title: Aggregation, dissolution, and transformation of copper nanoparticles in natural waters.
abstract: Time-dependent aggregation, sedimentation, dissolution, and transformation of three copper-based engineered nanomaterials (ENMs) of varied properties were measured in eight natural and artificial waters. Nano-Cu and Cu(OH)2 aggregated rapidly to >10(3) nm while the aggregate size of nano-CuO averaged between 250 and 400 nm. Aggregate size for both nano-Cu and nano-CuO showed a positive correlation with ionic strength with a few exceptions. Aggregate size did not correlate well with sedimentation rate, suggesting sedimentation was influenced by other factors. Controlling factors in sedimentation rates varied by particle: Cu(OH)2 particles remained stable in all waters but groundwater, nano-Cu was generally unstable except in waters with high organic content, and nano-CuO was stabilized by the presence of phosphate, which reversed surface charge polarity at concentrations as low as 0.1 mg PO4(3-) L(-1). Dissolution generally correlated with pH, although in saline waters, dissolved copper formed insoluble complexes. Nano-Cu was rapidly oxidized, resulting in dissolution immediately followed by the formation of precipitates. These results suggest factors including phosphate, carbonate, and ENM oxidation state may be key in determining Cu ENM behavior in natural waters.
authors: Bren School of Environmental Science and Management, University of California , Santa Barbara, California 93106, United States.
authors: Jon R
authors: JR
authors: Conway
authors: Adeyemi S
authors: AS
authors: Adeleye
authors: Jorge
authors: J
authors: Gardea-Torresdey
authors: Arturo A
authors: AA
authors: Keller
mesh_terms: D003300:Copper / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008956:Models, Chemical; D012623:Seawater / Q000737:chemistry*; D012995:Solubility; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D014874:Water Pollutants, Chemical; D003300:Copper