Speciation of Cr and As Leachates from CCA Treated Wood by Differential Pulse Polarography

Considerable research has been conducted to quantify the leaching rates of chromium and arsenic from timbers treated with the traditional wood preservative, CCA. However, much of this work has concentrated on measuring total metal concentrations. The environmental toxicity of these elements is significantly affected by their oxidation state. Therefore, quantification of individual metal species is considered important if the environmental effects of wood preservative leachates are to be determined. Laboratory leaching tests were conducted to allow speciation of both chromium and arsenic lost from CCA treated timbers exposed to artificial seawater for the first time. Differential pulse polarography was used to measure concentrations of As(III), Cr(VI) and Cr(III). Analysis indicated that less than 10% of the total As was leached as As(III), and that less than 1 % of the total Cr was leached as Cr(VI).