Effect of Inorganic Anions on The Bioavailability of Lead to Indian Rape in A Lead Spiked Loamy Sand Soil

Abstract

A greenhouse pot experiment was conducted to study the influence of different inorganic anions on growth and lead (Pb) content of Indian rape (Brassica compestris var. Toria) in a Pb spiked loamy sand soil. Soil was artificially contaminated with four levels of Pb (0, 50, 100, 200 mg Pb kg−1 soil). Potassium salts of four anions viz. H2PO4−, Cl−, SO42-, CO32- were applied to soil at four rates viz. 0, 60, 120 and 240 mg kg−1 soil. Soil was equilibrated for 30 days and Indian rape was grown for 60 days as a potherb. The results showed a significant increase in mean DTPA-Pb with increase in Pb contamination and it increased from 0.3 in control to 92.2 mg Pb kg−1 soil in 200 mg Pb kg−1 treated soil. Addition of H2PO4− and CO32- resulted in a decrease of DTPA-Pb but addition of Cl−and SO42- resulted in an increase in the DTPA-Pb. The dry matter yield (DMY) of Indian rape at 60 days was significantly reduced by the addition of increasing amounts of Pb but the magnitude of reduction in DMY with Pb contamination decreased with the addition of H2PO4− and CO32- anions but increased with the addition of Cl−. Similarly, the Pb content of plants also increased linearly and significantly with increase in Pb contamination levels but decreased with the addition of H2PO4 and CO32-anions. The results suggested that addition of H2PO4 and CO32-anions lowered the bioavailability and increased the geochemical stability of soil Pb, indicating their potential for in situ remediation in Pb-contaminated soils.