NSF-BSF: Understanding Evolution of Atmospheric Brown Carbon

褐碳(BRC)粒子是影响全球气候和人类健康的燃料不完全燃烧所排放的颗粒物，但其光学性质和化学成分仍不明确。这个以实验室为基础的项目旨在调查专门从生物质燃烧(BB)中产生的BRC气溶胶的关键特性。通过美国和以色列高等教育机构之间的国际合作，可以获得一系列独特的先进工具和互补的专业知识。资金通过NSF-BSF牵头机构协议提供，其中美国部分由NSF提供资金，以色列部分由美国-以色列双国科学基金会(BSF)提供资金。新的结果将被用于气候模型，并有助于更好地了解BRC颗粒对生态和人类健康的反应性。学生和早期职业科学家将在这项工作的各个方面发挥重要作用，从而有助于培养一支准备充分、具有全球意识的劳动力队伍。特别强调了研究最少的中等(M)和强(S)吸收BRC(M/S-BRC)子群。以色列魏兹曼科学研究所将开展的实验室部分包括：(1)在实验室控制的生物质/热解燃烧试验中产生M-BRC和S-BRC替代物；(2)模拟昼夜过程中的颗粒老化；(3)实时分析空气中颗粒物的粒度分级组合的依赖于波长的光学测量。生成的颗粒被收集并发送到美国普渡大学(PU)，用于离线分析过滤样品提取物中单个BRC发色团的分子表征和光吸收性能。此外，还进行了化学成像来表征颗粒的组成、大小、混合状态和形态(PU)。这两个机构之间的任务旨在相辅相成，提供关于M/S-BRC的组成、老化化学和光吸收性能的基本信息，最终目标是提高对BRC对大气环境和气候影响的预测性了解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Brown carbon (BrC) particles are emitted from the incomplete combustion of fuels affecting global climate and human health, yet their optical properties and chemical composition remain ill-defined. The laboratory-based project seeks to investigate key properties of BrC aerosols produced specifically from biomass burning (BB). Access to a unique array of advanced instruments and complementary expertise is secured through the international collaboration between U.S. and Israeli institutions of higher education. Funding is provided via the NSF-BSF Lead Agency Agreement in which the U.S. component is funded by NSF and the Israeli component by the U.S.-Israel Binational Science Foundation (BSF). Novel results will be used in climate models and help better understand reactivity of BrC particles toward ecological and human health. Students and an early career scientist are slated to play essential roles in every aspect of the work thus contributing to the development of a well-prepared globally aware workforce. Specific emphasis is on the least-studied subgroup of moderately (M) and strongly (S) absorbing BrC (M/S-BrC). The laboratory component to be carried out at the Israeli institution Weizmann Institute of Science (WIS) consists of (i) generation of M-BrC and S-BrC proxies in laboratory-controlled biomass/pyrolysis burning tests, (ii) particle ageing while mimicking day- and night-time processes, and (iii) real-time analysis of wavelength-dependent optical measurements of airborne size-fractionated ensembles of particles. Generated particles are collected and sent to the U.S. counterpart, Purdue University (PU), for off-line analyses of molecular characterization and light-absorbing properties of individual BrC chromophores from extracts of filter samples. In addition, chemical imaging is carried out to characterize particle composition, size, mixing state and morphology (PU). Tasks between the two institutions are intended to complement each other and provide fundamental information on the composition, aging chemistry and light-absorption properties of M/S-BrC with the ultimate goal of improving predictive understanding of BrC impacts on atmospheric environment and climate.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.