| Animal husbandry industry plays an important role in agriculture and the whole national economy. In many countries, this industry contributes to more than 50% of the value of agriculture output. However, with the explosive growth of the industry , potential environmental pollution caused by raising poultry becomes more serious as people's environmental protection awareness increases. Currently, a new tendency of poultry-raising pollution in China is that pollution is being spread from urban area to rural area and from point source to non-point source. The increasingly serious pollution has become a threat to the ecological safety in the country. And poultry excrements, fertilizers, poisons and films in agriculture are generally considered as main pollution source in the country. Because the number of poultry raised in China takes the lead in the world, with more than half of the world's poultry raised here, pollution resulted from poultry excrements is worse than any other country. Some developed countries such as Japan, Finland and America have started to deal with poultry excrements pollution since 1970s, China also has done this work in some cities (such as Beijing, Shanghai) ever since early 1990s and has obtained some constructive achievements.With 374 rivers each covering more than 50 square kilometers, Chongqing is abundent in water resource. Nowadays, almost all the rivers through agricultural areas and towns are over-nutrient. Water pollution in West Chongqing, for example, yongchuan.Dazu and Rongchang, is rather serious. The Liangtan river flowing from Jiulongpo district to Beibei district has become over-nutrient completely in Xiyong town .which is so badly polluted that it appears black when it arrives in Beibei district. Also, some signals indicate that Jiangling river has been over-nutrient, but also Changshou lake has become over-nutrient obviously. In recent years, 2500 tons of fish has died because of all kinds of pollution in the country of Chongqing, this figure is equivalent to the fish production decreasing by 50 percent of 1670 hectare of fish pond. Poultry excrements pollution was listed one of the ten most severe environmental problems of Chongqing in 2003.Chongqing has done much to prevent environmental pollution in many aspects .including social aspect and economic aspect since 1997.With investment on environment growing year by year, 3.05 billion yuan occupying1.7 percent of GDP was invested in 2001,which was more than 2.8 times as it in 1996. On account of years of persistent efforts, the quality of environment has become better and the tendency of deterioration in ecological environment has been restrained more or less. At present, 26 water sections in Chongqing rivers such as Yangtze River,Jialing River and Wujiang river generally keep at Two-Three level; The density of SO2 has decreased by 66.4%, and the frequency of acid rain decreases by 33.4%. In 207 days, about 56.7% of a year the airquality in main urban districts is fine. On the whole, evident effect has been achieved in pollution protection in Chongqing, but as main source of country non-point pollution, poultry excrements has not been effectively dealt with, and research in this field has been done little in Chongqing. Systematic and integrated research and study on poultry excrements pollution has not been carried on before, so the pollution througnout Chongqing has not been clear.therefore,it is urgent to conduct some research in this field .By collecting excreta parameters of poultry excrements home and abroad, and investigating some poultry-raising farms and farmers raising poultry in some districts , excreta parameters of poultry excrements are determined, based on the figures of the years 1995,1996 and 2000,2001 in every district and county of Chongqing per year; then the amount of poultry excrements are estimated ;by analyzing and comparing the estimated figures and analyzing the tendency of excreta amount of poultry shit per year, which area confronts major load and which area confronts minor load o... |
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