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芯中臭氧消耗物质溴甲烷 (CH3Br) 和氯甲烷 (CH3Cl) 以及含硫气体羰基硫 (OCS) 的分析。 广泛的科学目标是评估工业化前大气中这些气体的水平和变化。 这些信息将允许测试大气中这些气体的源和汇的当前模型，并间接评估人类活动对其生物地球化学循环的影响。 长期记录将揭示这些气体的大气负荷对气候的敏感性，并最终揭示控制它们的生物地球化学过程。 这些气体以万亿分之一的水平存在于冰中，当前的数据库完全由来自南极洲西普勒穹顶的浅冰芯进行的少量测量组成。 该项目将涉及对来自三个南极地点的冰芯样本的研究：Siple Station、Siple Dome 和南极。 采样策略旨在实现几个目标：1) 验证先前在 Siple Dome 浅层冰中观察到的 OCS、CH3Br 和 CH3Cl 的大气混合比，这些混合比在积累率和表面温度差异很大的地点进行； 2) 从高积累率站点（Siple Station）获得日期明确的高分辨率记录，该记录可以提供与南极冰雪空气样本的平均气体年龄的重叠； 3）探索全新世痕量气体混合比例的变化； 4）首次测量南极冰川中的这些痕量气体。 就对社会更广泛的影响而言，这项研究将有助于为监管消耗臭氧层气体和气候活性气体的生产和使用的政策决策提供更强有力的科学基础。具体来说，甲基溴的结果将有助于当前关于近期监管（通过《蒙特利尔议定书》及其修正案）对大气水平影响的辩论。 确定工业化前大气中臭氧消耗物质的变化将有助于对用于未来预测平流层臭氧及其气候影响的情景施加更现实的限制。 这项研究将涉及研究生和本科生的参与。