Seawater carbonate chemistry and titanium dioxide nanoparticles (nTiO2) in edible bivalve mollusks

Large amounts of anthropogenic CO2 in the atmosphere are taken up by the ocean, which leads to 'ocean acidification' (OA). In addition, the increasing application of nanoparticles inevitably leads to their increased release into the aquatic environment. However, the impact of OA on the bioaccumulation of nanoparticles in marine organisms still remains unknown. This study investigated the effects of OA on the bioaccumulation of a model nanoparticle, titanium dioxide nanoparticles (nTiO2), in three edible bivalves. All species tested accumulated significantly greater amount of nTiO2 in pCO2-acidified seawater. Furthermore, the potential health threats of realistic nTiO2 quantities accumulated in bivalves under future OA scenarios were evaluated with a mouse assay, which revealed evident organ edema and alterations in hematologic indices and blood chemistry values under future OA scenario (pH at 7.4). Overall, this study suggests that OA would enhance the accumulation of nTiO2 in edible bivalves and may therefore increase the health risk for seafood consumers.

大气中大量人为源二氧化碳（anthropogenic CO2）被海洋吸收，进而引发“海洋酸化（Ocean Acidification, OA）”。此外，纳米材料的应用规模持续扩大，不可避免地导致其向水生环境的释放量不断增加。但目前海洋酸化对纳米颗粒在海洋生物体内的生物富集过程的影响仍未明确。本研究针对三种食用双壳类生物，探究了海洋酸化对典型纳米颗粒——二氧化钛纳米颗粒（titanium dioxide nanoparticles, nTiO2）生物富集的影响。实验结果显示，所有受试物种在高二氧化碳分压酸化的海水中，体内的nTiO2积累量均显著升高。此外，研究通过小鼠实验，评估了未来海洋酸化情景下双壳类生物体内积累的实际剂量nTiO2所潜在的健康威胁。结果表明，在未来酸化情景（pH值为7.4）中，受试小鼠出现了明显的器官水肿，同时血液学指标与血液生化值均发生改变。综上，本研究表明海洋酸化会提升食用双壳类生物对nTiO2的富集水平，进而可能增加海鲜消费者的健康风险。