Although sediments are important reservoirs of plastics, most of the ecotoxicological studies on these contaminants are focused on the organisms living in the water column, while only a smaller number of evidence concerns the plastic impact on benthic species. Therefore, this study compared the multigenerational effects on the sediment-dwelling midge Chironomus riparius exposed to both virgin polystyrene microbeads (22,400–224,000 plastics/kg sediments dry weight), and plastic mixtures (40–420 plastics/kg dry weight) collected from four of the main tributaries of Po River (Ticino, Adda, Oglio and Mincio Rivers, Northern Italy) to evaluate the role played by other characteristics related to these physical contaminants in determining their toxicity as opposed to concentration alone. The modified Chironomid Life-Cycle Toxicity Test (OECD 233) was used to evaluate the multigenerational effects on the Emergence and Development Rates, Fecundity and Fertility. In addition, a biomarkers’ suite of cellular stress, neurotoxicity, and energetic metabolism was applied in the 2nd generation (2nd/3rd instar of larvae) to investigate the potential mechanisms associated to the apical effects. Our results showed no significant (p > 0.05) multigenerational effect for any of the endpoints tested for the virgin plastics’ exposures. Coherently, no significant effects on biomarkers were measured. Concerning the sampled plastics, the particles collected in Adda River instead induced a significant decrease (p < 0.05) of the Emergence Rate in the 2nd generation, suggesting that this parameter was the most susceptible among those measured. These results highlight that the different plethora of polymers, sizes and shapes of plastics sampled in natural ecosystems, compared to homogeneous characteristics of virgin polystyrene microbeads, appears to have considerable importance over concentration alone in determining the toxicity of these emerging contaminants.

中文翻译：

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原始塑料和样本塑料对底栖大型无脊椎动物 Chironomus riparius 的多代影响


尽管沉积物是塑料的重要储存库，但大多数关于这些污染物的生态毒理学研究都集中在生活在水柱中的生物，而只有少数证据涉及塑料对底栖物种的影响。因此，本研究比较了暴露于原始聚苯乙烯微珠（22,400-224,000 个塑料/千克沉积物干重）和从波河四条主要支流（意大利北部提契诺河、阿达河、奥格里奥河和明乔河）收集的塑料混合物（40-420 个塑料/千克干重）对沉积物栖息的蠓 Chironomus riparius 的多代影响，以评估与这些物理污染物相关的其他特性在确定其毒性方面的作用而不是单纯的专注。改良的 Chironomid 生命周期毒性试验 （OECD 233） 用于评估多代对出苗率和发育率、繁殖力和生育力的影响。此外，在第 2 代 （幼虫的第 2/3 龄） 中应用了细胞应激、神经毒性和高能代谢的生物标志物套件，以研究与顶端效应相关的潜在机制。我们的结果显示，对于原始塑料暴露测试的任何终点都没有显着 （p > 0.05） 多代影响。连贯地，没有测量到对生物标志物的显着影响。关于采样的塑料，在阿达河中收集的颗粒反而导致第 2 代出现率显着降低 （p < 0.05），表明该参数在被测参数中最易感。 这些结果强调，与原生聚苯乙烯微珠的均质特性相比，在自然生态系统中取样的聚合物数量、大小和形状各不相同，在确定这些新兴污染物的毒性方面，仅浓度似乎具有相当重要的意义。