Hydrogeologic Controls on Trace Metal and Nutrient Fluxes from Subterranean Estuaries

尽管地下水是陆地-海洋物质运输的主要载体，但地下水在海洋元素质量平衡中的作用一直没有得到很好的描述。在明确考虑地下水的地方，大多数研究都没有量化大气水与咸水孔隙水(地下河口)混合过程中发生的化学变化的重要性。在地表水排放之前。在这项研究中，伍兹霍尔海洋研究所的研究人员将研究沿海水文地质对地下河口(STE)中痕量元素和营养物质流动的重要性。为了准确量化STES对全球生物地球化学循环的影响，他们将调查各种沿海地貌中的反应和通量。这项研究将解决以下关键问题：1.沿海水文地质如何影响微量元素流入和流出地下河口的通量？他们将根据四个STES的水文和地质特征对其进行研究：(1)岩溶(墨西哥尤卡坦半岛)；(2)破碎的基岩(乌巴图巴，巴西)；(3)洋岛)火山和(B)碳酸盐台地(关岛)。这些地点的选择跨越了一系列的岩石类型、降雨量和含水层停留时间。2.这些通量对全球海洋中微量元素的质量平衡有什么影响？除了在STE内采样外，该团队还将使用镭同位素和氡来量化流向沿海海洋的痕量元素的流量。通过对这些地点进行季节性抽样，他们希望利用沿海类型学数据库将当地的通量扩大到全球估计的水平。这项工作的潜在更广泛影响预计将是巨大的。人类造成的营养丰富导致的富营养化是一种全球现象，可以说是沿海水域变化的最大动因。该项目将有助于更好地了解地下水在很大一部分沿海水域内输送微量金属和营养物质的行为，从而使社会受益。国际学生联合会将积极地让本科生和高中生参与这一项目，其中一些学生来自代表性不足的群体。一名全日制博士生将被资助参与这个项目。拟议的项目为研究生提供了各种具有挑战性的研究机会，这些机会跨越了传统学科的界限，如水文学、海洋地球化学和环境分析化学。其他更广泛的影响包括与其他国家的科学家合作。这项提案的外联部分将包括派？S参加美国军团的年度水资源教育培训。美国服务团成员参加在科德角各地的中学教室举行的地下水守护者水节，其中包括几个旨在向学生介绍科德角水循环的方方面面和水资源保护的动手演示。预计每年将有大约1800名学生参加这个项目。除了为志愿者提供培训讲座外，PI还将帮助开发用于该项目的新的海底地下水排放教学工具包。

Despite being a major vector for the land-ocean transport of materials, the role of groundwater in oceanic elemental mass balances has been poorly characterized. And where groundwater has been explicitly considered, most studies have not quantified the importance of chemical transformations that occur during the mixing of meteoric water with saline pore water (the ?subterranean estuary?) prior to surface water discharge. In this study, researchers at the Woods Hole Oceanographic Institution will examine the importance of coastal hydrogeology on the flux of trace elements and nutrients from subterranean estuaries (STEs). In order to accurately quantify the impact of STEs on global biogeochemical cycles, they will investigate reactions in, and fluxes from, a wide range of coastal geomorphologies. The study will address the following key questions: 1. How does coastal hydrogeology influence the fluxes of trace elements into and out of subterranean estuaries? They will conduct a study of four STEs on the basis of their hydrological and geological characteristics: (1) karst (Yucatan Peninsula, Mexico); (2) fractured bedrock (Ubatuba, Brazil); and (3) ocean island ) volcanic and (b) carbonate platform (Guam). These sites were chosen to span a range of rock type, rainfall, and aquifer residence time. 2. What effect do these fluxes have on the mass balance of trace elements in the global ocean? In addition to sampling within the STE, the team will use radium isotopes and radon to quantify the flux of trace elements to the coastal ocean. By sampling each of these sites on a seasonal basis, they expect to scale the local fluxes to the global estimates using a coastal typology database. The potential broader impacts of this work are expected to be significant. Eutrophication due to anthropogenic nutrient enrichment is a global phenomenon and is arguably the greatest agent of change in coastal waters. This project will benefit society by helping to develop a better understanding of the behavior of groundwater transported trace metal and nutrients within a large proportion of coastal waters. The PI will actively involve undergraduate and high school students in this project, some from underrepresented groups. One full time Ph.D. student will be funded to work on this project. The proposed project offers a graduate student a variety of challenging research opportunities that cross traditional disciplinary boundaries such as hydrology, marine geochemistry and environmental analytical chemistry. Other broader impacts include collaboration with scientists from other countries. The outreach component of this proposal will involve the PI?s participation in the annual AmeriCorps water resource education training. AmeriCorps members participate in the Groundwater Guardians Water Festivals, which are held in middle school classrooms across Cape Cod, and involve several hands-on demonstrations designed to introduce students to all aspects of the water cycle on Cape Cod and the protection of water resources. In all, approximately 1800 students are expected to participate in this program each year. In addition to providing a training lecture to the volunteers, the PI will aid in the development of new submarine groundwater discharge teaching aid kits for this program.