Lead-phase determination and demonstration of contaminated soil remediation mechanism by scanning electron microscopy and characteristic x-ray imaging

Abstract

The utility of microscopy and microanalysis in the study of contaminated atmospheres is well established. The particulate nature of soils suggests that these methods would be equally useful in the study of contaminated soils and similar materials; however, the focus on bulk contaminant concentrations, solution chemistry and leachability has obscured the role of microanalysis in elucidating the chemistry of contamination and in guiding remediation methods.A case in point is the study of lead contaminated soils and possible remediation strategies. Ma, et al, recognized that reaction of lead with hydroxyapatite provided a possible remediation method for lead contaminated soils by precipitation of hydroxypyromorphite [Pb10(PO4)6(OH)2], proposing that the mechanism of lead immobilization in contaminated soils is congruent alteration, that is, dissolution of hydroxyapatite [Ca10(PO4)6(OH)2]to give phosphate ion in solution, followed by precipitation of dissolved lead ion as hydroxypyromorphite.