Speciation and Availability of Heavy Metals On Serpentinized Paddy Soil and Paddy Tissue

There has been increasing concern in recent years regarding toxic elements transfer in the soil-plant system. Soils developed on serpentinitic rocks have serious limitations for agriculture. They have high levels of magnesium (Mg) and heavy metals such as nickel (Ni), chromium (Cr), cobalt (Co), and manganese (Mn) and are deficient in some essential macronutrients. The continuous accumulation of serpentine soil downward in the Ranau Valley paddy field brings by excessive erosion and high rainfalls through the main irrigation systems and overflowing flood streams. The presence of serpentine soil contamination is clearly evidenced by oily water and reddish paddy soil. Therefore the basic objective of this work is to examine the availability and mobility of certain elements by assessing the physicochemical properties of paddy soil and the soil-plant interaction as induced by the effect of serpentine. In this study the transfer of abundant metals (Ni, Cr, Co, Fe, Al and Mn) was investigated from a paddy field soils to different parts of Oryza sativa L. (cultivar YTM Sarawak Merah) tissue (root and shoot) through modified metal speciation procedures; that are available and residual fractions. The analyses in nutrient content and heavy metals accumulation in the paddy soil and tissues are reported at the full crop stage through the translocation factor (TF) and bioaccumulation factor (BAF) for a better understanding of the soil-plant system. The heavy metals in the area where potentially bioavailable since the soils are acidic (pH 5.60 - 6.15) which suggested a medium nutrient availability, have a high silt (33.21-69.02), lower clay (13.55-46.98) and sand (7.41-33.44) contents and higher metal concentrations associated with the residual fractions. (C) 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.