海南岛典型农业土壤产流与面源污染特征分析

采用径流场结合人工模拟降雨方式，研究各种降雨条件下海南岛不同土地类型产流产沙的规律与面源污染特征。结果表明：土壤（泥沙）产流系数与平均流失速率表现为暴雨＞大雨＞中雨，且暴雨时的泥沙平均流失速率为中雨时的416％、大雨时的261％，在中雨、大雨和暴雨强度下，平均径流系数分别为24.49％、33.97％和53.40％；雨强对土壤营养物质流失速率的影响达到显著水平，COD、有机质和氮素以径流流失为主，磷素以泥沙流失为主；土壤径流和泥沙中的COD、有机质、氮素和磷素流失速率随雨强的增大而增大，坡度也可明显影响面源污染物的流失；海南岛农业土壤平均流失量为3.79 t/（hm2·a），中雨强度条件时为1.92 t/（hm2·a），大雨强度条件时为2.57 t/（hm2·a），暴雨强度条件时为6.87 t/（hm2·a）。海南岛农业土壤的水土流失强度较高，海南农业土壤的水土流失与农田污染物输出状况不容乐观。

Runoff Characteristics of Agricultural Non-point Source Pollutants in Typical Soils in Hainan Island

In the present paper, a method that runoff field combined with artificially simulated rainfall was used to study the laws of runoff and sediment yield and the characteristics of nutrient losses under various rainfall conditions in the different land types of Hainan Island. Results showed that the soil(sand)runoff index and erosion rate were rainstorm >heavy rain>moderate rain. Under rainfall intensity of rainstorm, heavy rain and moderate rain, the average runoff index was 53.40%, 33.97% and 24.49%. The erosion rate by rainstorm was 261% of heavy rain and 416% of moderate rain, respectively. The effects of rainfall intensity on soil nutrients loss rate reached a significant level. The losses of COD, organic matter and nitrogen were mainly from runoff erosion, while phosphorus loss was mainly from sediment erosion. The loss rates of COD, organic matter, nitrogen and phosphorus in soil runoff and sediment increased with the increase of rainfall intensity. Meanwhile, the non-point source erosion in Hainan was greatly influenced by slope, soil texture and rainfall intensity. The average amount of soil erosion in Hainan island was 3.79 t/(hm2·a). Under rainfall intensity of moderate rain, heavy rain and rainstorm, the amount of soil erosion was 1.92, 2.57 and 6.87 t/(hm2·a), The strong agricultural soil erosion characteristics indicated the unoptimistic situation of soil, water conservation and farmland pollutants output.