On the Regional and Seasonal Ozone Depletion Potential of Chlorinated Very Short-Lived Substances
On the Regional and Seasonal Ozone Depletion Potential of Chlorinated Very Short-Lived Substances
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DOI：
10.1029/2018gl081455
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发表时间：
2019-05-28
影响因子：
5.2
通讯作者：
Wilson, Chris
中科院分区：
文献类型：
--
作者：
Claxton, Tom;Hossaini, Ryan;Wilson, Chris
三氯甲烷（CHCl 3）、二氯甲烷（CH 2Cl 2）、全氯乙烯（C2Cl 4）和1，2-二氯乙烷（C2 H4 Cl 2）是具有一系列商业/工业应用的氯化极短寿命物质（Cl-VSLS）。最近的研究强调了Cl-VSLS对平流层氯收支的影响越来越大，因此它们可能在臭氧消耗中发挥作用。在这里，我们评估的臭氧消耗潜能（ODP），这些氯-VSLS使用三维化学传输模型和调查的敏感性排放位置/季节。臭氧消耗潜能值的季节依赖性很小，但臭氧消耗潜能值因排放大陆而异，其系数为2-3：0.0143-0.0264（CHCl 3）、0.0097-0.0208（CH 2Cl 2）、0.0057-0.0198（C2Cl 4）和0.0029-0.0119（C2 H4 Cl 2）。亚洲的排放量产生的耗氧潜能值最大，这是因为亚洲靠近热带地区，而且来自工业化东亚的空气能够有效地从对流层输送到平流层。Cl-VSLS耗氧潜能值一般较小，但CHCl 3和CH 2Cl 2范围的上限与甲基氯的平均耗氧潜能值（0.02）相当，甲基氯是一种寿命较长的消耗臭氧层物质。自1970/1980年代以来，含氯氟烃的温室气体已导致全球臭氧层消耗，包括南极臭氧洞现象。1987年通过的《蒙特利尔议定书》禁止生产主要消耗臭氧层的气体，因此，有迹象表明臭氧层正在恢复。然而，近年来所谓的寿命极短的物质，如二氯甲烷的排放量有所增加。从历史上看，由于这些化合物的寿命相对较短，它们并不被认为是对平流层臭氧的主要威胁，而且也不受《议定书》的管制。鉴于这些化合物的产量预计将增加，因此必须确定其影响平流层臭氧的能力。我们量化的臭氧消耗潜能值（ODP）的氯仿和四氯乙烯，并首次，二氯甲烷和1，2-二氯乙烷，主要的氯化非常短的寿命的物质。我们表明，它们的ODP变化取决于排放发生的地方。例如，亚洲二氯甲烷排放的耗氧潜能值比欧洲排放的耗氧潜能值高出两倍。这反映了不同地理区域之间对流层向平流层输送的相对效率;来自东亚大陆的污染边界层空气的输送是一个相对有效的途径。
Chloroform (CHCl3), dichloromethane (CH2Cl2), perchloroethylene (C2Cl4), and 1,2-dichloroethane (C2H4Cl2) are chlorinated Very Short-Lived Substances (Cl-VSLS) with a range of commercial/industrial applications. Recent studies highlight the increasing influence of Cl-VSLS on the stratospheric chlorine budget and therefore their possible role in ozone depletion. Here we evaluate the ozone depletion potential (ODP) of these Cl-VSLS using a three-dimensional chemical transport model and investigate sensitivity to emission location/season. The seasonal dependence of the ODPs is small, but ODPs vary by a factor of 2-3 depending on the continent of emission: 0.0143-0.0264 (CHCl3), 0.0097-0.0208 (CH2Cl2 ), 0.0057-0.0198 (C2Cl4), and 0.0029-0.0119 (C2H4Cl2). Asian emissions produce the largest ODPs owing to proximity to the tropics and efficient troposphere-to-stratosphere transport of air originating from industrialized East Asia. The Cl-VSLS ODPs are generally small, but the upper ends of the CHCl3 and CH2Cl2 ranges are comparable to the mean ODP of methyl chloride (0.02), a longer-lived ozone-depleting substance.Plain Language Summary Anthropogenic emissions of long-lived chlorinated substances (e.g., chlorofluorocarbons) have led to global ozone layer depletion since the 1970s/1980s, including the Antarctic Ozone Hole phenomenon. The 1987 Montreal Protocol was enacted to ban production of major ozone-depleting gases, and in consequence, there are signs that the ozone layer is recovering. However, emissions of so-called very short-lived substances, such as dichloromethane, have increased in recent years. Historically, these compounds have not been considered a major threat to stratospheric ozone, due to relatively short lifetimes, and they are not controlled by the Protocol. Given that production of these compounds is projected to increase, it is important to determine their ability to affect stratospheric ozone. We quantify the ozone depletion potential (ODP) of chloroform and perchloroethylene and, for the first time, dichloromethane and 1,2-dichloroethane, the main chlorinated very short-lived substances. We show that their ODPs vary depending on where the emission occurs. For example, the ODP from Asian dichloromethane emissions is up to a factor of two greater than that from European emissions. This reflects the relative efficiency of troposphere to stratosphere transport between different geographical areas; the transport of polluted boundary layer air from continental East Asia being one relatively efficient route.