强降雨下果园除草对径流中颗粒物及营养盐的影响

为探究夏季果园除草对果园面源污染的影响,采用人工模拟降雨的方法,研究了3种雨强(60 mm/h、120 mm/h、180 mm/h)及2种下垫面(有草样地和无草样地)条件下,果园地表径流中颗粒物(SS)及营养盐(TN、TP)的流失情况。试验结果表明,径流中TN、TP质量浓度与SS质量浓度均呈线性相关关系,TP与SS质量浓度之间的线性相关性更强(R~2=0.921 5);人工割草造成了径流中SS、TN、TP质量浓度升高,使其单位面积流失量分别增加了30%～46%、11%～29%、11%～22%,尤其是增大了降雨后期的流失量。因此,在夏季多雨、尤其是暴雨发生时段,应减少对果园中杂草的收割频次。

Effect of orchard weeding on suspended solids and nutrients in runoff under heavy rainfall

In order to explore the effect of orchard weeding in summer on non-point source pollution of orchard, the loss of suspended solids(SS)and nutrients(TN, TP)in surface runoff was studied under three rainfall intensities(60mm/h, 120mm/h, 180mm/h)and two kinds of underlying surface(with grass and without grass). The results show that the mass concentration of TN and TP in runoff is linearly correlated with the mass concentration of SS, and the linear correlation between the mass concentration of TP and SS is stronger(R²=0.9215). Artificial weeding results in the increase of SS, TN and TP mass concentration in runoff, which cause the loss per unit area of SS, TN and TP increased by 30%-46%, 11%-29% and 11%-22%, respectively, especially in the later stage of rainfall. Therefore, the frequency of orchard weeding should be reduced during the rainy summer, especially during the rainstorm period.