Large porewater exchange reshapes saltmarsh carbon and greenhouse gas budgets on local and global scales  

作　　者：Xiaogang CHEN Isaac RSANTOS Lucheng ZHAN Yu Yan YAU Yan ZHANG Ling LI 

机构地区：[1]Key Laboratory of Coastal Environment and Resources of Zhejiang Province,School of Engineering,Westlake University,Hangzhou 310024,China [2]Department of Marine Sciences,University of Gothenburg,Gothenburg 41319,Sweden [3]College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210024,China

出　　处：《Science China Earth Sciences》2024年第7期2195-2209,共15页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.42006152);the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ21D060005);funding from the Swedish Research Council(Grant No.2020-00457)。

摘　　要：Saltmarshes are carbon-rich ecosystems that play a role in climate regulation by efficiently sequestrating atmospheric CO_(2).Climate change is a major threat to saltmarshes and will impact saltmarsh carbon sequestration.Notably,porewater-derived carbon outwelling emerges as a crucial pathway for carbon sequestration,but it has been largely overlooked in saltmarshes.Here,we assessed the drivers of dissolved carbon exports and greenhouse gas emissions in a saltmarsh and placed those observations into a global context.In our study site,porewater exchange(PEX)was the major process controlling dissolved carbon and greenhouse gas dynamics.Combining our results with 33 other studies in saltmarshes worldwide,porewater-derived carbon fluxes were equivalent to~48% of average global saltmarsh primary productivity and 2.2 times greater than global organic carbon burial.Hence,our local observations and global upscaling demonstrate the major role played by PEX in saltmarsh carbon budgets.While part of dissolved inorganic carbon returns to the atmosphere as CO_(2),the remaining bicarbonate fraction is stored in the ocean over long time scales.Our findings strengthen global blue carbon assessments and build arguments for the use of saltmarshes as nature-based solutions for global climate change.

关 键 词：Coastal carbon Global carbon budget Carbon neutrality Nature-based solutions Coastal wetlands Submarine groundwater discharge 

分 类 号：X171.1[环境科学与工程—环境科学] P467[天文地球—大气科学及气象学]