Department of Chemistry, Jagiroad College, Morigaon, Assam, India

Department of Chemistry, Gauhati University, Assam, India

Metal accumulation in the vegetables/crops growing on agricultural soils, contaminated due to long term irrigation with treated industrial wastewater has been assessed in an area of industrial complex, HPC, Nagaon, Assam (India). To predict the uptake of Cd, Cr, Mn, Ni and Pb by vegetables grown on agricultural soil, samples of 14 varieties of vegetables were collected from seven villages around the study area and the samples were analyzed by Atomic Absorption Spectrophotometer (AAS). Various physico-chemical properties such as pH, electrical conductivity, bulk density, organic carbon, water holding capacity (WHC) and HC of the soil were studied for both pre and post monsoon seasons and the data in the two seasons were compared. The comparison of physico-chemical properties of soil showed that pH, electrical conductivity, and organic carbon, sodium were found high in the pre monsoon season and bulk density, water holding capacity and HC were found high in the post monsoon season. The analysis of metal content in the soil and vegetables showed the order of Mn > Pb > Cr > Ni > Cd and Mn > Pb > Ni > Cr > Cd respectively. The metals were examined for dependency upon some soil factor through the use of correlation analysis, pH, electrical conductivity, organic carbon and HC correlated positively with Cd, Cr, Mn, Ni and Pb indicating that these factors greatly control the concentration of these metals in the soils. Metal transfer factors from soil to vegetable were found less significant for Mn, Ni and Pb, but significant values were obtained for Cd in some sites. The results from the study indicates that there is a need to develop appropriate agricultural management practices to ensure adequate measure of amendment with trace metal concentrations within the critical values for plant growth.

Keywords:Heavy metals; Physico-chemical parameters; Vegetables; Soil.