山地水田土壤环境质量评价及重金属来源解析

选择以非传统重点关注农区——广东省东部山地水田土壤作为研究对象，调查土壤中Cd、Hg、As、Pb、Cr、Cu等6种重金属的质量分数水平及空间分布情况，评价环境质量现状并进行重金属来源解析.研究结果表明:该区水田土壤环境中各重金属的平均质量分数未超过国家标准中的农田土壤污染风险管制值；基于筛选值的样本超标率均在10%以下，土壤环境质量总体良好，农产品重金属超标风险低；土壤中重金属的来源可能主要包括受人为干扰的土壤成土母质因素、工业污染因素、无干扰的土壤成土母质因素和交通污染因素，分别影响土壤中Cd、As、Cr、Cu、Hg、Pb的质量分数和空间变化特征，是导致土壤环境污染的潜在因素.建议该区在发展农业经济、工业经济、公共服务体系等时，注意做好环境规划、管理及污染防治；对超筛选值的轻度和中度污染土壤采取进一步的生态风险评估和农产品协同监测机制，对极少数重度污染土壤采取改种非食用农作物的措施.

The Assessment of Soil Environmental Quality and the Analysis of Heavy Metal Source in Paddy Field in Hilly Areas

The content and spatial distribution of Cd, Hg, As, Pb, Cr and Cu in paddy soils in hilly areas in the east of Guangdong Province, which are agricultural areas and not traditionally focused on, were investigated. The environmental quality was assessed and the source of heavy metals was analyzed. The results showed that the ave-rage concentrations of heavy metals in soil were all lower than the risk control values of pollution in farmland soil in the national standard. The exceeding standard rate of samples based on the screening value was less than 10%. The soil environmental quality was generally good, and the risk of exceeding the standard of heavy metals in agricultural products was low. The possible sources of heavy metals in the soil mainly include the soil parent material disturbed by human activities, the industrial pollution, the undisturbed soil parent material and traffic pollution, which affect the content and spatial distribution of the heavy metals Cd, As, Cr, Cu, Hg and Pb respectively. It is suggested that attention should be paid to environmental planning, management and pollution prevention and control in the development of agricultural economy, industrial economy and public service system. Further ecological risk assessment and cooperative monitoring of agricultural products should be carried out for mildly and moderately polluted soils based on the screening values. Non-edible crops should be planted in a very small number of area with severely polluted soil.