中国化肥面源污染环境风险时空变化

为了合理施肥,防治化肥面源污染,对中国化肥施用的环境风险进行研究。通过建立化肥施用环境安全阈值模型和环境风险评价方法,计算中国各省区时空维度化肥施用环境安全阈值,评价化肥施用环境风险程度及变化。研究结果表明:中国化肥施用环境安全阈值近25年来在200~300 kg·hm~(-2)之间变化,平均值为243 kg·hm~(-2),近15年来的平均值为251 kg·hm~(-2),与国家环保部生态乡镇建设规定的化肥施用强度标准基本吻合;总化肥施用在1994年由环境安全转为低度风险,氮、磷、钾单质化肥施用分别在1988、1999、2008年由环境安全转为低度风险状态;2014年中国总化肥施用环境安全阈值平均为285 kg·hm~(-2),化肥施用环境风险指数平均为0.54,氮、磷、钾化肥风险指数平均分别为0.54、0.53、0.49,化肥施用总体处于低度环境风险;2014年西藏等11个省区化肥施用处于环境安全状态,辽宁等16个省区处于低度环境风险状态,河南、海南和天津三省区处于中度环境风险,陕西处于严重环境风险。总之,中国化肥施用环境风险自1994年进入低度风险状态,并呈现上升的趋势,自2006年以后有所降低。2014年全国各省区的化肥施用环境风险程度总体为低度环境风险,但省区之间差异较大,各类风险呈现出聚集分布的特点。

Spatio-temoral changes of fertilization environmental risk of China

It is very important for non-point source pollution control to evaluate the risk of non-point source pollution from fertilization.Studies on the spatio-temporal changes of environmental risk of fertilization in China were carried out in order to fully recognize the differences in environmental risk of fertilization at national and provincial levels to accelerate eco-agriculture construction of China.Models of fertilization environmental threshold and risk assessment were established to calculate the fertilization thresholds and assess the fertilization environmental risk of China.Results showed that,the thresholds of fertilization safety were between 200~300 kg·hm^-2 over past 25 years with an average of 243 kg·hm^-2.The fertilization risk changed from safety to low risk degree in 1994;the risks of nitrogen,phosphorus and potash changed to low risk from safety in 1988,1999,2008,respectively;the environmental risk of fertilization has been decreasing since 2006.The environmental risk was at low degree in 2014 with averages of fertilization environmental safety thresholds and risk index of 285 kg·hm^-2 and 0.54,respectively.The risk indexes of nitrogen,phosphorus and potash were 0.54,0.53,0.49,respectively.The environmental risks at provincial level showed great differences,and the types of risks were aggregately distributed in 2014.There were 11 provincial areas at environmental safety degree,16 areas at low risk degree,three areas of Henan,Hainan and Tianjin at medium risk degree,and the area of Shaanxi at serious risk degree.