title: Influence of extracellular polymeric substances on the long-term fate, dissolution, and speciation of copper-based nanoparticles.
abstract: The influence of phytoplankton-derived soluble extracellular polymeric substances (EPS), pH, and ionic strength (IS) on the dissolution, speciation, and stability of nano-CuO, nano-Cu, and Kocide (a micron sized Cu(OH)2-based fungicide) was investigated over 90 days. EPS improved the stability of commercial copper-based nanoparticles (CBNPs) in most conditions, in addition to influencing their dissolution. The dissolution rate was pH 4≫pH 7>pH 11. The presence of EPS correlated with higher dissolved Cu at pH 7 and 11, and lower dissolved Cu at pH 4. More dissolution was observed at higher IS (NaCl) due to complexation with Cl-. Dissolution of nano-CuO at pH 7 increased from 0.93% after 90 days (without EPS) to 2.01% (with 5 mg-C EPS/L) at 10 mM IS. Nano-CuO dissolved even more (2.42%) when IS was increased to 100 mM NaCl (with EPS). The ratio of free-Cu2+/total dissolved Cu decreased in the presence of EPS, or as pH and/or IS increased. On a Cu mass basis, Kocide had the highest dissolved and suspended Cu at pH 7. However, dissolution of nano-Cu resulted in a higher fraction of free Cu2+, which may make nano-Cu more toxic to pelagic organisms.
authors.affiliation: Bren School of Environmental Science & Management, University of California , Santa Barbara, California 93106-5131, United States.
authors.forename: Adeyemi S
authors.initials: AS
authors.lastname: Adeleye
authors.forename: Jon R
authors.initials: JR
authors.lastname: Conway
authors.forename: Thomas
authors.initials: T
authors.lastname: Perez
authors.forename: Paige
authors.initials: P
authors.lastname: Rutten
authors.forename: Arturo A
authors.initials: AA
authors.lastname: Keller
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D058087:Haptophyta; D053768:Metal Nanoparticles / Q000737:chemistry*; D010839:Phytoplankton; D012995:Solubility
chemical_list: D001704:Biopolymers; D003300:Copper