Effects of salinity on the toxicity of ionic silver and Ag-PVP nanoparticles to Tisbe battagliai and Ceramium tenuicorne

The toxic effects of polyvinylpyrrolidone (PVP) coated silver nanoparticles (Ag-NPPVP) and ionic Ag, to Tisbe battagliai (Tb) and Ceramium tenuicorne (Ct) were investigated and the usefulness of standardised marine guidelines for ENP risk assessment were assessed. The toxicity of Ag-NPPVP [CtEC50=26.6 μg/L, TbEC50=7.9 μg/L] and Ag+ [CtEC50=2312.2 μg/L, Tb EC50=90.9 μg/L] to both test species differed, with the silver ENPs being more toxic. In contrast to Ag+ the toxicity of Ag-NPPVP increased significantly with increasing salinity, however, after thorough characterisation it was not possible to correlate the behaviour of the particles with an increase in toxicity and salinity. The results suggest that the observed toxicity is being elicited by the free ionic silver complexing in solution and also from an unknown potential particle related effect.

► We investigated the toxicity of Ag-NPPVP and Ag+ to T. battaligai and C. tenuicorne.
► Suitability of standard ENP characterisation techniques in saline media are discussed.
► The effects of salinity on the toxicity of AgNPPVP and AgNO3 were investigated.
► Toxicity of AgNPPVP increases significantly with increasing salinity compared to Ag+.