Hydrogen-producing nanosilicon gel spheres for remediation of copper-polluted aquatic ecosystems: Oxidative stress mitigation and ecological recovery

Pollutant-induced oxidative stress in aquatic ecosystems is a primary cause of damage to aquatic organisms. Hydrogen molecules, a novel antioxidant, can alleviate oxidative stress to promote early ecosystem restoration. However, their high diffusibility reduces their residence time in water, limiting their application in aquatic ecosystems. To address this issue, this study synthesized nanosilicon gel spheres using sodium alginate as an embedding carrier to achieve sustained hydrogen release and applied them to restore copper ion–contaminated aquatic ecosystems. This study examined oxidative stress alleviation in various aquatic organisms and its overall restoration effects. The nanosilicon gel spheres continuously released hydrogen for 6 days, effectively prolonging the antioxidant effects of hydrogen molecules and exhibiting a high copper ion adsorption rate (88.47 %) while posing low environmental risks. After 6 and 14 days of spherical application, Vallisneria growth increased by 83 % and 42 %, respectively. After 14 days of restoration, zebrafish mortality rate decreased from 36 % to 8 %. Analysis of oxidative stress indicators, revealed a recovery rate of 89.4 % for Vallisneria leaves and 78.5 % for zebrafish, indicating that the spheres exhibited good restoration effect in the simulated damaged aquatic ecosystem. Principal component analysis revealed differences in the responses of antioxidant systems of different organisms to Cu ions, confirming that the repair effect of hydrogen-producing materials was associated with increased catalase activity. This study established a method for using hydrogen gas for aquatic ecosystem restoration and developed an evaluation method for restoration effects, providing theoretical support for the application of hydrogen molecules in aquatic ecosystems.