中文摘要：

冻融交替影响土壤水分的有效性及土壤团聚体稳定性,进而影响土壤中微生物的活性及土壤有机碳的矿化。通过室内冻融模拟（即分别在-7℃和28℃下处理土壤）及培养实验,研究了不同冻融交替循环处理下土壤水溶性有机碳（WSOC）、微生物生物量及土壤有机碳矿化的变化规律。结果表明,1到3次冻融交替处理会增加土壤中水溶性有机碳的含量,其中经过1次冻融交替处理的2种土壤其WSOC含量分别增加了25%,20%;但在本实验条件下如果继续增加冻融交替次数则会使土壤水溶性有机碳含量减少。冻融交替处理降低土壤微生物生物量,因此也会影响土壤有机碳的矿化。冻融交替处理对培养第1天的土壤有机碳矿化具有激发效应,激发能力：1次冻融交替〉3次冻融交替〉6次冻融交替,经过1次冻融交替处理后的土壤其呼吸速率与对照相比增加了17%～40%;其后,冻融交替处理土壤呼吸速率迅速下降,在培养后期甚至低于对照处理。

英文摘要：

Freezing and thawing significantly affected the availability of soil water and the stability of aggregates,which would influence soil microbial activity and soil organic carbon mineralization.The content of water soluble organic carbon（WSOC）,microbial biomass and organic carbon mineralization of paddy soil under different freezing and thawing cycles were investigated by designing an incubation experiment.Results showed that one to three times of freezing and thawing cycles could increase the content of WSOC.One freezing and thawing cycle increased the content of WSOC by 20%-25%,but increasing cycles of freezing and thawing would led to decrease of WSOC.Meanwhile,freezing and thawing cycles decreased the soil microbial biomass,as resulted to affect mineralization of soil organic carbon.The freezing and thawing cycles also resulted in a significant increase in the C mineralization rate at the first day of incubation.The priming effects of different freezing and thawing cycles for the first incubation day were different,the order was： 1 cycle 〉 3 cycles 〉 6cycles.In one freezing and thawing cycle,the respiration rate of the soils increased about 17% to 40% compared with that of control,but decreased rapidly after the first day of incubation.