Divergent responses of wetland methane emissions to elevated atmospheric CO2 dependent on water table
Divergent responses of wetland methane emissions to elevated atmospheric CO2 dependent on water table
复制标题
湿地甲烷排放对大气二氧化碳浓度升高的不同反应取决于地下水位
DOI：
10.1016/j.watres.2021.117682
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发表时间：
2021
期刊：
影响因子：
12.8
通讯作者：
Ding Weixin
中科院分区：
文献类型：
--
作者：
Lin Yongxin;Yuan Junji;Liu Deyan;Kang Hojeong;Freeman Chris;Hu Hang-Wei;Ye Guiping;Ding Weixin
大气CO2浓度升高可能对湿地甲烷（CH 4）排放产生影响，但其幅度和方向仍然不可预测，因为相关机制尚未得到充分研究。在这里，我们建立了一个在situmacrocosm实验比较CO2浓度升高（700 ppm）对两个湿地的CH 4排放量的影响：间歇淹没Calamagrostis angustifoliamarsh和永久淹没苔草lasiocarpamarsh。CO2浓度的升高使C. angustifoliamarsh，而C.毛果芸香CO2引起的C. angustifoliamarsh与（1）植物光合作用释放的溶解有机碳（DOC）增加和（2）甲烷氧化（速率）降低有关，这是由于甲烷氧化菌群落组成发生了变化。相反，CO2诱导的C. lasiocarpamarsh与土壤氧化还原电位和pmoA基因丰度的增加有关。综合全球湿地生态系统的数据，发现CH 4排放对CO2浓度升高的响应取决于湿地地下水位和相关植物的泌氧能力。在CO2浓度升高的条件下，具有高氧分泌能力的植物抑制CH 4排放，而具有低氧分泌能力的植物刺激CH 4排放;这两种效应都是通过一个反馈回路介导的，该反馈回路涉及产甲烷菌和甲烷氧化菌的活动变化。
Elevated atmospheric CO2may have consequences for methane (CH4) emissions from wetlands, yet the magnitude and direction remain unpredictable, because the associated mechanisms have not been fully investigated. Here, we established anin situmacrocosm experiment to compare the effects of elevated CO2(700 ppm) on the CH4emissions from two wetlands: an intermittently inundatedCalamagrostis angustifoliamarsh and a permanently inundatedCarex lasiocarpamarsh. The elevated CO2increased CH4emissions by 27.6–57.6% in theC. angustifoliamarsh, compared to a reduction of 18.7–23.5% in theC. lasiocarpamarsh. The CO2-induced increase in CH4emissions from theC. angustifoliamarsh was paralleled with (1) increased dissolved organic carbon (DOC) released from plant photosynthesis and (2) reduced (rate of) CH4oxidation due to a putative shift in methanotrophic community composition. In contrast, the CO2-induced decrease in CH4emissions from theC. lasiocarpamarsh was associated with the increases in soil redox potential andpmoAgene abundance. We synthesized data from worldwide wetland ecosystems, and found that the responses of CH4emissions to elevated CO2was determined by the wetland water table levels and associated plant oxygen secretion capacity. In conditions with elevated CO2, plants with a high oxygen secretion capacity suppress CH4emissions while plants with low oxygen secretion capacity stimulate CH4emissions; both effects are mediated via a feedback loop involving shifts in activities of methanogens and methanotrophs.