| With the water pollution in rural areas becoming more and more serious, drinking water safety issues outstanding. As social and economic development, industrial pollution, agricultural pollution, garbage and other pollution are increasingly serious. Pollutants are continuously flocked to rural areas, polluting the water bodies and the environment in rural areas. Sichuan Province is a typical agricultural province. Due to uneven distribution of water resources, the area's unique natural environment, economic and geographic disparity in the social environment, the non-point source pollution in different levels of physical features and rural environment which is characterized by non-point source pollution problems has become increasingly prominent. Rural drinking water safety is an important task of the construction of new socialist countryside. Non-point source pollution prevention and control work are of great global significance.The domestic and abroad research actualities on the non-point source pollution were analysed in this paper, the mechanism of agricultural non-point source pollution, pollution factors and characteristic were also studied. Considering the introduction of the hilly area and the insecurity of rural drinking water, the drinking water sources of Daying County Huangla Stream was chosen for the study by comprehensive selection and analogy analysis. Monitored the water quality in the basin for 9 months continuously, based on principal component analysis to determine the pollutant characteristics of drinking water sources, and classified the water quality monthly based on the integrated pollution damage index. The results showed that:the highest score of first, second main points belonged to the April of following year, which can be attributed to the organic pollution, and the highest score of the third main points in September, which was on behalf of the nitrogen pollution. All these indicated that the main pollutants in this basin were CODcr, TN and NH3-N. Pollution mainly concentrated in August, September, March and April of the following year. Water quality changes little from November to February next year, relatively stable and quality is better; Comparing the cleanliness level, it was obvious that August, September and April the following year were in moderate pollution, October and January, February, March of the following year were in a light pollution, in November and December the water was clean, in a relatively good condition. Compared comprehensively, water pollution was mainly in August, September and March, April, of the following year, and water was in a good and stable quality from November to January.Based on the principal component analysis and integrated pollution damage index analysis, the water environmental capacity of major pollutants CODcr, TN and NH3-N were calculated. The results showed that:the basin needed to cut 4.9×103kg/a,15.34×103kg/a and 6.09×103kg/a of CODcr, TN, and NH3-N into the river to meet Grade III standard of drinking water sources.With the investigation of the non-point source pollution of Huangla stream and quantitative and qualitative analysis, and base on the three main factors, chemical fertilizer, livestock and rural domestic sewage, garbage, measures about how to reduce the non-point source pollution were proposed:combining planting and breeding, developing ecological agriculture, changing the mode of production and achieving resource utilization, making use of local conditions and strengthening environmental protection infrastructure construction in rural. |
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