紫色土坡地泥沙养分与泥沙流失的耦合特征

ARTIFICIALLY SIMULATED COUPLING CHARACTERISTICS OF DIFFERENT SEDIMENT NUTRIENT WITH SEDIMENT LOSSES IN SLOPELAND OF PURPLE SOIL,CHINA

通过人工降雨模拟试验,研究紫色土坡地泥沙全氮、全磷与泥沙三者流失的耦合特征及其受降雨和地形的影响。结果表明,泥沙全氮流失量随坡度及雨强的增加而减小,而全磷的流失量受雨强及坡度的影响均较小;相关性分析表明泥沙流失量愈大,全氮流失量愈小,而全磷愈大。全氮与泥沙流失随降雨时间而呈峰值特征,而全磷随时间变化较小。泥沙养分流失量的累积过程与泥沙累积过程一致,随泥沙累积量的增加而增加,且全氮流失累积量明显低于全磷流失累积量;坡地泥沙流失养分的富集比具差异性,即泥沙流失量愈大,氮富集比越低,磷富集比越高。分析坡地泥沙流失养分的富集比,可知全磷与泥沙的耦合稳定性较全氮高,更易呈现影响下游水质的滞后效应。

This paper revealed clearly the different coupling characteristics of sediment nitrogen and phosphorus with sediment losses in slopeland of purple soil,and also the influence of rainfall intensity （RI） and slope on the characteristics with simulated rainfall method. It is found that sediment nitrogen losses decreased with the increase of slope and RI, but sediment phosphorus losses were lightly influenced by both RI and slope. Correlation analysis demonstrated that with the increase of sediment losses, sediment nitrogen losses decreased, but sediment phosphorus losses increased. Both sediment nitrogen and sediment temporally showed peak values,while sediment phosphorus did not. The accumulated amount of sediment nutrient losses increased with the increase of the accumulated amount of sediment losses, but sediment phosphorus loss was obviously higher than sediment nitrogen loss. In addition, there were differences in sediment nutrient enrichment ratios （Er）,that is, the higher the amount of sediment losses, the lower sediment nitrogen Er,and the higher sediment phosphorus Er. Further, since sediment phosphorus Er was higher than sediment nitrogen Er,sediment phosphorus was more coupling stable than sediment nitrogen,so as more likely to exhibit latent effect of its influence on the water environment of the downsream.