利用CMAQ-Hg（Community Multi-scale Air Quality-Mercury）模式模拟了我国燃煤排放的大气汞在我国区域的沉降分布状况，其中气象模式为MM5。模式中包括了三种价态汞（气态元素汞（GEM）、气态活性汞（RGM）和颗粒汞（PHg））的气相、...利用CMAQ-Hg（Community Multi-scale Air Quality-Mercury）模式模拟了我国燃煤排放的大气汞在我国区域的沉降分布状况，其中气象模式为MM5。模式中包括了三种价态汞（气态元素汞（GEM）、气态活性汞（RGM）和颗粒汞（PHg））的气相、液相、非均相化学反应过程以及输送、干湿沉降等物理过程。中国燃煤排放的大气汞中RGM所占比例较高，约为58.4%-66.8%，这导致我国汞沉降量较大。模拟结果表明,在我国的西南地区、华东地区以及京津塘地区燃煤汞的沉降较高，在这些区域的沉降通量高达2-6μg m^-2 mon^-1。燃煤大气汞排放形态对汞的沉降有重要影响，减少燃煤汞排放中RGM的比例能够显著降低我国区域汞的沉降通量。展开更多
Geothermal power plants are receiving increasing attention as regards the mobilization of mercury （Hg） to the environment. Hg is a trace element that may be present in the geothermal fluid, but due to its volatility...Geothermal power plants are receiving increasing attention as regards the mobilization of mercury （Hg） to the environment. Hg is a trace element that may be present in the geothermal fluid, but due to its volatility, it is transferred mainly into the vapor phase. Hence, it may be mostly discharged to the atmosphere with the non-condensable gases. Olkaria geothermal field hosts 3 geothermal power plants. In this area Hg deposition fluxes have not been studied. Concentrations and wet deposition fluxes of total mercury （T-Hg） were determined from April 2009 to May 2010 at 2 sites in this field. Event-based precipitation samples were collected using fabricated bulk precipitation samplers. Samples were treated according to trace metal protocol and analyzed by cold vapor atomic fluorescence spectrometry （CVAFS）. This paper thus reports the first ever determination of T-Hg concentrations and fluxes in precipitation. The T-Hg concentration in samples ranged from 0.002-0.0602 μg/L at the two sites, however, the volume-weighted mean concentration and wet deposition flux were 0.01974 and 0.02884μg.L^-1 and 0.0167-1.45 μg.m2 during the study period. The annual volume-weighted mean wet deposition fluxes of T-Hg for 2 sites were 13.74 and 19.83 μg.m-2.yr-1 with an average flux of 16.785μg.m-2.yr-1. Hg concentrations and the Hg fluxes in precipitation showed seasonal trends being lowest in the short-rains and highest in the long rains. The concentrations of T-Hg for the 2 sites is negatively correlated with the precipitation depth （r2 = 0.26 ＆ r2 = 0.0065）, suggesting that scavenging of particle-bound mercury from the atmosphere is an important mechanism contributing to mercury in rainwater. Mean Hg concentrations in precipitation at the study sites were comparable to the ranges reported for Canada and the USA by the Mercury Deposition Network （MDN）.展开更多
文摘Geothermal power plants are receiving increasing attention as regards the mobilization of mercury （Hg） to the environment. Hg is a trace element that may be present in the geothermal fluid, but due to its volatility, it is transferred mainly into the vapor phase. Hence, it may be mostly discharged to the atmosphere with the non-condensable gases. Olkaria geothermal field hosts 3 geothermal power plants. In this area Hg deposition fluxes have not been studied. Concentrations and wet deposition fluxes of total mercury （T-Hg） were determined from April 2009 to May 2010 at 2 sites in this field. Event-based precipitation samples were collected using fabricated bulk precipitation samplers. Samples were treated according to trace metal protocol and analyzed by cold vapor atomic fluorescence spectrometry （CVAFS）. This paper thus reports the first ever determination of T-Hg concentrations and fluxes in precipitation. The T-Hg concentration in samples ranged from 0.002-0.0602 μg/L at the two sites, however, the volume-weighted mean concentration and wet deposition flux were 0.01974 and 0.02884μg.L^-1 and 0.0167-1.45 μg.m2 during the study period. The annual volume-weighted mean wet deposition fluxes of T-Hg for 2 sites were 13.74 and 19.83 μg.m-2.yr-1 with an average flux of 16.785μg.m-2.yr-1. Hg concentrations and the Hg fluxes in precipitation showed seasonal trends being lowest in the short-rains and highest in the long rains. The concentrations of T-Hg for the 2 sites is negatively correlated with the precipitation depth （r2 = 0.26 ＆ r2 = 0.0065）, suggesting that scavenging of particle-bound mercury from the atmosphere is an important mechanism contributing to mercury in rainwater. Mean Hg concentrations in precipitation at the study sites were comparable to the ranges reported for Canada and the USA by the Mercury Deposition Network （MDN）.
