近地表土壤水分条件对坡面农业非点源污染物运移的影响

Effects of Near-Surface Soil Water Conditions on Agricultural Non-point Source Pollutant Transport

采用人工模拟降雨实验,研究了近地表土壤水分条件,尤其是土壤水分饱和条件对土壤侵蚀过程中农业非点源污染物运移的影响.结果表明,前期近地表土壤水分条件对土壤侵蚀过程中农业非点源污染物的迁移有着很大影响.饱和含水量时径流及泥沙中非点源污染物的流失浓度和流失量大于非饱和含水量,且前期近地表土壤含水量越大,径流及泥沙中农业非点源污染物的流失浓度和流失量越大.土壤氮素的主要流失途径是降雨所产生的径流,约占总流失量的90.4%～99.8%;土壤磷素的流失途径是降雨径流和侵蚀产沙,分别占总流失量的2.67%～23.5%和76.5%～97.3%.同时,土壤质地对磷素养分的流失有很大影响,杨凌土随泥沙流失的DP浓度和流失量均大于安塞黄绵土.最后,提出了采取最佳管理措施等控制农业非点源污染的针对性建议.

Agricultural non-point source pollution is one of severe problems for water environment of agricultural area in China. The effects of near-surface soil water conditions on agricultural non-point source pollutant （AGNSP） transport during soil erosion processes, especially antecedent soil moisture was saturated, was developed by using artificial simulation rainfall experiment. The results showed that antecedent soil water content had great impact on AGNSP transport during soil erosive processes. Under the same soil texture, the AGNSP concentration and loading with runoff and sediment when the antecedent soil water content was saturated were greater than that of soil moisture un-saturated condition, and they would be increased as antecedent soil moisture increased. The approach of soil nitrogen loss was rainfall runoff; nitrogen loss with runoff was about 90.4% to 99.8% of total loss. The approaches of soil phosphorus were runoff and soil loss （sediment）, the loss with runoff was about 2.67 % to 23.5 %, and the loss with sediment was about 76.5 % to 97.3 %. Soil texture had great influence on soil phosphorus loss; the concentration and loading of dissolved phosphorus （DP） with sediment from Yangling Loutu were greater than that of Ansai Loess. Some pertinence suggestions were given to control agricultural non-point source pollution, such as the best management practices.