以北运河水系主要干支流2011年1～12月23项指标的监测数据为依据,采用水质类别法和平均综合污染指数法,对水质污染特征进行综合评价,运用主成分分析和系统聚类分析法,对水质指标主成分以及水质差异进行分类,并进一步对不同干支流污染来源进行分析.结果表明,北运河水系由于排污量大,她表水污染严重,除城市中心区部分河流水质为Ⅲ～Ⅳ类外,城市排水河流、远郊河流水质均为劣Ⅴ类.水质由3个主成分组成,COD、CODMn、BOD5、NH3-N、TP等为第一主成分;汞为第二主成分;石油类为第三主成分.干支流水质分为4类:第1类为清洁水源类河流,主要集中在城市中心区,降雨地表径流、雨污合流管网溢流引起的非点源污染是影响其水质达标的重要污染源；第2类为再生水水源类河流,主要集中在城市排水上游河流,城镇污水处理厂捧水是其主要污染源；第3类为再生水与污水混合水源类河流,主要集中在城市排水下游河流及部分远郊区河流,由于城市下游排水管网不健全,远郊区污水集中处理率低,生活源和农业源的污染贡献率较高,水质污染严重；第4类为污水水源类河流,分布于远郊区县,农业污染占比较大,水质污染最严重.%Based on the monthly monitoring data of 23 water quality indexes of the main streams and tributaries of Bei Canal river system in 2011, a comprehensive water quality evaluation was made using water quality category method and average comprehensive pollution index method. Principal components of water quality indexes and pollution sources were determined with principal component analysis (PCA) and system clustering analysis method (SCAM). The results showed that the surface water in Bei Canal river system was heavily polluted due to high pollution discharge. Except that the water quality of urban central rivers was in class Ⅲ～Ⅳ, the water quality in other areas such as urban drainage rivers and outsuburb rivers was below class V. According to the PCA results, the first principal component of water quality involved COD, CODMn、BOD5, NH3-N, TP, TN. The second principal component was Hg. The third principal component included petroleum contaminants. The rivers were classified into 4 categories based on their water pollution characteristics. Category 1 was composed of rivers that had clean water sources and were located mainly in urban central areas; the river water was polluted primarily by non-point source pollution. Category 2 was comprised of rivers with renewable water sources, chiefly located in the upstream of urban sewerage and drainages; the urban sewage treatment plant drainage was identified as the primary pollution source. Category 3 consisted of rivers with blended water sources including renewable and sewage water, which were located in the downstream of urban sewerage and drainages as well as in the outskirt areas; pollution level of these rivers were high due to domestic and agricultural pollution sources. Category 4 was rivers with polluted water as source, located in the outsuburb; the major pollution source of these rivers included sewage discharged from agricultural practices.
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