滇池流域农田土壤径流磷污染负荷影响因素

采用模拟试验的方法,研究了人工降雨和自然降雨条件下坡度、表土质地、降雨强度和地表状况等因素对农田土壤径流中磷污染物输出浓度和输出总量的影响.结果表明不同坡度土壤径流中总磷的浓度和磷的输出量不同,其中坡度为18°时径流中磷含量和磷的输出量最高,分别达到0.138mg·L^-1和6.14kg·hm^-2;在人工摸拟降雨与自然降雨2种条件下,土壤径流中总磷含量与输出量具有相同的变化趋势,径流中磷素的浓度和径流输出量随表土质地的变粗而减少;有作物种植条件土壤径流中总磷的浓度和输出负荷明显小于裸地条件,其中不同坡度磷的流失减少量为0.9～2.8kg·hm^-2,施肥后土壤地表径流中总磷的浓度比未施肥前成倍增加.

Factors Influencing Phosphorus Loss by Runoff Process from Farmlands in the Dianchi Watershed

By laboratory simulated experiment, the effects of soil factors on the farmland phosphorus losses and its concentration were studied under artificial rainfall and nature rainfall. A number of soil and landscape factors were taken into account such as slopeness, soil and plant covers, fertilizers and application performances as well as rainfall intensity. The study showed that the concentration of total phosphorus (TP) and the loss rate varied with slopeness, being highest at slopness of 18 degrees with the values of 0.138 mg.L-1 and 6.14 kg.hm-2. There was no significant difference in TP concentration and the loss rate between under artificial rainfall and under nature rainfall. Moreover, TP concentration in runoff was smaller with the courser soil surface texture, and obviously lower with crop covering than without covering, among which the loss decreased 0.9-2.8 kg.hm-2 at different level of slope. Fertilizer application remarkably enchanced TP concentration and, thus, total phosphorus loss by runoff.