流域水质时空分布特征及其影响因素初析

选取闽东南九龙江流域21个典型小流域开展2010年丰(8月)、平(11月)、枯(2月)3个水期的基流水质监测,并借助GIS、多元统计分析方法识别流域水质的时空分布特征及其影响因素,为九龙江流域水质监测、管理与控制提供依据.结果表明,九龙江水质枯水期最差,平水期次之,丰水期水质较好.表征生活污水、工业废水的污染因子对水质变化的贡献率为45.58%,表征农业污染的主成分的贡献率为21.28%.NH4+-N、SRP、高锰酸盐指数、K+、Cl-、Mg2+、Na+浓度与建设用地比例、人口密度呈显著的正相关,NO3--N浓度与耕地比例有显著的正相关,自然用地面积比例与NO3--N、K+、Cl-、Na+浓度有显著的负相关.建设用地比例较大、人口较密集的小流域NH4+-N、SRP、高锰酸盐指数、K+、Cl-的浓度较高,耕地比例较大的小流域NO3--N浓度则较高.在流域水质管理上,建议提高污水处理率,并重视由于化肥施用导致的农业非点源污染对水质的影响.

Preliminary Analysis of Spatiotemporal Variation of Water Quality and Its Influencing Factors in the Jiulong River Watershed

Twenty one sub-watersheds in the Jiulong River watershed were chosen for in-situ monitoring water quality of baseflow in flood season, dry season and average season in 2010. Geographical information system and multivariate analysis were coupled to characterize the spatiotemporal variation of water quality and identify its influencing factors. The results show that the water quality in dry season is the worst whereas the water quality in flood season is comparatively good. The first principal component representing sanitary and industrial wastewater pollution, explained 45.58% of the total variance of water quality. The second principal component concerning pollution due to agricultural activities, explained 21.28% of the total variance. NH₄⁺-N, SRP, potassium permanganate index, K⁺, Cl^-, Mg²⁺ and Na⁺had a significantly positive correlation with percentage of built-up and density of population. NO₃^--N was correlated positively with percentage of cropland. The sub-watersheds with high proportion of build-up area and density of population show high concentration of NH₄⁺-N, SRP, potassium permanganate index, K⁺, Cl^-. Comparatively, the sub-watersheds with high percentage of cropland show high level of nitrate concentration. Improvement of the wastewater treatment efficiency and increased recognition of agricultural non-point source pollution were finally highlighted from watershed management perspectives.