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采用室内模拟试验,在好气和淹水2个土壤水分条件下,研究了外源氮输入对沼泽湿地土壤有机碳矿化和土壤可溶性有机碳(DOC)含量的影响.结果表明,好气条件下,净氮输入量为1 mg.g-1(N1)的氮处理水平对土壤有机碳矿化和DOC含量的影响不显著,而净氮输入量为2和5 mg.g-1(N2、N3)时,土壤DOC含量显著增加,分别比对照(250.62 mg.kg-1)增加了187.22%和203.25%,并显著促进了土壤有机碳的矿化;淹水条件下,外源氮输入则抑制了土壤有机碳的矿化,N1、N2、N3处理下土壤DOC含量分别比对照(642.52 mg.kg-1)降低了88.34%、82.69%、80.04%;不同水分条件下,土壤DOC含量与有机碳的累积矿化量均呈显著正相关关系(R2分别为0.939、0.843),由外源氮输入引起土壤DOC含量的变化可能是导致土壤有机碳矿化差异的主要原因之一.研究结果还表明,伴随着沼泽湿地积水消退和外源氮输入的增多,将会加快湿地土壤有机碳的矿化和土壤DOC的淋失,造成湿地土壤有机碳的大量损失.
The effects of exogenous nitrogen input on soil organic carbon mineralization and soil dissolved organic carbon (DOC) content in swamp wetlands were studied using indoor simulation tests under aerobic and submerged conditions. The results show that under aerobic conditions, The effect of nitrogen treatment with 1 mg.g-1 (N1) net nitrogen on soil organic carbon mineralization and DOC content was insignificant, while the net nitrogen input was 2 and 5 mg.g-1 (N2 and N3 ), The soil DOC content increased significantly by 187.22% and 203.25%, respectively, compared with the control (250.62 mg.kg-1), and significantly promoted the mineralization of soil organic carbon. Under flooding conditions, the input of exogenous nitrogen was inhibited Under the condition of N1, N2 and N3, DOC content decreased by 88.34%, 82.69% and 80.04%, respectively, compared with the control (642.52 mg.kg-1). Under different water conditions, Carbon mineralization mineralization (R2 = 0.939, 0.843, respectively). The change of DOC content caused by input of exogenous nitrogen may be one of the main reasons for the difference of mineralization of soil organic carbon. It shows that with the extinction of marsh water and the increase of input of exogenous nitrogen, the wetland soil organic DOC and mineralization of soil leaching, resulting in a substantial loss of wetland soil organic carbon.