In this study, the toxicities of sediment-associated silver added to sediment as commercially available silver nanoparticles (Ag NPs, 20 and 80nm) and aqueous Ag (AgNO3) to the estuarine polychaete, Nereis (Hediste) diversicolor, were investigated for both individual and subcellular endpoints after 10 d of exposure. Both Ag NP types were characterized in parallel to the toxicity studies and found to be polydispersed and overlapping in size. Burrowing activity decreased (marginally) with increasing Ag concentration and depended on the form of Ag added to sediment. All worms accumulated Ag regardless of the form in which it was added to the sediment, and worm size (expressed as dry weight) was found to significantly affect bioaccumulation such that smaller worms accumulated more Ag per body weight than larger worms. Lysosomal membrane permeability (neutral red retention time, NRRT) and DNA damage (comet assay tail moment and tail DNA intensity %) of Nereis coelomocytes increased in a concentration-dependent manner in all three Ag treatments. Ag NP treatments were more toxic than aqueous Ag for all toxicity endpoints, even though bioaccumulation did not differ significantly among Ag forms. No significant difference in toxicity was observed between the two Ag NP treatments which was attributed to their overlap in particle size.
Bibliographical noteFunding Information:
This work was funded by Roskilde University (RUC), Denmark and the China Scholarship Council (CSC). The research leading to these results has also received funding from the European Union Seventh Framework Program (FP7/2007-2013) under grant agreement n° 214478 (NanoReTox). The authors gratefully acknowledge Janeck Scott-Fordsmand, Anne-Grete Winding, Klara Jensen, Anja Holden Damsholt, Anne Busk Faarborg and Rikke Guttesen for their technical guidance and assistance during experiments, and Stephen Klaine and Poul Bjerregaard for their comments on an earlier draft of the manuscript.
- Ag body burden
- Burrowing behavior
- DNA damage
- Lysosomal membrane stability
- Sediment exposure
- Silver nanoparticles