Key Laboratory for Heavy Metal Pollution Control and Reutilization, School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.
State Key Laboratory of Eco-hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, 710048, Shaanxi, China.
Environ Pollut. 2020 Dec;267:115671. doi: 10.1016/j.envpol.2020.115671. Epub 2020 Sep 17.
Perfluorooctane sulfonate (PFOS) potentially adsorbs on the surface of suspended sediment (SPS), which can develop a toxic "pool" bioavailable to benthic organisms. In this study, the freshwater clam Corbicula fluminea was employed as a zoobenthos model to study the effects of SPS (collected from the Yellow River) on the bioaccumulation and toxicity (from the molecular level to cellular and physiological levels) caused by PFOS exposure. Besides, the enhanced integrated biomarker response (EIBR) system was applied as an index to evaluate the in-depth toxic effects of PFOS and SPS single and co-exposure at various treatment levels. Our results demonstrated that PFOS-SPS co-exposure (at sub-lethal doses of PFOS) significantly increased the bioaccumulation of PFOS, and induced the elevated levels of reactive oxygen species (ROS), the significantly increased activities of superoxide dismutase (SOD) and catalase (CAT) enzymes, the significantly increased content of malondialdehyde (MDA), and the significantly upregulated expression levels of sod, selenium-dependent glutathione peroxidase (se-gpx), heat shock protein 22 (hsp22), heat shock protein 40 (hsp40) and cytochrome P450 30 (cyp30) genes. Further, the co-exposure induced the significantly higher histopathological alterations in the gonads and digestive glands, and even elevated the inhibition of siphoning behavior in clams. In addition, the EIBR index also revealed the highest values for PFOS and SPS co-exposure, compared to the individual SPS or PFOS exposure. The results indicated that at high levels of PFOS exposure (especially at 1000 μg/L), the presence of SPS might increase the generation of ROS by influencing the bioaccumulation of PFOS, which enhanced the toxicity of PFOS to C. fluminea. These results potentially provide basic information for the comprehensive evaluation of the toxic effects of PFOS on benthos in a multi-sediment river ecosystem.
全氟辛烷磺酸 (PFOS) 可能会吸附在悬浮沉积物 (SPS) 的表面，从而形成一种对底栖生物具有毒性的“池”状可利用物质。在这项研究中，我们选择淡水蚌贻贝 Corbicula fluminea 作为底栖动物模型，研究 SPS（取自黄河）对 PFOS 暴露引起的生物积累和毒性（从分子水平到细胞和生理水平）的影响。此外，我们应用增强型综合生物标志物响应 (EIBR) 系统作为一个指标，来评估 PFOS 和 SPS 单一及共暴露在不同处理水平下的深层次毒性效应。研究结果表明，PFOS-SPS 共暴露（在亚致死剂量的 PFOS 下）显著增加了 PFOS 的生物积累，并诱导活性氧（ROS）水平升高、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）酶活性显著增加、丙二醛（MDA）含量显著增加、 sod、硒依赖性谷胱甘肽过氧化物酶（se-gpx）、热休克蛋白 22（hsp22）、热休克蛋白 40（hsp40）和细胞色素 P450 30（cyp30）基因的表达水平显著上调。此外，共暴露还导致贻贝性腺和消化腺的组织病理学变化明显加剧，甚至导致摄食行为的抑制作用增强。此外，EIBR 指数也表明，PFOS 和 SPS 共暴露的数值最高，高于单独的 SPS 或 PFOS 暴露。这些结果表明，在 PFOS 暴露水平较高（尤其是在 1000μg/L 时）的情况下，SPS 的存在可能会通过影响 PFOS 的生物积累来增加 ROS 的产生，从而增强 PFOS 对贻贝的毒性。这些结果为在多泥沙河生态系统中全面评估 PFOS 对底栖生物的毒性效应提供了基础信息。
