New Methods For Analyzing SF₆ In The Atmosphere And Its Application

Sulfur hexafluoride(SF₆), mostly an anthropogenic compounds, is per molecule the strongest greenhouse gas known: it is three times stronger than an equivalent volume mixing ratio(VMR) of CFC-11 and 24 thousand times that of CO₂, and it too is increasing in the atmosphere. The sources of this compound are well understood. Once released into the atmosphere, SF₆ will only be removed exceedingly slowly due to its atmospheric lifetime of about 3200 yr^-1 These features have brought SF₆ into the climatic impact discussion aimed at reduction of emissions.For this research project, two gas chromatography/electron capture detection(GC/ECD) system was built to measure SF₆ in the atmosphere. Two different methods were tested to separate with SF₆. When tested in one valve and one column, all of the column effluents from the trap, including the O₂ peak passing through the ECD. The SF₆ peak didn't separate with other effluents well. In two valves and two columns, peaks that elute after the compounds of interest are vented to by pass the ECD. The compounds of interest were directed into the ECD. Therefore, the later system received a good result; also protect the column and ECD effectively. All of parameters were optimized under the best conditions, including the temperature, column and other parameters. This GC system analyzes a 10mL air ample for SF₆ at-1.77% precision, the MDL is 1.0pptv. The SF₆ data will help us to quantify variations in hemispheric mixing, and to characterize the history of the air masses being sampled at observed sites.Thus far, air samples were collected near a large urban and suburban area(Shijiazhuang, China) at Oct. 2005. The observed average SF₆ mixing ratio near Shijiazhuang city was in very good agreement with WDCGG background values, but lower than the values obtained from the location near New York City. These finding can indicate that the industrial production and sales in China was great less than in the United States and other industrial countries. Measurements at Shijiazhuang city showed that SF₆ mixing ratio was, on average, higher than those in the suburban area.Long-term trends in the atmospheric SF₆ mixing ratio were discussed using the data of SF6 sales and observed atmospheric SF₆ mixing ratio. Although the sources of SF6 have no short time variability, temporal variations were observed. This pattern can be explained as a result of convective activity of atmospheric transport.Its unique physical and chemical properties make SF₆ was an ideal tracer introduced to use...