Advancing our understanding of dimethyl sulfide oxidation products by field observations of formaldehyde and photolysis frequencies

通过甲醛和光解频率的现场观察增进我们对二甲硫醚氧化产物的理解

• 批准号: 2903836
• 金额: --
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2903836
• 关键词: Advancing; our; understanding; dimethyl; sulfide

Dimethyl sulfide (DMS) from marine biogenic emissions is the largest natural source of sulphur in the atmosphere and a major aerosol precursor (Carslaw et al., 2010). With anthropogenic sources of SO2 decreasing, knowledge of the fate of DMS is critical for understanding the formation of new sulphate aerosol particles, growth of existing aerosols to cloud condensation nuclei (CCN), and the burden/composition of aerosols in the remote marine environment. The recent discovery of a new molecule, hydroperoxy methylthioformate (HOOCH2SCHO; HPMTF) which is formed during the oxidation of DMS has highlighted that there are uncertainties in our knowledge of the main pathways and products of DMS chemistry (Veres et al., 2020). To address these key uncertainties, a large field and modelling project (Constraining the role of the marine sulfur cycle in the Earth System (CARES)) has been developed. As part of CARES, a comprehensive suite of measurements will be made on board a research ship and from the FAAM aircraft flying off the west coast of Ireland. Of particular relevance to this studentship, actinic flux observations, coupled with absorption cross sections for the functional groups (aldehydic and hydroperoxide) present in HPMTF will be measured and will enable photolysis rates for HPMTF to be determined and the photolytic products to be derived. HCHO observations, coupled with HCHO photolysis frequencies and observations of a suite of VOCs, CH4, CO, NOx (from which (a) the effective HCHO yield weighted over all OH reactions, can be derived) will provide a proxy for the OH concentration (Wolfe et al., 2019) and enable the loss of HPMTF via OH oxidation to be determined as well as the DMS oxidation rate via OH. Through these targeted field observations and subsequent modelling studies, an improved understanding of the role DMS plays in the marine sulfur cycle and the impact on the climate system will be achieved.

来自海洋生物源排放的二甲基硫（DMS）是大气中硫的最大天然来源，并且是主要的气溶胶前体（Carslaw等人，2010年）。随着SO2人为来源的减少，了解DMS的命运对于了解新的硫酸盐气溶胶颗粒的形成、现有气溶胶向云凝结核（CCN）的增长以及偏远海洋环境中气溶胶的负担/组成至关重要。最近发现了一种新分子，即在DMS氧化过程中形成的氢过氧甲基硫代甲酸酯（HOOCH 2SCHO; HPMTF），这突出表明我们对DMS化学的主要途径和产物的认识存在不确定性（Veres等人，2020年）。为了解决这些关键的不确定性，已经开发了一个大型的现场和建模项目（限制海洋硫循环在地球系统中的作用（CARES））。作为CARES的一部分，将在一艘研究船上和飞离爱尔兰西海岸的FAAM飞机上进行一套全面的测量。特别是相关的这个学生，光化通量观测，再加上吸收截面的功能团（氢过氧化物和过氧化氢）存在于HPMTF将被测量，并将使HPMTF的光解速率被确定和光解产物的衍生。HCHO观测，加上HCHO光解频率和一组VOC、CH 4、CO、NOx的观测（从中可以得出（a）在所有OH反应中加权的有效HCHO产率）将提供OH浓度的代表（Wolfe等人，2019），并能够确定HPMTF通过OH氧化的损失以及DMS通过OH的氧化速率。通过这些有针对性的实地观测和随后的建模研究，将更好地了解二甲基硫醚在海洋硫循环中的作用及其对气候系统的影响。