Research On Loads From Nitrogen And Phosphorus Loss In ANPS In The Three Gorges Reservoir At Hubei Region

In resent years, with the increase of modern agricultural inputs, the influence of non-point source pollution in the environment caused by agricultural production and rural life is increasing. More serious agricultural pollution is created by a more intensive agricultural production and extensive farming format in the Three Gorges Reservoir at Hubei region. Agricultural drainage water in the Three Gorges Reservoir at Hubei region goes directly into the Changjiang River, and the water quality is affected by agricultural non-point source pollution(ANPS)in this area. It is of very important significance to calculate pollution load for the quantitative indicators of pollution and estimating the pollution.Based on the conclusion of domestic and abroad agricultural non-point source pollution research improvement, Johnes Export Coefficient Model with the feature of less-and-available data and simple calculation was selected. In this paper,we pointed out the importance of rainfall in this areas and added the rainfall factor into the model in order to make it more reasonable and suitable for this areas. Then,the pollution loads of Nitrogen and Phosphorus in the Three Gorges Reservoir at Hubei region were estimated using the model. At the same time,the situation of ANPS in the Three Gorges Reservoir at Hubei in 2009 was evaluated using Equal Standard Pollution Load and Pollution Load Ratio.The main conclusions of this paper were as follows:1. The cultivated field,livestock breeding and living pollution were the main sources of the Three Gorges Reservoir at Hubei.The TN and TP export coefficients of human waste were 0.961 kg/(ca·a) and 0.022 kg/(ca·a), waste water were 1.325 kg/(ca·a) and 0.16 kg/(ca·a); the TN and TP export coefficients of livestock excretion were 10.584 kg/(ca·a) and 0.31 kg/(ca·a), pigs were 0.568 kg/(ca·a)and 0.142 kg/(ca·a), poultry were 0.03 kg/(ca·a) and 0.005 kg/(ca·a); the TN and TP export coefficients of cultivated fields were 15 kg/(hm2·a) and 1.15 kg/(hm2·a).2. According to the real situation of rainfall district, rainfall factor was added into the model, making that the results of export coefficient were closer to the calculated results of the actual ANPS situation in the Three Gorges Reservoir at Hubei region. That was to say it was reasonable to modify the model. Using the modified model, the pollution load estimated results of TN and TP showed that:the relative error of the modified method respectively decreased 0.95%and 10.21%than the traditional method. The traditional method showed the pollution loads under annual average conditions so that annual variation was only influenced by land use. The improved model reflected not only the changes of the characteristics of land-use types in traditional model, but also the impact of rainfall amount changes on the TN and TP load from the point of view of rainfall.3 From the different pollution sources,since 2001's, in the three major sources of pollution, that was cultivation field,livestock and poultry farming and rural life, TN load of rural life was the largest, TP load of livestock and poultry was the largest, the pollution load ratio of rural life, livestock farming and cultivation filed were 28.84%,30.64% and 40.52%。...