Chemical fertilizer losses is one of the main sources of non-point source pollution. This paper analyzed current situation of non-point source pollution from chemical fertilizer losses according to dosage, amount in unit area, types, structure proportion of chemical fertilizer and burden of non-point source pollution from chemical fertilizer losses in 19 counties of Three Gorges Reservoir Region from 1996 to 2001. As the same time, this paper summarized the causes of non-point source pollution from chemical fertilizer losses by observing 12 monitoring points in 4 counties (Shizhu, Kaixian, Yichang, Xingshan) and 15 artificial rainfall districts in the county of Zigui. It concludes that the amount of chemical fertilizer is high in unit area and distributes asymmetry, types of chemical fertilizer is monotonous, the dosage of nitrogenous and phosphorescence fertilizer is much more than kainite fertilizer, and the burden of non-point source pollution from Chemical fertilizer N, P losses is higher and higher. Chemical fertilizer N, P losses is positive correlated with the amount of chemical fertilizer in unit area[N: R2 = 0.51 > 0.468(n = 16, 95%); P: R2 = 0.68 > 0.549(n = 19, 99%)] and the contents of granule (0.002 ~ 0.02 mm) and soil clay (<0.002 mm) on farmland. The greater rainfall intensity and less vegetation on the earth's surface cause more N and P losses [R2 = 0.98R2 > 765(n = 8, 99%)].

Point and non-point source pollution are the main pollutant source in the Chongqing Three Gorges Reservoir Region,with the latter accounting for 77.85% of the total loadings.Non-point source pollution which generally occurred over an intermittent period from sporadic sources and closely correlated with climatic events is the main pollution source in Chongqing Three Gorges Reservoir region.On the basis of data in 2000,the non-point source pollution is evaluated by using the method of equivalent pollution loading,including rural domestic waste,solid waste,fertilizer runoff,pesticide runoff,poultry and livestock farm,soil erosion,surface flow of city and so on in Chongqing Three Gorges Reservoir region.The 40 administrative districts in Chongqing Three Gorges Reservoir region are divided into 8 areas according to the results of cluster analysis and equivalent pollution loadings.The main nutrients of non-point source pollution were total phosphorus,total nitrogen,ammonia nitrogen,chemical oxygen consumption etc,among which total phosphorus and total nitrogen amounted to 96.4% loadings.The main pollution sources were fertilizer runoff,soil erosion,poultry,livestock farm,rural domestic waste,pesticide runoff,solid waste and surface flow of city etc,among which loadings from fertilizer runoff,soil erosion,poultry and livestock farm accounted for 95.2%.The sum of mean evaluation indexes in each area varied fromⅠto Ⅷ,indicating the differences of non-point source pollution among different areas.In addition,non-point source pollution in each area showed its specific characteristics,which provided scientific basis for controlling non-point source pollution.

According to the statistics of Chongqing Three Gorges Reservoir Region in 2000,this paper analyzes the affecting factors,including rural domestic waste,solid waste,fertilizer run off,pesticide run off,poultry and livestock farm,soil erosion,surface flow of the city,and their contribution to COD,NH3-N,TN,TP of non-point source pollutant.Furthermore,according to the pollution loads of dissolved form and pollution loads of particulate form by using RUSLE simulation and calculation,the total pollution loads of non-point source in Chongqing Three Gorges Reservoir Region are estimated.It concluded that the particulate form N loadings(50.1% of TN) is almost equal to dissolved form N loadings(49.9% of TN);but the particulate form P loadings(58.0% of the total phosphorus) is more than dissolved form P loadings(42.0% of the total phosphorus).It is a simple and direct method of estimating non-point source pollution loadings,which can be applied in the nutriment migration of the water body's bottom sludge,such as lake and reservoir etc.

The reclaimed-water utilization can reduce the quantity of discarded water and alleviate the contradiction of water shortage.The western area of Chongqing is seriously short of water and it is the economic hinge of Sichuan and Chongqing,so they are not only necessary but also available to carry out the waste water's recycling in the western area of Chongqing and to develop the waste water's reuse.According to Bishan County condition of the western area of Chongqing,this paper analyzes the possibility and necessity of developing the towns' reclaimed-water utilization and raises the measures of developing the towns' reclaimed-water utilization.

Stability determination of municipal solid waste(MSW) composting is very important in environment,society and economy.However,present estimate indices are affected heavily by uneven waste component,and take on fluctuating.The main biodegradable materials in composting process were researched by simulating the biodegraded process using chemical method.The content of biologically degradable material(BDM) and organic matters in the static aerobic composting,with 1% thermophilic bacteria inoculated and small fluxes continuous aeration was determined.The results show that BDM is affected little by uneven waste component,and has good selectivity.Compared with other indices that determine the biodegration stability of MSW from the point of view of organic component change,BDM can better reflect the MSW biodegradable rules.From the point of view of kinetics,expressions of BDM's changing curve in the biodegradation of composting have been piecewise fitted using Matlab software,and its feasibility has been justified.