Effects of Silver nanoparticles in diatom Thalassiosira pseudonana and cyanobacterium Synechococcus sp.

Abstract

The aim of the present study was to investigate the effect of silver nanoparticles (AgNP) of different sizes towards two primary producer aquatic species. Thalassiosira pseudonana and Synechococcus sp. have been selected as representative models for the lower trophic organisms in marine and freshwater habitats, respectively. Time-dependent cellular growth was measured under exposure to both AgNP and silver nitrate (AgNO3). In addition, AgNP behavior in freshwater and marine waters has been followed by CPS disk centrifuge, in the time-frame of AgNP exposure studies, and the kinetic release of silver from AgNP of different sizes was measured by inductively coupled plasma mass spectrometry (ICP-MS). The combination and interpretation of all these data suggest that a shared effect of AgNP and free silver ions (Ag+ ) was responsible for the toxicity in both organisms, while the cyanobacteria were the most sensitive specie to both AgNP and Ag+. Furthermore the relative contribution of Ag+ and AgNP to the measured toxicity was dependent on the stability of the preparation.