Hu Bin, Wang Peifang, Hou Jun, Wang Chao, Qian Jin, Zhang Nannan, Yuan Qiusheng
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
Environ Pollut. 2017 Oct;229:19-28. doi: 10.1016/j.envpol.2017.05.061. Epub 2017 May 30.
Widely used titanium dioxide (TiO) nanoparticles are likely to accumulate ultimately in sediments and potentially pose a risk to water ecosystems. This study evaluated the effect of TiO nanoparticles on the photodissolution of particulate organic matter (POM) through fluorescence spectroscopy. Excitation-emission matrices and parallel factor analyses revealed that the fluorescent characteristics of produced dissolved organic matter (DOM) during photodissolution of suspended sediment and synthetic particulate organic matter (SPOM) were primarily humic-like. SPOM particles appeared to simulate well the photodissolution of suspended sediment. Quasi-complete increases in fluorescence intensity and chromophoric DOM (CDOM) abundance were reached after 90, 60, and 50 min irradiation for TiO concentrations of 0, 2, and 5 mg L, respectively. The faster increment of fluorescence intensity and CDOM abundance indicated the photocatalytic dissolution of SPOM, as opposite charges between TiO and SPOM at pH = 4 favored the adsorption of TiO onto SPOM. For sediments, the CDOM abundance and fluorescence intensity decreased with increasing TiO concentration, resulting from the photocatalytic degradation of photoproduced DOM from sediments. These results demonstrated that pH plays an important role in the photocatalytic dissolution of POM by TiO. Therefore, appropriate pH controls should be implemented when TiO are used to treat sediments contaminated with organic pollutants. Finally, with increasing use of TiO, its accumulation in sediments may affect the fate of carbon, nutrients, and heavy metals in shallow-water ecosystems.
广泛使用的二氧化钛（TiO）纳米颗粒最终可能会在沉积物中积累，并可能对水生态系统构成风险。本研究通过荧光光谱法评估了TiO纳米颗粒对颗粒有机物（POM）光溶解的影响。激发-发射矩阵和平行因子分析表明，悬浮沉积物和合成颗粒有机物（SPOM）光溶解过程中产生的溶解有机物（DOM）的荧光特性主要为类腐殖质。SPOM颗粒似乎能很好地模拟悬浮沉积物的光溶解。对于TiO浓度分别为0、2和5 mg/L的情况，在照射90、60和50分钟后，荧光强度和发色溶解有机物（CDOM）丰度分别达到准完全增加。荧光强度和CDOM丰度的更快增加表明SPOM的光催化溶解，因为在pH = 4时TiO和SPOM之间的相反电荷有利于TiO吸附到SPOM上。对于沉积物，CDOM丰度和荧光强度随TiO浓度增加而降低，这是由于沉积物光产生的DOM的光催化降解所致。这些结果表明，pH在TiO对POM的光催化溶解中起重要作用。因此，在使用TiO处理受有机污染物污染的沉积物时，应实施适当的pH控制。最后，随着TiO使用的增加，其在沉积物中的积累可能会影响浅水生态系统中碳、养分和重金属的归宿。
