中文摘要：

为研究硝酸根（NO3-）对水体中甲基汞（MMHg）光化学降解的影响,采用室内模拟试验,验证了不同波长光照条件下,NO3-在MMHg光化学反应中的作用,探讨了NO3-浓度对MMHg光解速率及产物的影响,并根据溶液中Hg2＋的浓度分析了MMHg光解反应的进行程度.结果表明,在自然光（NL）和紫外光（UV）条件下,只加入了NO3-的处理MMHg光降解速率分别为0.10、0.046 L.（ng·h）-1,Hg0的释放通量分别为1.05、1.27 ng,Hg2＋的最终浓度分别为16.97、28.92 ng·L-1;在未加入NO3-和加入了C6H5COOH的条件下,MMHg的剩余浓度相差不大,其光降解速率也分别在0.052、0.015 L.（ng·h）-1左右,Hg0的释放通量分别为23.81、15.38 ng,Hg2＋的浓度均小于10 ng·L-1,且呈现先增加后减小趋势.在可见光（VL）照射下,各处理下MMHg的光降解速率无显著性差异（P=0.56）,为0.003 L.（ng·h）-1左右,Hg0的释放通量均为5 ng左右,Hg2＋的浓度未超过3 ng·L-1,也呈现出先增加后减小的趋势.在NL条件下,随浓度NO3-的增加,MMHg的光降解速率也增加,且各处理间存在显著性差异（P〈0.05）,Hg0的生成量随NO3-浓度的增加而减少,而Hg2＋的浓度也随NO3-浓度的增加而增加.可见在有紫外光的条件下,NO3-对MMHg光降解反应历程、反应速率以及产物有重要影响.

英文摘要：

To study effects of nitrate（NO3-） on monomethylmercury（MMHg） photodecomposition（PD）,laboratory experiments were conducted to investigate the role of NO3-in MMHg PD under various light radiations,and to examine effects of NO3-concentration gradients on MMHg PD rates and end products.We analysed the react processes according to Hg2＋ concentration.The results indicated that in the reactor exposed to natural and ultraviolet radiation,and treated with NO3-,the rates of MMHg PD were calculated to be 0.10 L.（ng.h）-1 and 0.046 L.（ng.h）-1,respectively,Hg0 fluxes were 1.05 and 1.27 ng,respectively,and Hg2＋concentrations were 16.97 ng.L-1 and 28.92 ng.L-1 respectively.In the experiments which were not spiked with nitrate or spiked with benzoic acid,MMHg PD rates were calculated to be 0.052 L.（ng.h）-1 and 0.015 L.（ng.h）-1,respectively,Hg0 fluxes were 23.81 ng and 15.38 ng,respectively,and all concentrations of Hg2＋（10 ng.L-1） represented a trend of increasing firstly and then decreasing.There were no differences among the reactions exposed to visible light（P = 0.56）,the PD rate was about 0.003 L.（ng.h）-1,Hg0 flux was about 5 ng,and Hg2＋ concentrations showed a trend of increasing firstly and then decreasing.In the reactor exposed to natural light,with the increasing concentration of NO3-,MMHg PD rate increased,Hg0 flux decreased,and Hg2＋ concentration increased with respect to time.All results indicate that NO3-has a significant effect on the react process,PD rate,and end products.