TOWARD AN IMPROVED UNDERSTANDING OF AIR-SEA EXCHANGE OF GASEOUS ORGANIC CARBON AND ITS ROLE IN OCEAN CARBON FLUXES

长期以来，大气沉降被认为是氮、各种微量元素和特定有机化合物向海洋迁移的重要来源。然而，目前大气有机碳（OC）输入海洋的总量和形式基本上是未知的。其中一个原因是，有机碳的海气交换直到最近才被认为是一个具有全球意义的潜在来源，有机气体沉积估计数超过了干、湿大气沉积和河流流入海洋的有机碳通量。大的大气输入的生物活性有机碳也可能足以解释所观察到的净异养活动的亚热带东北大西洋和其他偏远的海洋系统。因此，可以合理地断言，海气沉积可能是海洋储层和活性有机质池的OC的重要来源。此外，人为排放的有机气体对当今大气的贡献可能代表了大量老化前的OC流入海洋。在该项目中，弗吉尼亚海洋科学研究所的研究人员将开发和验证用于测量三个操作定义的OC池在空气中和溶解在海水中的可靠方法，以便可以定量确定每个OC池的海气通量。 目前的假设是，有机碳在海洋中的气体沉积量比干湿大气沉积通量高出一个数量级以上，大气输入量与流入海洋的河流有机碳输入量相似，甚至可能超过。海气传质系数的计算表明，它是关键的区分气态OC根据其空气-水的分配特性，以准确地量化海气通量的可交换的OC这一不同的池。为此，将开发技术，分别评估空气和地表沃茨中的挥发性、半挥发性和水溶性挥发性有机碳。将通过气相/液相色谱分析对散装OC测量进行补充，以评估OC在每个操作定义阶段的分布，并在可能的情况下识别特定的有机化合物或化合物类别。初步采样和OC气体通量估计也将在西北大西洋的河口，沿海和公海沃茨进行。在更广泛的影响方面，该项目将包括教育和社区推广，并将有助于制定一个更完整的理解人类活动如何可能改变OC库存在海洋中。研究生，本科生和高中生，包括代表性不足的群体的成员，将被招募通过几个正在进行的教育计划在海洋科学的弗吉尼亚研究所（VIMS）在这两个PI参与这个项目。将通过参加VIMS海洋科学日的实践活动、讲座和展览来实现社区外联，这是一项年度活动，2006年有1 800人参加（52/48%儿童/成人）。拟议的研究还将有助于正在进行的国家和国际海洋碳通量计划，包括百慕大时间序列（BATS），海洋通量计划（OFP），和表面海洋？低层大气研究（SOLAS）。

Atmospheric deposition has long been recognized as an important source of allochthonous nitrogen, various trace elements, and specific organic compounds to the oceans. However, at present the magnitude and forms of total atmospheric organic carbon (OC) inputs to the oceans are essentially unknown. One reason for this is that air-sea gas exchange of OC has only recently been recognized as a potential source of global significance, with organic gas deposition estimates exceeding both dry and wet atmospheric deposition and riverine fluxes of OC to the oceans. Large atmospheric inputs of biologically reactive OC may also be sufficient to account for the observed net heterotrophic activity of the subtropical northeast Atlantic and other remote marine systems. Thus, would be reasonable to assert that air-sea gas deposition may be an important source of OC to ocean reservoirs and reactive organic matter pools. Moreover, the contribution of anthropogenic emissions of organic gases to the present-day atmosphere may represent a significant influx of pre-aged OC to the oceans.In this project, researchers at the Virginia Institute of Marine Science will develop and validate robust methods for measuring three operationally defined OC pools in air and dissolved in seawater, so that the air-sea gas fluxes for each OC pool can be quantitatively determined. The working hypothesis is that gas deposition of organic carbon to the oceans is more than an order of magnitude higher than wet and dry atmospheric deposition fluxes, and that atmospheric inputs are similar in magnitude to, and may exceed, riverine inputs of organic carbon to the oceans. Calculations of air-sea mass transfer coefficients demonstrate that it is critical to distinguish gaseous OC according to its air-water partitioning properties in order to accurately quantify air-sea gas fluxes of this diverse pool of exchangeable OC. To this end, techniques will be developed to separately evaluate volatile, semi-volatile and water-soluble volatile OC in air and surface waters. Bulk OC measurements will be supplemented with gas/liquid chromatography analysis to evaluate the distribution of OC in each operationally defined phase, and to identify specific organic compounds or compound classes where possible. Preliminary sampling and OC gas flux estimates will also be conducted in estuarine, coastal, and open ocean waters of the northwestern Atlantic Ocean.In terms of broader impacts, the project will include education and community outreach, and will help formulate a more complete understanding of how human activity may be modifying OC inventories in the ocean. Graduate, undergraduate and high school students, including members of under-represented groups, will be recruited to work on this project through several ongoing educational programs at the Virginia Institute of Marine Science (VIMS) in which both of the PIs participate. Community outreach will be achieved through participation in hands-on activities, lectures, and displays at VIMS Marine Science Day, an annual event, which was attended by 1800 people in 2006 (52/48% children/adults). The proposed study will also contribute to ongoing national and international ocean carbon flux programs, including the Bermuda Time Series (BATS), the Ocean Flux Program (OFP), and the Surface Ocean ? Lower Atmosphere Study (SOLAS).