Exploration of Heavy Metal(loid)s Immobilizing Agents Available for Agricultural Lands and Their Combination Effects

Abstract

Heavy metal(loid)s contamination in Korean agricultural lands is mostly caused by tailing wastes, debris, and leachate from abandoned mines. For safe agricultural production, immobilizing agents have been actively studied to reduce phytoavailability of heavy metal(loid)s. However, more various immobilizing materials need to be explored to achieve a practical application of this technique. This study aims to examine and compare the effects of known and unknown immobilizing agents on decrease plant-available heavy metal(loid)s. Lime, gypsum, guano, and bone meal were applied in metal contaminated soils in isolation or in combination. After the treatment, changes in soil pH and dissolved organic carbon were analyzed. Lettuce was grown for 7 weeks in each soil, and heavy metal(loid)s concentration in lettuce was determined. The mixed immobilizing agents reduced phytoavailability of heavy metal(loid)s more effectively than the isolate treatments. A mixture of lime, gypsum, and guano was the most effective combination, followed by a mixture of lime, gypsum, and bone meal. Future study on a practical application of the immobilizing agents is required to increase both safety and productivity of agricultural crops. Cumulated heavy metal(loid) immobilizing rates of gypsum, lime, guano, and bone meal, treated either alone or in selected combinations