Atmospheric and Lateral Inputs of Trace Metals in the Indonesian Through-Flow

南方蓝鳍金枪鱼（SBT）的产卵场位于澳大利亚西北海岸和印度尼西亚之间。来自太平洋的沃茨流经东南亚岛屿，形成印度尼西亚洋流（ITF），流入西印度洋。ITF的营养条件不足以支持SBT幼虫的最佳摄食和生长，营养循环和食物链之间的许多联系仍然未知。该地区对氮、磷和铁等主要和微量营养素的测量很少。 这些营养物质支持浮游植物，形成食物链的基础，并影响更高的营养级，包括SBT。这项工作将调查该地区主要和次要营养物质的潜在来源，包括岛屿输入，澳大利亚灰尘，季风雨和沉积通量，这将有助于制定一个“营养预算”，并揭示哪些来源对早期SBT生命阶段的成功贡献最大。该项目是美国对第二次国际印度洋考察（IIOE-2）的贡献，将促进对研究不足的东印度洋的地球化学和生态动力学的了解。该项目将支持一个早期的职业博士后研究人员和外联活动将包括在家里institution.The ITF的开放日活动和REU夏季计划的参与可能会发生变化的主要和微量营养物质的分布在通过东南亚岛屿亚洲海峡的通道。沿岸流可以使含有Si和Fe等营养物质的陆架沉积物重新悬浮，而来自澳大利亚和东南亚的天然和人工来源的物质的大气沉积可以提供N，P，Fe和其他微量金属。季风雨也通过气溶胶的湿沉降和径流提供营养。这些输入将营养物质引入ITF的表层海洋，浮游植物可以将无机营养物质转化为生物量，从而为整个食物链提供燃料。在这项研究中，将调查气溶胶和水柱痕量金属，作为另一个NSF资助的BLOOFINZ项目的补充组成部分，该项目旨在了解南方蓝鳍金枪鱼产卵场的N循环和食物网动态。拟议的研究将解决三个假设：（H1）ITF接收输入的生物活性微量元素从湿和干大气沉积物和再悬浮沉积物，和（H2）运输这些营养物质通过南赤道流（SEC）在印度洋。(H3)大气沉积的矿物和人为气溶胶或大陆架的铁输入可能有助于减轻ITF的N限制。为了调查这些假设并了解ITF中痕量金属的输入、去除和循环，将对气溶胶和海洋溶解态和颗粒态中物质的浓度、元素比和通量进行量化和比较。该奖项反映了NSF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。

The spawning grounds of the Southern Bluefin Tuna (SBT) lie between the northwestern Australian coast and Indonesia. Waters from the Pacific flow through Island Southeast Asia as the Indonesian Through-Flow (ITF) and into the western Indian Ocean. Nutrient conditions in the ITF are insufficient to support optimum feeding and growth of SBT larvae, and numerous links between the nutrient cycles and food chain remain unknown. There are very few measurements of both major and trace nutrients like nitrogen, phosphorus, and iron made in the region. These nutrients support phytoplankton that form the base of the food chain and affect higher trophic levels, including SBT. This work will investigate the potential sources of major and minor nutrients to the region, including island inputs, Australian dust, monsoon rains, and sedimentary fluxes which will help develop a “nutrient budget” and reveal which sources contribute the greatest to the success of early SBT life stages. This project is a US contribution to the 2nd International Indian Ocean Expedition (IIOE-2) that will advance understanding of biogeochemical and ecological dynamics in the poorly studied eastern Indian Ocean. The project will support an early career postdoctoral researcher and outreach activities will include participation in Open House events and REU summer program at home institution.The ITF can undergo potential changes to the distributions of major and trace nutrients during passage through the straits of southeast island Asia. Coastal currents can resuspend shelf sediments containing nutrients like Si and Fe, while the atmospheric deposition of both natural and anthropogenically derived material from Australia and southeastern Asia can supply N, P, Fe, and other trace metals. Monsoon rains also supply nutrients via wet deposition of aerosols and runoff. These inputs introduce nutrients to the surface ocean of the ITF, where phytoplankton can convert inorganic nutrients to biomass and in turn fuel the entire food chain. In this research aerosols and water column trace metals will be investigated, as a complementary component to another NSF-funded BLOOFINZ project which seeks to understand the N cycling and food-web dynamics of the southern bluefin tuna spawning grounds. The proposed research will address three hypotheses: (H1) The ITF receives inputs of bioactive trace elements from wet and dry atmospheric deposition and resuspended sediments, and (H2) transports these nutrients across the Indian Ocean via the South Equatorial Current (SEC). (H3) Inputs of Fe from atmospheric deposition of mineral and anthropogenic aerosols or continental shelves could help alleviate N limitation in the ITF. To investigate these hypotheses and understand the inputs, removals, and cycles of trace metals in the ITF, the concentrations, elemental ratios, and fluxes of material in aerosols and marine dissolved and particulate phases will be quantified and compared.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.