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Xu M, Zhang J, Zhang Z, Wang M, Chen H, Peng C, Yu D, Zhan H, Zhu Q. Global responses of wetland methane emissions to extreme temperature and precipitation. ENVIRONMENTAL RESEARCH 2024; 252:118907. [PMID: 38642638 DOI: 10.1016/j.envres.2024.118907] [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: 12/22/2023] [Revised: 04/03/2024] [Accepted: 04/08/2024] [Indexed: 04/22/2024]
Abstract
As global warming continues, events of extreme heat or heavy precipitation will become more frequent, while events of extreme cold will become less so. How wetlands around the globe will react to these extreme events is unclear yet critical, because they are among the greatest natural sources of methane(CH4). Here we use seven indices of extreme climate and the rate of methane emission from global wetlands(WME) during 2000-2019 simulated by 12 published models as input data. Our analyses suggest that extreme cold (particularly extreme low temperatures) inhibits WME, whereas extreme heat (particularly extreme high temperatures) accelerates WME. Our results also suggest that daily precipitation >10 mm accelerates WME, while much higher daily precipitation levels can slow WME. The correlation of extreme high temperature and precipitation with rate of WME became stronger during the study period, while the correlation between extreme low temperature and WME rate became weaker.
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Affiliation(s)
- Min Xu
- College of Geography and Remote Sensing, Hohai University, Nanjing, 210098, China
| | - Jiang Zhang
- Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhen Zhang
- National Tibetan Plateau Data Center (TPDC), State Key Laboratory of Tibetan Plateau Earth System, Environment and Resource (TPESER), Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Meng Wang
- School of Geographical Sciences, Northeast Normal University, Changchun, 130024, China
| | - Huai Chen
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China
| | - Changhui Peng
- Institute of Environment Sciences, Department of Biology Sciences, University of Quebec at Montreal, Montreal, H3C 3P8, Canada
| | - Dongxue Yu
- College of Geography and Remote Sensing, Hohai University, Nanjing, 210098, China
| | - Hao Zhan
- College of Geography and Remote Sensing, Hohai University, Nanjing, 210098, China
| | - Qiuan Zhu
- College of Geography and Remote Sensing, Hohai University, Nanjing, 210098, China.
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2
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Määttä T, Malhotra A. The hidden roots of wetland methane emissions. GLOBAL CHANGE BIOLOGY 2024; 30:e17127. [PMID: 38337165 DOI: 10.1111/gcb.17127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/24/2023] [Accepted: 12/02/2023] [Indexed: 02/12/2024]
Abstract
Wetlands are the largest natural source of methane (CH4 ) globally. Climate and land use change are expected to alter CH4 emissions but current and future wetland CH4 budgets remain uncertain. One important predictor of wetland CH4 flux, plants, play an important role in providing substrates for CH4 -producing microbes, increasing CH4 consumption by oxygenating the rhizosphere, and transporting CH4 from soils to the atmosphere. Yet, there remain various mechanistic knowledge gaps regarding the extent to which plant root systems and their traits influence wetland CH4 emissions. Here, we present a novel conceptual framework of the relationships between a range of root traits and CH4 processes in wetlands. Based on a literature review, we propose four main CH4 -relevant categories of root function: gas transport, carbon substrate provision, physicochemical influences and root system architecture. Within these categories, we discuss how individual root traits influence CH4 production, consumption, and transport (PCT). Our findings reveal knowledge gaps concerning trait functions in physicochemical influences, and the role of mycorrhizae and temporal root dynamics in PCT. We also identify priority research needs such as integrating trait measurements from different root function categories, measuring root-CH4 linkages along environmental gradients, and following standardized root ecology protocols and vocabularies. Thus, our conceptual framework identifies relevant belowground plant traits that will help improve wetland CH4 predictions and reduce uncertainties in current and future wetland CH4 budgets.
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Affiliation(s)
- Tiia Määttä
- Department of Geography, University of Zürich, Zürich, Switzerland
| | - Avni Malhotra
- Department of Geography, University of Zürich, Zürich, Switzerland
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
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3
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Li Z, Kong L, Hu L, Wei J, Zhang X, Guo W, Shi W. Greenhouse gas emissions from constructed wetlands: A bibliometric analysis and mini-review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 906:167582. [PMID: 37797756 DOI: 10.1016/j.scitotenv.2023.167582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/20/2023] [Accepted: 10/02/2023] [Indexed: 10/07/2023]
Abstract
Constructed wetlands (CWs) have been widely applied in wastewater treatment; however, the degradation of organic pollutants within CWs leads to substantial emissions of greenhouse gases (GHGs), such as carbon dioxide, methane and nitrous oxide. Under the low-carbon economy, GHG emissions have emerged as a major concern, and have been intensively studied in the CW field. In this study, we conducted a bibliometric review using CiteSpace and a global-scale analysis of GHG emission levels based on 286 records and proposed potential approaches for the future control of GHG emissions in CWs. We found that the research has generally evolved through three stages over the past 15 years: GHG emission level assessment (2007-2010), mechanisms (2011-2016), and control (2017-2022). The type of CWs is closely related to GHG emissions, with free water surface CWs emitting higher levels of methane and vertical subsurface flow CWs emitting higher levels of carbon dioxide and nitrous oxide. By optimizing CW operation, it is conceivable to synergistically reduce GHG emissions while enhancing pollutant removal.
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Affiliation(s)
- Ziqian Li
- Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technologies, Jiangsu Key Laboratory of Atmospheric Environmental Monitoring & Pollution Control, School of Environmental Science & Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China
| | - Lingwei Kong
- Key Laboratory of Coastal Environment and Resources of Zhejiang Province, School of Engineering, Westlake University, Hangzhou, Zhejiang 310030, China
| | - Liping Hu
- Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technologies, Jiangsu Key Laboratory of Atmospheric Environmental Monitoring & Pollution Control, School of Environmental Science & Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China
| | - Jun Wei
- Power China Huadong Engineering Corporation Limited, Hangzhou 311122, China
| | - Xinzhi Zhang
- Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technologies, Jiangsu Key Laboratory of Atmospheric Environmental Monitoring & Pollution Control, School of Environmental Science & Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China
| | - Weijie Guo
- Basin Water Environmental Research Department, Changjiang River Scientific Research Institute, Wuhan 430010, China
| | - Wenqing Shi
- Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technologies, Jiangsu Key Laboratory of Atmospheric Environmental Monitoring & Pollution Control, School of Environmental Science & Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China.
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4
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Feron S, Malhotra A, Bansal S, Fluet-Chouinard E, McNicol G, Knox SH, Delwiche KB, Cordero RR, Ouyang Z, Zhang Z, Poulter B, Jackson RB. Recent increases in annual, seasonal, and extreme methane fluxes driven by changes in climate and vegetation in boreal and temperate wetland ecosystems. GLOBAL CHANGE BIOLOGY 2024; 30:e17131. [PMID: 38273508 DOI: 10.1111/gcb.17131] [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: 08/23/2023] [Revised: 11/15/2023] [Accepted: 12/15/2023] [Indexed: 01/27/2024]
Abstract
Climate warming is expected to increase global methane (CH4 ) emissions from wetland ecosystems. Although in situ eddy covariance (EC) measurements at ecosystem scales can potentially detect CH4 flux changes, most EC systems have only a few years of data collected, so temporal trends in CH4 remain uncertain. Here, we use established drivers to hindcast changes in CH4 fluxes (FCH4 ) since the early 1980s. We trained a machine learning (ML) model on CH4 flux measurements from 22 [methane-producing sites] in wetland, upland, and lake sites of the FLUXNET-CH4 database with at least two full years of measurements across temperate and boreal biomes. The gradient boosting decision tree ML model then hindcasted daily FCH4 over 1981-2018 using meteorological reanalysis data. We found that, mainly driven by rising temperature, half of the sites (n = 11) showed significant increases in annual, seasonal, and extreme FCH4 , with increases in FCH4 of ca. 10% or higher found in the fall from 1981-1989 to 2010-2018. The annual trends were driven by increases during summer and fall, particularly at high-CH4 -emitting fen sites dominated by aerenchymatous plants. We also found that the distribution of days of extremely high FCH4 (defined according to the 95th percentile of the daily FCH4 values over a reference period) have become more frequent during the last four decades and currently account for 10-40% of the total seasonal fluxes. The share of extreme FCH4 days in the total seasonal fluxes was greatest in winter for boreal/taiga sites and in spring for temperate sites, which highlights the increasing importance of the non-growing seasons in annual budgets. Our results shed light on the effects of climate warming on wetlands, which appears to be extending the CH4 emission seasons and boosting extreme emissions.
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Affiliation(s)
- Sarah Feron
- Knowledge Infrastructures, Campus Fryslân, University of Groningen, Groningen, The Netherlands
- Department of Earth System Science, Stanford University, Stanford, California, USA
- Department of Physics, Universidad de Santiago, Santiago, Chile
| | - Avni Malhotra
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Sheel Bansal
- U.S. Geological Survey, Northern Prairie Wildlife Research Center, Jamestown, North Dakota, USA
| | - Etienne Fluet-Chouinard
- Earth Systems Science Division, Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Gavin McNicol
- Department of Earth System Science, Stanford University, Stanford, California, USA
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, Illinois, USA
| | - Sara H Knox
- Department of Geography, The University of British Columbia, Vancouver, British Columbia, Canada
- Department of Geography, McGill University, Montreal, Quebec, Canada
| | - Kyle B Delwiche
- Department of Earth System Science, Stanford University, Stanford, California, USA
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, USA
| | - Raul R Cordero
- Department of Physics, Universidad de Santiago, Santiago, Chile
| | - Zutao Ouyang
- Department of Earth System Science, Stanford University, Stanford, California, USA
| | - Zhen Zhang
- Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China
| | - Benjamin Poulter
- Biospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - Robert B Jackson
- Department of Earth System Science, Stanford University, Stanford, California, USA
- Woods Institute for the Environment, Stanford University, Stanford, California, USA
- Precourt Institute for Energy, Stanford, California, USA
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5
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Arnold W, Taylor M, Bradford M, Raymond P, Peccia J. Microbial activity contributes to spatial heterogeneity of wetland methane fluxes. Microbiol Spectr 2023; 11:e0271423. [PMID: 37728556 PMCID: PMC10580924 DOI: 10.1128/spectrum.02714-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 07/12/2023] [Indexed: 09/21/2023] Open
Abstract
The emission of methane from wetlands is spatially heterogeneous, as concurrently measured surface fluxes can vary by orders of magnitude within the span of a few meters. Despite extensive study and the climatic significance of these emissions, it remains unclear what drives large, within-site variations. While geophysical factors (e.g., soil temperature) are known to correlate with methane (CH4) flux, measurable variance in these parameters often declines as spatial and temporal scales become finer. As methane emitted from wetlands is the direct, net product of microbial metabolisms which both produce and degrade CH4, it stands to reason that characterizing the spatial variability of microbial communities within a wetland-both horizontally and vertically-may help explain observed variances in flux. To that end, we surveyed microbial communities to a depth of 1 m across an ombrotrophic peat bog in Maine, USA using amplicon sequencing and gene expression techniques. Surface methane fluxes and geophysical factors were concurrently measured. Across the first meter of peat at the site, we observed significant changes in the abundance and composition of methanogenic taxa at every depth sampled, with variance in methanogen abundance explaining 70% of flux heterogeneity at a subset of plots. Among measured environmental factors, only peat depth emerged as correlated with flux, and had significant impact on the abundance and composition of methane-cycling communities. These conclusions suggest that a heightened awareness of how microbial communities are structured and spatially distributed within wetlands could offer improved insights into predicting CH4 flux dynamics. IMPORTANCE Globally, wetlands are one of the largest sources of methane (CH4), a greenhouse gas with a warming impact significantly greater than CO2. Methane produced in wetlands is the byproduct of a group of microorganisms which convert organic carbon into CH4. Despite our knowledge of how this process works, it is still unclear what drives dramatic, localized (<10 m) variance in emission rates from the surface of wetlands. While environmental conditions, like soil temperature or water table depth, correlate with methane flux when variance in these factors is large (e.g., spring vs fall), the explanatory power of these variables decline when spatial and temporal scales become smaller. As methane fluxes are the direct product of microbial activity, we profiled how the microbial community varied, both horizontally and vertically, across a peat bog in Maine, USA, finding that variance in microbial communities was likely contributing to much of the observed variance in flux.
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Affiliation(s)
- Wyatt Arnold
- Department of Chemical and Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut, USA
| | - Meghan Taylor
- Yale School of the Environment, Yale University, New Haven, Connecticut, USA
| | - Mark Bradford
- Yale School of the Environment, Yale University, New Haven, Connecticut, USA
| | - Peter Raymond
- Yale School of the Environment, Yale University, New Haven, Connecticut, USA
| | - Jordan Peccia
- Department of Chemical and Environmental Engineering, School of Engineering and Applied Science, Yale University, New Haven, Connecticut, USA
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6
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Candry P, Abrahamson B, Stahl DA, Winkler MKH. Microbially mediated climate feedbacks from wetland ecosystems. GLOBAL CHANGE BIOLOGY 2023; 29:5169-5183. [PMID: 37386740 DOI: 10.1111/gcb.16850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 06/15/2023] [Indexed: 07/01/2023]
Abstract
Wetlands are crucial nodes in the carbon cycle, emitting approximately 20% of global CH4 while also sequestering 20%-30% of all soil carbon. Both greenhouse gas fluxes and carbon storage are driven by microbial communities in wetland soils. However, these key players are often overlooked or overly simplified in current global climate models. Here, we first integrate microbial metabolisms with biological, chemical, and physical processes occurring at scales from individual microbial cells to ecosystems. This conceptual scale-bridging framework guides the development of feedback loops describing how wetland-specific climate impacts (i.e., sea level rise in estuarine wetlands, droughts and floods in inland wetlands) will affect future climate trajectories. These feedback loops highlight knowledge gaps that need to be addressed to develop predictive models of future climates capturing microbial contributions. We propose a roadmap connecting environmental scientific disciplines to address these knowledge gaps and improve the representation of microbial processes in climate models. Together, this paves the way to understand how microbially mediated climate feedbacks from wetlands will impact future climate change.
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Affiliation(s)
- Pieter Candry
- Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - Britt Abrahamson
- Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - David Allan Stahl
- Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
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7
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Li J, Pei J, Fang C, Li B, Nie M. Opposing seasonal temperature dependencies of CO 2 and CH 4 emissions from wetlands. GLOBAL CHANGE BIOLOGY 2023; 29:1133-1143. [PMID: 36385719 DOI: 10.1111/gcb.16528] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Wetlands are critically important to global climate change because of their role in modulating the release of atmospheric greenhouse gases (GHGs) carbon dioxide (CO2 ) and methane (CH4 ). Temperature plays a crucial role in wetland GHG emissions, while the general pattern for seasonal temperature dependencies of wetland CO2 and CH4 emissions is poorly understood. Here we show opposite seasonal temperature dependencies of CO2 and CH4 emissions by using 36,663 daily observations of simultaneous measurements of ecosystem-scale CO2 and CH4 emissions in 42 widely distributed wetlands from the FLUXNET-CH4 database. Specifically, the temperature dependence of CO2 emissions decreased with increasing monthly mean temperature, but the opposite was true for that of CH4 emissions. Neglecting seasonal temperature dependencies may overestimate wetland CO2 and CH4 emissions compared to the use of a year-based static and consistent temperature dependence parameter when only considering temperature effects. Our findings highlight the importance of incorporating the remarkable seasonality in temperature dependence into process-based biogeochemical models to predict feedbacks of wetland GHG emissions to climate warming.
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Affiliation(s)
- Jinquan Li
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China
| | - Junmin Pei
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China
| | - Changming Fang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China
| | - Bo Li
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China
- Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming, China
| | - Ming Nie
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, Shanghai, China
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Zhang Y, Wang S, Feng Z, Song Y. Influenza incidence and air pollution: Findings from a four-year surveillance study of prefecture-level cities in China. Front Public Health 2022; 10:1071229. [PMID: 36530677 PMCID: PMC9755172 DOI: 10.3389/fpubh.2022.1071229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Accepted: 11/14/2022] [Indexed: 12/04/2022] Open
Abstract
Background Influenza is a serious public health problem, and its prevalence and spread show significant spatiotemporal characteristics. Previous studies have found that air pollutants are linked to an increased risk of influenza. However, the mechanism of influence and the degree of their association have not been determined. This study aimed to determine the influence of the air environment on the spatiotemporal distribution of influenza. Methods The kernel density estimation and Getis-Ord Gi * statistic were used to analyze the spatial distribution of the influenza incidence and air pollutants in China. A simple analysis of the correlation between influenza and air pollutants was performed using Spearman's correlation coefficients. A linear regression analysis was performed to examine changes in the influenza incidence in response to air pollutants. The sensitivity of the influenza incidence to changes in air pollutants was evaluated by performing a gray correlation analysis. Lastly, the entropy weight method was used to calculate the weight coefficient of each method and thus the comprehensive sensitivity of influenza incidence to six pollution elements. Results The results of the sensitivity analysis using Spearman's correlation coefficients showed the following ranking of the contributions of the air pollutants to the influenza incidence in descending order: SO2 >NO2 >CO> PM2.5 >O3 >PM10. The sensitivity results obtained from the linear regression analysis revealed the following ranking: CO>NO2 >SO2 >O3 >PM2.5 >PM10. Lastly, the sensitivity results obtained from the gray correlation analysis showed the following ranking: NO2 >CO>PM10 >PM2.5 >SO2 >O3. According to the sensitivity score, the study area can be divided into hypersensitive, medium-sensitive, and low-sensitive areas. Conclusion The influenza incidence showed a strong spatial correlation and associated sensitivity to changes in concentrations of air pollutants. Hypersensitive areas were mainly located in the southeastern part of northeastern China, the coastal areas of the Yellow River Basin, the Beijing-Tianjin-Hebei region and surrounding areas, and the Yangtze River Delta. The influenza incidence was most sensitive to CO, NO2, and SO2, with the occurrence of influenza being most likely in areas with elevated concentrations of these three pollutants. Therefore, the formulation of targeted influenza prevention and control strategies tailored for hypersensitive, medium-sensitive, low-sensitive, and insensitive areas are urgently needed.
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Affiliation(s)
- Yu Zhang
- School of Geographical Sciences, Northeast Normal University, Changchun, China
| | - Shijun Wang
- School of Geographical Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, Changchun, China
| | - Zhangxian Feng
- School of Geographical Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, Changchun, China
| | - Yang Song
- School of Geographical Sciences, Northeast Normal University, Changchun, China
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, Changchun, China
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9
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Wetland emission and atmospheric sink changes explain methane growth in 2020. Nature 2022; 612:477-482. [PMID: 36517714 DOI: 10.1038/s41586-022-05447-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 10/14/2022] [Indexed: 12/15/2022]
Abstract
Atmospheric methane growth reached an exceptionally high rate of 15.1 ± 0.4 parts per billion per year in 2020 despite a probable decrease in anthropogenic methane emissions during COVID-19 lockdowns1. Here we quantify changes in methane sources and in its atmospheric sink in 2020 compared with 2019. We find that, globally, total anthropogenic emissions decreased by 1.2 ± 0.1 teragrams of methane per year (Tg CH4 yr-1), fire emissions decreased by 6.5 ± 0.1 Tg CH4 yr-1 and wetland emissions increased by 6.0 ± 2.3 Tg CH4 yr-1. Tropospheric OH concentration decreased by 1.6 ± 0.2 per cent relative to 2019, mainly as a result of lower anthropogenic nitrogen oxide (NOx) emissions and associated lower free tropospheric ozone during pandemic lockdowns2. From atmospheric inversions, we also infer that global net emissions increased by 6.9 ± 2.1 Tg CH4 yr-1 in 2020 relative to 2019, and global methane removal from reaction with OH decreased by 7.5 ± 0.8 Tg CH4 yr-1. Therefore, we attribute the methane growth rate anomaly in 2020 relative to 2019 to lower OH sink (53 ± 10 per cent) and higher natural emissions (47 ± 16 per cent), mostly from wetlands. In line with previous findings3,4, our results imply that wetland methane emissions are sensitive to a warmer and wetter climate and could act as a positive feedback mechanism in the future. Our study also suggests that nitrogen oxide emission trends need to be taken into account when implementing the global anthropogenic methane emissions reduction pledge5.
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Cheng C, He Q, Zhang J, Chen B, Pavlostathis SG. Is the role of aerobic methanotrophs underestimated in methane oxidation under hypoxic conditions? THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 833:155244. [PMID: 35427622 DOI: 10.1016/j.scitotenv.2022.155244] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/21/2022] [Accepted: 04/08/2022] [Indexed: 06/14/2023]
Abstract
Microbial methane oxidation is the major biological methane (CH4) sink in the carbon cycle. Methanotrophs can use various electron acceptors in addition to oxygen; understanding the role and contribution of methanotrophs is thus an important topic. However, anaerobic oxidation of methane (AOM) mediated by methanotrophs is poorly explored and understood. This article summarizes the role aerobic methanotrophic bacteria play in AOM. Though AOM was originally considered to be mediated by anaerobic methanotrophic archaea, intra-aerobic methane-oxidizing bacteria (Candidatus Methylomirabilis oxyfera) appear to be involved in nitrite-dependent AOM. In addition, aerobic methanotrophs of the Methylomonadaceae and Methylocystaceae, are more versatile than previously assumed and can also be involved in nitrate/nitrite- or mineral oxide-dependent AOM under oxygen-limitation. Furthermore, the simultaneous reduction of nitrous oxide and oxidation of CH4 may be another new metabolic trait of aerobic methanotrophs. We discuss the potential metabolic pathways of CH4 oxidation under hypoxic conditions. It is of great ecological importance not only for the quantification of CH4 oxidation and emissions, but also for the definition of a new function of aerobic methanotrophs in anaerobic/hypoxic environments.
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Affiliation(s)
- Cheng Cheng
- College of Environment and Ecology, Chongqing University, Chongqing 400045, PR China.
| | - Qiang He
- College of Environment and Ecology, Chongqing University, Chongqing 400045, PR China
| | - Jian Zhang
- College of Safety and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, PR China; Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science & Engineering, Shandong University, Qingdao, Shandong 266237, PR China
| | - Bowen Chen
- College of Environment and Ecology, Chongqing University, Chongqing 400045, PR China
| | - Spyros G Pavlostathis
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
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11
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Temporal and Spatial Variation of Wetland CH4 Emissions from the Qinghai–Tibet Plateau under Future Climate Change Scenarios. ATMOSPHERE 2022. [DOI: 10.3390/atmos13060854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Wetlands are an important natural source of methane (CH4), so it is important to quantify how their emissions may vary under future climate change conditions. The Qinghai–Tibet Plateau contains more than a third of China’s wetlands. Here, we simulated temporal and spatial variation in CH4 emissions from natural wetlands on the Qinghai–Tibet Plateau from 2008 to 2100 under Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5. Based on the simulation results of the TRIPLEX-GHG model forced with data from 24 CMIP5 models of global climate, we predict that, assuming no change in wetland distribution on the Plateau, CH4 emissions from natural wetlands will increase by 35%, 98% and 267%, respectively, under RCP 2.6, 4.5 and 8.5. The predicted increase in atmospheric CO2 concentration will contribute 10–28% to the increased CH4 emissions from wetlands on the Plateau by 2100. Emissions are predicted to be majorly in the range of 0 to 30.5 g C m−2·a−1 across the Plateau and higher from wetlands in the southern region of the Plateau than from wetlands in central or northern regions. Under RCP8.5, the methane emissions of natural wetlands on the Qinghai–Tibet Plateau increased much more significantly than that under RCP2.6 and RCP4.5.
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12
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Li Q, Fernandez RP, Hossaini R, Iglesias-Suarez F, Cuevas CA, Apel EC, Kinnison DE, Lamarque JF, Saiz-Lopez A. Reactive halogens increase the global methane lifetime and radiative forcing in the 21st century. Nat Commun 2022; 13:2768. [PMID: 35589794 PMCID: PMC9120080 DOI: 10.1038/s41467-022-30456-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 04/28/2022] [Indexed: 11/09/2022] Open
Abstract
CH4 is the most abundant reactive greenhouse gas and a complete understanding of its atmospheric fate is needed to formulate mitigation policies. Current chemistry-climate models tend to underestimate the lifetime of CH4, suggesting uncertainties in its sources and sinks. Reactive halogens substantially perturb the budget of tropospheric OH, the main CH4 loss. However, such an effect of atmospheric halogens is not considered in existing climate projections of CH4 burden and radiative forcing. Here, we demonstrate that reactive halogen chemistry increases the global CH4 lifetime by 6-9% during the 21st century. This effect arises from significant halogen-mediated decrease, mainly by iodine and bromine, in OH-driven CH4 loss that surpasses the direct Cl-induced CH4 sink. This increase in CH4 lifetime helps to reduce the gap between models and observations and results in a greater burden and radiative forcing during this century. The increase in CH4 burden due to halogens (up to 700 Tg or 8% by 2100) is equivalent to the observed atmospheric CH4 growth during the last three to four decades. Notably, the halogen-driven enhancement in CH4 radiative forcing is 0.05 W/m2 at present and is projected to increase in the future (0.06 W/m2 by 2100); such enhancement equals ~10% of present-day CH4 radiative forcing and one-third of N2O radiative forcing, the third-largest well-mixed greenhouse gas. Both direct (Cl-driven) and indirect (via OH) impacts of halogens should be included in future CH4 projections.
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Affiliation(s)
- Qinyi Li
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, 28006, Spain.
| | - Rafael P Fernandez
- Institute for Interdisciplinary Science (ICB), National Research Council (CONICET), FCEN-UNCuyo, Mendoza, Argentina
| | - Ryan Hossaini
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Fernando Iglesias-Suarez
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, 28006, Spain.,Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
| | - Carlos A Cuevas
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, 28006, Spain
| | - Eric C Apel
- Atmospheric Chemistry Observations & Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
| | - Douglas E Kinnison
- Atmospheric Chemistry Observations & Modeling Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
| | - Jean-François Lamarque
- Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
| | - Alfonso Saiz-Lopez
- Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, 28006, Spain.
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13
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Sun B, Jiang M, Han G, Zhang L, Zhou J, Bian C, Du Y, Yan L, Xia J. Experimental warming reduces ecosystem resistance and resilience to severe flooding in a wetland. SCIENCE ADVANCES 2022; 8:eabl9526. [PMID: 35080980 PMCID: PMC8791607 DOI: 10.1126/sciadv.abl9526] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Climate warming and extreme hydrological events are threatening the sustainability of wetlands across the globe. However, whether climate warming will amplify or diminish the impact of extreme flooding on wetland ecosystems is unknown. Here, we show that climate warming significantly reduced wetland resistance and resilience to a severe flooding event via a 6-year warming experiment. We first found that warming rapidly altered plant community structure by increasing the dominance of low-canopy species. Then, we showed that warming reduced the resistance and resilience of vegetation productivity to a 72-cm flooding event. Last, we detected slower postflooding carbon processes, such as gross ecosystem productivity, soil respiration, and soil methane emission, under the warming treatment. Our results demonstrate how severe flooding can destabilize wetland vegetation structure and ecosystem function under climate warming. These findings indicate an enhanced footprint of extreme hydrological events in wetland ecosystems in a warmer climate.
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Affiliation(s)
- Baoyu Sun
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264000, China
| | - Ming Jiang
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
| | - Guangxuan Han
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264000, China
- University of Chinese Academy of Sciences, Beijing 100000, China
| | - Liwen Zhang
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264000, China
- University of Chinese Academy of Sciences, Beijing 100000, China
| | - Jian Zhou
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Chenyu Bian
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Ying Du
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Liming Yan
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Jianyang Xia
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
- Corresponding author.
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14
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Utilizing Earth Observations of Soil Freeze/Thaw Data and Atmospheric Concentrations to Estimate Cold Season Methane Emissions in the Northern High Latitudes. REMOTE SENSING 2021. [DOI: 10.3390/rs13245059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The northern wetland methane emission estimates have large uncertainties. Inversion models are a qualified method to estimate the methane fluxes and emissions in northern latitudes but when atmospheric observations are sparse, the models are only as good as their a priori estimates. Thus, improving a priori estimates is a competent way to reduce uncertainties and enhance emission estimates in the sparsely sampled regions. Here, we use a novel way to integrate remote sensing soil freeze/thaw (F/T) status from SMOS satellite to better capture the seasonality of methane emissions in the northern high latitude. The SMOS F/T data provide daily information of soil freezing state in the northern latitudes, and in this study, the data is used to define the cold season in the high latitudes and, thus, improve our knowledge of the seasonal cycle of biospheric methane fluxes. The SMOS F/T data is implemented to LPX-Bern DYPTOP model estimates and the modified fluxes are used as a biospheric a priori in the inversion model CarbonTracker Europe-CH4. The implementation of the SMOS F/T soil state is shown to be beneficial in improving the inversion model’s cold season biospheric flux estimates. Our results show that cold season biospheric CH4 emissions in northern high latitudes are approximately 0.60 Tg lower than previously estimated, which corresponds to 17% reduction in the cold season biospheric emissions. This reduction is partly compensated by increased anthropogenic emissions in the same area (0.23 Tg), and the results also indicates that the anthropogenic emissions could have even larger contribution in cold season than estimated here.
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15
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Nisbet EG, Dlugokencky EJ, Fisher RE, France JL, Lowry D, Manning MR, Michel SE, Warwick NJ. Atmospheric methane and nitrous oxide: challenges alongthe path to Net Zero. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20200457. [PMID: 34565227 PMCID: PMC8473950 DOI: 10.1098/rsta.2020.0457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 07/06/2021] [Indexed: 06/13/2023]
Abstract
The causes of methane's renewed rise since 2007, accelerated growth from 2014 and record rise in 2020, concurrent with an isotopic shift to values more depleted in 13C, remain poorly understood. This rise is the dominant departure from greenhouse gas scenarios that limit global heating to less than 2°C. Thus a comprehensive understanding of methane sources and sinks, their trends and inter-annual variations are becoming more urgent. Efforts to quantify both sources and sinks and understand latitudinal and seasonal variations will improve our understanding of the methane cycle and its anthropogenic component. Nationally declared emissions inventories under the UN Framework Convention on Climate Change (UNFCCC) and promised contributions to emissions reductions under the UNFCCC Paris Agreement need to be verified independently by top-down observation. Furthermore, indirect effects on natural emissions, such as changes in aquatic ecosystems, also need to be quantified. Nitrous oxide is even more poorly understood. Despite this, options for mitigating methane and nitrous oxide emissions are improving rapidly, both in cutting emissions from gas, oil and coal extraction and use, and also from agricultural and waste sources. Reductions in methane and nitrous oxide emission are arguably among the most attractive immediate options for climate action. This article is part of a discussion meeting issue 'Rising methane: is warming feeding warming? (part 1)'.
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Affiliation(s)
- Euan G. Nisbet
- Department of Earth Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK
- NCAS, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Edward J. Dlugokencky
- US National Oceanic and Atmospheric Administration, Global Monitoring Laboratory, 325 Broadway, Boulder, CO 80305, USA
| | - Rebecca E. Fisher
- Department of Earth Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK
| | - James L. France
- Department of Earth Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK
- British Antarctic Survey, Natural Environment Research Council, Cambridge CB3 0ET, UK
| | - David Lowry
- Department of Earth Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK
| | - Martin R. Manning
- New Zealand Climate Change Research Institute, School of Geography Environment and Earth Studies, Victoria University of Wellington, Wellington, New Zealand
| | - Sylvia E. Michel
- Institute of Arctic and Antarctic Research, Univ. of Colorado, Boulder, CO 80309-0450, USA
| | - Nicola J. Warwick
- NCAS, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
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16
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Zhang (张臻) Z, Poulter B, Knox S, Stavert A, McNicol G, Fluet-Chouinard E, Feinberg A, Zhao (赵园红) Y, Bousquet P, Canadell JG, Ganesan A, Hugelius G, Hurtt G, Jackson RB, Patra PK, Saunois M, Höglund-Isaksson L, Huang (黄春林) C, Chatterjee A, Li (李新) X. Anthropogenic emission is the main contributor to the rise of atmospheric methane during 1993–2017. Natl Sci Rev 2021; 9:nwab200. [PMID: 35547958 PMCID: PMC9084358 DOI: 10.1093/nsr/nwab200] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/03/2021] [Accepted: 11/03/2021] [Indexed: 11/12/2022] Open
Abstract
Atmospheric methane (CH4) concentrations have shown a puzzling resumption in growth since 2007 following a period of stabilization from 2000 to 2006. Multiple hypotheses have been proposed to explain the temporal variations in CH4 growth, and attribute the rise of atmospheric CH4 either to increases in emissions from fossil fuel activities, agriculture and natural wetlands, or to a decrease in the atmospheric chemical sink. Here, we use a comprehensive ensemble of CH4 source estimates and isotopic δ13C-CH4 source signature data to show that the resumption of CH4 growth is most likely due to increased anthropogenic emissions. Our emission scenarios that have the fewest biases with respect to isotopic composition suggest that the agriculture, landfill and waste sectors were responsible for 53 ± 13% of the renewed growth over the period 2007–2017 compared to 2000–2006; industrial fossil fuel sources explained an additional 34 ± 24%, and wetland sources contributed the least at 13 ± 9%. The hypothesis that a large increase in emissions from natural wetlands drove the decrease in atmospheric δ13C-CH4 values cannot be reconciled with current process-based wetland CH4 models. This finding suggests the need for increased wetland measurements to better understand the contemporary and future role of wetlands in the rise of atmospheric methane and climate feedback. Our findings highlight the predominant role of anthropogenic activities in driving the growth of atmospheric CH4 concentrations.
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Affiliation(s)
- Zhen Zhang (张臻)
- Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA
| | - Benjamin Poulter
- Biospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - Sara Knox
- Department of Geography, University of British Columbia, Vancouver V6T 1Z2, Canada
| | - Ann Stavert
- Global Carbon Project, CSIRO Oceans and Atmosphere, Canberra, ACT 2601, Australia
| | - Gavin McNicol
- Department of Earth and Environmental Sciences, University of Illinois Chicago, Chicago, IL 60607, USA
| | | | - Aryeh Feinberg
- Institute for Data, Systems and Society, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yuanhong Zhao (赵园红)
- College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266000, China
| | - Philippe Bousquet
- Laboratoire des Sciences du Climat et de l’Environment, LSCE-IPSL (CEA-CNRS-UVSQ), Université Paris-Saclay, Gif-sur-Yvette 91191, France
| | - Josep G Canadell
- Global Carbon Project, CSIRO Oceans and Atmosphere, Canberra, ACT 2601, Australia
| | - Anita Ganesan
- School of Geographical Sciences, University of Bristol, Bristol BS8 1RL, UK
| | - Gustaf Hugelius
- Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, Stockholm SE-106 91, Sweden
| | - George Hurtt
- Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA
| | - Robert B Jackson
- Department of Earth System Science, Stanford University, Stanford, CA 94305, USA
- Woods Institute for the Environment and Precourt Institute for Energy, Stanford University, Stanford, CA 94305, USA
| | - Prabir K Patra
- Research Institute for Global Change, JAMSTEC, Yokohama 236-0001, Japan
| | - Marielle Saunois
- Laboratoire des Sciences du Climat et de l’Environment, LSCE-IPSL (CEA-CNRS-UVSQ), Université Paris-Saclay, Gif-sur-Yvette 91191, France
| | - Lena Höglund-Isaksson
- International Institute for Applied Systems Analysis (IIASA), Laxenburg A-2361, Austria
| | - Chunlin Huang (黄春林)
- Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Abhishek Chatterjee
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Universities Space Research Association, Columbia, MD 21046, USA
| | - Xin Li (李新)
- Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
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17
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Biogeochemistry of Mediterranean Wetlands: A Review about the Effects of Water-Level Fluctuations on Phosphorus Cycling and Greenhouse Gas Emissions. WATER 2021. [DOI: 10.3390/w13111510] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Although Mediterranean wetlands are characterized by extreme natural water level fluctuations in response to irregular precipitation patterns, global climate change is expected to amplify this pattern by shortening precipitation seasons and increasing the incidence of summer droughts in this area. As a consequence, a part of the lake sediment will be exposed to air-drying in dry years when the water table becomes low. This periodic sediment exposure to dry/wet cycles will likely affect biogeochemical processes. Unexpectedly, to date, few studies are focused on assessing the effects of water level fluctuations on the biogeochemistry of these ecosystems. In this review, we investigate the potential impacts of water level fluctuations on phosphorus dynamics and on greenhouse gases emissions in Mediterranean wetlands. Major drivers of global change, and specially water level fluctuations, will lead to the degradation of water quality in Mediterranean wetlands by increasing the availability of phosphorus concentration in the water column upon rewetting of dry sediment. CO2 fluxes are likely to be enhanced during desiccation, while inundation is likely to decrease cumulative CO2 emissions, as well as N2O emissions, although increasing CH4 emissions. However, there exists a complete gap of knowledge about the net effect of water level fluctuations induced by global change on greenhouse gases emission. Accordingly, further research is needed to assess whether the periodic exposure to dry–wet cycles, considering the extent and frequency of the cycles, will amplify the role of these especial ecosystems as a source of these gases and thereby act as a feedback mechanism for global warming. To conclude, it is pertinent to consider that a better understanding about the effect of water level fluctuations on the biogeochemistry of Mediterranean wetlands will help to predict how other freshwater ecosystems will respond.
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18
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Microbial Communities in Methane Cycle: Modern Molecular Methods Gain Insights into Their Global Ecology. ENVIRONMENTS 2021. [DOI: 10.3390/environments8020016] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The role of methane as a greenhouse gas in the concept of global climate changes is well known. Methanogens and methanotrophs are two microbial groups which contribute to the biogeochemical methane cycle in soil, so that the total emission of CH4 is the balance between its production and oxidation by microbial communities. Traditional identification techniques, such as selective enrichment and pure-culture isolation, have been used for a long time to study diversity of methanogens and methanotrophs. However, these techniques are characterized by significant limitations, since only a relatively small fraction of the microbial community could be cultured. Modern molecular methods for quantitative analysis of the microbial community such as real-time PCR (Polymerase chain reaction), DNA fingerprints and methods based on high-throughput sequencing together with different “omics” techniques overcome the limitations imposed by culture-dependent approaches and provide new insights into the diversity and ecology of microbial communities in the methane cycle. Here, we review available knowledge concerning the abundances, composition, and activity of methanogenic and methanotrophic communities in a wide range of natural and anthropogenic environments. We suggest that incorporation of microbial data could fill the existing microbiological gaps in methane flux modeling, and significantly increase the predictive power of models for different environments.
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19
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Zhu D, Wu N, Bhattarai N, Oli KP, Chen H, Rawat GS, Rashid I, Dhakal M, Joshi S, Tian J, Zhu Q, Chaudhary S, Tshering K. Methane emissions respond to soil temperature in convergent patterns but divergent sensitivities across wetlands along altitude. GLOBAL CHANGE BIOLOGY 2021; 27:941-955. [PMID: 33222345 DOI: 10.1111/gcb.15454] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 11/08/2020] [Indexed: 06/11/2023]
Abstract
Among the global coordinated patterns in soil temperature and methane emission from wetlands, a declining trend of optimal soil temperature for methane emissions from low to high latitudes has been witnessed, while the corresponding trend along the altitudinal gradient has not yet been investigated. We therefore selected two natural wetlands located at contrasting climatic zones from foothill and mountainside of Nepal Himalayas, to test: (1) whether the optimal temperature for methane emissions decreases from low to high altitude, and (2) whether there is a difference in temperature sensitivity of methane emissions from those wetlands. We found significant spatial and temporal variation of methane emissions between the two wetlands and seasons. Soil temperature was the dominant driver for seasonal variation in methane emissions from both wetlands, though its effect was perplexed by the level of standing water, aquatic plants, and dissolved organic carbon, particularly in the deep water area. When integrative comparison was conducted by adding the existing data from wetlands of diverse altitudes, and the latitude-for-altitude effect was taken into account, we found the baseline soil temperatures decrease whilst the altitude rises with respect to a rapid increase in methane emission from all wetlands, however, remarkably higher sensitivity of methane emissions to soil temperature (apparent Q10 ) was found in mid-altitude wetland. We provide the first evidence of an apparent decline in optimal temperature for methane emissions with increasing elevation. These findings suggest a convergent pattern of methane emissions with respect to seasonal temperature shifts from wetlands along altitudinal gradient, while a divergent pattern in temperature sensitivities exhibits a single peak in mid-altitude.
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Affiliation(s)
- Dan Zhu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
- Zoige Wetland Ecosystem Research Station, Chinese Academy of Sciences, Hongyuan, China
- Key Laboratory of Mountain Ecological Restoration and Bio-resources Utilization, Chinese Academy of Sciences, Chengdu, China
| | - Ning Wu
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Nabin Bhattarai
- International Centre for Integrated Mountain Development, Kathmandu, Nepal
| | | | - Huai Chen
- Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
- Zoige Wetland Ecosystem Research Station, Chinese Academy of Sciences, Hongyuan, China
- Key Laboratory of Mountain Ecological Restoration and Bio-resources Utilization, Chinese Academy of Sciences, Chengdu, China
| | - Gopal Singh Rawat
- Faculty of Wildlife Sciences, Wildlife Institute of India, Dehradun, India
| | - Irfan Rashid
- Department of Botany, University of Kashmir, Srinagar, India
| | - Maheshwar Dhakal
- Ministry of Forests and Environment, Government of Nepal, Kathmandu, Nepal
| | - Srijana Joshi
- International Centre for Integrated Mountain Development, Kathmandu, Nepal
| | - Jianqing Tian
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Qiu'an Zhu
- College of Hydrology and Water Resources, Hohai University, Nanjing, China
| | - Sunita Chaudhary
- International Centre for Integrated Mountain Development, Kathmandu, Nepal
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20
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Disproportionate Changes in the CH4 Emissions of Six Water Table Levels in an Alpine Peatland. ATMOSPHERE 2020. [DOI: 10.3390/atmos11111165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The Zoige alpine peatlands are one of the highest and largest alpine peatlands in the world and play an important role in the global carbon cycle. Drainage is the main disturbance at Zoige, and the drawdown of the water table level changes CH4 emissions. There is still much uncertainty relating to how CH4 emissions respond to multiple water table levels. Here, we simulated six gradients (−30 cm, −20 cm, −10 cm, 0 cm, 10 cm, and 20 cm) of the water table level through a mesocosm manipulation experiment in the Zoige peatlands. The water table level had a significant effect on CH4 emissions. CH4 emissions did not change with water table levels from −30 cm to −10 cm, but significantly increased as the water table level increased above −10 cm. A significant log-linear relationship (R2 = 0.44, p < 0.001) was found between CH4 emissions and a water table level range from −10 to 20 cm. This study characterized the responses of CH4 emissions to multiple water table levels and provide additional data for accurately evaluating CH4 emissions. The results of this study also have several conservation implications for alpine peatlands.
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