基于稻米摄入风险的稻田土壤镉临界值研究:个案研究

研究了浙江富阳某乡土壤Cd的污染,以及水稻对土壤Cd的吸收,并应用基于稻米摄入风险的方法推导了土壤Cd的临界值。结果表明,研究区土壤与稻米Cd污染严重。结合土壤总Cd和土壤pH应用多元回归分析建立了稻米Cd含量的预测模型。应用预测模型计算表明,pH分别为5、6、7、8时土壤Cd的临界值分别为0.42mgkg-1、0.79mgkg-1、1.49mgkg-1和2.81mgkg-1。土壤性质差异使得Cd的临界值具有较大的空间变异。在研究区,有73%地区总Cd含量超过了所对应的临界值,因此需要实施合理的风险管理措施。土壤Cd的临界值推导过程中不确定性来源主要为风险评估模型以及水稻Cd的预测模型,土壤pH是最敏感的参数。

CRITICAL VALUES FOR Cd IN PADDY FIELD BASED ON Cd RISK OF RICE CONSUMPTION:A CASE STUDEY

Cadmium contamination of the soil in Fuyang Valley, Zhejiang Province and Cd uptake by rice were studied, and critical values for Cd in soils deduced based on Cd risk of rice consumption. Results show that high concentrations of Cd in soil and rice grains were detected in the study area. A model is established for prediction of Cd concentration in rice grains based on multi-factor regression analysis, taking into account soil total Cd and pH. With the aid of the model, critical values of Cd in different soil pH were derived, being 0.42 mg kg^-1, 0.79 mg kg^-1, 1.49 mg kg^-1 and 2.81 mg kg^-1 for soils with pH at 5, 6, 7 and 8, respectively. Due to the spatial heterogeneity of soil pH in the study area, a high spatial variability was observed of critical values of Cd in soil. The results indicated that total Cd content in soil exceeded their critical values in 73 % of the sampling sites. Therefore, sound strategies for risk management should be implemented to protect human health. In addition, uncertainties in deduction of soil Cd critical values come mainly from the risk assessment model and rice grain Cd uptake model and soil pH is the most sensitive parameter.