小店污灌区浅层地下水Cd(Ⅱ)和Cr(Ⅵ)分布特征及健康风险评价

Distribution and Health Risk Assessment of Cd(Ⅱ) and Cr(Ⅵ) of Groundwater in the Irrigation Area of Xiaodian

为了解污灌区浅层地下水中重金属Cd和Cr的污染水平,在小店污灌区采集22组地下水样品,采用常规的统计方法和健康风险评价模型,定量分析了2种重金属元素的质量浓度及空间分布特征,并评价了地下水中Cd、Cr的健康风险水平。结果表明,地下水中Cr的平均质量浓度（14.4μg/L）显著高于Cd（2.06μg/L）,但二者均未超过地下水环境质量三级标准。重金属质量浓度的高值区主要分布在灌溉渠附近。Cd与Cr的Spearman相关系数为0.499,呈实相关。地下水中Cd的单项污染指数大于Cr,这与二者在地下水中的质量浓度关系相反。Cr经饮水途径的平均致癌风险约为Cd的9.2倍;22个评价点中,Cd的年致癌风险水平均低于ICRP推荐的年最大可接受风险水平（5×10-5）,而Cr仅有8个评价点的致癌风险低于ICRP推荐的年最大可接受风险水平（5×10-5）,但均高于导则（HJ25.3—2014）推荐的年最大可接受风险水平（10-6）;Cd和Cr的总致癌风险系数为15.33×10-6~123.14×10-6,其中Cd的致癌风险贡献率为6%~42%,显著低于Cr。

In order to investigate the contamination levels of groundwater in the irrigation districts of Xiao- dian, twenty-two groundwater samples were collected and analyzed. Health risks associated with two met- als（Cd and Cr）were assessed using water pollution index and health risk assessment model. The results in- dicated that the average concentration of Cr with 14.4 μg/L was higher than the concentration of Cd with 2.06 μg/L. The high value areas of the two metals were near irrigation canals. Single pollution indexes of Cd were higher than those of Cr, which was opposed to potency of two metals in groundwater. Health risk of Cr was 9.2 times as that of Cd. The total risks of Cd and Cr ranged from 15.33×10-6 to 123.14×10-6 in drinking water, and the contribution rates of Cd in the total carinogenic risks were 6 % ~42%, which were obviously lower than those of Cr.