常年淹水稻田甲烷产生潜力和产生途径的季节变化  

Seasonal Variations in Methane Production Potential and Methanogenic Pathway in a Permanently Flooded Rice Field

作　　者：朱小莉 黄琼 宋开付 马静[1] 张广斌[1] 徐华[1] ZHU Xiaoli;HUANG Qiong;SONG Kaifu;MA Jing;ZHANG Guangbin;XU Hua(State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008 [2]中国科学院大学,北京100049

出　　处：《土壤学报》2023年第2期503-511,共9页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41877325);中国科学院青年创新促进会项目(2018349);国家重点研发计划项目(2017YFD0300105)资助。

摘　　要：甲烷的减排问题已成为各国政府和科研人员关注的焦点。稻田是温室气体甲烷的重要排放源,甲烷产生是排放的前提条件,主要有乙酸发酵和CO_(2)/H_(2)还原两条途径。常年淹水稻田甲烷排放量高,减排潜力大,但关于这类稻田甲烷产生途径的季节变化规律尚少见报道。于四川省资阳市的常年淹水稻田,采集水稻4个重要生育期(分蘖期、孕穗期、抽穗期、成熟期)的新鲜土样,通过室内厌氧培养试验观测了甲烷产生潜力,并采用稳定性碳同位素方法和氟甲烷(CH_(3)F,2%)抑制法,量化CO_(2)/H_(2)产甲烷的碳同位素分馏系数(α(CO_(2)/CH_(4))),从而定量评估乙酸产甲烷途径的相对贡献率(ƒ_(乙酸))。结果表明:添加CH_(3)F显著降低甲烷产生,甲烷产生潜力在成熟期最大,变化范围为3.22~12.71μg·g^(-1)·d^(-1);产生CH_(4)的δ^(13)C值(δ^(13)CH_(4))为-66.83‰~-59.62‰,较添加CH_(3)F的δ^(13)CH_(4)显著偏正(-90.83‰~-82.26‰);α_(CO_(2)/CH_(4))在分蘖期最大,孕穗期最小,变化范围为1.064~1.076;ƒ_(乙酸)由分蘖期的54%~61%急剧下降至孕穗期的30%~35%,在成熟期又上升至54%~61%。进一步分析发现:甲烷产生潜力的季节变化与土壤溶解性有机碳(DOC)含量的季节变化显著正相关,ƒ_(乙酸)的季节变化与土壤乙酸含量的季节变化显著正相关。综上,常年淹水稻田的甲烷产生潜力和产生途径均存在明显的季节变化,且分别主要受土壤DOC和乙酸含量的影响。【Objective】The mitigation of methane(CH_(4))emission has long been the focus of governments and researchers worldwide.Rice fields are an important source of CH_(4) emission,and CH_(4) production is the precondition of CH_(4) emission.It is mainly produced by acetate fermentation and CO_(2)/H_(2)reduction.Substantial CH_(4) emissions are observed from the permanently flooded rice fields,thus leaving a high mitigation potential of emission.However,reports on the seasonal variation of the methanogenic pathway in these rice fields are limited.【Method】Fresh soil samples from four rice growth stages(tillering stage,booting stage,heading stage,and ripening stage)were collected from a permanently flooded rice field in Ziyang City,Sichuan Province,China.The CH_(4) production potential(MPP)was observed through anaerobic incubation experiments.Both stable carbon isotope technique and methyl fluoride(CH_(3)F,2%)inhibition method were used to quantify the carbon isotopic fractionation factor for the conversion of CO_(2)to CH_(4)(α(CO_(2)/CH_(4))),as well as to quantitatively estimate the relative contribution of acetate-dependent methanogenesis(ƒ_(acetate)).【Result】The addition of CH_(3)F significantly decreased the CH_(4) production,and the MPP reached the highest value at the ripening stage,ranging from 3.22 to 12.71μg·g^(-1)·d^(-1).Theδ^(13)C-value of produced CH_(4)(δ^(13)CH_(4))varied from-66.83‰to-59.62‰,which was much more positive than that of produced CH_(4) with CH_(3)F addition(from-90.83‰to-82.26‰).The()CO_(2)/CH_(4)αreached its maximum and minimum values at tillering and booting stages,respectively,which was between 1.064 and 1.076.Theƒ_(acetate)(30%-61%)decreased sharply from 54%-61%at the tillering stage to 30%-35%at the booting stage and then increased to 54%-61%at the ripening stage.Further analysis showed that the seasonal variation of MPP was positively correlated with the variation of soil dissolved organic carbon(DOC)content,and the seasonal variation ofƒ_(acetate) was signif

关 键 词：常年淹水稻田 碳同位素分馏 抑制剂氟甲烷 乙酸产甲烷 溶解性有机碳 

分 类 号：S153[农业科学—土壤学]