Department of Aquatic Ecotoxicology, Goethe University Frankfurt am Main, Max-von-Laue-Str. 13, Frankfurt am Main 60438, Germany.
Department of Biology, Norwegian University of Science and Technology, Høgskoleringen 5, Trondheim 7491, Norway.
Environ Sci Technol. 2021 Feb 16;55(4):2491-2499. doi: 10.1021/acs.est.0c07911. Epub 2021 Feb 4.
The aging of microplastics in the environment changes their physicochemical properties. While this may affect their toxicity, comparative data on the effects of aged compared to pristine microplastics are scarce. One of those aging processes is the sorption of chemicals, which has mainly been studied for individual pollutants present in marine ecosystems. To investigate how the sorption of a complex mixture of freshwater pollutants affects the toxicity of microplastics, we incubated irregular polystyrene particles (≤63 μm) in either wastewater or ultrapure water. We exposed to these aged microplastics and their pristine counterparts (80, 400, 2000, and 10,000 particles mL) over four generations using food limitation as an additional, environmentally realistic stressor. Both particle types affect the survival, reproduction, adult and neonate body lengths, and growth. An exposure to pristine microplastics results in the extinction of the third generation of daphnids. In contrast, wastewater-incubated particles induced a lower mortality. The incubation with wastewater does not change the microplastics' size, surface charge, and structure. Consistent with the literature, we assume that the adsorption of dissolved organic matter is a key aging process reducing the toxicity of microplastics. Consequently, toxicity testing using pristine microplastics may overestimate the effects of plastic particles in nature.
微塑料在环境中的老化会改变其物理化学性质。虽然这可能会影响其毒性，但关于老化与原始微塑料相比的影响的比较数据却很少。其中一个老化过程是对化学物质的吸附，这主要针对海洋生态系统中存在的单个污染物进行了研究。为了研究淡水污染物的复杂混合物的吸附如何影响微塑料的毒性，我们将不规则聚苯乙烯颗粒（≤63μm）在废水或超纯水中孵育。我们用食物限制作为额外的、现实环境中的胁迫因素，用这些老化的微塑料及其原始的微塑料（80、400、2000 和 10000 个颗粒/mL）对两代进行了暴露。两种颗粒类型都影响到了浮游生物的生存、繁殖、成虫和幼体体长以及生长。暴露于原始微塑料会导致第三代表浮游生物灭绝。相比之下，废水孵育的颗粒诱导的死亡率较低。用废水孵育不会改变微塑料的大小、表面电荷和结构。与文献一致，我们假设溶解有机质的吸附是一个关键的老化过程，降低了微塑料的毒性。因此，使用原始微塑料进行毒性测试可能会高估自然中塑料颗粒的影响。
