Biotic and Abiotic Interactions in Freshwater Mesocosms Determine Fate and Toxicity of CuO Nanoparticles
Tonya Gräf, Viviane Koch, Jan Köser, Jonas Fischer, Christian Tessarek, Juliane Filser
Abstract
Transformation, dissolution, and sorption of copper oxide nanoparticles (CuO-NP) play an important role in freshwater ecosystems. We present the first mesocosm experiment on the fate of CuO-NP and the dynamics of the zooplankton community over a period of 12 months. Increasingly low (0.08–0.28 mg Cu L –1 ) and high (0.99–2.99 mg Cu L –1 ) concentrations of CuO-NP and CuSO 4 (0.10–0.34 mg Cu L –1 ) were tested in a multiple dosing scenario. At the high applied concentration (CuO-NP_H) CuO-NP aggregated and sank onto the sediment layer, where we recovered 63% of Cu applied. For the low concentration (CuO-NP_L) only 41% of applied copper could be recovered in the sediment. In the water column, the percentage of initially applied Cu recovered was on average 3-fold higher for CuO-NP_L than for CuO-NP_H. Zooplankton abundance was substantially compromised in the treatments CuSO 4 ( p < 0.001) and CuO-NP_L ( p < 0.001). Community analysis indicated that Cladocera were most affected (b k = −0.49), followed by Nematocera (b k = −0.32). The abundance of Cladocera over time and of Dixidae in summer was significantly reduced in the treatment CuO-NP_L ( p < 0.001; p < 0.05) compared to the Control. Our results indicate a higher potential for negative impacts on the freshwater community when lower concentrations of CuO-NP (<0.1 mg Cu L –1 ) enter the ecosystem.