纳米TiO2对底泥中汞释放及活化的影响

为了研究纳米TiO2对底泥汞的释放及活化的影响,采用模拟淹水实验,分析纳米TiO2对底泥和上覆水中总汞和甲基汞浓度的影响,并结合底泥中各形态汞的变化情况探讨纳米TiO2对汞的迁移转化的影响.结果表明,纳米TiO2可促进底泥中汞的释放,导致更多的汞释放到水中,与对照相比,4g·kg-1纳米TiO2导致上覆水中总汞浓度最高时上升91.32%,最终土壤汞的释放量增加约10%,主要原因是纳米TiO2可促进氧化态汞的溶解,这可能会提高水体汞污染的风险.此外,在本实验条件下,短期内纳米TiO2可能降低了底泥甲基汞的形成和释放,但长期淹水后没有明显的影响.总体来看,纳米TiO2对底泥汞释放和转化的影响随浓度升高而增大.因此,随着底泥或土壤中纳米TiO2含量的升高,其对汞的地球化学循环过程的影响可能加剧.

Effect of Nano-TiO2 on the Release and Activation of Mercury in Sediment

To investigate the effects of nano-TiO₂ on mercury release and activation in sediment, flooding simulation experiments were conducted. The impacts of nano-TiO₂ on total mercury and methylmercury concentrations in overlying water were analyzed. And the influences of nano-TiO₂ on the migration and transformation of mercury were discussed based on changes of mercury speciation in sediment. The results indicated that nano-TiO₂ promoted the release of mercury in sediment, leading to more mercury released into the water. Compared with the control, 4 g·kg^-1 TiO₂ nanoparticles increased the total mercury by 91.32%, when the concentration of total mercury in overlying water was the highest. Release of mercury in soil was increased by approximately 10% finally. The main reason may be that the dissolution of oxidation state mercury was improved by nano-TiO₂. It indicated that the risk of mercury contamination in water may increase. Moreover, under the experimental conditions, nano-TiO₂ may reduce the formation of methylmercury in sediment in the short term, but no significant effects in the long term. Generally, the effects of nano-TiO₂ on the release and transformation of mercury in sediment showed concentration dependence. Thus, with increasing nano-TiO₂ content in sediment or soil, its impact on the geochemical cycle of mercury may increase.