3种不同类型水稻土溶解性有机碳生物降解特性研究

为了解水稻土DOC生物降解特性及其在农田生态系统碳循环中的作用，采用室内培养试验，研究了3种不同类型水稻土（红壤性水稻土、黄泥土、乌栅土）溶解性有机碳(DOC)的含量及其生物降解特性。结果表明：不同类型水稻土DOC含量为31.64~49.25 g/kg，其中乌栅土DOC含量略高于黄泥土，红壤性水稻土最低；经过42天的培养，3种水稻土DOC的生物降解率为54.8%~66.6%，表现为：黄泥土大于乌栅土和红壤性水稻土。3种水稻土DOC降解数据符合双指数衰变模型，DOC分别由降解速率不同的2个库组成：易分解部分（周转时间1~2天）和难分解部分（周转时间64~278天）。培养过程中，DOC溶液中结构较复杂的芳环物质比例前期呈上升趋势，后期趋于稳定略有下降，这与其中易降解组分的降解有关。

Biodegradation of Dissolved Organic Carbon Derived from Three Kinds of Paddy Soils

In order to understand the biodegradation and the role of DOC in carbon cycle in farmland ecosystems, with incubation experiments, the author selected three kinds of paddy soil which were the red paddy soil, huangni soil and wushan soil, and then extracted the DOC from paddy soil to estimate the biodegradation of the DOC. The resuhs showed that： the DOC content and three kinds of paddy soils were 31.64-49.25 g/kg, wushan soil had a slightly higher DOC content than huangni soil, while red paddy soil had the lowest DOC content. During the 42 days of incubation, there was a broad range of biodegradation DOC （from 54.8% to 66.6% of total DOC）, and decreased in the order of huangni soil, wushan soil, red paddy soil. The law was consistent with a double exponential decay model. DOC was composed of two different degradation rate constituents which were labile DOC and refractory DOC, the turnaround time of easily degradable part （labile DOC） was within 1-2 days and the turnaround time of hard degradable part （refractory DOC） was within 64-278 days. During the incubation, the ratio of complex structure dissolved organic matter in DOC solution increased in the period of early incubation, and then declined in the late period, which was related to the rapidbiodegradation of labile composition in DOC solution.