SINTEF Ocean, Department of Environment and New Resources, Trondheim, Norway.
Norwegian University of Science and Technology, Department of Chemistry, Trondheim, Norway.
Environ Pollut. 2020 Mar;258:113844. doi: 10.1016/j.envpol.2019.113844. Epub 2019 Dec 17.
Organic chemical pollutants associated with microplastic (MP) may represent an alternative exposure route for these chemicals to marine biota. However, the bioavailability of MP-sorbed organic pollutants under conditions where co-exposure occurs from the same compounds dissolved in the water phase has rarely been studied experimentally, especially where pollutant concentrations in the two phases are well characterized. Importantly, higher concentrations of organic pollutants on ingested MP may be less bioavailable to aquatic organisms than the same chemicals present in dissolved form in the surrounding water. In the current study, the sorption kinetics of two model polycyclic aromatic hydrocarbons (PAHs; fluoranthene and phenanthrene) to MP particles in natural seawater at 10 and 20 °C were studied and the bioavailability of MP-sorbed PAHs to marine copepods investigated. Polyethylene (PE) and polystyrene (PS) microbeads with mean diameters ranging from 10 to 200 μm were used to identify the role of MP polymer type and size on sorption mechanisms. Additionally, temperature dependence of sorption was investigated. Results indicated that adsorption dominated at lower temperatures and for smaller MP (10 μm), while absorption was the prevailing process for larger MP (100 μm). Monolayer sorption dominated at lower PAH concentrations, while multilayer sorption dominated at higher concentrations. PE particles representing ingestible (10 μm) and non-ingestible (100 μm) MP for the marine copepod species Acartia tonsa and Calanus finmarchicus were used to investigate the availability and toxicity of MP-sorbed PAHs. Studies were conducted under co-exposure conditions where the PAHs were also present in the dissolved phase (C), thereby representing more environmentally relevant exposure scenarios. C reduction through MP sorption was reflected in a corresponding reduction of lethality and bioaccumulation, with no difference observed between ingestible and non-ingestible MP. This indicates that only free dissolved PAHs are significantly bioavailable to copepods under co-exposure conditions with MP-sorbed PAHs.
与微塑料（MP）相关的有机化学污染物可能代表这些化学物质进入海洋生物群的另一种暴露途径。然而，在同一化合物同时存在于水相和 MP 吸附相的情况下，实验很少研究 MP 吸附的有机污染物的生物可利用性，特别是当两个相中的污染物浓度得到很好的描述时。重要的是，与溶解在周围水中的相同化学物质相比，摄入的 MP 上的高浓度有机污染物可能对水生生物的生物利用度较低。在当前的研究中，研究了两种模型多环芳烃（PAH；荧蒽和菲）在 10 和 20°C 下在天然海水中与 MP 颗粒的吸附动力学，并研究了 MP 吸附的 PAH 对海洋桡足类动物的生物可利用性。使用平均直径范围为 10 至 200μm 的聚乙烯（PE）和聚苯乙烯（PS）微珠来确定 MP 聚合物类型和尺寸对吸附机制的作用。此外，还研究了吸附的温度依赖性。结果表明，在较低温度和较小的 MP（10μm）下，吸附占主导地位，而在较大的 MP（100μm）下，吸收是主要过程。在较低的 PAH 浓度下，单层吸附占主导地位，而在较高的浓度下，多层吸附占主导地位。使用可被海洋桡足类物种桡足亚目和真刺水蚤摄入的（10μm）和不可摄入的（100μm）PE 颗粒来研究 MP 吸附的 PAH 的可用性和毒性。研究在 PAH 也存在于溶解相（C）的共暴露条件下进行，从而代表了更具环境相关性的暴露情况。通过 MP 吸附实现的 C 减少反映在相应的致死率和生物积累减少方面，可摄入和不可摄入的 MP 之间没有观察到差异。这表明，只有自由溶解的 PAH 在与 MP 吸附的 PAH 共暴露条件下对桡足类动物具有显著的生物可利用性。
