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Assessing the Release of Copper from Nanocopper-treated and Conventional Copper-treated Lumber into Marine Waters I: Concentrations and Rates
Citation:
Parks, A., M. Cantwell, D. Katz, M. Cashman, T. Luxton, K. Ho, AND R. Burgess. Assessing the Release of Copper from Nanocopper-treated and Conventional Copper-treated Lumber into Marine Waters I: Concentrations and Rates. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 37(7):1956-1968, (2018).
Impact/Purpose:
In recent years, copper nanomaterials have been selected to be used as wood preservatives in lumber applied in exterior and aquatic construction. For example, if a porch is being built, it is now likely the wood preservative that the lumber is treated with to defend against insects and molds damage is a copper nanomaterial. Unfortunately, there is limited information about the behavior of nanocopper if it released into the environment from treated lumber. For this research, we examined how much copper was released from nanocopper pressure-treated lumber under estuarine and marine conditions. Overall, copper was released from the treated lumber samples we evaluated. Under the leaching conditions, the total release ranged from 5 - 55% of the measured copper originally in the lumber with release rates ranging from 0.09 to 2.4 mg copper/L/d. Generally, both release and rate of release were significantly higher under estuarine conditions (1 and 10‰) compared to either freshwater (0‰) or marine (30‰) salinities. This work indicates that copper is released into estuarine and marine waters from lumber treated with nanocopper.
Description:
Little is known about the release of metal engineered nanomaterials (ENMs) from consumer goods, including lumber treated with micronized copper. Micronized copper is a recent form of antifouling wood preservative containing nanosized copper particles for use in pressure‐treated lumber. The present study investigated the concentrations released and the release rate of total copper over the course of 133 d under freshwater, estuarine, and marine salinity conditions (0, 1, 10, and 30‰) for several commercially available pressure‐treated lumbers: micronized copper azole (MCA) at 0.96 and 2.4 kg/m3, alkaline copper quaternary (ACQ) at 0.30 and 9.6 kg/m3, and chromated copper arsenate (CCA) at 40 kg/m3. Lumber was tested as blocks and as sawdust. Overall, copper was released from all treated lumber samples. Under leaching conditions, total release ranged from 2 to 55% of the measured copper originally in the lumber, with release rate constants from the blocks of 0.03 to 2.71 (units per day). Generally, measured release and modeled equilibrium concentrations were significantly higher in the estuarine conditions compared with freshwater or marine salinities, whereas rate constants showed very limited differences between salinities. Furthermore, organic carbon was released during the leaching and demonstrated a significant relationship with released copper concentrations as a function of salinity. The results indicate that copper is released into estuarine/marine waters from multiple wood treatments including lumber amended with nanoparticle‐sized copper.
