大气CO_(2)浓度缓增对稻田硝酸盐型甲烷厌氧氧化过程的影响  

Effect of gradual increase of atmospheric CO_(2) concentration on nitrate-dependent anaerobic methane oxidation in paddy soils

作　　者：黄翯宸 金靖昊 沈李东[1] 田茂辉 刘心 杨王挺 胡正华 HUANG He-chen;JIN Jing-hao;SHEN Li-dong;TIAN Mao-hui;LIU Xin;YANG Wang-ting;HU Zheng-hua(Department of Ecology,Nanjing University of Information Science and Technology,Nanjing 210044,China;Department of Applied Meteorology,Nanjing University of Information Science and Technology,Nanjing 210044,China)

机构地区：[1]南京信息工程大学生态系,南京210044 [2]南京信息工程大学应用气象学系,南京210044

出　　处：《应用生态学报》2022年第9期2441-2449,共9页Chinese Journal of Applied Ecology

基　　金：江苏省自然科学基金项目(BK20190092);国家自然科学基金项目(41977037);江苏省大学生创新创业训练计划重点项目(202210300062Z)资助。

摘　　要：硝酸盐型甲烷厌氧氧化(AOM)是控制稻田甲烷排放的一种新途径,大气CO_(2)浓度升高会对稻田甲烷排放产生重要影响,但有关其对硝酸盐型AOM过程的影响知之甚少。本研究依托开顶式气室组成的CO_(2)浓度自动调控平台,采用^(13)CH_(4)稳定性同位素示踪技术,从甲烷氧化活性、相关功能微生物Candidatus Methanoperedens nitroreducens(M.nitroreducens)-like古菌丰度与群落组成等方面,系统研究了稻田土壤中硝酸盐型AOM过程对大气CO_(2)浓度缓增的响应。试验设置背景CO_(2)浓度和CO_(2)浓度缓增处理(背景CO_(2)浓度基础上每年增加40μL·L^(-1),直至增幅达160μL·L^(-1))。结果表明:稻田土壤硝酸盐型AOM速率为0.7~11.3 nmol CO_(2)·g^(-1)·d^(-1);定量PCR结果显示,M.nitroreducens-like古菌mcrA基因丰度为2.2×10^(6)~8.5×10^(6)copies·g^(-1)。与对照相比,CO_(2)浓度缓增处理使土壤中硝酸盐型AOM速率和M.nitroreducens-like古菌mcrA基因丰度均有一定幅度提高,特别是在5~10 cm深度下两者均显著提高。CO_(2)浓度缓增处理未显著改变M.nitroreducens-like古菌群落结构,但使其多样性显著降低。相关性分析表明,土壤有机碳含量可能是影响硝酸盐型AOM过程的重要因子。综上,大气CO_(2)浓度缓增在一定程度上促进了硝酸盐型AOM反应,暗示在未来气候变化背景下其在控制稻田甲烷排放中具有积极作用。Nitrate-dependent anaerobic oxidation of methane(AOM)is a new pathway to reduce methane emissions from paddy ecosystems.The elevated atmospheric CO_(2)concentration can affect methane emissions from paddy ecosystems,but its impact on the process of nitrate-dependent AOM is poorly known.Based on the automatic CO_(2)control platform with open top chambers and the ^(13)CH_(4) stable isotope experiments,the responses of the activity of nitrate-dependent AOM,abundance and community composition of Candidatus Methanoperedens nitroreducens(M.nitroreducens)-like archaea to the gradual increase of CO_(2)concentration were investigated in paddy fields.We set up two CO_(2)concentration treatments,including an ambient CO_(2)and a gradual increase of CO_(2)(increase of 40μL·L^(-1)per year above ambient CO_(2)concentration until 160μL·L^(-1)).The results showed the nitrate-dependent AOM rate of 0.7-11.3 nmol CO_(2)·g^(-1)·d^(-1)in the studied paddy fields,and quantitative PCR showed the abundance of M.nitroreducens-like archaeal mcrA genes of 2.2×10^(6)-8.5×10^(6)copies·g^(-1).Compared to the ambient CO_(2)treatment,the slow elevated CO_(2)treatment enhanced the nitrate-dependent AOM rate and stimulated the abundance of M.nitroreducens-like archaea,particularly in 5-10 cm soil layer.The gradual increased CO_(2)concentration treatment did not change the community composition of M.nitroreducens-like archaea,but significantly decreased their diversity.The soil organic carbon content was an important factor influencing the nitrate-dependent AOM process.Overall,our results showed that the gradual increase of CO_(2)concentration could promote the nitrate-dependent AOM,suggesting its positive role in mitigating methane emissions from paddy ecosystems under future climate change.

关 键 词：稻田 硝酸盐型甲烷厌氧氧化 CO_(2)浓度升高 群落组成 

分 类 号：X144[环境科学与工程—环境科学] X16