城镇化对我国食物消费系统氮素水体排放的影响

城镇化的快速发展,将带来巨大的生态环境压力和严重的污染问题.以1982年、1992年和2002年我国城镇与农村居民食用氮的流动去向为对象,探讨了城镇化对氮素水体排放的影响.结果表明:城镇居民食用氮与排泄的粪尿氮高于农村居民;人均排入水体氮量,1982年城镇与农村居民大体相当,1992年、2002年城镇居民是农村居民2.8倍;粪尿氮排入水体比率,1982年城镇与农村基本相当,在7.5%左右,但到2002年城镇粪尿氮排入水体比率高达56.7%,城镇比农村要高34个百分点.情景分析结果表明,如果在人口增加的同时还要改善食物结构增加蛋白质摄入量, 2020年粪尿氮总产生量将增加121～155万t,排入水体氮量也将增加41～64万t.提高粪尿还田率、污水处理率及氮的去除率可以降低粪尿氮排入水体比率.

The influence of urbanization on nitrogen emission to water in food consumption system of China

The fast development of urbanization in China may bring huge ecological pressure and serious environmentally pollution. This article studied the nitrogen fluxes in food consumption systems of households of rural and urban inhabitants of China in 1982 1992 and 2002 and explored the influence of urbanization on nitrogen emission into water. The results showed that the amount of excreled urine nitrogen and the emission of nitrogen into water was higher for urban inhabitants than that for rural inhabitants.The nitrogen emission into water per capita of urban inhabitants was about the same as that of rural inhabitants in 1982. However the nitrogen into water per capita of urban inhabitants was 2.8 times of that of rural inhabitants in 1992 and 2002. The emission of urine nitrogen into water was about equal for urban and rural inhabitants in 1982. The emission of urine nitrogen into water of urban inhabitants increased up to 56.7% by 2002;the emission of urban inhabitants was 34% lower. The scenario analysis showed that the emission of urine nitrogen into water increases up to 121-155 ten thousand tons in 2020,if the protein consumption increases because of a increasing population.Improving the use of urine nitrogen and sewage handling can reduce the emission of nitrogen into water.