The water quality and pollution character in QingShuiHai lake valley-typical urban drinking water sources

Water Pollution sources dissection has important guiding significance for drinking water sources protection. Focused on QingShuiHai valley, the research investigated water quality by uniform distribution sampling in the area in 2007~2008, and analyzed pollution sources characteristics. The results showed that the concentration of Total Nitrogen (TN)(0.15-7.99 mg L^-1) was 0.3 ~ 15.98 times higher than the national second-class surface water standard; TN, Total Phosphorus (TP) and Chemical Oxygen Demand (COD ) were the main factors deciding water quality. Based on a typical agriculture economy, QingShuiHai lake valley had developed slowly, with a population of which 91.68% were agricultural population, and with 90% economic output coming from farm production. Non-point source pollution was the major source of nitrogen and phosphorus, from which 96.95% COD, 94.03% TN and 95.48% TP produced. The annual output of COD, TN and TP from non-point source were respectively 1956.8ta^-1, 450.60 ta^-1, and 68.42ta^-1. Of the non-point sources, agricultural runoff, animal manure and rural sewage contributed the most part of the COD, TN and TP load . Spatial distribution character analysis of pollution load showed that COD, TN and TP mainly came from second protected area, which was a serious threat because of its close location from water bodies. Therefore, non-point source pollution control, especially agricultural production and livestock & poultry breeding was the key for the control of nitrogen and phosphorus pollution in QingShuiHai lake valley.