Collaborative Research: Particulate Organic Carbon in the Air and Snow at Summit, Greenland

这是格鲁吉亚理工学院、新罕布什尔州大学和威斯康星-麦迪逊大学的主要研究人员的合作提案。大气气溶胶令人关切，因为它们可以通过改变地球的辐射平衡来影响气候，并对人类健康有害。 细颗粒物质（直径小于2.5微克的颗粒）含有大量的有机碳（OC）和元素碳（EC），其可以占细颗粒质量的相当大的部分。有机碳部分由各种各样的化合物组成，这些化合物来自人类和自然来源。对含碳气溶胶的历史浓度、来源和排放知之甚少。冰芯中有机碳和特定有机化合物的浓度可以提供有关过去碳质气溶胶对气候的影响以及这些气溶胶来源的信息。在评估与颗粒物沉积有关的含碳化合物的冰芯浓度之前，重要的是要确定空气和雪中浓度之间的联系。此外，碳质气溶胶在沉积成雪后被改变的程度需要在特定化合物被用来推断过去的大气浓度之前确定。水不溶性颗粒有机碳（IPOC）在雪坑从首脑会议，格陵兰岛的初步结果显示，IPOC浓度在顶部50厘米的下降约50%，暗示早期后沉积过程可能是非常重要的。这些结果是一致的，最近的建议，表面雪中的有机碳可能发挥重要作用，雪光化学。主要调查人员将于2006年在首脑会议上进行实地研究，以测量颗粒OC，EC和特定有机化合物的浓度，这些化合物可作为空气，表面雪和雪坑中的源示踪剂。为了评估表面雪中沉积后过程的影响，他们将测量大气和积雪空气中水溶性气相有机化合物（WSGOC）的浓度，预计表面雪中IPOC的降解会导致WSGOC的形成。 他们将把存款碳-13和氘标记的颗粒有机化合物沉积到雪表面，并测量在整个野外季节的浓度变化。此外，他们还将在地面雪不受太阳辐射的情况下进行具体实验，以确定光化学对沉积在地面雪上的颗粒有机化合物降解的相对影响。 该研究将深入了解影响Summit空气和雪中颗粒碳浓度的过程，并将为未来的建模、实验室和实地研究奠定基础，这些研究将重点关注雪中颗粒有机化合物的沉积和转化。这项研究将通过培训几名研究生和本科生，包括来自代表性不足的少数群体的学生，促进教育。这些信息将通过会议演讲，出版物和网页以及研究生和本科生课程传播。 主要研究人员将在K-12学校发表演讲。研究工作将导致新的测量技术的发展以及对现有技术的独特修改。该项目将深入了解对大气科学和古气候社区具有重要意义的过程。这项研究可能会为基于雪中沉积的特定有机化合物浓度来解决气溶胶的历史来源和影响的研究打开大门。

This is a collaborative proposal by Principal Investigators at Georgia Institute of Technology, Universities of New Hampshire, and Wisconsin-Madison. Atmospheric aerosols are of concern because they can influence climate by altering the radiation balance of the Earth and are harmful to human health. Fine particulate matter (particles having diameters less than 2.5 micrograms) contains a significant amount of both organic carbon (OC) and elemental carbon (EC), which can account for a considerable fraction of the fine particulate mass. The OC fraction is composed of a wide variety of compounds from both anthropogenic and natural sources. Little is known about the historical concentrations, sources and emissions of carbonaceous aerosols. Ice core concentrations of OC and specific organic compounds could yield information on the past influence of carbonaceous aerosols on climate and the sources of these aerosols. Before ice core concentrations of carbonaceous compounds related to particulate matter deposition can be evaluated, it is important to determine the link between the concentrations in air and snow. In addition, the extent to which carbonaceous aerosol is modified after deposition to snow needs to be determined before specific compounds can be used to infer past atmospheric concentrations. Preliminary results of water insoluble particulate organic carbon (IPOC) in a snow pit from Summit, Greenland show a decrease of ~ 50% in IPOC concentrations in the top 50 cm, hinting that early post depositional processes may be very important. These results are consistent with recent suggestions that organic carbon in surface snow may play an important role in snow photochemistry. The Principal Investigators will conduct a field study at Summit in 2006 to measure the concentrations of particulate OC, EC, and specific organic compounds that serve as source tracers in the air, surface snow, and snow pits. To assess the influence of post depositional processes in surface snow, they will measure the concentrations of water-soluble gas-phase organic compounds (WSGOC) in the atmospheric and firn air with the expectation that the degradation of IPOC in surface snow leads to the formation of WSGOC. They will deposit carbon-13 and deuterium-labeled particulate organic compounds to surface snow and measure the change in concentration over the duration of the field season. In addition, they will conduct specific experiments where surface snow is shaded from solar radiation in order to determine the relative influence of photochemistry on the degradation of particulate organic compounds deposited to surface snow. The research will yield insights into the processes that influence the concentrations of particulate carbon in the air and snow at Summit and will serve as the groundwork for future modeling, laboratory, and field studies that will focus on the deposition and transformation of particulate organic compounds in snow.Broader Impacts: The research will advance education through the training of several graduate and undergraduate students, including students from under-represented minority groups. The information will be disseminated through conference presentations, publications, and a webpage as well as within graduate and undergraduate courses. The Principal Investigators will give presentations at K-12 schools. The research effort will result in the development of new measurement techniques as well as unique modifications to existing techniques. The project will yield insights into processes that are of importance to the atmospheric sciences as well as paleoclimate communities. The research will potentially open the door for studies that address the historical sources and impacts of aerosols based on the concentrations of specific organic compounds deposited in snow.