Dissolved trace elements in the tropical Northwest Pacific Ocean

热带西北太平洋溶解的微量元素

• 批准号: 1925503
• 负责人: Christopher Hayes
• 金额: $ 32.04万
• 依托单位: University of Southern Mississippi
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1925503&HistoricalAwards=false
• 关键词: Dissolved; trace; elements; tropical; Northwest

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.

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。这次巡洋舰（编号GP09）是国际合作研究项目GEOTRACES的一部分，该项目旨在研究海洋中微量元素和同位素的分布情况。有些微量元素是海洋中的微量营养素，有些微量元素在少量时具有潜在毒性，还有一些可以是各种海洋过程（如热液输入或生产力）程度的示踪剂或指标。GP09巡航提供了一个从地质复杂的地区获取微量元素清洁水样本的机会，同时也是各种洋流和水团的聚集地。它将在北太平洋副热带环流的西南角取样，这是最大的少营养（即低营养）海洋区域之一，可以说是地球上最大的连续生态系统。该区域可能受到灰尘输入（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相关的岛屿效应的影响。确定该地区的物质来源、汇和循环对于理解该地区生产力的控制至关重要。许多待测定的微量元素也与古替代应用相关（即，了解这些元素的沉积物记录告诉我们过去海洋过程的信息）。然而，成功的古代理应用程序通常需要进一步了解影响代理元素循环的过程。由于GP09参与者需要确定的参数范围很广，因此这次巡航为与中国同事合作提供了大量机会。从这个项目中获得的知识和经验将被纳入首席研究员的海洋学课程。在与南密西西比大学海洋教育中心合作的推广活动中，高中学生将被邀请参加科学家关于他们研究的讲座。一名博士后学者也将作为该项目的一部分接受培训。来自南密西西比大学的一名研究人员将从2019年年中西北太平洋的一次海洋学研究巡航中获得清洁、过滤的微量元素样本。这次航行（GP09）是GEOTRACES计划的一部分，由中国厦门大学的研究人员领导，其他参与者来自中国其他主要海洋机构。地质和水文的复杂性，以及GP09巡航轨道的寡营养性质，使这个地区成为一个特别有趣的研究区域。微量元素的分布可能提供对各种源、汇和循环过程的深入了解。例如，我们将研究的许多元素已被（或拟被）用作古氧化还原和古生产力的代用元素[如钡（Ba）、稀土元素（REEs）、钒(V)、镉（Cd）]，但需要更好地了解它们的海洋循环，才能更全面地理解它们的代用信号。这里提出的研究也涉及到重要的问题，包括矿物粉尘和营养铁向海洋表面的传递[镓（Ga），稀土，可能还有Cd和V]，微量元素[Ba， REEs]的去除和内部循环，包括边缘源[Ba，锰（Mn），稀土，V]在内的物质来源的示踪和热液影响[Mn， Ba, REEs]，以及对示踪剂分布[Ba， REEs， V]的保守和非保守变化的理解。游轮还允许与其他调查人员（主要是中国调查人员）进行广泛合作。因此，溶解的Ga数据将与同事获得的其他快速清除的成岩元素如铝（Al）和钍-232的分布数据进行比较；溶解的Ba数据将与测定镭和Ba同位素的数据共享；稀土元素数据将提供给那些检测钕同位素的人，并与其他清除示踪剂（如Ga， Al和Th）进行比较。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。