Effects of Pine Bark Compost on the Distribution of Cd and Pb in Organic Fractions over Time in Contaminated Soils
AbstractHeavy metal contamination in rural soils severely threatens the food chain, and consequently, human health. The addition of organic amendments to contaminated soils is considered an effective method to immobilize heavy metals. However, the sequential decomposition of soil organic matter still poses a risk, the rerelease of heavy metals, to animals and plants. This study aims to determine the amount of Cd and Pb in different organic fractions including dissolved organic matter, humic acid (HA), fulvic acid (FA), and residual fraction after the addition of a pine bark compost to tropical acidic soils. Four controlled samples, contaminated to 20, 40, 60, and 80  mg/kg for Cd, and 200, 400, 600, and 800  mg/kg for Pb, were used in this study. The soil samples, both with and without the pine bark compost, were incubated for 120 days for further analysis. The results of the sequential extraction of organic matter indicated that the proportions of Cd and Pb were transferred from the residual fraction int...