US GEOTRACES GP17-OCE and GP17-ANT: Atmospheric Deposition and Aerosol Fractional Solubility in Remote Ocean Regions

痕量元素的定义是它们在公海中的低浓度，它们的添加和去除速度是我们理解海洋化学的关键不确定因素。尽管微量元素稀缺，但它们在决定生物在开阔海洋中繁衍生息的位置上发挥着巨大的作用。在海岸附近，这些元素可能大量存在，因为河流等特征将大陆的原始物质带到海洋中。然而，远离陆地的地方，微量元素稀缺。这些元素对开阔海洋的最重要来源可能来自尘埃和其他颗粒，它们直接或通过雨滴落到水面上。对这一过程的更好理解将进一步了解海洋中的元素循环，包括碳循环。该项目将对南太平洋和南极洲周围南太平洋的太平洋部分的大气进行采样。大气对这些水域的输入还不是很清楚，研究结果将为科学界提供急需的信息。该项目将支持一名早期职业研究人员和一名研究生。地表水域中气溶胶的沉积和随后的溶解仍然是海洋学界的一个关键研究领域。大部分海洋的采样仍然很差，有必要改进通量估计、化学表征和分数溶解度估计，以提高对这一重要微量元素来源的理解。该项目将包括一艘南太平洋邮轮和一艘南大洋阿蒙森海区的邮轮，这两个项目都是GEOTRACES计划的一部分。巡航轨道将覆盖澳大利亚沙尘产生区的顺风向区域，以及大气沉积可能在决定水柱中痕量元素分布方面发挥作用的区域。跨越海-气界面的气溶胶通量是地球空间研究中心和更广泛的海洋学界的一个关键研究领域。从大气到海洋的流动是高度间歇性的，这使得在公海上很难捕捉到这个重要的术语。通量速率将通过使用宇宙成因的同位素7Be来确定，从而提供比巡航周期更长的时间尺度的速率估计。气溶胶中痕量元素组分的溶解度限制较差，这是生物地球化学模型对海洋痕量元素分布表现出较差一致性的原因之一。气溶胶溶解将在几种不同化学成分的溶液中进行测试，以提供一系列溶解度估计，这些估计代表降水、表层海水和更具侵略性的环境中的条件，从而提供高端的溶解度估计。由于这种不确定性，像停留时间这样的计算条件也没有得到很好的约束。该项目将通过采集散装和分级气溶胶样品以及降水样品来解决这些问题。这项研究将促进对尘埃和可溶气溶胶痕量元素从大气到海洋的通量的理解，并为与这些GEOTRACES部分巡航相关的免费研究提供背景数据。该奖项反映了NSF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。

Trace Elements are defined by their low concentrations in the open ocean and their addition and removal rates are key uncertainties in our understanding of ocean chemistry. In spite of their scarcity, trace elements can play an outsized role in determining where living things thrive in the open ocean. Near the coasts, these elements may be found in abundance because of features like rivers which bring source material from the continents to the ocean. Far from land, however, trace elements are scarce. The most significant source of these elements to the open ocean may come from dust and other particles falling onto the surface water either directly, or within rain droplets. An improved understanding of this process will further knowledge of element cycling in the ocean, including the carbon cycle. This project will sample the atmosphere of the South Pacific Ocean and the Pacific sector of the Southern Ocean around Antarctica. Input from the atmosphere to these waters is not well known and the research results will provide much needed information to the scientific community. This project will support an early career researcher as well as a graduate student.The deposition and subsequent dissolution of aerosols in surface waters remains a critical research area in the oceanographic community. Much of the ocean remains poorly sampled and improvements in flux estimates, chemical characterization, and fractional solubility estimates are necessary to improve the understanding of this important trace element source. This project will include a cruise in the South Pacific Ocean and one in the Amundsen Sea sector of the Southern Ocean, both as part of the GEOTRACES program. The cruise tracks will cover regions which lie downwind of dust producing regions of Australia and where atmospheric deposition could play a role in dictating distributions of trace elements in the water column. The flux of aerosols across the air-sea interface is a key research area within GEOTRACES and the broader oceanographic community. Flux from the atmosphere to the ocean is highly episodic making the capture of this important term difficult in the open ocean. Flux rates will be determined by the use of the cosmogenic isotope 7Be, providing a rate estimate for time scales longer than the cruise period. Aerosol trace element fractional solubility remains poorly constrained and is one of the reasons that biogeochemical models show poor agreement for marine trace element distributions. Aerosol dissolution will be tested in several solution of varying chemistry to provide a range of solubility estimates which are representative of conditions in precipitation, surface seawater, and in more aggressive environments which provide a high-end solubility estimate. Calculated terms like residence time are also poorly constrained due to this uncertainty. This project will address these questions by capturing bulk and size-fractionated aerosol samples as well as samples of precipitation. The study will advance understanding of dust and soluble aerosol trace element flux from the atmosphere to the ocean and provide contextual data for complimentary studies associated with these GEOTRACES section cruises.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.