广州市万亩果园土壤重金属污染调查与评价

Heavy Metals Pollution in the Soil of Guangzhou Wanmu Orchard:Investigation and Assessment

运用实地调查采样及地积累指数法、单因子污染指数法、综合污染指数法等方法对广州市万亩果园土壤的重金属(Cd、Pb、Cu、Zn)污染情况进行了调查分析与评价.结果表明:万亩果园土壤中Cd、Cu污染不容忽视,其中Cd污染最为严重,Cu、Zn次之,Pb污染较少;在《广州市海珠区果树保护区总体规划》划分的不同等级保护区中,针对研究区域,一级保护区土壤重金属综合污染指数为0.732,属较清洁(警戒线)等级,二级保护区土壤重金属综合污染指数为1.792,属轻度污染等级,其中Cd为主要污染物,其次是Cu;三级保护区Cd污染严重,单因子污染指数高达6.390,土壤重金属综合污染指数为4.699,属于重污染等级.在垂直分布上,随土层深度增加,万亩果园土壤重金属含量呈现Cd递增,Cu、Zn递减,Pb先增后减的规律;一级保护区以农业污染源为主,二级保护区农业污染源与工业污染源并存,三级保护区以工业污染源为主.通过在轻污染区添加石灰、羟基磷灰石等化学修复剂,在重污染区积极调整种植结构,发展清洁生产,防止土壤重金属通过食物链危害人体健康.

Based on investigation and sample analysis, environmental quality of orchard soil was as- sessed using Geoaccumulation index, Index, in order to find out the Single-Factor Pollution Index and spatial Nemerow Synthetical Pollution and vertical distribution characteristics of heavy metals in the Wanmu Orchard soil, and to address causes of the contamination and provide pollution control ad- vices. The results indicated that Cd pollution is the most serious in the orchard soil, followed by Cu and Zn pollution, and Pb pollution is slight; In a plan called Guangzhou Wanmu Orchard Reserve Planning which divides orchard lands into three conservation districts of three grades, the quality of soil in the first-grade conservation district is clean （its Nemerow Synthetical Pollution Index is 0. 732）, soil in the second-grade conservation district is slightly polluted （ in which Cd is the domi-nant pollutant, followed by Cu）, and soil in the third-grade conservation district is heavily polluted by Cd （its Single-Factor Pollution Index is 6. 390 and its Nemerow Synthetical Pollution Index is 4. 699, both at heavy pollution level）. The content of Cd increases with depth, while that of Pb, Cu and Zn decrease. Compound pollution of Cu and Zn is ubiquitous in the orchard soil. These show that agriculture pollution source is the uppermost one for the first-grade conservation district, agricultural pollution source and industry pollution source exist in the second-grade conservation district, and indus-try pollution source is the root cause for pollution in the third-grade conservation district. Chemical pol-lution remediation and ecological agriculture can be applied to control heavy metal pollutions in the soil.