The impact of nanoplastics using model polystyrene nanoparticles (PS NPs), anionic (PS-COOH) and cationic (PS-NH2), has been investigated on the marine rotifer Brachionus plicatilis, a major component of marine zooplanktonic species. The role of different surface charges in affecting PS NP behaviour and toxicity has been considered in high ionic strength media. To this aim, the selected media were standardized reconstituted seawater (RSW) and natural sea water (NSW), the latter resembling more natural exposure scenarios. Hatched rotifer larvae were exposed for 24Â h and 48Â h to both PS NPs in the range of 0.5â50Â Î¼g/ml using PS NP suspensions made in RSW and NSW. No effects on lethality upon exposure to anionic NPs were observed despite a clear gut retention was evident in all exposed rotifers. On the contrary, cationic NPs caused lethality to rotifer larvae but LC50values resulted lower in rotifers exposed in RSW (LC50=2.75Â±0.67Â Âµg/ml) compared to those exposed in NSW (LC50=6.62Â±0.87Â Âµg/ml). PS NPs showed similar pattern of aggregation in both high ionic strength media (RSW and NSW) but while anionic NPs resulted in large microscale aggregates (Z-average 1109 Â± 128Â nm and 998Â±67Â nm respectively), cationic NP aggregates were still in nano-size forms (93.99 Â± 11.22Â nm and 108.3 Â± 12.79Â nm). Both PDI and Z-potential of PS NPs slightly differed in the two media suggesting a role of their different surface charges in affecting their behaviour and stability. Our findings confirm the role of surface charges in nanoplastic behaviour in salt water media and provide a first evidence of a different toxicity in rotifers using artificial media (RSW) compared to natural one (NSW). Such evidence poses the question on how to select the best medium in standardized ecotoxicity assays in order to properly assess their hazard to marine life in natural environmental scenarios.
|Titolo:||Comparative ecotoxicity of polystyrene nanoparticles in natural seawater and reconstituted seawater using the rotifer Brachionus plicatilis|
|Appare nelle tipologie:||1.1 Articolo in rivista|
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