针铁矿吸附态和包裹态有机碳在稻田土壤中的矿化及其激发效应  

Mineralization of Goethite-Adsorbed and-Encapsulated Organic Carbon and Its Priming Effect in Paddy Soil

作　　者：江家彬 祝贞科[2] 林森 李宇虹 李科林 王小利[1] 葛体达[2] 吴金水[2] JIANG Jiabin;ZHU Zhenke;LIN Sen;LI Yuhong;LI Kelin;WANG Xiaoli;GE Tida;WU Jinshui(Agricultural College of Guizhou University,Guiyang 550025,China;Key Laboratory of Agro Ecological Processes in Subtropical Region,Institute of Subtropical Agriculture,Chinese Academy of Sciences,Changsha 410125,China;School of Environmental Science and Engineering,Central South Forestry University,Changsha 410004,China)

机构地区：[1]贵州大学农学院,贵阳550025 [2]中国科学院亚热带农业生态研究所亚热带农业生态过程重点实验室,长沙410125 [3]中南林业科技大学环境科学与工程学院,长沙410004

出　　处：《土壤学报》2021年第6期1530-1539,共10页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41761134095,41877104,31860160)资助。

摘　　要：南方水稻土富含铁氧化物,土壤有机碳通过与铁氧化物结合的形式长期固存于土壤中;由于土壤中氧化铁和有机碳主要通过吸附、键和与包裹等形式存在,所以不同的碳铁复合物的稳定性存在一定的差异。尽管已有较多研究分析了土壤中有机碳与铁矿的结合与赋存形式,但是有机碳与铁矿间的结合方式对有机碳在水稻土中矿化及其激发效应的影响机制尚不明确。以葡萄糖为典型小分子外源有机碳,通过制备针铁矿吸附态葡萄糖和包裹态葡萄糖,采用室内模拟培养实验,研究两种铁矿结合态葡萄糖在淹水水稻土中的矿化特征及其激发效应。结果表明:与单独添加葡萄糖处理相比,碳铁复合物的添加分别使CO_(2)和^(13)CO_(2)释放量增加了0.39倍~0.53倍和0.87倍~1.07倍,却使CH_(4)和^(13)CH_(4)释放量分别降低了0.44倍~0.59倍和0.25倍~0.44倍。相对于针铁矿吸附态葡萄糖,针铁矿包裹态葡萄糖显著抑制了CH_(4)释放。而且,碳铁复合物的添加均在一定程度上促进了土壤原有有机碳矿化释放CO_(2),但抑制了来源于土壤原有有机碳的CH_(4)释放。其中,针铁矿包裹态葡萄糖对来源于土壤原有有机碳的CH_(4)释放量是针铁矿吸附态葡萄糖的1.33倍。针铁矿包裹态葡萄糖的快速矿化的碳库比例显著高于针铁矿吸附态葡萄糖,且其半衰期(T_(1/2))较针铁矿吸附态葡萄糖大10.85倍,其快库转化速率(k1)和慢库转化速率(k2)比铁矿吸附态葡萄糖的小10.74倍和19倍。其次,针铁矿包裹态葡萄糖对土壤有机质CO_(2)累积激发效应表现为较弱的正激发(6.44 mg·kg^(-1)),而对土壤有机质CH_(4)累积激发效应则表现为负激发(–15.49 mg·kg^(-1)),即针铁矿包裹态葡萄糖的添加抑制了土壤原有有机碳的矿化(–9.05 mg·kg^(-1)),从而增强了土壤有机碳的固持潜力。因此,不同结构碳铁复合物的添加抑制了土壤原有有机碳的矿化,且针铁矿�【Objective】The paddy soil in South China rich in iron oxides has soil organic carbon(OC)stored for a long time in association with iron oxides.As the iron oxide and organic carbon in the soil exist mainly in adsorbed-,bonded,and encapsulated forms,the carbon-goethite association vary in stability with the form.Although a large volume of studies have analyzed how OC and iron oxides associate in the soil and what form they exist in.However,so far little is known about mechanism of the association,relative to type,between iron oxides and OC affecting mineralization of OC and its priming effects(PE)in paddy soil.【Method】Glucose was used as the typical low molecular weight exogenous C,and prepared into goethite-adsorbed glucose(Goe-G)and goethite-encapsulated glucose(Goe*G),which were then incubated in the experiment to explore characteristics of the mineralization of the two iron oxides-glucose associations and their PE in paddy soil.【Result】Results show that compared with the pots amended with glucose alone,the pots amended with the two types of carbon-goethite association,separately,had CO_(2) and 13CO_(2) emission increased by 0.39–0.53 times and 0.87–1.07 times,respectively,and CH_(4) and 13CH_(4) emission decreased by 0.44–0.59 fold and 0.25–0.44 fold,respectively.Relative to amendment of goethite-adsorbed glucose,amendment of goethite-encapsulated glucose significantly inhibited CH_(4) release.What is more,amendment of carbon-goethite association,regardless of type,promoted the mineralization of SOC into CO_(2) but inhibited the release of native SOC-derived CH_(4).The inhibitory effect of goethite-encapsulated glucose on the release of native SOC-derived CH_(4) was significantly greater than that of goethite adsorbed glucose.The fast pool of goethite-encapsulated glucose was higher than that of goethite adsorbed glucose,and its half-life(T_(1/2))was 10.85 times longer than that of goethite adsorbed glucose,and the turnover rate of the fast pool(k1)and slow pool(k2)was 10.74 and 19 times sma

关 键 词：水稻土 碳铁复合物 碳同位素标记 激发效应 碳固持 

分 类 号：X144[环境科学与工程—环境科学]