Paddy soil heavy metal contamination and uptake in rice plants from the adjacent area of Barapukuria coal mine, northwest Bangladesh

This study was carried out to estimate the heavy metal contamination in paddy soil and subsoil and uptake by rice plants collected from Barapukuria coal mine area of Bangladesh. The mean contents of As, Cr, Cu, Mn, Ni, Pb, and Zn in paddy soil and subsoil exceed the world averages, and the observed soils are moderately to extremely polluted with inputs from mining activities. Correlation and regression model analyses suggest that pH and TOC have distinct effect on the availability of observed metals in soils. Sequential extraction of paddy soil and subsoil samples demonstrate that the mobility of heavy metals increases in the order of Cu> Zn> Pb> Fe> Cr> Ni> Mn> As. The uptake of metals in rice root is much higher than those in straw and rice grains. Arsenic, Cr, and Pb uptake in rice grains are 6.87-, 1.58-, and 5.26-fold higher than the maximum permissible concentration which shows a tendency of transformation of these elements from contaminated soil to rice plants.