Regional sources of methyl chloride, chloroform and dichloromethane identified from AGAGE observations at Cape Grim, Tasmania, 1998-2000
Regional sources of methyl chloride, chloroform and dichloromethane identified from AGAGE observations at Cape Grim, Tasmania, 1998-2000
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DOI：
10.1023/a:1024022320985
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发表时间：
2003-05-01
影响因子：
2
通讯作者：
O'Doherty, S
中科院分区：
文献类型：
--
作者：
Cox, ML;Sturrock, GA;O'Doherty, S
在确定和量化氯甲烷-甲基氯（CH 3Cl）、氯仿（CHCl 3）和二氯甲烷（CH 2Cl 2）的自然和人为来源方面存在很大的不确定性，这些物质占平流层总氯的15%左右。我们报告了在塔斯马尼亚岛格里姆角（41 degreesS，145 degreesE）进行的AGAGE（高级全球大气气体实验）计划对这些物种进行的两年原位观测。1998-2000年期间，CH 3Cl、CHCl 3和CH 2Cl 2的平均背景水平分别为551+/-8，6.3 +/-0.2和8.9+/-0.2 ppt（干空气摩尔分数，以每10（12）份表示），背景空气中季节性周期的两年平均幅度分别为25、1.1和1.5 ppt。格里姆角的CH 3Cl和CHCl 3记录显示，混合比明显升高，分别高达1300 ppt和55 ppt，两者高度相关，表明有共同的来源。轨迹分析表明，CH 3Cl和CHCl 3的来源，负责这些升高的意见是位于沿海陆地和/或沿海海水地区在塔斯马尼亚州和东南部的澳大利亚大陆。CH 2Cl 2水平升高（高于背景值70 ppt）主要与墨尔本/菲利普港地区的排放有关，该地区是格里姆角以北300公里处的一个大型城市/工业综合体（人口350万）。
There are large uncertainties in identifying and quantifying the natural and anthropogenic sources of chloromethanes-methyl chloride (CH3Cl), chloroform (CHCl3) and dichloromethane (CH2Cl2), which are responsible for about 15% of the total chlorine in the stratosphere. We report two years of in situ observations of these species from the AGAGE (Advanced Global Atmospheric Gas Experiment) program at Cape Grim, Tasmania (41degreesS, 145degreesE). The average background levels of CH3Cl, CHCl3 and CH2Cl2 during 1998-2000 were 551+/-8, 6.3+/-0.2 and 8.9+/-0.2 ppt (dry air mole fractions expressed in parts per 10(12)) respectively, with a two-year average amplitude of the seasonal cycles in background air of 25, 1.1 and 1.5 ppt respectively. The CH3Cl and CHCl3 records at Cape Grim show clear episodes of elevated mixing ratios up to 1300 ppt and 55 ppt respectively, which are highly correlated, suggesting common source(s). Trajectory analyses show that the sources of CH3Cl and CHCl3 that are responsible for these elevated observations are located in coastal-terrestrial and/or coastal-seawater regions in Tasmania and the south-eastern Australian mainland. Elevated levels of CH2Cl2 (up to 70 ppt above background) are associated mainly with emissions from the Melbourne/Port Phillip region, a large urban/industrial complex (population 3.5 million) 300 km north of Cape Grim.