Cadmium and lead uptake by edible crops grown in a silt loam soil.

Abstract

There is increasing public concern about health effects resulting from ingestion of food containing toxic metals such as Cd and Pb. For example, a wide range of metabolic disorders and neuropsychological deficits in children have been noted, and chronic exposure to Cd has been linked to kidney failure and bone disease. The potential harm posed by the uptake of heavy metals such as Cd and Pb by plants is dependent on their abundance, mobility and bioaccumulation. Plant uptake of heavy metals was also influenced by soil pH. There is a linear relationship between soil concentrations of heavy metal and concentrations in vegetation around a zinc-lead tailing pond. The ability of the soil to retain metals depends on several factors; pH, cation exchange capacity (CEC), organic matter content, and their specific geochemical properties. Overall, the metal burden of a crop depends on: (a) uptake via the root system; (b) direct foliar uptake and translocation within the plant; and (c) surface deposition of particulate matter. Numerous studies have been conducted with agronomic crops regarding heavy metals in soils and plant uptake from sewage sludge, but only a few studies have dealt with the uptake of heavy metal mixtures in vegetables. This papermore » reports on germination/emergence, biomass and uptake of Cd and Pb in lettuce and radish grown in a loam soil spiked with known mixtures of CdCl{sub 2} and Pb(NO{sub 3}){sub 2}. Lettuce and radish have been used in this study because they are among the two groups of vegetable crops (leafy and root) consumed by humans. Also, earlier studies have reported that lettuce and radish bioaccumulate Cd and Pb from heavy metal polluted soils. 38 refs., 7 tabs.« less