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Ho L, Barthel M, Pham K, Bodé S, Van Colen C, Moens T, Six J, Boeckx P, Goethals P. Regulating greenhouse gas dynamics in tidal wetlands: Impacts of salinity gradients and water pollution. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 364:121427. [PMID: 38870790 DOI: 10.1016/j.jenvman.2024.121427] [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: 03/26/2024] [Revised: 05/22/2024] [Accepted: 06/07/2024] [Indexed: 06/15/2024]
Abstract
Tidal wetlands play a critical role in emitting greenhouse gases (GHGs) into the atmosphere; our understanding of the intricate interplay between natural processes and human activities shaping their biogeochemistry and GHG emissions remains lacking. In this study, we delve into the spatiotemporal dynamics and key drivers of the GHG emissions from five tidal wetlands in the Scheldt Estuary by focusing on the interactive impacts of salinity and water pollution, two factors exhibiting contrasting gradients in this estuarine system: pollution escalates as salinity declines. Our findings reveal a marked escalation in GHG emissions when moving upstream, primarily attributed to increased concentrations of organic matter and nutrients, coupled with reduced levels of dissolved oxygen and pH. These low water quality conditions not only promote methanogenesis and denitrification to produce CH4 and N2O, respectively, but also shift the carbonate equilibria towards releasing more CO2. As a result, the most upstream freshwater wetland was the largest GHG emitter with a global warming potential around 35 to 70 times higher than the other wetlands. When moving seaward along a gradient of decreasing urbanization and increasing salinity, wetlands become less polluted and are characterized by lower concentrations of NO3-, TN and TOC, which induces stronger negative impact of elevated salinity on the GHG emissions from the saline wetlands. Consequently, these meso-to polyhaline wetlands released considerably smaller amounts of GHGs. These findings emphasize the importance of integrating management strategies, such as wetland restoration and pollution prevention, that address both natural salinity gradients and human-induced water pollution to effectively mitigate GHG emissions from tidal wetlands.
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Affiliation(s)
- Long Ho
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium.
| | - Matti Barthel
- Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Kim Pham
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Samuel Bodé
- Department of Green Chemistry and Technology, Isotope Bioscience Laboratory - ISOFYS, Ghent University, Gent, Belgium
| | - Carl Van Colen
- Marine Biology Research Group, Ghent University, Krijgslaan 281/S8 9000, Gent, Belgium
| | - Tom Moens
- Marine Biology Research Group, Ghent University, Krijgslaan 281/S8 9000, Gent, Belgium
| | - Johan Six
- Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Pascal Boeckx
- Department of Green Chemistry and Technology, Isotope Bioscience Laboratory - ISOFYS, Ghent University, Gent, Belgium
| | - Peter Goethals
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium
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Panique-Casso DG, Goethals P, Ho L. Modeling greenhouse gas emissions from riverine systems: A review. WATER RESEARCH 2024; 250:121012. [PMID: 38128303 DOI: 10.1016/j.watres.2023.121012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 11/20/2023] [Accepted: 12/10/2023] [Indexed: 12/23/2023]
Abstract
Despite the recognized importance of flowing waters in global greenhouse gas (GHG) budgets, riverine GHG models remain oversimplified, consequently restraining the development of effective prediction for riverine GHG emissions feedbacks. Here we elucidate the state of the art of riverine GHG models by investigating 148 models from 122 papers published from 2010 to 2021. Our findings indicate that riverine GHG models have been mostly data-driven models (83%), while mechanistic and hybrid models were uncommonly applied (12% and 5%, respectively). Overall, riverine GHG models were mainly used to explain relationships between GHG emissions and biochemical factors, while the role of hydrological, geomorphic, land use and cover factors remains missing. The development of complex and advanced models has been limited by data scarcity issues; hence, efforts should focus on developing affordable automatic monitoring methods to improve data quality and quantity. For future research, we request for basin-scale studies explaining river and land-surface interactions for which hybrid models are recommended given their flexibility. Such a holistic understanding of GHG dynamics would facilitate scaling-up efforts, thereby reducing uncertainties in global GHG estimates. Lastly, we propose an application framework for model selection based on three main criteria, including model purpose, model scale and the spatiotemporal characteristics of GHG data, by which optimal models can be applied in various study conditions.
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Affiliation(s)
- Diego G Panique-Casso
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Ghent, Belgium.
| | - Peter Goethals
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Ghent, Belgium
| | - Long Ho
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Ghent, Belgium
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Ho L, Barthel M, Panique-Casso D, Vermeulen K, Bruneel S, Liu X, Bodé S, Six J, Boeckx P, Goethals P. Impact of salinity gradient, water pollution and land use types on greenhouse gas emissions from an urbanized estuary. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 336:122500. [PMID: 37669700 DOI: 10.1016/j.envpol.2023.122500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 08/25/2023] [Accepted: 08/31/2023] [Indexed: 09/07/2023]
Abstract
Estuaries have been recognized as one of the major sources of greenhouse gases (GHGs) in aquatic systems; yet we still lack insights into the impact of both anthropogenic and natural factors on the dynamics of GHG emissions. Here, we assessed the spatiotemporal dynamics and underlying drivers of the GHG emissions from the Scheldt Estuary with a focus on the effects of salinity gradient, water pollution, and land use types, together with their interaction. Overall, we found a negative impact of salinity on carbon dioxide (CO2) and nitrous oxide (N2O) emissions which can be due to the decrease of both salinity and water quality when moving upstream. Stronger impact of water pollution on the GHG emissions was found at the freshwater sites upstream compared to saline sites downstream. In particular, when water quality of the sites reduced from good, mainly located in the mouth and surrounded by arable sites, to polluted, mainly located in the upstream and surrounded by urban sites, CO2 emissions from the sites doubled while N2O emissions tripled. Similarly, the effects of water pollution on methane (CH4) emissions became much stronger in the freshwater sites compared to the saline sites. These decreasing effects from upstream to the mouth were associated with the increase in urbanization as sites surrounded by urban areas released on average almost two times more CO2 and N2O than sites surrounded by nature and industry areas. Applied machine learning methods also revealed that, in addition to salinity effects, nutrient and organic enrichment stimulated the GHG emissions from the Scheldt Estuary. These findings highlight the importance of the interaction between salinity, water pollution, and land use in order to understand their influences on GHG emissions from dynamic estuarine systems.
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Affiliation(s)
- Long Ho
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium.
| | - Matti Barthel
- Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Diego Panique-Casso
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Kaat Vermeulen
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Stijn Bruneel
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Xingzhen Liu
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium
| | - Samuel Bodé
- Department of Green Chemistry and Technology, Isotope Bioscience Laboratory - ISOFYS, Ghent University, Ghent, Belgium
| | - Johan Six
- Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland
| | - Pascal Boeckx
- Department of Green Chemistry and Technology, Isotope Bioscience Laboratory - ISOFYS, Ghent University, Ghent, Belgium
| | - Peter Goethals
- Department of Animal Sciences and Aquatic Ecology, Ghent University, Gent, Belgium
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Wang X, Yu L, Liu T, He Y, Wu S, Chen H, Yuan X, Wang J, Li X, Li H, Que Z, Qing Z, Zhou T. Methane and nitrous oxide concentrations and fluxes from heavily polluted urban streams: Comprehensive influence of pollution and restoration. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 313:120098. [PMID: 36075337 DOI: 10.1016/j.envpol.2022.120098] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 06/15/2023]
Abstract
Streams draining urban areas are usually regarded as hotspots of methane (CH4) and nitrous oxide (N2O) emissions. However, little is known about the coupling effects of watershed pollution and restoration on CH4 and N2O emission dynamics in heavily polluted urban streams. This study investigated the CH4 and N2O concentrations and fluxes in six streams that used to be heavily polluted but have undergone different watershed restorations in Southwest China, to explore the comprehensive influences of pollution and restoration. CH4 and N2O concentrations in the six urban streams ranged from 0.12 to 21.32 μmol L-1 and from 0.03 to 2.27 μmol L-1, respectively. The calculated diffusive fluxes of CH4 and N2O were averaged of 7.65 ± 9.20 mmol m-2 d-1 and 0.73 ± 0.83 mmol m-2 d-1, much higher than those in most previous reports. The heavily polluted streams with non-restoration had 7.2 and 7.8 times CH4 and N2O concentrations higher than those in the fully restored streams, respectively. Particularly, CH4 and N2O fluxes in the fully restored streams were 90% less likely than those found in the unrestored ones. This result highlighted that heavily polluted urban streams with high pollution loadings were indeed hotspots of CH4 and N2O emissions throughout the year, while comprehensive restoration can effectively weaken their emission intensity. Sewage interception and nutrient removal, especially N loadings reduction, were effective measures for regulating the dynamics of CH4 and N2O emissions from the heavily polluted streams. Based on global and regional integration, it further elucidated that increasing environment investments could significantly improve water quality and mitigate CH4 and N2O emissions in polluted urban streams. Overall, our study emphasized that although urbanization could inevitably strengthen riverine CH4 and N2O emissions, effective eco-restoration can mitigate the crisis of riverine greenhouse gas emissions.
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Affiliation(s)
- Xiaofeng Wang
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China.
| | - Lele Yu
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
| | - Tingting Liu
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, 200241, China
| | - Yixin He
- Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China; Zoige Peatland and Global Change Research Station, Chinese Academy of Sciences, Hongyuan, 624400, China
| | - Shengnan Wu
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
| | - Huai Chen
- Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China; Zoige Peatland and Global Change Research Station, Chinese Academy of Sciences, Hongyuan, 624400, China
| | - Xingzhong Yuan
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing, 400030, China
| | - Jilong Wang
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
| | - Xianxiang Li
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
| | - Hang Li
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
| | - Ziyi Que
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
| | - Zhaoyin Qing
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
| | - Ting Zhou
- Chongqing Key Laboratory of Wetland Science Research of the Upper Reaches of the Yangtze River, Chongqing, 401331, China; Three Gorges Reservoir Area Earth Surface Ecological Processes of Chongqing Observation and Research Station, Chongqing, 405400, China; School of Geography and Tourism, Chongqing Normal University, Chongqing, 400047, China
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Lee YJ, Lin BL, Lei Z. Nitrous oxide emission mitigation from biological wastewater treatment - A review. BIORESOURCE TECHNOLOGY 2022; 362:127747. [PMID: 35964917 DOI: 10.1016/j.biortech.2022.127747] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Abstract
Nitrous oxide (N2O) emitted from wastewater treatment processes has emerged as a focal point for academic and practical research amidst pressing environmental issues. This review presents an updated view on the biological pathways for N2O production and consumption in addition to the critical process factors affecting N2O emission. The current research trends including the strain and reactor aspects were then outlined with discussions. Last but not least, the research needs were proposed. The holistic life cycle assessment needs to be performed to evaluate the technical and economic feasibility of the proposed mitigation strategies or recovery options. This review also provides the background information for the proposed future research prospects on N2O mitigation and recovery technologies. As pointed out, dilution effects of the produced N2O gas product would hinder its use as renewable energy; instead, its use as an effective oxidizing agent is proposed as a promising recovery option.
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Affiliation(s)
- Yu-Jen Lee
- Department of Chemical Engineering, National Taiwan University, Taipei 10649, Taiwan
| | - Bin-le Lin
- Research Institute of Science for Safety and Sustainability, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Zhongfang Lei
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
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