An Investigation of Sulfur Chemistry in the Antarctic Troposphere (ISCAT)

建议的工作是对南极大气中的硫化学进行为期四年的研究，包括1998-99年和2000-01年在南极站的两个夏季野外季节。这是一个重大项目，涉及5个机构的10名主要和高级研究人员以及另外7名贡献研究人员。这项研究有两个广泛的目标：大大提高我们目前对极地环境中生物硫氧化化学的理解，并改进南极冰芯记录中硫基信号的气候解释。决定以南极为研究基地，是因为认识到内部的大气边界层将提供一个均匀且相对简单的环境，可以解开二甲硫醚（DMS）的光化学驱动氧化化学。它是在过去十年中许多其他硫研究的基础上发展而来的，包括这组研究人员在南极沿海地区进行的一项早期研究。大气硫化学是气候变化问题的一个重要组成部分，因为自然和人为排放的硫化合物在大气中形成微小颗粒（所谓的气溶胶），反射太阳辐射，产生大气雾霾和酸雨，并影响臭氧消耗。大气中的硫酸盐颗粒也可作为水蒸气的凝结核，增强全球云量。硫的主要自然来源是火山排放物和海洋浮游植物产生的DMS。在千年时间尺度上，通过保存的冰芯硫氧化产物古记录可以重建大气气溶胶的变率和自然背景水平。然而，有必要了解氧化过程的物理和化学环境如何影响埋藏在冰中的氧化产物的相对浓度。这项研究需要同时观察一系列广泛的硫物质，如DMS及其氧化产物：二氧化硫、二甲亚砜、二甲砜、甲烷磺酸和硫酸，以及光化学上重要的化合物，如一氧化碳、一氧化二氮、水蒸气和非甲烷碳氢化合物。次要目标将是检查南极内部空气样本，寻找其他重要的DMS氧化产物，如硫酸和甲烷亚磺酸，并评估当地羟基和过羟基自由基的变化，这是衡量大气氧化能力的一种指标。这项研究将首次提供一幅定量的图片，准确地说明哪些大气硫化合物被平流到南极内部，并详细地说明在南极大气中活跃的硫化学。* * * ? ?

*** 9809962 McMurry The proposed work is a four-year study of the sulfur chemistry in the antarctic atmosphere, including two summer field seasons at South Pole station in 1998-99 and 2000-01. It is a major project, involving ten principal and senior investigators at five institutions with seven additional contributing investigators. The study has two broad-based goals: to substantially improve our current understanding of the oxidation chemistry of biogenic sulfur in the polar environment, and to improve the climatic interpretation of sulfur-based signals in antarctic ice core records. The decision to base the proposed study at South Pole came from the recognition that the atmospheric boundary layer in the interior would present a homogeneous and relatively simple environment from which to unravel the photochemically driven oxidation chemistry of dimethyl sulfide (DMS). It is based on and has evolved from a number of other sulfur studies during the last decade, including an earlier study at a coastal antarctic site by this group of investigators. Atmospheric sulfur chemistry is an important component in climate change issues because both naturally and anthropogenically emitted sulfur compounds form minute particles in the atmosphere (so-called aerosols) that reflect solar radiation, produce atmospheric haze and acid rain, and affect ozone depletion. Sulfate particles in the atmosphere may also act as condensation nuclei for water vapor and enhance global cloudiness. The primary natural sources of sulfur are volcanic emissions and DMS production by oceanic phytoplankton. On the millenial time scale the variability and natural background level of atmospheric aerosols can be reconstructed from the preserved paleorecords of sulfur oxidation products in ice cores. It is however necessary to understand how the physical and chemical environment of the oxidation process affects the relative concentrations of the oxidation products that become buried in the ice. This study requires simultaneous observations of a wide-ranging suite of sulfur species such as DMS and its oxidation products: sulfur dioxide, dimethyl sulfoxide, dimethyl sulfone, methane sulfonic acid, and sulfuric acid, as well as photochemically important compounds such as carbon monoxide, nitrous oxide, water vapor, and non-methane hydrocarbons. Secondary objectives will be to examine interior antarctic air samples for other significant DMS oxidation products such as sulfurous acid and methane sulfinic acid, and to assess the local variation in hydroxyl and perhydroxyl radicals, a measure of the oxidizing power of the atmosphere. This study will for the first time provide a quantitative picture of exactly which atmospheric sulfur compounds are advected into the antarctic interior, and a detailed picture of the sulfur chemistry that is active in the antarctic atmosphere. *** ??