微塑料和纳米TiO2颗粒对毛蚶的联合毒性效应

Combined Toxic Effects of Microplastics and Nano TiO2 Particles on Scapharca subcrenata

摘要:

微塑料（microplastics, MPs）和人工纳米颗粒（ manufactured nanomaterials, MNPs）作为新兴海洋污染物，在近海生态系统中具有高度共存性，其联合毒性效应已成为环境毒理学研究的热点。然而，MPs对MNPs生物有效性及其体内行为的调控作用仍缺乏认识。本文以滤食性双壳贝类毛蚶（Scapharca subcrenata）为研究对象，设置对照组、纳米二氧化钛（TiO2NPs）单一暴露组、MPs单一暴露组及二者复合暴露组，系统研究了不同暴露条件下TiO2在毛蚶体内的富集与净化特征，并结合组织学、电镜观察及氧化应激生物标志物分析，结果表明，TiO2NPs可在毛蚶体内显著富集，消化腺和鳃为主要靶器官；MPs减缓了TiO2的体内富集，但在净化阶段显著抑制其排出。病理组织学和超微结构结果显示，复合暴露引起消化腺和鳃结构破坏，并伴随溶酶体系统异常激活。氧化应激分析表明，长期暴露导致抗氧化防御系统失衡并诱发脂质过氧化损伤。研究结果揭示了MPs通过吸附TiO2NPs，影响其生物有效性并加剧生理损伤的复杂作用模式，为海洋复合污染生态风险评估提供了重要依据。

Abstract:

Microplastics (MPs) and nanomaterials (NPs), as emerging marine pollutants, exhibit high co-occurrence in coastal ecosystems. Their combined toxic effects have become a focus in environmental toxicology research. However, the regulatory role of MPs on the bioavailability and in vivo behavior of NPs remains poorly understood. In this study, the filter-feeding bivalve Scapharca subcrenata was used as the model organism. Experimental groups included a control, a nano?titanium dioxide (TiO2NPs) single-exposure group, an MPs single-exposure group, and a combined exposure group. The accumulation and depuration characteristics of TiO2 in S. subcrenata under different exposure conditions were systematically investigated. Combined with histopathological examination, electron microscopy observation, and oxidative stress biomarker analysis, the results demonstrated that TiO2NPs could significantly accumulate in S. subcrenata, with the digestive gland and gills being the main target organs. MPs slowed the in vivo accumulation of TiO2 but significantly inhibited its elimination during the depuration phase. Histopathological and ultrastructural observations revealed that combined exposure caused structural damage to the digestive gland and gills, accompanied by abnormal activation of the lysosomal system. Oxidative stress analysis indicated that long-term exposure led to an imbalance in the antioxidant defense system and induced lipid peroxidation damage. These findings reveal the complex mechanism by which MPs, through adsorbing TiO2NPs, influence their bioavailability and exacerbate physiological damage, providing important insights for the ecological risk assessment of marine co-contamination.