Unique Characteristics of Pb in Soil Contaminated by Red Lead Anti-Corrosion Paint

Abstract

Red lead (Pb 3 O 4 ) has been extensively used in the past in anti-corrosion paints for the protection of steel constructions such as electricity pylons or bridges. Until recently, little has been known about the behavior of these Pb compounds in soils. Therefore, three pylon soils and six red lead anti-corrosion paints were characterized in terms of solubility, Pb mineral composition, extractability, sorption and desorption, and the chemical speciation of Pb in soil extracts. The pylon soils were characterized by moderate total Pb concentrations (≈700 mg kg −1 ), while NH 4 NO 3 extractable Pb was exceptionally high (up to 15% of total Pb). In soil extracts, the free Pb 2+ fraction ranged from 33 to 81% of total soluble Pb. The equilibrium concentration of Pb derived from Pb 3 O 4 in ultra-pure water reached 68.5 mg L −1 . This high solubility explains the observed high extractability in soils and contradicts earlier reports of much lower water solubilities of the compound.

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“…Several kinds of inorganic red pigments are available for use, e.g., red iron oxide, red lead, cadmium red, vermilion, and cinnabar [9][10][11][12]. However, they all suffer from several disadvantages.…”

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