Migration and transfer of chromium in soil-vegetable system and associated health risks in vicinity of ferro-alloy manufactory

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.