摘要:选择黄河口新生湿地为研究对象，基于野外原位氮输入模拟试验，探讨了不同氮输入梯度下（NN：对照处理；LN：低氮处理；MN：中氮处理；HN：高氮处理）湿地土壤磷赋存形态的动态变化特征。结果表明，不同氮处理下土壤中闭蓄态磷（HCl-P_i和Residual-P）均是TP的主体（87.75%-90.04%），而活性磷（Resin-P、NaHCO₃-P_i和NaHCO₃-P_o）和中等活性磷（NaOH-P_i、NaOH-P_o、Sonic-P_i和Sonic-P_o）占TP的比例均较低，分别为4.81%-5.58%和5.14%-6.57%。相对于NN处理，MN和HN处理下的活性磷含量分别增加了9.16%和12.44%，而LN、MN和HN处理下的中等活性磷含量分别增加了2.25%，6.92%和24.24%，说明外源氮输入整体增加了土壤中的活性磷含量。与之相比，闭蓄态磷含量在LN、MN和HN处理下均呈降低趋势，其值相对于NN处理分别降低了3.08%、3.08%和5.22%。尽管不同氮处理下土壤养分条件、水盐及酸碱状况均是影响不同磷形态赋存的关键因素，但随着氮输入量的增加，影响磷赋存形态的养分类型发生了明显改变，即由NN和LN处理下主要受N和S影响逐步转变为MN和HN处理下主要受P影响。研究发现，外源氮输入不但可能影响不同磷形态之间的转化，而且亦可能通过改变植物生长节律以及土壤养分及酸碱状况来影响土壤中各形态磷的赋存。



Abstract:The typical Suaeda salsa marsh in the newly created marshes of the Yellow River estuary was selected as study object. The variations of phosphorus (P) fractions in soils during the growing season were investigated by in situ nitrogen (N) import experiment which included four treatments (NN, no N enrichment; LN, low N enrichment; MN, middle N enrichment; and HN, high N enrichment). Results showed that the contents of non-available P (HCl-P_i and Residual-P) were the main part of total phosphorus (TP) in soils of different treatments accounting for 87.75%-90.04%, while both the proportions of available P and moderately available P in TP were very low with 4.81%-5.58% and 5.14%-6.57%, respectively. Compared to NN, the contents of available P in MN and HN increased by 9.16% and 12.44%, respectively, whereas the values of moderately available P in LN, MN, and HN increased by 2.25%, 6.92%, and 24.24%, respectively, indicating that N enrichment generally increased the contents of available P in soils. By comparison, the contents of non-available P in LN, MN, and HN decreased by 3.08%, 3.08%, and 5.22% compared to those in NN, respectively. Although soil nutrients, moisture, salinity and acid-base status in different treatments were the key factors affecting the amounts of P factions, with increasing of N input, the types of nutrients affecting P fractions changed significantly from NN and LN which were mainly affected by N and sulfur (S) to MN and HN which were mainly affected by P. This study found that exogenous N import not only might affect the transformations among P fractions, but also might influence the variations of P fractions in soil by altering the growth rhythm of plants and the nutrients and acid-base status of soils.





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