Seasonal dynamics of dissolved organic carbon and its impact factors in the Doyeuxia augustifolia marsh soil
小叶章湿地表土水溶性有机碳季节动态变化及影响因素分析

The soil dissolved organic C (DOC) plays an important role in the cycling of wetland ecosystem. However, few studies have considered the seasonal dynamics of DOC and its impact factors in the marsh. The seasonal dynamics of DOC and its impact factors in the Doyeuxia augustifolia marsh soil was investigated. The results showed that the concentrations of DOC ranged from 373.9 to 443.7m g?kg-1, the mean was 414.61mg?kg-1, and the variance coefficient was 7.7% (P<0.0001) in the growing season. The variance of DOC concentration was significant in the growing season in the Doyeuxia augustifolia marsh soil. The concentration of DOC was higher in May. From June to July, the concentrations declined to the lowest value (373.9mg?kg-1) in July. The concentrations of DOC obviously increased from August to September and reached to highest value (443.7mg?kg-1) in September. Meanwhile, the absorption values at 280 nm increased with time. In contrast, A250/A365 ratio decreased, showing the compositions of DOC also changed obviously in the growing season. Seasonal dynamics of DOC were controlled by the recent production of C, microbial lysis and metabolize, rather than by organic C that has accumulated in soil. Temperature and soil water content affected the DOC indirectly via microbial activity. Precipitation might induce leaching of DOC. The freeze-thawing also affected concentrations and compositions of DOC.