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以受季节性冻融过程影响显著的黑土、暗棕壤和水稻土为例,采用实验室模拟的方法,研究交替冻融循环过程(分别在-20℃和20℃下处理)对土壤可溶性有机碳(DOC)的影响。研究表明,初次交替冻融后暗棕壤和水稻土DOC升高,黑土DOC仅降低1.3%。随着冻融次数增加,黑土和暗棕壤DOC含量逐渐下降,并趋于稳定,水稻土DOC呈交替上升趋势。15次交替冻融后,黑土DOC含量下降21%,水稻土DOC含量上升9%,暗棕壤DOC含量未出现明显变化。三维荧光分析结果验证了土壤DOC的变化趋势,15次交替冻融后,黑土可溶性有机物结构变复杂,分子量增加;水稻土可溶性有机物结构变简单,分子量变小;暗棕壤产生的新物质,一部分使可溶性有机物结构变复杂,分子量变大,另一部分使有机物分子量变小。
Taking the black soil, dark brown soil and paddy soil, which are significantly affected by the seasonal freezing and thawing process, as an example, the effects of seasonal freezing and thawing processes on soil soluble organic The impact of carbon (DOC). The results showed that the DOC of dark brown soil and paddy soil increased after initial alternate freezing and thawing, and the DOC of black soil decreased by only 1.3%. With the increase of the number of freeze-thaw cycles, the DOC content of black soil and dark brown soil decreased gradually and tended to be stable, and the DOC of the paddy soil tended to increase alternately. After 15 cycles of freezing and thawing, DOC content in black soil decreased by 21%, DOC content in paddy soil increased by 9%, and DOC content in dark brown soil did not change obviously. The results of three-dimensional fluorescence analysis validated the trend of soil DOC. After 15 freeze-thaw cycles, the structure of soluble organic matter in black soil became complicated and the molecular weight increased. The structure of soluble organic matter in paddy soil became simple and the molecular weight became smaller. Soluble organic structure becomes complex, the molecular weight becomes larger, the other part of the organic matter molecular weight becomes smaller.