自养微生物同化碳在土壤腐殖质组分及团聚体中的分配  

Input and Distribution of Autotrophic Microbe-Assimilated Carbon in Humus and Aggregate Fractions of Soils

作　　者：简燕[1,2] 曾冠军[2] 周萍[2] 袁红朝[2] 葛体达[2] 邹冬生[1] 吴金水[2] 

机构地区：[1]湖南农业大学生物科学技术学院,湖南长沙410128 [2]中国科学院亚热带农业生态研究所、中国科学院亚热带农业生态过程重点实验室,湖南长沙410125

出　　处：《环境科学研究》2014年第12期1499-1504,共6页Research of Environmental Sciences

基　　金：国家自然科学基金项目(41271279,41090283)

摘　　要：采用14C-CO2(碳同位素)连续标记技术结合室内模拟培养试验,采用土壤有机质的物理、化学分组方法,研究了不同种植方式〔P-R(盘塘水稻土)、P-U(盘塘水旱轮作土)和U-C(盘塘坡旱土)〕下14C-SOC(自养微生物同化碳)在土壤腐殖质组分和团聚体中的分配特征.结果表明:不同种植方式显著影响自养微生物的固碳能力,P-R的自养微生物固碳能力最强〔w(14C-SOC)为38.32mg/kg〕,约为P-U和U-C的2倍;P-R和P-U中w(14C-DOC)、w(14C-MBC)显著大于U-C中.14C-SOC不同程度地进入了土壤的3种腐殖质组分(胡敏素、胡敏酸、富啡酸)中,其中进入胡敏素中的14C-SOC占总量的67.7%.14C-SOC亦进入了不同粒径的土壤团聚体中,其中主要进入了Ⅲ级(0.020 mm≤粒径<0.200 mm)和Ⅱ级(0.200 mm≤粒径<2.000 mm)粒径的大团聚体中,表现出了碳汇效应;不同种植方式的土壤中,以P-R土壤各粒径土壤团聚体中w(14C-SOC)最高.相关分析表明,全土中的w(14C-SOC)与各粒径土壤团聚体中w(14C-SOC)和胡敏酸中w(14C-SOC)均呈显著正相关.The importance of microbial decomposition processes in soils subject to climate and planting type change has been recognized as a critical gap in our understanding of carbon balances between soils and the atmosphere. Autotrophic microbes, found abundantly in soil, have the ability to photosynthesize carbon by assimilating atmospheric carbon dioxide （CO2 ）. However, the distribution of autotrophic microbe- assimilated carbon in soil composition as well as in aggregate fractions of soil under different planting type is yet to be ascertained. Therefore, this study used continuous carbon isotope （J4C-CO2） labeling along with ex-situ simulated incubation experiments and chemical and physical fractionatiou of soil organic matter to examine the distribution characteristics of microbe-assimilated carbon in humus and aggregate fractions of soils obtained from three different planting type （rice paddy systems （P-R）, paddy-upland rotation systems （P-U）, and upland rice cultivation systems （U-C）. Resuhs showed that planting type has an effect on autotrophic microbial carbon fixation. Autotrophic microbes in rice paddy soils （P-R） had the maximum ability to fix carbon （w（14C-SOC） was 38.32 mg/kg, approximately two times that in P-U and U-C soils）. In addition, the 14C content in active carbon pools （14C-DOC and 14C-MBC） present in P-R and P-U soils was considerably greater than that in U-C soils. Furthermore, autotrophic microbe-assimilated carbon entered the three s0il humus components to varying extents, as follows： it primarily entered the humins, which comprises 67.7% of the humus. The assimilated carbon also entered the differently sized soil particles in aggregates, thereby sequestering the carbon. It primarily entered those aggregates with particle diameters ranging from O. 020 to O. 200 mm and from O. 200 to 2. 000 mm. Of the three tested soils obtained from different land uses, the rice paddy soil exhibited the highest 14C-SOC content for each particle size.

关 键 词：自养微生物同化碳 种植方式 团聚体 腐殖质 14C连续标记 

分 类 号：X171[环境科学与工程—环境科学]