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CD SPECIATION ASSOCIATED WITH IRON OXIDES AND BIOSOLIDS
Citation:
SCHECKEL, K. G., G. HETTIARACHCHI, AND JAMES A. RYAN. CD SPECIATION ASSOCIATED WITH IRON OXIDES AND BIOSOLIDS. IN: Advanced Photon Source Activity Report 2003, Argonne National Laboratory, Argonne, ILANL-04/16, (2004).
Description:
The environmental impact and potential hazards of metals in biosolids to plants, animals and the human food chain have been studied for decades. From this body of work, it has been concluded the addition of biosolids to the soil alters the chemical phases in the soil system beyond that of the simple addition of greater quantities of trace elements. Further, it is that this alteration does not require large additions of biosolids. The phase responsible for this alteration has and continues to be in dispute. In its development of regulations designed to protect human health and the environment from reasonably anticipated adverse effects of land application of biosolids, the U.S. Environmental Protection Agency's reliance on this difference in phytoavailability of metals in soil systems amended with biosolids, intensified the debate. Beckett et al. (1)postulated the "time-bomb" hypothesis in which it is assumed that the responsible phase is organic and as the organic material decomposes its complexing nature will be lost with a subsequent release of metal to the inorganic system where it will behave as a salt addition to the soil. In contrast, Corey et al. (2)predicted that biosolids adsorption chemistry related to inorganic surfaces control the activity in the soil after reaching saturated soil metal binding sites. Based on these understandings, researchers began attempting to characterize the chemical aspects of biosolids, which made metals so much less available to plants (phytoavailable) or biological systems (bioavailablity) than were metal-salts. Studies from long-term application sites illustrated that bioavailability does not increase as the added organic matter decreases.