密云水库上游流域水体营养物质现状及来源分析

密云水库作为北京地区最重要的地表饮用水水源地,其水质优劣直接关系到首都的社会经济发展,开展密云水库水污染监测和治理研究具有重要的现实意义。以密云水库上游流域为研究区,通过不同尺度流域水体营养物质监测,分析了水库上游河流水体营养物质现状;通过分割流量过程线,划分了水体营养物质来自点源和非点源污染的比例。研究结果表明,依据标准(GB3838-2002)要求,密云水库上游河流水体TN含量几乎全部超标,且15.9%样本的TP含量超标。密云水库的营养物质平均40.3%来自点源污染,59.7%来自非点源污染;入库水体中50.1%的TN,49.1%的NO₃^--N,39.0%的NH₄⁺-N,26.5%的TP和36.8%的COD_Mn来自点源污染;49.9%的TN,50.9%的NO₃^--N,61.0%的NH₄⁺-N,73.5%的TP和63.2%的COD_Mn来自非点源污染。

Occurrences and Sources of Nutrients in Upper-river Basin of Miyun Reservoir

Miyun Reservoir has become the most important source of drinking water for Beijing area.In the past 20 years,with the economic growth and development,nutrient load of Miyun Reservoir increased gradually,which will result in an increasing risk of the bloom of harmful algae.To address this issue,water samples collected from the river basins at different scales were analyzed.Total nitrogen(TN),nitrate(NO₃^--N),ammonium (NH₄⁺-N),total phosphorus(TP)and index of potassium permanganate(COD_Mn)were measured to estimate flux and occurrence of nutrients.Based on the analysis of hydrological processes for each basin,the sources of nutrients that entered into the Miyun Reservoir were estimated.The results showed that TN concentrations in almost all the samples exceeded the environmental quality standards for drinking surface water of China. Concentrations of TP in 15.9%samples were exceeded the standards.It was estimated that 40.3%of nutrients in Miyun reservoir were from point-source pollution,while the other 59.7% were from non-point source pollution.Meanwhile,50.1%of the TN,49.1%of the NO₃^--N,39.0%of the NH₄⁺-N,26.5%of the TP and 36.8%of the COD_Mn that entered into the Miyun reservoir were from point-source pollution,while 49.9%of the TN,50.9%of the NO₃^--N,61.0% of the NH₄⁺-N,73.5% of the TP and 63.2% of the COD_Mn that entered into the Miyun Reservoir were from non-point source pollution.