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Impact of Surface Water Conditions on Preservative Leaching and Aquatic Toxicity from Treated Wood Products
journal contribution
posted on 2007-05-15, 00:00 authored by Brajesh Dubey, Timothy Townsend, Helena Solo-GabrieleNew alternative wood preservatives contain higher levels
of copper (Cu) which can promote aquatic toxicity in
natural water systems. Earlier work focused on evaluating
toxicity using laboratory generated leaching solutions. In
this study, the impact on preservative leaching and aquatic
toxicity from treated wood products was evaluated using
natural surface waters including waters from two rivers, three
lakes, two wetlands, and one seawater, in addition to
synthetic moderate hard water and deionized water. Blocks
of wood treated with Cu based alternatives such as
alkaline copper quaternary (ACQ) and copper boron azole
(CBA), along with chromated copper arsenate (CCA)-treated wood, were leached under quiescent conditions,
and total Cu, labile Cu, and heavy metal toxicity were
measured. Results show that ACQ- and CBA-treated wood
leach approximately 10 and 20 times more total Cu
relative to CCA-treated wood and that the presence of
organic and inorganic ligands in natural waters lowered
the labile fraction of Cu relative to that from laboratory
generated leaching solutions. Aquatic toxicity was found
to correlate with the labile Cu fraction, and hence, the aquatic
toxicity of the treated wood leachates was lower in
natural waters in comparison to laboratory leaching
solutions. The results of the present study suggest that
studies designed to evaluate the impacts of treated wood
should therefore consider the role of complexation in
reducing the labile Cu fraction and its potential role in
decreasing toxicity.