长沙市郊大气CH4浓度变化特征 |
摘要点击 3035 全文点击 1647 投稿时间:2013-03-29 修订日期:2013-06-03 |
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中文关键词 大气CH4 长沙 季节变化 地面风 后向轨迹 |
英文关键词 CH4 Changsha seasonal variation surface wind backward trajectory |
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中文摘要 |
为研究长江中游地区大气CH4浓度(体积分数)变化特征,2007~2011年,利用内表面硅烷化的苏玛罐采样、GC/FID方法对长沙市郊空气样品中CH4浓度进行测定分析,并结合地面气象要素和后向轨迹,探讨CH4浓度变化特征与源汇的关系. 结果表明,观测期间,大气CH4年平均浓度变化范围在2012×10-9~2075×10-9之间,季节变化特征为秋季高,春季低,浓度年较差为152×10-9. 通过分析地面风和气团传输对长沙市郊大气CH4的影响表明,长沙市郊大气CH4浓度受西北风和偏南风交替控制,贡献率分别为41.1%和20.4%; 引起CH4抬升的地面风包括:4个季节中的W-WNW-NW、夏季ESE-SE和冬季S,春夏季节S则导致CH4浓度降低; 夏秋季节源自水稻产区的气团、冬春季节源自能源消费量较高地区的气团,对长沙市郊CH4浓度的抬升有显著贡献,南方长距离传输气团有利于CH4扩散和清除. |
英文摘要 |
To study the variation of atmospheric CH4 concentration in the Yangtze River region, air samples which collected weekly using flasks from the suburb of Changsha City from 2007 to 2011 and the CH4 concentration was measured by gas chromatography. CH4 concentrations were analyzed combined with ground meteorological elements and backward trajectories to explore the CH4 concentration variations with source-sink relationships. The results showed that during the observation period, the annual mean concentration of CH4 was in the range 2012×10-9-2075×10-9 (volume mixing ratio, the same below). The difference between the maximum and minimum monthly mean of CH4 concentrations was 152×10-9, with the highest concentration observed in autumn and the lowest in spring. Analysis of the surface wind showed that the concentration of CH4 was controlled by northwest wind and southerly winds alternately, and the contribution rate was 41.1% and 20.4%, respectively. Surface winds causing CH4 concentration uplift included W-WNW-NW in all four seasons, ESE-SE in summer and S in winter; while S in spring and summer have resulted in the decrease of CH4 concentration. Analysis of the air mass transport showed that the concentration of CH4 in the suburb of Changsha was significantly contributed by air masses from rice-producing areas in summer and high energy consumption areas in winter, and was cleared by air masses of long-distance transport from southern district. |
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