连续降雨对淡水河流域非点源污染的影响

Impact of consecutive rainfall on non-point source pollution in the Danshui River catchment

利用淡水河流域污染物通量站的连续流量水质监测数据,研究了4场连续降雨对流域非点源污染的影响.相关分析结果表明,在连续降雨期间,污染浓度与流量相关性不显著,但NH4+-N、TP及TN通量与流量之间存在显著相关关系,污染物通量与流量的相关系数大小顺序如下:TP>NH4+-N>TN>SS>NO3--N.另外,统计结果表明,在降雨历时比较长的条件下,降雨事件3中的SS、TN和NH4+-N的输出通量与降雨事件1相比分别下降了36%、29%和28%;而在降雨历时较短的情况下,降雨事件4中的SS、TN和NH4+-N的输出通量与降雨事件2相比分别下降了8%、32%和26%;与SS、TN及NH4+-N相比,NO3--N在连续降雨条件下的输出通量有显著增长(降雨1事件VS降雨3事件,降雨2事件VS降雨4事件),而TP的输出通量则保持稳定.

The aim of this study was to investigate the impact of 4 consecutive rainfalls on non-point source pollution in the Danshui River catchment.Continuous measurements for water flows and water quality constituents were obtained at a pollutant flux station at the outlet of the Danshui River catchment.Results of regression analysis showed that there were no significant correlations between pollutant concentrations and water flows during consecutive rainfall,whereas significant correlations with water flows were found for pollutant fluxes.The sequence of correlations between pollutant fluxes and run off was as follows：TPNH＋4-NTNSSNO-3-N.Statistical analysis was performed to compare pollutant output in storm events under similar rainfall condition.For long duration rainfall,fluxes of SS,TN and NH＋4-N of storm 3 decreased by 36%,29% and 28% in comparison with storm 1.In the case of short duration rainfall,fluxes of SS,TN and NH＋4-N of storm 4 dropped by 8%,32% and 26% when compared with storm 2.In contrast,NO-3-N fluxes increased by 70% and 98% respectively（also storm 1 vs.storm 3,storm 2 vs.storm 4）,while TP fluxes remained stable during consecutive rainfall events.