Bio-concentration and translocation of chromium in soil-plant system: Health risks in Usangu agro-ecosystem

Abstract

Determination and analysis of total chromium (Cr) in soil and plant tissues help estimate the associated health risk; however, this might overestimate the risk because not all Cr from the soil is transported to above-ground plant tissues, mainly the edible part of most plants. Here we present the analysis of Cr partition in soils and paddy rice plant samples which currently missing in Usangu agro-ecosystem. The bio-concentration (BF) and translocation factors (TF) estimating the distribution and partitions of Cr in plant tissues (roots, straws, and grains), and associated environmentally and health risks were determined in Usangu agro-ecosystem. The Cr concentration in soils ranged from 4.58 to 42.76 mg/kg which was within maximum permissible limits (100 mg/kg), with the total Cr in plants samples ranging from 12.88 to 57.34 mg/kg. It was found that straws and roots had higher Cr concentrations than grains indicating a less health risk in edible parts. The BF > 1 was observed in 83.3% of the studied sites indicating higher Cr uptakes by plants. Furthermore, TF < 1 was observed in 67.33% of the studied sites indicating more Cr accumulated in below-ground biomass (roots) than above-ground biomass (straws and grains) (33.33%), thus less risk to edible plant parts. This study indicates that high Cr in agricultural soils may accelerate Cr accumulation in plant tissues or above-ground plant biomass leading to health risks.