The environmental fate, transformation, and speciation of nano copper oxide in a freshwater environment

The use and production of engineered nanomaterials have grown rapidly over the past few decades due to their unique properties and versatility. As a result of widespread industrial applications, nanomaterials have evolved into their own unique class of emerging contaminants. However, the full extent of nanomaterials’ impact on the environment is currently unknown. In this study, we use the Water Quality Analysis Simulation Program (WASP, version 8.32) to investigate the fate, transformation, and speciation of nano copper oxide (nanoCuO), a common component of antifouling boat-bottom paints, in a freshwater environment over the course of 101 years. WASP serves as a powerful modeling framework that allows users to create dynamic, mechanistic water quality models. WASP’s recently upgraded Advanced Toxicant module allows for novel investigations of nanomaterials, including the parameterization of heteroaggregation and dissolution processes. To our knowledge, our study is the first to use WASP to investigate the fate and transport of any copper-based nanomaterial. In addition to nanoCuO, we also modeled the byproduct of its dissolution (ionic copper, Cu2+), which is of particular interest to regulatory agencies due to its well-known toxic effects on aquatic organisms. Using WASP, we modeled the variables, including dissolved organic carbon and suspended particulate matter, and processes governing the behavior of both nanoCuO and Cu2+ once released to the surface waters and sediments of Lake Waccamaw, North Carolina from boats coated with nanoCuO bottom paint. We also simulated water temperature to investigate the effects that temperature has on the behavior of nanoCuO and Cu2+. After 101 years, we found the highest nanoCuO and Cu2+ accumulation in Lake Waccamaw’s surface sediments, reaching total concentrations of 4.9 mg Cu/kg and 1.3 mg Cu/kg, respectively. Our results may benefit research efforts to predict the toxicity of nanoCuO used widely in aquatic systems.