大兴区农用地畜禽粪便氮负荷估算及污染风险评价

Estimation of Livestock Manure Nitrogen Load and Pollution Risk Evaluation of Farmland in Daxing District

利用畜禽养殖的统计数据计算了畜禽粪便养分含量,利用畜禽粪便养分空间化方法实现了畜禽粪便养分从统计数据到农用地养分的转换,在此基础上,结合农用地面积计算出农用地畜禽粪便氮负荷量,并以北京市大兴区为例实现了以地块为单元的畜禽粪便氮负荷估算及污染风险评价,最后以农用地土壤耕层和亚耕层中水解氮含量及变化进一步说明了畜禽粪便对土壤环境污染风险.结果表明,2005年大兴区农用地氮负荷平均值为214.02 kg/hm2,最小值仅为10.64 kg/hm2,最大值达到5 996.26 kg/hm2,有近一半的农用地受到了不同程度的畜禽粪便氮污染威胁,占大兴区总农用地个数的42.14%,这些受污染威胁农用地地块面积小、养分需求少且主要分布在居民地和规模养殖场附近.耕层及亚耕层的水解氮变异系数分别为64.3%和53.65%,耕层及亚耕层的水解氮平均值分别为65.93μg/g和45.25μg/g,富集系数(耕层/亚耕层)为1.46,变异系数和富集系数进一步说明了畜禽粪便对土壤环境存在的污染风险及对环境的影响程度.

Based on the livestock statistical data, the nutrient content of livestock manure was calculated and the nutrient transformation from livestock manure to farmland was realized by using the method of spatializing livestock manure nutrient. On this basis, this paper calculated nitrogen load of livestock manure combining with the area of farmland and realized the estimation of nitrogen load of livestock manure and potential pollution evaluation in landmass for unit taking Daxing District in Beijing as an example. The result showed that the average, minimum and maximum nitrogen loads of farmland were 214. 02 kg/hm^2, 10.64 kg/hm^2 and 5 996. 26 kg/hm^2 respectively and near half of farmland was threaten by nitrogen load of livestock manure, accounting for 42. 14% of the total farmland. These farmland threaten to polluted had the characters of small area and few nutrient demand and mainly located nearby the inhabitant and the scale raising. The coefficients of variation and average of available nitrogen in topsoil and subsoil were 64. 3% , 53.65% and 65.93 μg,/g, 45.25 μg/g respectively and the enriehment coefficient was 1.46, which explained the existing pollution risk and the influence degree of livestock manure to soil environment pollution.