【摘要】 六氟化硫（SF₆）是一种增温潜能极高、主要来自人为排放的温室气体,对其大气背景浓度进行长期监测,对于研究全球变化具有重要意义.利用南极中山站区2008年2月²013年1月近5年SF₆浓度的观测资料,对SF₆本底浓度和变化趋势进行了研究,结果表明:中山站风向为偏东风时大气中SF₆浓度较低,风向为偏西风时浓度较高,这主要是受海陆气团差异引起,而局地源和风速的影响可忽略不计.大气SF₆浓度的变化范围为6.01⁷.80 pptv,(1 pptv=1×10^-12L/L,下同),平均浓度为6.90±0.40 pptv.SF₆浓度呈明显稳定的年增长趋势,年平均增长速率为0.28 pptv a^-1,其变化趋势与全球其他观测点较接近,中山站的观测结果可代表南极地区SF₆的本底浓度.通过与全球其他观测点大气SF₆浓度数据对比,结果显示:南半球大气SF₆平均浓度明显低干北半球,北半球是SF₆排放的主要源区;而南半球SF₆主要来源干北半球大气传输和南北半球间大气高度混合,能较好地反映全球大气SF₆本底浓度。南极受人类活动影响很小,是研究全球SF₆浓度变化趋势的理想区域。更多还原

【Abstract】 Sulfur hexafluoride（SF₆） is one kind of highly stable anthropogenic greenhouse gas with a global warming potential（GWP） of 2.35×10⁴ over a 100-year time horizon.SF₆ emissions are targeted for reduction under the Kyoto Protocol.Therefore it is important for the research about global change to observe atmospheric SF₆ background concentrations.Here,we present the patterns for the seasonal and annual variations of atmospheric SF₆ concentrations at Zhongshan Station,east Antarctica from February 2008 to January 2013.The prevailing wind direction at the observation site was from the east with the frequency of 92.0%.The average SF₆ concentration was about 6.89 pptv under east wind,lower than that under west wind（7.16 pptv）.More frequent west wind occurred in autumn and thus average SF₆ concentration was higher in autumn than other seasons,indicating that the airflow from western sea area contained higher SF₆concentration than the airflow from east Antarctic continent.On the whole,SF₆ concentrations showed an insignificant change under different wind speeds and directions,indicating that the influence of wind and local pollution could be ignored.Our results could represent the background concentrations for atmospheric SF₆ at Zhongshan Station.The SF₆concentrations ranged from 6.01 to 7.80 pptv with the average of 6.90±0.40 pptv from February 2008 to January 2013.Annual SF₆ concentrations in the atmosphere steadily increased at the rate of 0.28 pptv a^-1,and the increasing magnitudes were very close to each other per year during the period of 2008-2012,similar to the results from other global observation sites,indicating that annual SF₆ emission amount could be almost stable each year.No evident periodical changes in SF₆ concentrations were observed during the five years.The seasonal SF₆ concentration did not show insignificant variation in spring and summer,but an evident decrease in its level occurred in autumn,and then it rose back to normal level in winter.Combined our data with those from other nine observation sites,atmospheric SF₆concentrations showed an evident gradient change with the latitudes at the global scale,and its concentrations in the Northern Hemisphere were 0.3-0.4 pptv higher than those in the Southern Hemisphere because the main emission sources for atmospheric SF₆ concentrated in the Northern Hemisphere.The primary source for atmospheric SF₆ is industrial emissions in the Northern Hemisphere,whereas its main source is the SF₆ southward transportation in the Southern Hemisphere.Our results prove that atmospheric SF₆ concentration is continuously growing and its industrial emission control needs to be strengthened.Antarctica is less affected by human activities on the globe,which makes it an ideal area to observe SF₆ background concentrations.Our data in the present study will guide industry in optimizing and controlling the SF₆ emissions.The SF₆ sources and its transportation pathways will be further studied at Zhongshan Station in the future.更多还原