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-NP(PVP)) 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-NP(PVP) [CtEC(50)=26.6μg/L, TbEC(50)=7.9μg/L] and Ag(+) [CtEC(50)=2312.2μg/L, Tb EC(50)=90.9μg/L] to both test species differed, with the silver ENPs being more toxic. In contrast to Ag(+) the toxicity of Ag-NP(PVP) 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.