Bioavailability Evaluation of Cadmium in Soil with Rhizospher - Based Extraction Method.

Heavy metal pollution in soil has been a critical issue for ecosystem and human health in worldwide. In particular, remained hazardous materials in abandoned mines such as tailings and refuge can be introduced to adjacent crop field and cause adverse effect on not only crops but also human health. For this reason, assessment of bioavailability for heavy metals in soil is necessary and 0.01M LMOAc (Low Molecular Organic Acid) extraction method was evaluation in this study. Soil and crop samples were collected from rice field located near at the abandoned metal mine in Korea. Concentration of cadmium in soil and crops was quantified with ICP-ASE after extracting heavy metals with 0.01M LMOAc for soil and aqua regia for crops respectively. Organic acids in soil (Acetic, Lactic, Malenic, and Citric acid) were extracted with deionized water and quantified with LC/MS. Statistical analysis was conducted to evaluate correlation of heavy metal concentration between soil and crops. Organic acid concentration in soil was ranged from 3.71 to 71.64 mg kg^-1 depending on organic acid species. Based on concentration of organic acid, 0.01M LMOAc extractant was determined as 4:2:1:1 of acetic: lactic: citric: malenic acid. Concentration of cadmium in soil and crops separated with straw and root was ranged 0.61 – 1.46, 2.80 – 10.41, 8.84 – 32.48 mg kg^-1 respectively. The result of correlation between Cd concentration in soil and straw or root showed that much higher correlation (R²=0.70) was observed when Cd concentration in soil was compared with straw rather than root (R²=0.22). This result clearly showed that LMOAc extraction method can be adapted to evaluate Cd bioavailability from soil to crops and crop straw might be more valuable to evaluate bioavailability of heavy metals than crop root.

 

 Keywords: Heavy metals, Soil, Bioavailability, Low molecular organic acid.