Methyl chloride and methyl bromide in Antarctic ice cores

南极冰芯中的氯甲烷和溴甲烷

• 批准号: 0338359
• 负责人: Eric Saltzman
• 金额: $ 45.69万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-01 至 2007-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0338359&HistoricalAwards=false
• 关键词: Methyl; chloride; methyl; bromide; Antarctic

This award supports the analysis, in Antarctic ice cores, of the ozone depleting substances methyl bromide (CH3Br) and methyl chloride (CH3Cl), and the sulfur-containing gas, carbonyl sulfide (OCS). The broad scientific goal is to assess the level and variability of these gases in the preindustrial atmosphere. This information will allow testing of current models for sources and sinks of these gases from the atmosphere, and to indirectly assess the impact of anthropogenic activities on their biogeochemical cycles. Longer-term records will shed light on the climatic sensitivity of the atmospheric burden of these gases, and ultimately on the biogeochemical processes controlling them. These gases are present in ice at parts per trillion levels, and the current database consists entirely of a small number of measurements made in from a shallow ice core from Siple Dome, Antarctica. This project will involve studies of ice core samples from three Antarctic sites: Siple Station, Siple Dome, and South Pole. The sampling strategy is designed to accomplish several objectives: 1) to verify the atmospheric mixing ratios previously observed in shallow Siple Dome ice for OCS, CH3Br, and CH3Cl at sites with very different accumulation rates and surface temperatures; 2) to obtain a well-dated, high resolution record from a high accumulation rate site (Siple Station), that can provide overlap in mean gas age with Antarctic firn air samples; 3) explore Holocene variability in trace gas mixing ratios; and 4) to make the first measurements of these trace gases in Antarctic glacial ice. In terms of broader impact on society, this research will help to provide a stronger scientific basis for policy decisions regulating the production and use of ozone-depleting and climate-active gases. Specifically, the methyl bromide results will contribute to the current debate on the impact of recent regulation (via the Montreal Protocol and its Amendments) on atmospheric levels. Determination of pre-industrial atmospheric variability of ozone-depleting substances will help place more realistic constraints on scenarios used for future projections of stratospheric ozone and its climatic impacts. This research will involve the participation of both graduate and undergraduate students.

该奖项支持对南极冰核的分析，对臭氧耗竭的物质甲基溴化物（CH3BR）和氯化甲基（CH3CL）以及含硫的气体，羰基硫化物（OCS）的分析。 广泛的科学目标是评估工业前大气中这些气体的水平和可变性。 这些信息将允许测试当前模型，从大气中的这些气体的来源和水槽进行测试，并间接评估人为活动对其生物地球化学周期的影响。 长期记录将阐明这些气体大气负担的气候灵敏度，并最终在控制它们的生物地球化学过程中。 这些气体以每万亿美元的零件为单位存在，目前的数据库完全由南极Siple Dome的浅冰芯进行的少量测量。 该项目将涉及来自三个南极地点的冰核样品的研究：Siple站，Siple Dome和South Pole。 采样策略旨在实现几个目标：1）验证在浅层圆顶冰中以OCS，CH3BR和CH3CL在累积速率和表面温度非常不同的位点上观察到的大气混合比； 2）从高累积速率位点（SIPLE位）获得良好的高分辨率记录，该记录可以在平均气体时代与南极FIRN空气样品相重叠； 3）探索痕量气体混合比的全新世变异性； 4）在南极冰川冰中对这些痕量气体进行首次测量。 在对社会的更广泛影响方面，这项研究将有助于为规范臭氧动力和气候活性气体的生产和使用的政策决策提供更强大的科学基础。具体而言，甲基溴化物的结果将有助于当前关于最近调节的影响（通过蒙特利尔方案及其修正案）对大气水平的辩论。 确定消耗臭氧的物质的工业前大气变异性将有助于对平流层臭氧的未来预测及其气候影响更现实的限制。 这项研究将涉及研究生和本科生的参与。