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FOOD CHAIN TRANSFER AND BIOAVAILABILITY OF CD AND OTHER ELEMENTS IN PLANTS GROWN ON BIOSOLIDS AMENDED SOILS
Citation:
Chaney, R. L., P. G. Reeves, U. Kukier, J A. Ryan*, AND C. E. Green. FOOD CHAIN TRANSFER AND BIOAVAILABILITY OF CD AND OTHER ELEMENTS IN PLANTS GROWN ON BIOSOLIDS AMENDED SOILS. Presented at Sustainable Land Application Conference, Lake Buena Vista, FL, January 04 - 08, 2004.
Impact/Purpose:
To inform the public.
Description:
Application of biosolids, livestock manures, compost, and many byproducts add heavy metals to soil. Exposure of humans, livestock and wildlife to these added heavy metals continues to be a concern despite the research and risk assessments which suggest otherwise. Key concepts governing phytoavailability of heavy metals in residual amended soils include (1) the salt effect, (2) the plateau effect, and (3) the soil-plant barrier. These will be discussed and illustrated as time permits. Metal toxicity and bioavailability in metal salt spiked soil is greater metal in residual-treated soil. Plant metal content plateaus at high residual loadings and the plateau is related to the residual's metal concentration and sorption capacity. The soil-plant barrier limits transmission of many heavy metals through the food chain. Additionally factors which govern bioavailability of foodchain metals will be discussed. Cadmium, an important human health concern, passes through the soil-plant barrier. After decades of research to clarify potential Cd risk to humans from land-applied residuals, it has become clear that only one population group has experienced Cd disease from food, the subsistence rice consumers who ate home-grown rice produced on contaminated paddy soils.