华中地区偏远站点金沙站气态污染物的变化特征

对于2006年6月到2007年7月在华中地区的金沙区域大气本底站站址科学论证实验期间获得的近地面O₃、SO₂、NO_x和CO等观测资料进行分析, 讨论其浓度水平、变化特征和影响因素. 结果表明, 观测期间O₃、SO₂、NO_x和CO的平均浓度分别为24.6±17.0 ppb、2.8±5.5 ppb、5.6±5.5 ppb和502±222 ppb, 低于同纬度位于长三角地区的临安大气本底站的同期观测水平. 金沙站局地O₃光化学生成不显著, 一次污染物的平均日变化比较平稳, 有别于临安和位于华北地区的上甸子大气本底站的变化特征. 由于观测点相对孤立且海拔相对较高, 可受到自由大气的影响, 使O₃浓度持续多日保持较高水平, 而一次污染物浓度很低, 相对湿度显著降低且与O₃浓度变化明显反相关. 因此, 该站数据可以在更大的尺度上反映出区域本底信号的变化情况.

Characteristics of gaseous pollutants at Jinsha,a remote mountain site in Central China

Ground O₃, SO₂, NO_x, CO and meteorological data were obtained from June 2006 to July 2007 at Jinsha regional atmospheric background station in Central China. The concentration levels and variations of O₃, SO₂, NO_x and CO were analyzed and their influencing factors were discussed. The results showed that during the observation period, the average concentrations of O₃, SO₂, NO_x and CO were 24.6 ± 17.0 ppb, 2.8 ± 5.5 ppb, 5.6 ± 5.5 ppb and 502 ± 222 ppb, respectively, which were lower than those observed at a similar latitude site, Linan regional atmospheric background station in the Yangtze River Delta region. At Jinsha station, local photochemical production of O₃ is not significant and the average daily change of pollutants is relatively stable, which are different from those observed at Lin'an and Shangdianzi (North China) Regional atmospheric background station. Because of its relative isolation and relatively high altitude, some feature of free atmosphere can be able to be captured at Jinsha station. The feature can be characterized as that O₃ concentration maintained high concentrations for days, while the other pollutants of NO_x, SO₂ and CO kept a very low concentration; during the event, relative humidity significantly decreased to a lower level and showed an apparent anti-correlation with O₃ variation. Therefore, it can be able to reflect the changes of the background signals in a larger scale.