Treatment wetlands for water purification are typically designed to allow for various physical and biological processes to reduce levels of organic contaminants, metals, bacteria, and suspended solids. Grazing by filter feeding zooplankton such as Daphnia magna can significantly remove pollutants in treatment wetlands. Silver nanoparticles (AgNP) are widely used due to their antimicrobial properties. As a result, the environmental concentrations of AgNP and dissolved Ag are likely to increase. Silver is toxic to aquatic organisms and understanding the impacts of this contaminant on zooplankton that are critical to treatment wetland function is necessary. Our overarching research objective is to characterize aqueous and dietborne uptake and loss of 109Ag (in dissolved and NP form) in Daphnia magna at environmentally relevant concentrations (i.e. 0.01 – 2.5 µg L-1 Ag). We show that both forms of Ag are bioavailable and that there is greater retention of AgNP compared to AgNO3, which has implications for trophic transfer. Both waterborne and dietborne uptake result in measurable influx and retention of Ag. Evidence of feeding inhibition through dietary exposure at higher concentrations of Ag may have negative impacts on daphnid growth and reproduction. We also determined that water chemistry impacts waterborne influx, showing the importance of using environmentally relevant media. A poster session deriving from laboratory work with Niveen Ismail, Assistant Professor of Engineering.
by Emma Lesser ‘22 and Noor Sheikh ‘22