The increase of the worlds' population is being accompanied by the exponential growth in waste of electrical and electronic equipment (e-waste) generation as a result of the rapid technological implementations. The inappropriate processing and disposal of this e-waste, containing rare-earth elements (REEs) such as gadolinium (Gd), may enhance its occurrence in the environment. In particular, the presence of Gd in marine systems may lead to environmental risks which are still unknown, especially considering foreseen climate modifications such as water salinity shifts due to extreme weather events. Within this context, the present study intended to assess the combined effects of Gd at variable salinities. For that, biochemical modifications were assessed in mussels, Mytilus galloprovincialis, exposed to Gd (0 and 10 μg/L) and different salinity levels (20, 30 and 40), acting individually and in combination. A decrease in salinity, induced an array of biochemical effects associated to hypotonic stress in non-contaminated and contaminated mussels, including metabolism, antioxidant and biotransformation defenses activation. Moreover, in Gd-contaminated organisms, the increase in salinity was responsible for a significant reduction of metabolic and defense mechanisms, possibly associated with a mussels’ physiological response to the stress caused by the combination of both factors. In particular, Gd caused cellular damage at all salinities, but mussels adopted different strategies under each salinity to limit the extent of oxidative stress. That is, an increase in metabolism was associated to hypotonic stress and Gd exposure, an activation of defense enzymes was revealed at the control salinity (30) and a decrease in metabolism and non-activation of defenses, associated with a possible physiological defense trait, was evidenced at the highest salinity. The different strategies adopted highlight the need to investigate the risk of emerging contaminants such as REEs at present and forecasted climate change scenarios, thus providing a more realistic environmental risk assessment.

由于技术的快速实施，世界人口的增加正伴随着电气和电子设备（电子废物）产生的废物呈指数增长。对这种含有钆 (Gd) 等稀土元素 (REE) 的电子废物进行不当处理和处置，可能会增加其在环境中的发生率。特别是，海洋系统中 Gd 的存在可能导致仍然未知的环境风险，特别是考虑到可预见的气候变化，例如极端天气事件导致的水盐分变化。在此背景下，本研究旨在评估 Gd 在不同盐度下的综合影响。为此，在贻贝中评估了生化修饰，Mytilus galloprovincialis, 暴露于 Gd（0 和 10 μg/L）和不同的盐度水平（20、30 和 40），单独或组合作用。盐度的降低会在未受污染和受污染的贻贝中引起一系列与低渗压力相关的生化效应，包括新陈代谢、抗氧化和生物转化防御激活。此外，在受 Gd 污染的生物体中，盐度的增加是代谢和防御机制显着降低的原因，这可能与贻贝对两种因素组合引起的压力的生理反应有关。特别是，Gd 在所有盐度下都会引起细胞损伤，但贻贝在每种盐度下采用不同的策略来限制氧化应激的程度。也就是说，新陈代谢的增加与低渗压力和 Gd 暴露有关，在对照盐度 (30) 处显示防御酶的激活，并且在最高盐度处证明与可能的生理防御特征相关的代谢减少和防御未激活。所采用的不同策略突出了调查当前和预测的气候变化情景等新兴污染物的风险的必要性，从而提供更现实的环境风险评估。