In Situ Measurement of CuO and Cu(OH)2 Nanoparticle Dissolution Rates in Quiescent Freshwater Mesocosms

Recent studies have characterized copper-based nanoparticles (CBNPs) as relatively insoluble, raising potential persistence, accumulation, and toxicological concerns about their long-term application as agricultural pesticides. The dissolution rates of two CBNPs were measured in natural and artificial waters under both saturated and unsaturated conditions with respect to CuO(s) (total Cu, <1 mg/kg). Kocide 3000, an agricultural pesticide formulation with nanoscale Cu(OH)2 particles, rapidly dissolved with an experimental half-life of <8 h in natural water. Copper oxide nanoparticles were longer-lived, with an experimental half-life of 73 h in natural water. In contrast to prior reports of CuONP dissolution, our results suggest that even in moderately alkaline waters, CuO and Cu(OH)2 NPs may persist as particles for days to weeks under quiescent conditions in a freshwater environment.