粉煤灰堆场基质-农作物系统中重金属生态风险及健康风险评价

Ecological risk and health risk assessment of heavy metals in fly ash yard matrix-crop system

贵州喀斯特山区存有大量燃煤电厂,由这些燃煤电厂产生的粉煤灰在电厂周边山沟峡谷中长期露天堆置,形成了较为平整开阔的山区“坝子”型粉煤灰堆场。周边农户在粉煤灰堆场上直接大面积种植农作物后,堆场耕作层粉煤灰基质和农作物中重金属是否存在相关环境风险、生态风险及健康风险迄今鲜见报道。以贵州某大型粉煤灰堆场上直接大面积种植的不同类型农作物,玉米、辣椒、花生、南瓜、茄子和向日葵及相应粉煤灰基质为研究对象,分析植物经济器官及灰渣中重金属Cd、Cr、Cu、Pb、As含量,并利用污染指数(P_(i))、综合污染指数(P_(N))、生态危害指数(RI)和健康风险指数(HRI)综合评价了样品中重金属的污染水平及其对消费者的健康风险。结果表明:1)堆场基质存在重金属污染的潜在生态风险,其中Cd存在极强的生态风险;2)粉煤灰堆场上种植的花生、南瓜、茄子和向日葵中可食用部分均存在不同程度的重金属污染;3)农作物健康风险评价结果表明,As的重金属风险指数大于1,儿童长期食用通过该粉煤灰堆场基质种植的茄子和南瓜可能带来健康风险。

A large number of coal-fired power plants were established in the karst mountainous area of Guizhou,and the fly ash produced by these coal-fired power plants was piled in the open air for a long time in the ravines and valleyed surrounding the power plant,forming a relatively flat and open mountainous“baz”type fly ash storage yard.After the surrounding farmers directly planted large-scale crops on the fly ash storage yard,there were few reports so far whether there were related environmental risks,ecological risks and health risks in the fly ash substrate and the heavy metals in the crops in the farming layer of the storage yard.In this paper,such as corn,pepper,peanuts,pumpkin,eggplant,and sunflower,these different types of crops directly planted on the yard,and fly ash substrates were the research objects.The contents of heavy metals Cd,Cr,Cu,Pb,As in plant organs and fly ash slag were tested,and Pollution Index(P_(i)),Comprehensive Pollution Index(P_(N)),Ecological Hazard Index(RI)and Health Risk Index(HRI)were used to comprehensively evaluate the pollution level of heavy metals in samples and their health risks to consumers.The result showed:1)The potential ecological risk of heavy metal pollution in the substrate of the storage yard was found,and the ecological risk of Cd was extremely strong.2)The edible parts of peanuts,pumpkins,eggplants and sunflowers grown on the fly ash yard were found to be polluted by heavy metals to varying degrees.3)The crop health risk assessment results showed that the heavy metal risk index of As was greater than 1.If children eat eggplants and pumpkins grown on the fly ash storage yard for a long time,it may bring health risks.