Assessing the Release of Copper from Nanocopper-treated and Conventional Copper-treated Lumber into Marine Waters: (1) Concentrations and Rates

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 anti-fouling wood preservative containing nano-sized copper particles for use in pressure treated lumber. This study investigated the concentrations released and release rate of total copper over 133 days 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/m 3 , alkaline copper quaternary (ACQ) at 0.30 and 9.6 kg/m 3 , and chromated copper arsenate (CCA) at 40 kg/m 3 . Lumber was tested as blocks and 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 in units of /day. Generally, measured release and modelled equilibrium concentrations were significantly higher in the estuarine conditions compared to freshwater or marine salinities while rate constants showed very limited differences between salinities. Further, organic carbon was released during the leaching and demonstrated a significant relationship with released copper concentrations as a function of salinity. This work indicates copper is released into estuarine/marine waters from multiple wood treatments including lumber amended with nanoparticle size copper.