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China
| | - Cai Qing
- State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China
| | - Wang Kun
- State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China
| | - Yao Cheng
- State Environmental Protection Key Laboratory for Lake Pollution Control, Institute of Lake Environment, Chinese Research Academy of Environmental Sciences (CRAES), Beijing, 100012, China; College of Water Science, Beijing Normal University, Beijing, 100875, China
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Xiong J, Xie R, Zhang H, Gao J, Wang J, Liang Q. Nitrite-responsive hydrogel for long-term and smart control of cyanobacteria bloom. JOURNAL OF HAZARDOUS MATERIALS 2021; 411:125150. [PMID: 33858106 DOI: 10.1016/j.jhazmat.2021.125150] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/18/2020] [Accepted: 01/04/2021] [Indexed: 06/12/2023]
Abstract
Frequent cyanobacteria bloom has caused serious environmental consequences and economic loss, especially in aquaculture. Direct algaecide addition, the most commonly used method, suffered from the poor control and overdose of algaecide. In this manuscript, we designed a smart nitrite-responsive hydrogel (DHPG) loading algaecide (BZK@DHPG) based on selective crosslinker: a kind of dihydropyridine derivatives termed DHPL. The network of the polymer could be decomposed by the nitrite-induced cleavage of DHPL. Compared to the traditional method, BZK@DHPG can adjust releasing speed according to the concentration of NO2-, the marker of cyanobacteria bloom level, and elongate the releasing time. Furthermore, BZK@DHPG could shift the effective dose of algaecide much ahead of the safety threshold, thus reducing deterioration of water quality caused by the overdose of algaecide.
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Affiliation(s)
- Jialiang Xiong
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Beijing Key Laboratory of Microanalytical Methods & Instrumentation, Department of Chemistry, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, PR China
| | - Ruoxiao Xie
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Beijing Key Laboratory of Microanalytical Methods & Instrumentation, Department of Chemistry, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, PR China
| | - Huiying Zhang
- School of Chemistry and Bioengineering, Hechi University, Yizhou 546300, Guangxi Province, PR China
| | - Jianyi Gao
- Astronaut Centre of China, Beijing 100094, PR China
| | - Jiaping Wang
- Astronaut Centre of China, Beijing 100094, PR China
| | - Qionglin Liang
- MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Beijing Key Laboratory of Microanalytical Methods & Instrumentation, Department of Chemistry, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, PR China.
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Dan Z, Chuan W, Qiaohong Z, Xingzhong Y. Sediments nitrogen cycling influenced by submerged macrophytes growing in winter. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2021; 83:1728-1738. [PMID: 33843755 DOI: 10.2166/wst.2021.081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Restoration of submerged macrophytes is one of the important measures for ecological treatment of eutrophic lakes. The changes in physical and chemical conditions caused by submerged macrophytes also affect the process of benthic nitrogen cycling. The growth period of Potamogeton crispus is mainly in winter. In order to understand the effect of submerged macrophytes growing in winter on nitrification rate and denitrification rate in the process of nitrogen cycling, experiments were carried out from winter to summer with vegetated and non-vegetated treatments. The results showed that the effect of submerged macrophytes on water temperature was not significant in winter. The nitrogen cycling was mainly affected by variables, which were inorganic nitrogen and dissolved oxygen. Submerged macrophytes had little effect on nitrification rate, but had a certain inhibition on denitrification rate by providing oxygen from photosynthesis. In total, submerged macrophytes growing in winter have little effect on nitrogen cycling in sediment. However, submerged macrophytes growing in winter can increase the attachment surface of microbes and inhibit resuspension of sediment, which play a complementary role to submerged macrophytes growing in summer for maintaining stability of eutrophic lakes.
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Affiliation(s)
- Zhang Dan
- Faculty of Architecture and Urban Planning, Chongqing University, Chongqing 400030, China; Key Laboratory of Eco-environment in the Three Gorges Reservoir Region of the Ministry of Education, Chongqing 400715, China and Chongqing Key Laboratory of Wetland Science Research Center of the Upper Reaches of the Yangtze River, Chongqing 401331, China
| | - Wang Chuan
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences,, Wuhan, Hubei 430072, China
| | - Zhou Qiaohong
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences,, Wuhan, Hubei 430072, China
| | - Yuan Xingzhong
- Faculty of Architecture and Urban Planning, Chongqing University, Chongqing 400030, China; Key Laboratory of New Technology for Construction of Cities in Mountain Area, Chongqing 400030, China and Chongqing Key Laboratory of Wetland Science Research Center of the Upper Reaches of the Yangtze River, Chongqing 401331, China E-mail:
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Deng HG, Zhang J, Wu JJ, Yao X, Yang LW. Biological denitrification in a macrophytic lake: implications for macrophytes-dominated lake management in the north of China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:42460-42471. [PMID: 32710360 DOI: 10.1007/s11356-020-10230-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
Denitrification plays an important role in nitrogen (N) removal in freshwater ecosystems. Aquatic plants might have an impact on the sediment denitrification of water body, especially in macrophytes-dominated lake; however, there were different opinions about it. Our hypothesis was that the sediment denitrification rates differ significantly in different vegetation zones and seasons because of direct and indirect effect of the aquatic plants. Therefore, we studied sediment denitrification in Dongping Lake, a typical macrophytes-dominated lake located in the north of China. The acetylene inhibition technique was used to quantify the sediment denitrification rates (DRs) in the Phragmites communis (P. communis) zone, aquaculture zone, Potamogeton crispus (P. crispus) zone and mixed vegetation zone in July (summer), October (autumn), December (winter) of 2015 and March (spring) of 2016. The results showed that the average DRs were significantly higher in the P. communis zone (69.0 ± 91.6 μmol N m-2 h-1) than the mixed vegetation zone (8.70 ± 5.44 μmol N m-2 h-1), and the average DRs represented significant seasonal difference as in the order of winter (74.5 ± 88.3 μmol N m-2 h-1) > autumn (15.7 ± 18.6 μmol N m-2 h-1) ≈ summer (10.7 ± 5.90 μmol N m-2 h-1) > spring (3.85 ± 1.29 μmol N m-2 h-1). The DRs generally decreased with the increasing of depth; however, significant increase of DRs with depth were found in certain seasons at the vegetated zones except the non-vegetated zone (the aquaculture zone) indicating the possible rhizosphere effect of aquatic plants on denitrification. The higher DRs and cycling rates of nitrate in the P. communis zone might be related to the larger biomass and oxygen transporting capacity of P. communis than those of the other aquatic plants. Winter peaks of DRs might be attributed to the higher NO3- load and the absence of the plant uptake. The high cycling rates of nitrate in Dongping Lake indicated an enhanced internal N cycling by aquatic plants. Sediment denitrification could remove about 537.7 t N every year, which was about 26.5% of annual TN loading in Dongping Lake.
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Affiliation(s)
- Huan-Guang Deng
- School of Environment and Planning, Liaocheng University, Liaocheng, 252000, China.
| | - Ju Zhang
- School of Environment and Planning, Liaocheng University, Liaocheng, 252000, China
| | - Jin-Jia Wu
- School of Environment and Planning, Liaocheng University, Liaocheng, 252000, China
- The Grand Canal Research Institute, Liaocheng University, Liaocheng, 252000, China
| | - Xin Yao
- School of Environment and Planning, Liaocheng University, Liaocheng, 252000, China
| | - Li-Wei Yang
- School of Geography, Geomatics and Planning, Jiangsu Normal University, Xuzhou, 221116, China
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Potential Pollution Sources from Agricultural Activities on Tropical Forested Floodplain Wetlands Revealed by Soil eDNA. FORESTS 2020. [DOI: 10.3390/f11080892] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tropical floodplain wetlands are found in low-lying areas that are periodically inundated. During wet periods, these wetlands can receive large amounts of suspended and dissolved material from the catchment, including many potential pollutants. In this study, we use traditional isotope tracers (δ15N and δ13C) along with soil eDNA to investigate the sources of transported materials and potential contaminants in seven forested floodplain wetlands in tropical Australia. We hypothesised that eDNA and isotope tracers in the soil would reflect the land use of the catchment. Our goal was to test whether eDNA could be used as a potential tool to identify and monitor pollutants in floodplain wetlands. The sampling sites were located within catchments that have a mosaic of land types, from well-conserved rainforests to intensive agricultural land uses, such as grazing, sugar cane, wood production, and horticulture. The soil eDNA was comprised of a mix of plant species consistent with the land use of the catchments. Most of the eDNA pool was derived from native trees, accounting for 46.2 ± 6.5% of the total; while cultivated species associated with agricultural activities contributed to 1–24% of the total. From the cultivated species, highest contributions (>5%) were from Sorghum sp. used for grazing, banana (Musa ornata), melons (Cucumis melo), and Pinus radiata and Juniperus sp. grown for wood production. Interestingly, tropical wetlands on sites 15 km offshore had soil eDNA from agricultural activities of the mainland, highlighting the connectivity of these wetlands, probably during extensive floods. Overall, soil eDNA, more than isotopic tracers, showed promising results for tracing and monitoring potential pollutants in tropical floodplain wetlands that are highly connected and susceptible to environmental degradation.
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Ma L, Jiang X, Liu G, Yao L, Liu W, Pan Y, Zuo Y. Environmental Factors and Microbial Diversity and Abundance Jointly Regulate Soil Nitrogen and Carbon Biogeochemical Processes in Tibetan Wetlands. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:3267-3277. [PMID: 32101417 DOI: 10.1021/acs.est.9b06716] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Wetlands have numerous critical ecological functions, some of which are regulated by several nitrogen (N) and carbon (C) biogeochemical processes, such as denitrification, organic matter decomposition, and methane emission. Until now, the underlying pathways of the effects of environmental and biological factors on wetland N and C cycling rates are still not fully understood. Here, we investigated soil potential/net nitrification, potential/unamended denitrification, methane production/oxidation rates in 36 riverine, lacustrine, and palustrine wetland sites on the Tibet Plateau. The results showed that all the measured N and C cycling rates did not differ significantly among the wetland types. Stepwise multiple regression analyses revealed that soil physicochemical properties (e.g., moisture, C and N concentration) explained a large amount of the variance in most of the N and C cycling rates. Microbial abundance and diversity were also important in controlling potential and unamended denitrification rates, respectively. Path analysis further revealed that soil moisture and N and C availability could impact wetland C and N processes both directly and indirectly. For instance, the indirect effect of soil moisture on methane production rates was mainly through the regulating the soil C content and methanogenic community structure. Our findings highlight that many N and C cycling processes in high-altitude and remote Tibetan wetlands are jointly regulated by soil environments and functional microorganisms. Soil properties affecting the N and C cycling rates in wetlands through altering their microbial diversity and abundance represent an important but previously underestimated indirect pathway.
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Affiliation(s)
- Lin Ma
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China
- Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China
| | - Xiaoliang Jiang
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Guihua Liu
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China
- Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan 430074, P. R. China
| | - Lunguang Yao
- Collaborative Innovation Center of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang Normal University, Nanyang 473061, P. R. China
| | - Wenzhi Liu
- CAS Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China
- Hubei Key Laboratory of Wetland Evolution & Ecological Restoration, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, P. R. China
- Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan 430074, P. R. China
- Collaborative Innovation Center of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang Normal University, Nanyang 473061, P. R. China
| | - Yongtai Pan
- Research Center for Ecology and Environment of Qinghai-Tibetan Plateau, Tibet University, Lhasa 850000, P. R. China
| | - Yanxia Zuo
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, P. R. China
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Shen Y, Huang Y, Hu J, Li P, Zhang C, Li L, Xu P, Zhang J, Chen X. The nitrogen reduction in eutrophic water column driven by Microcystis blooms. JOURNAL OF HAZARDOUS MATERIALS 2020; 385:121578. [PMID: 31732343 DOI: 10.1016/j.jhazmat.2019.121578] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/01/2019] [Accepted: 10/30/2019] [Indexed: 06/10/2023]
Abstract
During the bloom seasons, the dissolved inorganic nitrogen declines, which results in the occurrence of nitrogen limitation. It is unclear where the nitrogen goes. Our enclosure experiments and batch tests suggested that Microcystis blooms could significantly reduce the nitrogen in water bodies and the key mechanisms for the nitrogen reduction in different layers were different. The assimilation was the main pathway for nitrogen reduction in the surface layer, while denitrification played an important role both at the sediment-water interface and in the overlying water. Stable nitrogen isotope experiments showed that the nitrate reduction efficiency at sediment-water interface was enhanced by Microcystis, reaching to 76.5∼84.7 %. Dissimilation accounted for 63.8∼67.3 % of the nitrate reduction, and the denitrification rate was 7.4∼8.5 times of DNRA rate. In the water column, the Microcystis bloom facilitated the formation of dark/anoxic condition, which favored the denitrification. The Microcystis aggregates collected from the field showed a great potential in removing nitrogen, and the TN in the overly water was reduced by 3.76∼6.03 mg L-1 within two days. This study provided field evidences and deeper insights into the relationship between Microcystis blooms and nitrogen reduction in the whole water column and gave more details about the enhancing effects of Microcystis on nitrogen reduction.
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Affiliation(s)
- Yingshi Shen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China
| | - Yingying Huang
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China.
| | - Jun Hu
- Shanghai Qingpu Environmental Monitoring Station, Xi Dayinggangyi Road 15, Shanghai, 201700, PR China
| | - Panpan Li
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China
| | - Chen Zhang
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China
| | - Lei Li
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China
| | - Ping Xu
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China
| | - Junyi Zhang
- Wuxi Environmental Monitoring Centre, Zhou Xindong Road 123, Wuxi, 214023, PR China
| | - Xuechu Chen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai, 200241, PR China; Institute of Eco-Chongming, 3663 N. Zhongshan Road, Shanghai, 200062, PR China.
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11
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Nizzoli D, Welsh DT, Viaroli P. Denitrification and benthic metabolism in lowland pit lakes: The role of trophic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 703:134804. [PMID: 31757540 DOI: 10.1016/j.scitotenv.2019.134804] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 10/02/2019] [Accepted: 10/02/2019] [Indexed: 06/10/2023]
Abstract
Over recent decades, a great number of pit lakes have been formed, as a result of sand and gravel quarrying in river floodplains that are often also heavily exploited for agriculture. These lakes can act as nutrient filters and regulate the nitrogen pollution resulting from agricultural fertiliser use. In this paper we report the main outcomes of a study of the major nitrogen pathways in five pit lakes of differing trophic status, located along a lowland stretch of the Po river (Northern Italy). Benthic nitrogen fluxes and denitrification rates were determined in the hypolimnion and denitrification and reactive nitrogen assimilation by microphytobenthos in the littoral zone. We tested the hypothesis that lake depth and trophic status can impair denitrification and/or reactive nitrogen assimilation, compromising the function of the lakes as nutrient filters. In the studied lakes, denitrification and reactive nitrogen assimilation by primary producer communities accounted for substantial nitrogen removal rates, which were among the highest reported in the literature. Benthic nitrogen fluxes and denitrification varied between and within lakes, with depth. The littoral zone and surface waters also supported primary production, favouring nitrogen assimilation and temporal retention in the primary producer biomass. In all lakes, denitrification rates decreased from littoral to hypolimnetic sites. Denitrification rates and net nitrogen assimilation also diminished from oligotrophic to eutrophic conditions. To some extent, in eutrophic lakes there was a transfer of primary production from the benthos to the water column and the benthic system became heterotrophic, reducing the capacity for net nitrogen removal. Overall these results highlight that floodplain pit lakes can provide ecosystem services formerly supplied by natural wetlands. An important factor for management is the development of extensive littoral and shallow water zones, which are critical for maximising the nitrogen removal.
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Affiliation(s)
- Daniele Nizzoli
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy.
| | - David T Welsh
- School of Environment and Environmental Futures Research Institute, Griffith University, Gold Coast Campus, PMB 50 GC Mail Centre, Bundall 9726, Queensland, Australia
| | - Pierluigi Viaroli
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parco Area delle Scienze 11/A, 43124 Parma, Italy
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12
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Denitrification characterization of dissolved oxygen microprofiles in lake surface sediment through analyzing abundance, expression, community composition and enzymatic activities of denitrifier functional genes. AMB Express 2019; 9:129. [PMID: 31428884 PMCID: PMC6702497 DOI: 10.1186/s13568-019-0855-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 08/08/2019] [Indexed: 12/12/2022] Open
Abstract
The responses of denitrifiers and denitrification ability to dissolved oxygen (DO) concent in different layers of surface lake sediments are still poorly understood. Here, the optimal denitrification condition was constructed based on response surface methodology (RSM) to analyze the denitrification characteristics of surface sediments. The aerobic zone (AEZ), hypoxic zone (HYZ), up-anoxic zone (ANZ-1) and sub-anoxic zone (ANZ-2) were partitioned based on the oxygen contents, and sediments were collected using a customized-designed sub-millimeter scale sampling device. Integrated real-time quantitative PCR, Illumina Miseq-based sequencing and denitrifying enzyme activities analysis revealed that denitrification characteristics varied among different DO layers. Among the four layers, the DNA abundance and RNA expression levels of norB, nirS and nosZ were the highest at the aerobic layer, hypoxic layer and up-axoic layer, respectively. The hypoxia and up-anaerobic layer were the active nitrogen removal layers, since these two layers displayed the highest DNA abundance, RNA expression level and enzyme activities of denitrification functional genes. The abundance of major denitrifying bacteria showed significant differences among layers, with Azoarcus, Pseudogulbenkiania and Rhizobium identified as the main nirS, nirK and nosZ-based denitrifiers. Pearson’s correlation revealed that the response of denitrifiers to environmental factors differed greatly among DO layers. Furthermore, napA showed higher DNA abundance and RNA expression level in the aerobic and hypoxic layers than anaerobic layers, indicating that aerobic denitrifiers might play important roles at these layers.
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13
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Qiu X, Huang T, Zeng M, Zhou S. Three-year Survey of Nitrogen Dynamics in a Stratified Reservoir of the North China Plain. ACTA ACUST UNITED AC 2019. [DOI: 10.1088/1755-1315/252/5/052040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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14
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Wallace KJ, Laughlin DC, Clarkson BD, Schipper LA. Forest canopy restoration has indirect effects on litter decomposition and no effect on denitrification. Ecosphere 2018. [DOI: 10.1002/ecs2.2534] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- K. J. Wallace
- Environmental Research Institute University of Waikato Private Bag 3105 Hamilton 3240 New Zealand
| | - Daniel C. Laughlin
- Department of Botany University of Wyoming 1000 East University Avenue Laramie Wyoming 82071 USA
| | - Bruce D. Clarkson
- Environmental Research Institute University of Waikato Private Bag 3105 Hamilton 3240 New Zealand
| | - Louis A. Schipper
- Environmental Research Institute University of Waikato Private Bag 3105 Hamilton 3240 New Zealand
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15
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Zhou S, Xia C, Huang T, Zhang C, Fang K. Seasonal variation of potential denitrification rate and enhanced denitrification performance via water-lifting aeration technology in a stratified reservoir-A case study of Zhoucun reservoir. CHEMOSPHERE 2018; 211:1123-1136. [PMID: 30223328 DOI: 10.1016/j.chemosphere.2018.08.043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 08/04/2018] [Accepted: 08/09/2018] [Indexed: 06/08/2023]
Abstract
Zhoucun reservoir is one of the major water resources in Zao Zhuang city, northern China. The seasonal distribution of surface sediment denitrification rate and enhanced performance of denitrification via water-lifting aeration technology were explored using the acetylene-inhibition technique. Surface sediment denitrification rates ranged from 2.57 ± 1.32 to 923.90 ± 86.81 nmol N2/(g dw·h), with the highest rates in November (ANOVA, p < 0.05) and significantly low rates in June, July, and August (ANOVA, p < 0.05), mainly because of the seasonal differences in nitrate concentration, water temperature, and sediment total nitrogen (STN). Meanwhile, the N2/(N2+N2O) ratio (83.44-91.70% for the highest sediment denitrification period) indicated that N2 accounted for a majority of denitrification. Correlation analysis between various environmental factors and denitrification was conducted, and nitrate concentration, STN, low molecular weight organic carbon, the number of aerobic denitrifying bacteria, and the environmental parameters of oxidation-reduction potential (ORP), pH, electrical conductivity (EC), and chlorophyll a (Chl-a) presented significant relationships during the entire study period. On the basis of the multiple regression model, nitrate and low molecular weight organic carbon concentration were the most influential factors on denitrification variability. Moreover, the denitrification rates of the surface sediment clearly increased, from 5.28 to 13.22 nmol N2/(g dw·h) to 1117.02-3129.47 nmol N2/(g dw·h), which were higher than those in the non-operating year. This suggests that the denitrification in the sediment system could be enhanced in situ by water-lifting and aeration technology in the reservoir ecosystem.
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Affiliation(s)
- Shilei Zhou
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China.
| | - Chao Xia
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Tinglin Huang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China.
| | - Chunhua Zhang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
| | - Kaikai Fang
- Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, PR China
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16
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Chen X, Huang Y, Chen G, Li P, Shen Y, Davis TW. The secretion of organics by living Microcystis under the dark/anoxic condition and its enhancing effect on nitrate removal. CHEMOSPHERE 2018; 196:280-287. [PMID: 29306780 DOI: 10.1016/j.chemosphere.2017.12.197] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 12/27/2017] [Accepted: 12/31/2017] [Indexed: 06/07/2023]
Abstract
Recent studies indicated that the algal decomposition produces particulate and dissolved organic carbon (DOC), and can enhance denitrification in eutrophic lakes. However, the effects of the living cyanobacteria on nitrogen cycling in eutrophic lakes were still an unknown question. This study explores a new underlying mechanism of nitrate removal which is driven by living Microcystis. The results suggested that living Microcystis significantly enhanced the nitrate removal at sediment-water interface, with a nitrate removal rate of 0.54 d-1, which was 2.57 times higher than the nitrate removal rate in the treatment without the addition of Microcystis. Measurements of Chl a and Fv/Fm confirmed that Microcystis was tolerant to the dark/anoxic condition, and the recovery experiments suggested that Microcystis could survive under such stress conditions for at least seven days. Meanwhile, DOC secreted by living Microcystis reached to 4.55 mg C mg-1 Chl a. These secretions were biodegradable hydrophilic and contained carbohydrates and proteins. Our study indicated that during blooms, sinking Microcystis cells could directly provide DOC as carbon source, then consequently enhanced the denitrification at sediment-water interface, and the interactive relationship between living cyanobacteria and permanent nitrate removal should be taken into account while studying nitrogen cycling in aquatic ecosystem.
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Affiliation(s)
- Xuechu Chen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China; Shanghai Engineering Research Center of Landscaping on Challenging Urban Sites, Shanghai, 200232, PR China.
| | - Yingying Huang
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China; Institute of Eco-Chongming, 3663 N. Zhongshan Road, Shanghai, 200062, PR China.
| | - Guiqin Chen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China
| | - Panpan Li
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China
| | - Yingshi Shen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dong Chuan Road, Shanghai, 200241, PR China
| | - Timothy Walter Davis
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH, 43403, USA
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17
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Liu W, Yao L, Jiang X, Guo L, Cheng X, Liu G. Sediment denitrification in Yangtze lakes is mainly influenced by environmental conditions but not biological communities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 616-617:978-987. [PMID: 29102190 DOI: 10.1016/j.scitotenv.2017.10.221] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 10/20/2017] [Accepted: 10/21/2017] [Indexed: 05/05/2023]
Abstract
Globally, shallow lakes have suffered from excessive nitrogen (N) loading due to increased human activities in catchments, resulting in water quality degradation and aquatic biodiversity loss. Sediment denitrification, which reduces nitrate (NO3-) to N gaseous products, is the most important mechanism for permanent N removal in freshwater lakes. However, the relative contribution of abiotic and biotic factors to the sediment denitrification is highly variable. Here, we determined the unamended denitrification rate and nitrous oxide (N2O) production rate of 74 sediment samples from 22 eutrophic lakes in the Yangtze River basin. We also quantified the diversity and abundance of denitrifying communities using nirK and nirS genes. The results of variance partitioning analyses showed that water physicochemical properties (e.g., dissolved oxygen) and nutrients (e.g., NO3- concentration) but not denitrifier communities and submerged vegetation were the major factor groups predicting denitrification and N2O production rates. Path analyses further revealed that water physicochemical properties and nutrients could affect denitrification and N2O production rates both directly and indirectly, and the direct effects were considerably higher than the indirect effects mediated through changes in sediment characteristics, denitrifier communities and submerged vegetation. These findings suggest that the dominant N removal process in Yangtze lakes is largely regulated by abiotic factors rather than diversity and abundance of denitrifiers and submerged macrophytes. Additionally, the findings in this study are helpful in developing a targeted strategy to assess and enhance the N removal capability of eutrophic lakes in China.
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Affiliation(s)
- Wenzhi Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China; School of Freshwater Sciences, University of Wisconsin-Milwaukee, Milwaukee 53204, USA
| | - Lu Yao
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Xiaoliang Jiang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Laodong Guo
- School of Freshwater Sciences, University of Wisconsin-Milwaukee, Milwaukee 53204, USA
| | - Xiaoli Cheng
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China
| | - Guihua Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, PR China.
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18
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Yao L, Chen C, Liu G, Liu W. Sediment nitrogen cycling rates and microbial abundance along a submerged vegetation gradient in a eutrophic lake. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 616-617:899-907. [PMID: 29102199 DOI: 10.1016/j.scitotenv.2017.10.230] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/14/2017] [Accepted: 10/22/2017] [Indexed: 06/07/2023]
Abstract
Decline of submerged vegetation is one of the most serious ecological problems in eutrophic lakes worldwide. Although restoration of submerged vegetation is widely assumed to enhance ecological functions (e.g., nitrogen removal) and aquatic biodiversity, the evidence for this assumption is very limited. Here, we investigated the spatio-temporal patterns of sediment potential nitrification, unamended denitrification and N2O production rates along a vegetation gradient in the Lake Honghu, where submerged vegetation was largely restored by prohibiting net-pen aquaculture. We also used five functional genes as markers to quantify the abundance of sediment nitrifying and denitrifying microorganisms. Results showed that unvegetated sediments supported greater nitrification rates than rhizosphere sediments of perennial or seasonal vegetation. However, the absence of submerged vegetation had no significant effect on denitrification and N2O production rates. Additionally, the abundance of functional microorganisms in sediments was not significantly different among vegetation types. Season had a strong effect on both nitrogen cycling processes and microbial abundances. The highest nitrification rates were observed in September, while the highest denitrification rates occurred in December. The temporal variation of sediment nitrification, denitrification and N2O production rates could be due to changes in water quality and sediment properties rather than submerged vegetation and microbial abundances. Our findings highlight that vegetation restoration in eutrophic lakes improves water quality but does not enhance sediment nitrogen removal rates and microbial abundances. Therefore, for reducing the N level in eutrophic lakes, major efforts should be made to control nutrients export from terrestrial ecosystems.
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Affiliation(s)
- Lu Yao
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Australian Rivers Institute and Griffith School of Environment, Griffith University, Brisbane 4111, Australia; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chengrong Chen
- Australian Rivers Institute and Griffith School of Environment, Griffith University, Brisbane 4111, Australia
| | - Guihua Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Wenzhi Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China.
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19
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Huang Y, Chen X, Li P, Chen G, Peng L, Pan L. Pressurized Microcystis can help to remove nitrate from eutrophic water. BIORESOURCE TECHNOLOGY 2018; 248:140-145. [PMID: 28712781 DOI: 10.1016/j.biortech.2017.07.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 06/29/2017] [Accepted: 07/04/2017] [Indexed: 06/07/2023]
Abstract
The aim of this study was to investigate the feasibility of using harmful cyanobacterium Microcystis to help remove nitrate from eutrophic water. The results showed that after treatment by pressurization at 0.4MPa, Microcystis quickly sank to the bottom. Pressurization did not significantly affect the viability of Microcystis and this cyanobacterium maintained high viability over three days under dark/anoxic conditions. Meanwhile, the amount of dissolved organic carbon (DOC) secreted from living Microcystis cells reached 2.48mgCmg-1 Chl a, and a significant enhancement of pressurized Microcystis on nitrate removal at the sediment-water interface was observed, with a 2.85-fold increase in the specific NOX--N removal rate. The results of this study support the novel idea that harmful Microcystis could be converted to a carbon source for removing nitrate from eutrophic water by a simple pressurization measure.
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Affiliation(s)
- Yingying Huang
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai 200241, PR China
| | - Xuechu Chen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai 200241, PR China.
| | - Panpan Li
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai 200241, PR China
| | - Guiqin Chen
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai 200241, PR China
| | - Lin Peng
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai 200241, PR China
| | - Liping Pan
- Shanghai Key Lab for Urban Ecological Processes and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, Dong Chuan Road 500, Shanghai 200241, PR China
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20
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Macrofaunal Functional Diversity Provides Resilience to Nutrient Enrichment in Coastal Sediments. Ecosystems 2017. [DOI: 10.1007/s10021-017-0113-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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21
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Yao X, Zhang L, Zhang Y, Xu H, Jiang X. Denitrification occurring on suspended sediment in a large, shallow, subtropical lake (Poyang Lake, China). ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 219:501-511. [PMID: 27321881 DOI: 10.1016/j.envpol.2016.05.073] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/24/2016] [Accepted: 05/26/2016] [Indexed: 06/06/2023]
Abstract
Many lakes and rivers are enriched with high levels of suspended sediments (SPS). Denitrification occurring on suspended sediments (DSS) may play an important role in nitrogen removal in water columns with high SPS concentrations. Poyang Lake, with dramatic hydrologic variations, has high spatial and seasonal variation of SPS, and we hypothesized that DSS and nitrogen removal in this lake would vary similarly. DSS in Poyang Lake was determined by the traditional acetylene-inhibition method combined with a batch mode assay. Laboratory simulation experiments were also conducted to examine the factors controlling denitrification occurring on SPS. Seasonally, DSS rates at 15 sampling sites in Poyang Lake were 0.63 ± 0.24, 0.29 ± 0.17, 0.25 ± 0.18, and 0.52 ± 0.37 μmol N·L-1·d-1, respectively in spring, summer, autumn, and winter. Spatially, average DSS rates were higher in the northern lake area, which is connected to the Yangtze River, than in the upstream and central lake area. Lowest DSS rates occurred in semi-closed bay and dish lakes. Spatial and seasonal variations of DSS rates were affected by a combination of factors, in which nitrate concentrations, SPS composition, and concentrations of organic-SPS were the most important. These influencing factors were seasonally dependent, with nitrate concentrations having stronger effects on DSS during wet seasons than dry seasons. Results from a multiple stepwise regression model also demonstrated that DSS tended to occur on fine particles (e.g., clay particles, <4 μm). Evaluation of annual nitrogen loss by DSS was estimated according to the seasonal water budget and DSS rates in Poyang Lake. The total nitrogen loss by DSS was estimated to be 10800 ± 6090 t, which accounted for 2.8-9.9% of the nitrogen input, and this proportion was comparable to nitrogen removal by sediment denitrification. This result confirms that DSS was an important nitrogen sink in this large, turbid lake.
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Affiliation(s)
- Xiaolong Yao
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Lu Zhang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
| | - Yunlin Zhang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Huixian Xu
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xingyu Jiang
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; University of the Chinese Academy of Sciences, Beijing 100049, China
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22
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Highton MP, Roosa S, Crawshaw J, Schallenberg M, Morales SE. Physical Factors Correlate to Microbial Community Structure and Nitrogen Cycling Gene Abundance in a Nitrate Fed Eutrophic Lagoon. Front Microbiol 2016; 7:1691. [PMID: 27826296 PMCID: PMC5078687 DOI: 10.3389/fmicb.2016.01691] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 10/10/2016] [Indexed: 12/04/2022] Open
Abstract
Nitrogenous run-off from farmed pastures contributes to the eutrophication of Lake Ellesmere, a large shallow lagoon/lake on the east coast of New Zealand. Tributaries periodically deliver high loads of nitrate to the lake which likely affect microbial communities therein. We hypothesized that a nutrient gradient would form from the potential sources (tributaries) creating a disturbance resulting in changes in microbial community structure. To test this we first determined the existence of such a gradient but found only a weak nitrogen (TN) and phosphorous gradient (DRP). Changes in microbial communities were determined by measuring functional potential (quantification of nitrogen cycling genes via nifH, nirS, nosZI, and nosZII using qPCR), potential activity (via denitrification enzyme activity), as well as using changes in total community (via 16S rRNA gene amplicon sequencing). Our results demonstrated that changes in microbial communities at a phylogenetic (relative abundance) and functional level (proportion of the microbial community carrying nifH and nosZI genes) were most strongly associated with physical gradients (e.g., lake depth, sediment grain size, sediment porosity) and not nutrient concentrations. Low nitrate influx at the time of sampling is proposed as a factor contributing to the observed patterns.
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Affiliation(s)
- Matthew P Highton
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Stéphanie Roosa
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
| | - Josie Crawshaw
- Department of Marine Science, University of Otago Dunedin, New Zealand
| | | | - Sergio E Morales
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago Dunedin, New Zealand
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23
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Chen X, He S, Zhang Y, Huang X, Huang Y, Chen D, Huang X, Tang J. Enhancement of nitrate removal at the sediment-water interface by carbon addition plus vertical mixing. CHEMOSPHERE 2015; 136:305-310. [PMID: 25556005 DOI: 10.1016/j.chemosphere.2014.12.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2014] [Revised: 11/23/2014] [Accepted: 12/04/2014] [Indexed: 06/04/2023]
Abstract
Wetlands and ponds are frequently used to remove nitrate from effluents or runoffs. However, the efficiency of this approach is limited. Based on the assumption that introducing vertical mixing to water column plus carbon addition would benefit the diffusion across the sediment-water interface, we conducted simulation experiments to identify a method for enhancing nitrate removal. The results suggested that the sediment-water interface has a great potential for nitrate removal, and the potential can be activated after several days of acclimation. Adding additional carbon plus mixing significantly increases the nitrate removal capacity, and the removal of total nitrogen (TN) and nitrate-nitrogen (NO3(-)-N) is well fitted to a first-order reaction model. Adding Hydrilla verticillata debris as a carbon source increased nitrate removal, whereas adding Eichhornia crassipe decreased it. Adding ethanol plus mixing greatly improved the removal performance, with the removal rate of NO3(-)-N and TN reaching 15.0-16.5 g m(-2) d(-1). The feasibility of this enhancement method was further confirmed with a wetland microcosm, and the NO3(-)-N removal rate maintained at 10.0-12.0 g m(-2) d(-1) at a hydraulic loading rate of 0.5 m d(-1).
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Affiliation(s)
- Xuechu Chen
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Dong Chuan Road 800, Shanghai 200240, PR China; Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA.
| | - Shengbing He
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Dong Chuan Road 800, Shanghai 200240, PR China
| | - Yueping Zhang
- Shanghai East Sea Marine Engineering Survey & Design Institute, Shanghai 200137, PR China
| | - Xiaobo Huang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Dong Chuan Road 800, Shanghai 200240, PR China
| | - Yingying Huang
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Dong Chuan Road 800, Shanghai 200240, PR China
| | - Danyue Chen
- School of Environmental Science and Engineering, Shanghai Jiao Tong University, Dong Chuan Road 800, Shanghai 200240, PR China
| | - Xiaochen Huang
- Shanghai East Sea Marine Engineering Survey & Design Institute, Shanghai 200137, PR China
| | - Jianwu Tang
- Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA
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24
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Soranno PA, Cheruvelil KS, Wagner T, Webster KE, Bremigan MT. Effects of Land Use on Lake Nutrients: The Importance of Scale, Hydrologic Connectivity, and Region. PLoS One 2015; 10:e0135454. [PMID: 26267813 PMCID: PMC4534397 DOI: 10.1371/journal.pone.0135454] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 07/22/2015] [Indexed: 12/03/2022] Open
Abstract
Catchment land uses, particularly agriculture and urban uses, have long been recognized as major drivers of nutrient concentrations in surface waters. However, few simple models have been developed that relate the amount of catchment land use to downstream freshwater nutrients. Nor are existing models applicable to large numbers of freshwaters across broad spatial extents such as regions or continents. This research aims to increase model performance by exploring three factors that affect the relationship between land use and downstream nutrients in freshwater: the spatial extent for measuring land use, hydrologic connectivity, and the regional differences in both the amount of nutrients and effects of land use on them. We quantified the effects of these three factors that relate land use to lake total phosphorus (TP) and total nitrogen (TN) in 346 north temperate lakes in 7 regions in Michigan, USA. We used a linear mixed modeling framework to examine the importance of spatial extent, lake hydrologic class, and region on models with individual lake nutrients as the response variable, and individual land use types as the predictor variables. Our modeling approach was chosen to avoid problems of multi-collinearity among predictor variables and a lack of independence of lakes within regions, both of which are common problems in broad-scale analyses of freshwaters. We found that all three factors influence land use-lake nutrient relationships. The strongest evidence was for the effect of lake hydrologic connectivity, followed by region, and finally, the spatial extent of land use measurements. Incorporating these three factors into relatively simple models of land use effects on lake nutrients should help to improve predictions and understanding of land use-lake nutrient interactions at broad scales.
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Affiliation(s)
- Patricia A. Soranno
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
| | - Kendra Spence Cheruvelil
- Lyman Briggs College, Michigan State University, East Lansing, Michigan, United States of America
| | - Tyler Wagner
- U.S. Geological Survey, Pennsylvania Cooperative Fish & Wildlife Research Unit, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Katherine E. Webster
- School of Natural Sciences, Department of Zoology, Trinity College, Dublin, Ireland
| | - Mary Tate Bremigan
- Department of Fisheries and Wildlife, Michigan State University, East Lansing, Michigan, United States of America
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25
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Yang JK, Cheng ZB, Li J, Miao LH. Community composition of nirS-type denitrifier in a shallow eutrophic lake. MICROBIAL ECOLOGY 2013; 66:796-805. [PMID: 23884715 DOI: 10.1007/s00248-013-0265-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 07/08/2013] [Indexed: 06/02/2023]
Abstract
Denitrification is a major biological process to reduce nitrate to molecular nitrogen (N2). In shallow eutrophic lakes, this process can remove the largest portion of fixed nitrogen and plays an important role in self-purification of this ecosystem. To understand the structure of denitrifying communities in a shallow eutrophic lake, denitrifier communities in four sub-lakes of East Lake in Wuhan, China, were explored by restriction fragment length polymorphisms (RFLP) analysis and sequencing of nirS gene clone libraries. nirS is a functional marker gene for denitrification encoding cytochrome cd 1-containing nitrite reductase, which catalyzes the reduction of nitrite to nitric oxide. Both RFLP fingerprints clustering analysis and phylogeny analysis based on the amino acid sequences of NirS revealed that NirS-type communities in East Lake sediment could be roughly divided into three clusters. Cluster I accounted for 74-82 % of clones from the moderately eutrophic sub-lakes Tuan, Tang Ling, and Guo Zheng. Cluster II accounted for 76 % of the communities in hypertrophic sub-lake Miao Lake and cluster III as a minor group (7 % of the total), mainly presented in Miao Lake. Phylogenetic analysis revealed that cluster I was related to the reference clones from a broad range of ecological environments, and clusters II and III were more phylogenetically related to the reference clones from entrophic environments. Canonical correspondence analysis indicated that total nitrogen, total phosphate, total organic carbon, and NH4-N and NO2-N were important environmental factors affecting the dispersion of NirS-type denitrifier in the sediments. Cluster I showed a weak relationship with the nutrient content, while cluster II and III were positively related with the nutrient content. Principal coordinates analysis indicated that NirS-type communities from Tuan Lake, Tang Ling Lake, and Guo Zheng Lake sediments were divergent from those found in river, estuary sediment, and forest soil but similar to communities in constructed wetland sediment despite large geographic distances. The communities from the hypertrophic sub-lake Miao Lake deviated from other sub-lakes and the reference communities and clustered independently. Our results support the argument that environmental factors regulate the composition and distribution of the functional bacterial groups.
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Affiliation(s)
- Jiang-Ke Yang
- School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, 430023, China,
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27
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Carey CC, Ibelings BW, Hoffmann EP, Hamilton DP, Brookes JD. Eco-physiological adaptations that favour freshwater cyanobacteria in a changing climate. WATER RESEARCH 2012; 46:1394-407. [PMID: 22217430 DOI: 10.1016/j.watres.2011.12.016] [Citation(s) in RCA: 316] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 11/28/2011] [Accepted: 12/06/2011] [Indexed: 05/22/2023]
Abstract
Climate change scenarios predict that rivers, lakes, and reservoirs will experience increased temperatures, more intense and longer periods of thermal stratification, modified hydrology, and altered nutrient loading. These environmental drivers will have substantial effects on freshwater phytoplankton species composition and biomass, potentially favouring cyanobacteria over other phytoplankton. In this Review, we examine how several cyanobacterial eco-physiological traits, specifically, the ability to grow in warmer temperatures; buoyancy; high affinity for, and ability to store, phosphorus; nitrogen-fixation; akinete production; and efficient light harvesting, vary amongst cyanobacteria genera and may enable them to dominate in future climate scenarios. We predict that spatial variation in climate change will interact with physiological variation in cyanobacteria to create differences in the dominant cyanobacterial taxa among regions. Finally, we suggest that physiological traits specific to different cyanobacterial taxa may favour certain taxa over others in different regions, but overall, cyanobacteria as a group are likely to increase in most regions in the future.
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Affiliation(s)
- Cayelan C Carey
- Department of Ecology and Evolutionary Biology, Corson Hall, Cornell University, Ithaca, NY 14853, USA.
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28
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Jones HFE, Pilditch CA, Bruesewitz DA, Lohrer AM. Sedimentary environment influences the effect of an infaunal suspension feeding bivalve on estuarine ecosystem function. PLoS One 2011; 6:e27065. [PMID: 22046446 PMCID: PMC3203948 DOI: 10.1371/journal.pone.0027065] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 10/10/2011] [Indexed: 11/19/2022] Open
Abstract
The suspension feeding bivalve Austrovenus stutchburyi is a key species on intertidal sandflats in New Zealand, affecting the appearance and functioning of these systems, but is susceptible to several environmental stressors including sedimentation. Previous studies into the effect of this species on ecosystem function have been restricted in space and time, limiting our ability to infer the effect of habitat change on functioning. We examined the effect of Austrovenus on benthic primary production and nutrient dynamics at two sites, one sandy, the other composed of muddy-sand to determine whether sedimentary environment alters this key species' role. At each site we established large (16 m2) plots of two types, Austrovenus addition and removal. In winter and summer we deployed light and dark benthic chambers to quantify oxygen and nutrient fluxes and measured sediment denitrification enzyme activity to assess denitrification potential. Rates of gross primary production (GPP) and ammonium uptake were significantly increased when Austrovenus was added, relative to removed, at the sandy site (GPP, 1.5 times greater in winter and summer; ammonium uptake, 8 times greater in summer; 3-factor analysis of variance (ANOVA), p<0.05). Denitrification potential was also elevated in Austrovenus addition plots at the sandy site in summer (by 1.6 times, p<0.1). In contrast, there was no effect of Austrovenus treatment on any of these variables at the muddy-sand site, and overall rates tended to be lower at the muddy-sand site, relative to the sandy site (e.g. GPP was 2.1 to 3.4 times lower in winter and summer, respectively, p<0.001). Our results suggest that the positive effects of Austrovenus on system productivity and denitrification potential is limited at a muddy-sand site compared to a sandy site, and reveal the importance of considering sedimentary environment when examining the effect of key species on ecosystem function.
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Affiliation(s)
- Hannah F E Jones
- Department of Biological Sciences, University of Waikato, Hamilton, New Zealand.
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