铬在铁合金厂周边土壤-蔬菜系统中的迁移转化及健康风险

摘要

Study was carried out to analyze the distribution and migration patterns,soil-to-plant transfer and potential health risks of chromium in soil-vegetable system in areas near a ferro-alloy manufactory in Hunan province.The results show that soils near sewer outlet,sewer channel and in control area are averaged 2 239.5,995.33 and 104.9 mg/kg,respectively.The total Cr has a relative accumulation in soil depth of 200-400 mm near the sewer outlet,mainly enriches in the surface layer (0-200 mm) near the sewer channel and decreases gradually in unpolluted soils.The differential concentration level of enrichment between layers is little.The results also indicate that the three vegetables of celery,lettuce and Chinese cabbage are able to convert the potentially toxic Cr (Ⅵ)species into the non-toxic Cr (Ⅲ) species,and the chromium contents in the edible parts of the vegetables are averaged 11.95 mg/kg.The transfer factors of the three vegetables follow the order:Chinese cabbage ＞ lettuce ＞ celery.The estimated total daily intake of chromium substantially exceeds the dietary allowable value,which may pose health risks to local population.%分析湖南省某铁合金厂附近重金属铬在土壤中的分布及迁移特征,在土壤-植物系统中的迁移转化规律,以及铬污染蔬菜对人体的健康风险.结果表明:铁合金厂外排污口、污灌区和对照区土壤的铬含量平均值分别为2 239.5,995.33和104.9 mg/kg.总铬在排污口附近土壤中主要富集在地表下200-400 mm；在污灌区,主要富集于地表下0-200 mm;而在对照区,铬浓度从上至下逐渐降低且各层之间富集浓度相差不大.结果也表明芹菜、莴苣和白菜均能够把土壤中吸收的致毒性较强的六价铬转化成低毒的三价铬,且蔬菜中的铬含量平均值为11.95mg/kg.铬在土壤-蔬菜中的生物富集因子大小依次为:白菜＞莴苣＞芹菜.居民每天摄入的铬含量严重超过食物中最大铬允许摄入量,表明铬污染对当地居民存在一定的健康风险.