Collaborative Research: Impact of Atmospheric Deposition on the Distribution and Speciation of Trace Elements in the Upper Ocean - Focus on Iron in the Sargasso Sea

最近在马尾藻海（最佳可行技术区域）进行的研究表明，表层沃茨中溶解铁（Fe）浓度有很大的季节性变化，其浓度从2003年夏季气溶胶Fe浓度高时的~1-2 nM下降到2004年春季气溶胶Fe浓度低时的~0.1-0.2 nM。这些变化被解释为结果的季节性粉尘输入到高度分层，贫营养的表面沃茨在夏季，然后通过去除风成铁由于对流混合，生物吸收和颗粒清除在冬季早春。来自百慕大生物研究站、特拉华州大学和伍兹霍尔海洋研究所的研究人员设计了一个简单的模型，该模型表明，风成作用于海洋表面的溶解铁与总的气溶胶铁浓度不成比例。 为了验证这一假设，科学家们将以马尾藻海为天然实验室，开展以下目标：（1）实现对矿物气溶胶沉积影响的定量认识（干和湿）对马尾藻海表层沃茨中铁的浓度和形态的影响;（2）对新建立的马尾藻海气溶胶铁溶解度模型进行检验，并评价该模型在全球范围内的应用潜力;和（3）评估是否需要一个自主的、安装在水下的气溶胶采样器，用于量化公海上空气溶胶铁的浓度和溶解度。为了实现这些目标，将进行时间序列观测和深入的过程研究。 这项工作将包括船上水柱取样，在百慕大都铎山塔进行大气取样，在百慕大试验台系泊上使用自主气溶胶取样器，随后分析海水、气溶胶和雨水样品中铁和其他微量金属的浓度和形态。至于更广泛的影响，这项研究将提供所需的数据，以提高地球化学生态系统模型的预测能力。 此外，该项目还将记录一个自主的、安装在空气中的气溶胶取样系统的效用，该系统将大气和海洋过程联系起来，用于海洋地球化学和海洋地球化学的环境监测和研究。 这项研究的目标是兼容的SOLAS和GEOTRACES计划的重点。 来自特拉华州大学的一名研究生和一名本科生（作为REU计划的一部分资助）将作为该项目的一部分接受培训。

Recent studies in the Sargasso Sea (BATS region) have revealed a large, seasonal-scale change in the dissolved iron (Fe) concentration of the surface waters where concentrations decreased from ~1-2 nM in summer 2003, when aerosol Fe concentrations were high, to ~0.1-0.2 nM in spring 2004, when aerosol Fe concentrations were low. These changes were interpreted as the result of the seasonal dust input into the highly-stratified, oligotrophic surface waters during the summer, followed by the removal of this aeolian iron due to the convective mixing, biological uptake and particle scavenging during the winter-early spring. Researchers from the Bermuda Biological Station for Research, the University of Delaware and Woods Hole Oceanographic Institute have devised a simple model that implies that aeolian input of dissolved Fe into the surface ocean does not scale with total aerosol Fe concentrations. To test this hypothesis, the scientists will use the Sargasso Sea as a natural laboratory to carry out the following objectives: (1) achieve a quantitative understanding of the impact of mineral aerosol deposition (dry and wet) on the concentration and speciation of Fe in surface waters of the Sargasso Sea; (2) test the new model for aerosol Fe solubility that have been developed for the Sargasso Sea, and thus evaluate the potential for application of this model at the global scale; and (3) evaluate the need for an autonomous, buoy-mounted aerosol sampler for quantifying the concentration and solubility of aerosol iron over the open ocean. To attain these goals, both time-series observations and intensive process studies will be done. The work will include shipboard water-column sampling, atmospheric sampling at the Tudor Hill tower on Bermuda, the use of an autonomous aerosol sampler on the Bermuda Testbed Mooring, and subsequent analyses of the concentration and speciation of Fe and other trace metals in seawater, aerosol, and rainwater samples. As regards broader impacts, this study will provide needed data to improve predictive capabilities of biogeochemical-ecosystem models. In addition, this project will document the utility of an autonomous, buoy-mounted aerosol sampling systems linking atmospheric and oceanographic processes for environmental monitoring and research in marine geochemistry and biogeochemistry. The goals of this research are compatible with the focus of the SOLAS and GEOTRACES programs. One graduate student and one undergraduate student (funded as part of the REU program) from the University of Delaware will be trained as part of this project.