Bioavailability and Uptake of Cadmium and Lead in Soil-Plant Systems: A Combined DGT and Sequential Extraction Elfina Rahmania Zelfi
Universitas Indonesia
Abstract
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Heavy metal contamination in agricultural soils, particularly by cadmium (Cd) and lead (Pb), represents a critical environmental and public health concern due to their toxicity, persistence, and potential for bioaccumulation within the food chain. This study aims to evaluate the bioavailability of Cd and Pb in soil and to assess their uptake and accumulation in spring onion (Allium fistulosum L.) through the integration of sequential extraction and Diffusive Gradients in Thin Films (DGT) techniques. The Tessier sequential extraction procedure was employed to elucidate the distribution of metals among distinct geochemical fractions, while the DGT technique was utilized to quantify the labile and bioavailable metal species under near in situ conditions.
The experimental approach comprised soil physicochemical characterization, including pH, cation exchange capacity, organic matter content, and total metal concentrations, followed by sequential extraction analysis and controlled pot experiments with varying Cd and Pb concentrations. The DGT devices were fabricated using Saccharomyces cerevisiae-based biomass as a novel binding agent. Metal concentrations in soil extracts and plant tissues (roots, stems, and leaves) were determined using Atomic Absorption Spectrophotometry (AAS).
The findings are expected to demonstrate that Cd and Pb are partitioned into multiple soil fractions with differing degrees of mobility and bioavailability, where the labile fraction significantly influences plant uptake. The DGT technique is anticipated to provide a more reliable estimation of bioavailable metal concentrations compared to conventional extraction methods and to exhibit a strong correlation with metal accumulation in plant tissues. Moreover, the accumulation of Cd and Pb in Allium fistulosum may pose potential risks to environmental sustainability and food safety when concentrations exceed established threshold limits.
Overall, the integration of DGT and sequential extraction methods offers a comprehensive approach for assessing heavy metal bioavailability in soils and its implications for crop contamination and human health risk.
Keywords: bioavailability, cadmium (Cd), lead (Pb), Diffusive Gradients in Thin Films (DGT), sequential extraction, Allium fistulosum, heavy metals
