巫山建坪燃煤型氟中毒地区土壤高镉的来源及赋存状态研究

The Source and Geochemical Speciation of High Cadmium in Soil in the Jianping Area,Wushan,Chongqing,with Endemic Fluorosis Related to Coal Combustion

重庆巫山建坪燃煤型氟中毒地区土壤具有明显的地带性高Cd地球化学异常,土壤Cd含量范围为1.85-22.7 mg/kg,平均值为7.5 mg/kg,为富Cd的黑色泥页岩、碳质粉砂岩和煤层的风化作用所致。土壤中Cd的赋存形态分析表明,Cd的生物有效性含量很高,约占总量的36%,而残渣态含量较低,有利于Cd被农作物吸收富集而危害食物链安全。在三峡库区燃煤型氟中毒地区进行地方病防治时,不能忽视Cd可能诱发的环境健康问题,以保障食物链安全和公众健康。

The soils from the Jianping area with endemic fluorosis related to coal combustion in Wushan, Chongqing, were characterized by obvious zonal geochemical abnorlies with high cadmium, Cadmium concentrations in local soils ranged from 1.85 to 22.7 mg/kg with an average value of 7. 5 mg/kg. The sources of high cadmium in soils were attributed to the weathering processes of Cd-rich black shale, carbonaceous siltstone and coal seems. The sequential extraction tests showed that cadmium was present in quite high concentrations with a high bioavailability, whieha accounts for about 36% of the total Cd in soils. The high Cd contents occurring in speciations with a high bioavailability but low contents in residues implied for ready uptake of Cd by crops from soils, which would potentially risk the food chain safety. It is pointed out in this paper that the Cd-induced em vironmental and healthy problems in the Three Gorges region with endemic fluorosis related to coal combustion should not be neglected so as to safeguard the food chain safety and public health.