The Phosphate Knowledge Center
|Title:||Effects of phosphate rock on sequential chemical extraction of lead in contaminated soils|
|Author:||Lena Q., Gade N. Rao|
Lead contamination is of great concern because of its adverse effects on human health, especially children. This research evaluated the effects of phosphate rock on chemical associationsof Pb in eight Pb-contaminated soils using a sequential extraction procedure. The chemicalfractionsare operationally defined by an extraction sequence in the order of increasing ability to dissolve Pb of lower solubilities. Additionally, more soluble forms of Pb are considered to be potentially more bioavailable than the less soluble forms. Lead in these soils was primarily associated the carbonate and Fe-Mn oxide fractions Up to 21% of the Pb in these soilswas associated with either the organic or residual fraction and was associated with the water-soluble and the exchangeablefractions. Phosphate rocks effectively converted Pb from the water soluble, exchangeable, carbonate, Fe-Mn oxide, and organic fractions (collectively the residual fraction) to the residual fraction, thus reducing Pb solubility and presumably bioavailability. Lead precipitation as a morphite-like mineral in contaminated soils was suggested as the primary mechanism for reduced Pb solubility and Pb reduction in the nonresidual The effectiveconversion ofPb from potentially available fractions to the residual fraction suggests that phosphate rock has potential for in-situ immobilization in Pb contaminated soils.
|Submited to Green Pi:||2010-05-20 By admin|
|Modified on Green Pi:||2013-03-21 By farzi|