Dissolved trace elements in the tropical Northwest Pacific Ocean

该项目涉及与中国科学家合作分析2019年年中在西北太平洋采集的海水样本。这艘邮轮(编号为GP09)是一项名为GEOTRACES的国际合作研究工作的一部分，该工作正在研究整个海洋中微量元素和同位素的分布。一些微量元素是海洋中的微量营养物质，另一些元素少量具有潜在毒性，还有一些元素可以作为各种海洋过程的示踪物或指示物，例如热液投入或生产力。GP09邮轮提供了一个从一个地质复杂的地区获取痕量清洁水样的机会，该地区也是各种洋流和水团的汇合地。它将对北太平洋副热带环流的西南角进行采样，北太平洋副热带环流是最大的少营养(即低营养)海洋区域之一，也可以说是地球上最大的连续生态系统。这一区域可能受到沙尘输入(包括人为气溶胶)、固氮、热液输入以及与菲律宾风化和边缘循环有关的岛屿效应的影响。确定该地区的材料来源、汇和循环对于了解对该地区生产力的控制至关重要。许多待测定的微量元素对古替代应用(即了解这些元素的沉积物记录告诉我们有关过去海洋过程的信息)也是相关的。然而，成功的古代理应用通常需要对影响代理元素循环的过程有进一步的了解。由于GP09参与者需要确定的参数范围很广，因此邮轮为与中国同行提供了大量的合作机会。从该项目中获得的知识和经验将纳入首席调查员的海洋学课程。在外展活动方面，将与南密西西比大学海洋教育中心合作，邀请高中生参加科学家关于他们的研究的讲座。一名博士后学者还将接受培训，作为来自南密西西比大学的Projecta研究人员的一部分，他将从2019年年中西北太平洋的一次海洋研究巡航中获得干净、过滤的微量元素样本。这次邮轮(GP09)是GEOTRACES项目的一部分，由厦门大学的研究人员中国领导，还有来自中国其他主要海洋机构的其他参与者。地质和水文的复杂性，以及GP09邮轮轨道的寡养性，使这一地区成为一个特别有趣的研究区域。微量元素分布可能提供对各种源、汇和循环过程的广泛兴趣的洞察。例如，我们将要研究的一些元素已经被用作(或拟用作)古氧化还原和古生产力的代用元素[例如，钡(BA)、稀土元素(REE)、钒(V)、镉(Cd)]，但需要更好地了解它们的大洋循环，才能更充分地理解它们的代用信号。这里提议的研究还涉及重要问题，包括矿物粉尘和营养铁向表层海洋的输送[镓(Ga)，稀土，可能还有镉和钒]，痕量元素[巴，稀土]的去除和内循环，追踪物质来源，包括边缘来源[巴，锰(锰)，稀土，钒]和热液影响[锰，巴，稀土]，以及对示踪剂分布的保守和非保守变化[巴，稀土，钒]的理解。这艘游轮还允许与其他调查人员(主要是中国人)进行广泛合作。因此，溶解的Ga数据将与同事获得的关于铝(Al)和钍-232等其他致岩、快速清除元素的分布的数据进行比较；溶解的Ba数据将与那些确定Re和Ba同位素的人共享；REE数据将提供给那些检查钕同位素的人，以及与其他清除示踪剂(如Ga、Al和Th.)进行比较的数据。这项裁决反映了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。

This project involves a collaboration with Chinese scientists in the analysis of seawater samples collected during mid-2019 in the Northwest Pacific Ocean. The cruise (designated GP09) is part of an international collaborative research effort known as GEOTRACES, which is examining the distributions of trace elements and isotopes throughout the oceans. Some trace elements are micro-nutrients in the ocean, others are potentially toxic in small quantities, and still others can be tracers or indictors of the extent of various ocean processes such as hydrothermal inputs or productivity. The GP09 cruise affords an opportunity to obtain trace element clean water samples from a region that is geologically complex as well as being a meeting place for various ocean currents and water masses. It will sample the southwest corner of the North Pacific subtropical gyre, one of the largest oligotrophic (i.e., low nutrient) ocean regions and arguably the largest continuous ecosystem on Earth. This region is likely impacted by dust input (including anthropogenic aerosols), nitrogen fixation, hydrothermal inputs, and island effects associated with weathering of the Philippines and margin cycling. Determining material sources, sinks, and cycling in this region is ultimately important for understanding controls on the region's productivity. Many of the trace elements to be determined are also of relevance for paleo-proxy applications (i.e., for understanding what the sediment records of these elements tell us about past ocean processes). However, successful paleo-proxy applications generally require further insight into the processes that affect the cycling of the proxy elements. Because of the wide range of parameters to be determined by GP09 participants, the cruise affords substantial opportunities for collaboration with Chinese colleagues. The knowledge and experience gained from this project will be incorporated into the principle investigator's courses in oceanography. For outreach activities, in collaboration with the University of Southern Mississippi Marine Education Center, high school students will be invited to attend lectures given by scientists about their research. A postdoctoral scholar will also be trained as part of the projectA researcher from the University of Southern Mississippi will obtain clean, filtered trace element samples from a mid-2019 oceanographic research cruise in the Northwest Pacific Ocean. The cruise (GP09) is part of the GEOTRACES program and was led by researchers from Xiamen University, China, with additional participants from other major Chinese oceanographic institutions. The geological and hydrographic complexity, along with the oligotrophic nature of the GP09 cruise track, make this an especially interesting region for study. Trace element distributions are likely to provide insight into various source, sink, and cycling processes of broad interest. For example, a number of the elements we will study have been used (or proposed to be used) as paleoredox and paleoproductivity proxies [e.g., barium (Ba), rare earth elements (REEs), vanadium (V), cadmium (Cd)], but a better understanding of their oceanic cycling is needed to more fully understand their proxy signals. The studies proposed here are also pertinent to important issues including delivery of mineral dust and nutrient iron to the surface ocean [gallium (Ga), REEs and possibly Cd and V], removal and internal cycling of trace elements [Ba, REEs], tracing sources of material including margin sources [Ba, manganese (Mn), REEs, V] and hydrothermal influences [Mn, Ba, REEs], as well as understanding of conservative versus non-conservative changes in tracer distributions [Ba, REEs, V]. The cruise also allows extensive collaboration with other, mainly Chinese, investigators. Thus, the dissolved Ga data will be compared with data obtained by colleagues on distributions of other lithogenic, rapidly-scavenged elements like aluminum (Al) and thorium-232; the dissolved Ba data will be shared with those determining radium and Ba isotopes; and, the REE data will be made available to those examining neodymium isotopes, as well as compared with other scavenging tracers such as Ga, Al, and Th.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.