围垦对滨海稻田土壤N2O还原潜力的影响  

Effects of reclamation on the N2O reduction potential of paddy soils in coastal wetlands

作　　者：汪方圆 张耀鸿[1] 饶旭东 谢晴 贾仲君[2] WANG Fang-yuan;ZHANG Yao-hong;RAO Xu-dong;XIE Qing;JIA Zhong-jun(Collaborative Innovation Center for Forecast and Evaluation of Meteorological Disasters/Jiangsu Provincial Key Laboratory of Agricultural Meteorology,Nanjing University of Information Science and Technology,Nanjing 210044,China;State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China)

机构地区：[1]南京信息工程大学气象灾害预报预警与评估协同创新中心/江苏省农业气象重点实验室,南京210044 [2]中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室,南京210008

出　　处：《农业环境科学学报》2020年第11期2668-2674,共7页Journal of Agro-Environment Science

基　　金：国家自然科学基金项目(41671247,41103039);江苏省自然科学基金项目(BK20171455);国家留学基金项目(201908320185)。

摘　　要：稻田湿地生态系统的N2O还原消耗潜力对缓解大气温室气体效应具有重要意义,而滨海自然湿地围垦改造成稻田后耕层土壤的N2O还原速率及其微生物机制却鲜有报道。选取崇明岛光滩湿地为对照(WK0),比较研究不同围垦年限(19、27、51、86 a)的围垦区稻田耕作层土壤N2O还原速率演替规律及其微生物数量变异特征。结果表明,土壤总有机碳含量(TOC)随围垦年限增长而显著增加,而土壤pH值、SO4^2-浓度和EC值则均随围垦年限增长而呈逐渐下降趋势。土壤N2O还原速率随围垦年限增长而显著增加,其中围垦86 a稻田土壤达到25.5μg N2O·g^-1·d^-1,与光滩湿地相比增加了58.4%。定量PCR结果发现,功能基因nosZⅠ和nosZⅡ拷贝数也随着围垦年限增长而显著增加,其中围垦86 a的稻田土壤功能基因分别为1.72×10^8copies·g^-1和4.36×10^8copies·g^-1,比光滩湿地稻田高出一个数量级。相关性分析发现土壤N2O还原速率与功能基因nosZⅠ拷贝数呈显著正相关,而功能基因nosZⅡ拷贝数随围垦年限的增加率远高于功能基因nosZⅠ;N2O还原速率、功能基因nosZⅠ、nosZⅡ拷贝数与3个土壤理化指标(pH、EC、SO4^2-)均呈负相关。因此,围垦造田促进了滨海湿地土壤N2O还原过程,而功能基因nosZⅠ数量的大幅增加是N2O还原速率增加的重要原因。The nitrous oxide(N2O)reduction potential of paddy fields is of great significance for mitigating atmospheric greenhouse gas emissions.However,N2O reduction rates of tillage layer soil and the underlying microbial mechanisms remain unclear after the reclamation of coastal natural wetland as paddy fields.In this study,the Chongming Dongtan Natural Wetland in the Yangtze River estuary was selected as the control(WK0),and N2O reduction potential and related microbial quantity characteristics were investigated in paddy field soils with different reclamation years(19,27,51 a,and 86 a).The results showed that total organic carbon(TOC)soil content increased significantly as the reclamation period increased,whereas pH,EC value,and SO24-concentration gradually decreased.The N2O reduction rates increased significantly as the reclamation period increased,and the N2O reduction rate in the paddy field with an 86 a reclamation period was 25.5μg N2O·g-1·d-1,which was 58.4%higher than that of natural wetlands(WK0).The copy numbers of nosZⅠand nosZⅡgenes increased as the reclamation period increased,and the copy numbers of the paddy field with an 86 a reclamation period were 1.72×108 copies·g-1 and 4.36×108 copies·g-1,which were one order of magnitude higher than those of natural wetlands.The correlation analysis showed that the N2O reduction rate was positively correlated with the abundance of nosZⅠgene,whereas the increase in the copy number of the nosZⅡgene was much higher than that of the nosZⅠgene as the reclamation period increased.The N2O reduction rate and the copy number of nosZⅠand nosZⅡgenes was negatively correlated with pH,EC,and SO24-concentration in the soil.Therefore,the reclamation of coastal wetlands into paddy fields promote the N2O reduction potential of topsoil;the significant increase in the number of nosZⅠgenes is one of the primary factors controlling the N2O reduction rate increase.

关 键 词：围垦 滨海稻田 nosZ基因 N_2O还原 

分 类 号：S154.1[农业科学—土壤学]