杭嘉湖平原典型水耕人为土的碳库构成与^(13)C稳定性同位素分布特征

Components of organic carbon pool and profile distribution of δ^(13)C values in typical stagnic anthrosols from Hangzhou-Jiaxing-Huzhou Plain

采集杭嘉湖平原的黄斑田、青紫泥田和烂青紫泥田3种代表性水耕人为土分层土样,测定土壤有机碳、颗粒态有机碳和黑碳在土壤剖面中的分布,不同粒径团聚体与土壤颗粒中有机碳和黑碳的差异及13C稳定性同位素的剖面分异.结果表明:黄斑田土壤有机碳库低于青紫泥田和烂青紫泥田;颗粒态有机碳占土壤有机碳总量的10.6%～29.3%,并随剖面深度的增加而下降;黑碳占有机碳总量的4.2%～24.6%,在黄斑田和青紫泥田中随深度降低,而在烂青紫泥田中剖面上下差异不大;稳定性团聚体中有机碳和颗粒态有机碳含量随粒径增加而增加,而黑碳含量的高低与水稳定性团聚体颗粒大小无关;研究发现土壤中的黑碳颗粒较小,主要出现在粘粒"粒级中,随剖面深度增加黑碳颗粒趋向减小;同位素δ13C值:黑碳>总有机碳>颗粒态有机碳,随深度增加而增加.

Three typical stagnic anthrosols,including silty-clayey yellow mottled paddy soil on fluvialmarine,blue clayey paddy soil,and gleyed blue clayey paddy soil,were collected from the Hangzhou-Jiaxing-Huzhou Plain to characterize vertical distribution of total organic C,particulate organic C,black C and δ^13C values in the soil profile,and distribution of organic C and black C in different sizes of water-stable aggregates.The results showed that total organic C pool in 1-m soil profile was lower in silty-clayey yellow mottled paddy soil on fluvialmarine than those of blue clayey paddy soil and gleyed blue clayey paddy soil.Particulate organic C,accounted for 10.6%-29.3% of the total soil organic carbon,decreased with increasing profile depth.Black C,accounted for 4.2%-24.6% of the total soil organic carbon,decreased with increasing depth for silty-clayey yellow mottled paddy soil on fluvialmarine and blue clayey paddy soil,and was even for gleyed blue clayey paddy soil.Contents of total organic C and particulate organic C increased with increasing size of water-stable aggregates,but content of black C in aggregates was not related to the size of aggregates.However,black C tended to be richened in clay component.The size of black C decreased with increasing profile depth.The δ^13C values decreased in the order of black C 〉total organic C〉 particulate organic C,and increased with profile depth.