Ecotoxicological Effects of Nanoparticles of ZnWO4 and CuWO4 On a Freshwater Planktonic Foodchain: Evaluating Possible Environmental Impacts of Emerging Contaminants

Abstract

The development and production of nanomaterials (NMs) (< 100nm) are fast-growing worldwide. However, environmental studies in the Nanotoxicology field are not following the rapid increase of these NMs, thus the effects of NMs to the environment, especially on aquatic biota, are often unknown, being the environmental legislation about NMs very scarce. The NMs of copper tungstate (CuWO4) and zinc tungstate (ZnWO4) have potential to be used in many sectors such as healthcare, environmental remediation, food industry, cosmetics, electronics, among others. Regard the applications in healthcare and environmental sectors, these NMs have potential as bactericide agent and as decontaminating agent for many pollutants dissolved in water, thus these NMs may end up in aquatic ecosystems. Based on that, the aim of our study is evaluating for the first time the toxicological effects of CuWO4 and ZnWO4 on a freshwater planktonic food chain of herbivory, composed by the microalga Raphidocelis subcapitata and by the cladoceran Ceriodaphnia silvestrii, both widely used test-organisms in ecotoxicology assays. For R. subcapitata, we will analyze the parameters of growth (cell density), morphology (size cell and cell complexity), photosynthesis (photosynthetic efficiency), biochemical (lipidic classes, carbohydrates, chlorophyll a), production of reactive oxygen species (ROS) and bioaccumulation. For C. silvestrii, we will analyze: immobility (under lethal concentrations), bionomy (reproduction, survival, time of first brood), physiological endpoints (ingestion, filtration and respiration rates) and oxidative stress (ROS production and antioxidant enzymes). Cladocerans will be exposed to the NMs both via waterborne and dietary exposures. We believe that our results, obtained based on the response of two organisms from two different trophic levels, would be helpful to guide national and international environmental agencies to elaborate normative regarding the presence of NMs in aquatic ecosystems.