Investigation of Sulfur Chemistry in the Antarctic Troposphere (ISCAT)

* 9809164 Arimoto 建议的工作是一个为期四年的南极大气中硫化学的研究，包括两个夏季现场季节在南极站在1998 - 99年和2000 - 01年。 这是一个重大项目，涉及五个机构的十名主要和高级调查员，另有七名调查员参与。 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，并改善南极冰芯记录中硫基信号的气候解释。之所以决定在南极开展拟议的研究，是因为认识到内部的大气边界层将提供一个均匀和相对简单的环境，从中可以解开二甲基硫醚（DMS）的光化学驱动氧化化学。 它是基于并从过去十年中的一些其他硫研究中发展而来的，包括这组调查人员在沿海南极点的早期研究。 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以作为水汽的凝结核，增加全球云量。 硫的主要自然来源是火山排放物和海洋浮游植物产生的二甲硫醚。 在千年时间尺度上，利用冰芯中保存的硫氧化产物的古记录，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测一系列广泛的硫物种，如DMS及其氧化产物：二氧化硫，二甲亚砜，二甲基砜，甲磺酸和硫酸，以及光化学重要的化合物，如一氧化碳，一氧化二氮，水蒸气和非甲烷烃。 第二个目标将是检查室内防冻空气样本中是否有其他重要的二甲基硫醚氧化产物，如亚硫酸和甲烷亚磺酸，并评估羟基和过羟基自由基的局部变化，这是衡量大气氧化能力的一个指标。 这项研究将首次提供一个定量的图片，究竟是大气硫化合物平流到南极洲内部，和一个详细的图片硫化学是活跃在南极洲大气。 *** ??

*** 9809164 Arimoto 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. *** ??