于桥水库富营养化时间特征及污染源解析

Temporal characteristics of eutrophication and pollution source analysis in Yuqiao reservoir

基于2000-2010年水质数据和降水资料,应用层次聚类分析、后退式判别分析和正定矩阵因子分解模型,系统地分析了于桥水库富营养化的时间特征及其潜在污染源。结果表明:于桥水库富营养化主要表现为氮超标,磷为限制因子,时间上可划分为2个时段——时段Ⅰ(7-9月)和时段Ⅱ(4-6月、10-11月),对降水存在水质响应延迟现象。其中,时段Ⅰ水体中SS、CODMn、CODCr、BOD5、TP明显高于时段Ⅱ,DO、TN、NO3-N明显低于时段Ⅱ,NH3-N在两个时段相差不大。揭示了时段Ⅰ水体富营养化比时段Ⅱ严重,流域内面源污染对富营养化的影响高于点源污染。正定矩阵因子分解模型解析得到影响于桥水库富营养化的污染源可能有6类,分别是农业面源磷排放、含氮工业废水、库底沉积物、农业面源氮排放、村落生活污水和有机工业废水。

Based on the records of water quality and precipitation data from 2000 to 2010,the paper used hierarchical cluster analysis,backward discriminant analysis and positive matrix factorization model( PMF) to systematically assess the temporal characteristics of eutrophication and the potential pollution sources in Yuqiao Reservoir. The results indicated that the key exceeded standard factor of eutrophication is N,and the limit factor is P. At temporal scale,eutrophication of water bodies can be divided into period I( from July to September) and period Ⅱ( from April to June,October to November),and there is a delay for the response of water quality to precipitation. Moreover,the concentrations of SS,CODMn,CODCr,BOD5 and TP in period I are much higher than that in period Ⅱ,and the concentrations of DO,TN and NO3-N in period I are much lower than that in period Ⅱ,while NH3-N in both periods is similar.These findings revealed that eutrophication in period I is more serious than that in period Ⅱ,and the influence of non-point source pollution on eutrophication is higher than that of point source pollution. The results of PMF identified six possible pollution sources of eutrophication in Yuqiao Reservoir such as agricultural non-point source phosphorus pollution,nitrogen industrial wastewater,reservoir sediment,agricultural non-point source nitrogen pollution,village sewage,and organic industrial wastewater.