海南五指山大气气态总汞含量变化特征

Variation Characteristics of Total Gaseous Mercury at Wuzhi Mountain( Wuzhishan) Background Station in Hainan

利用高时间分辨率自动测汞仪(Tekran 2537B)于2011-05~2012-05对五指山大气气态总汞(TGM)进行了连续1 a的观测.结果表明,五指山TGM含量为(1.58±0.71)ng·m-3,与全球大气汞背景值相当,表明五指山大气几乎没有受到明显的大气汞污染.TGM的月变化特征表现为2011年6~8月和2012年3~5月TGM含量较低,2011年9月~次年1月含量较高,热带季风是影响TGM月变化的主要因素.五指山TGM具有明显的日变化特征,小时均值最低值出现在09:00,峰值出现在19:00,白天TGM浓度低于晚上.日变化受汞长距离迁移和本地气象条件的共同影响.后向轨迹分析结果表明大气汞从中国大陆的长距离迁移为五指山TGM浓度升高的主要原因.

Total gaseous mercury( TGM) was continuously monitored at Wuzhi mountain( Wuzhishan) using the high-resolution automatic atmospheric mercury vapor analyzer( Tekran 2537B) from May 2011 to May 2012. The annual geometric mean TGM concentration was( 1. 58 ± 0. 71) ng·m- 3,suggesting that the atmosphere was not obviously polluted. The TGM level at Wu Zhi mountain remained low from June to August in 2011 and from March to May in 2012,while higher values were observed from September in 2011 to January in 2012. Tropical monsoons played an important role in the monthly variation of TGM. TGM concentrations showed a clear diurnal trend with the minimum concentration occurring at 09: 00 AM and the peak concentration at 19: 00 PM due to the combined impact of the long-range transport of atmospheric mercury and local meteorological conditions. The temporal trend of TGM highlighted the impact of long-range transport from the mainland of China on the distribution of TGM in ambient air at Wuzhi mountain by the results of backward trajectory analysis using HYSPLIT.