青藏高原东南缘贡嘎山地区大气总汞时间序列分析及其影响因子

Annual time-series analyses of total gaseous mercury measurement and its influence factors in the Gongga Mountain on the south-eastern fringe of the Tibetan Plateau,China

使用Tekran 2537A大气汞自动分析仪对中国科学院贡嘎山高山生态系统观测试验站磨西基地站（102°72＇＇E 29°92＇＇N）进行了为期1a的大气总汞（TGM）高时间分辨率观测.研究区域的平均TGM浓度为（4±1.38） ng m-3（N=57310）,高于全球大气总汞背景值1.5～2.0 ng m-3.不同季节表现出相似的日变化模式,即白天相对夜晚具有较高的TGM浓度,最大TGM浓度出现在中午,最小值出现在日出前,春季和夏季日变化高峰值出现时间比秋季和冬季早1～2h.以冬季TGM浓度最高,为（6.13±1.78） ng m-3;夏季最低,为（3.17±0.67） ng m-3.观测期间不同风向间TGM浓度无显著差异.相关分析表明,TGM浓度与温度、饱和水汽压、降水量、紫外辐射、大气压有显著相关性,这种相关性随季节而变化.贡嘎山地区大气汞浓度主要受局地源的影响和调节.

Long-term monitoring programs of atmospheric mercury concentrations are presently recognized as powerful tools for local, regional and global studies of atmospheric long-range transport processes, and they could also provide valuable information about the impact of emission controls on the global budget of atmospheric mercury, their observance and an insight into the global mercury cycle. Several highly-time resolved mercury monitoring stations have been constructed in the North America and Europe with the aid of fast advancement in automatization techniques of Hg determination since the mid- 1990s. China is believed to be an increasing atmospheric mercury emission source; however, only a few measurements of mercury, to our knowledge, have been done in ambient air of China. Measurement of highly-time resolved atmospheric mercury concentrations have been measured at Moxi Base Station （102°72＇E 29°92＇N, 1640m a. s. 1. ） of the Gongga Alpine Ecosystem Observation and Experiment Station of Chinese Academy of Sciences （CAS） during the period of May 2005 --June 2006 by using a set of Automatic Atmospheric Mercury Speciation Analyzers （Tekran 2537A）. Measurements were carried out with a time resolution of every 5 or 15 minutes. The overall average TGM covering the measurement periods was （4 ± 1.38 ） ngm^-3 （ N = 57310）, which is higher than the global background level of approximately 1.5 --2.0 ng m^-3 The measurements in all seasons showed a similar diurnal change pattern with a high concentration during daytime relative to nighttime and maximum concentration near solar noon and minimum concentration immediately before sunrise. The presence of diurnal TGM peaks during spring and summer is found earlier than during fall and winter. When divided seasonally, it was found that the concentrations of TGM were highest in winter with （6.13 ± 1.78） ngm^-3and lowest during summer with （3.17 ± 0.67 ） ng m^-3 There are not significantly TGM differences between each wind sectors during each season. Whereas Hg generally exhibited significant correlations with such parameters as temperature, saturated vapor pressure, precipitation, ultraviolet radiation （UV） and atmospheric pressure during the whole measurement stage, its relationship varied seasonally. Our results suggest that the local or regional sources （ the abundant geothermal activity such as thermal spring, anthropogenic source processes and changes in meteorological conditions） regulate and affect Hg behavior in the study area.