US GEOTRACES GP17-ANT: Quantifying the Properties of Atmospheric Trace Elements and Their Fluxes to the Amundsen Sea

The goal of the international GEOTRACES program is to understand the distributions of many chemical elements and their isotopes in the oceans. The National Science Foundation is supporting a U.S. GEOTRACES sampling expedition in the Southern Ocean and Amundsen Sea. This three-year project, for the first time, measures the atmospheric properties of trace elements and their fluxes to the Amundsen Sea as part of the US GEOTRACES GP17-ANT section. This project will focus on the measurement of trace elements in atmospheric aerosols, which are an important source of trace elements to many areas of the oceans. In addition, the investigators will determine the sources of dust and aerosol particles, and quantify the amounts of trace metals delivered to the surface ocean, where they provide essential nutrients to phytoplankton blooms. The new observational data from this project can be used to support both atmospheric and ocean models for coupled air-sea interaction simulations and projections, promoting interdisciplinary sciences. This project will make significant broader impacts by involving female and minority students in research at both the doctoral and undergraduate levels. The lead investigator will incorporate the results from this project into her teachings to promote classroom learning with examples of real-world research, and she will actively participate in the GEOTRACES outreach program to contribute to its education activities. The primary goal of this project is to quantify the key properties of atmospheric trace elements and their fluxes to the Amundsen Sea. The ultimate goal is to advance the knowledge of the atmosphere-ocean-ice interactions for improved understanding of the Earth climate system. The working objectives of this project are: (1) To determine aerosol composition and mineralogy and to explore the sources of dust and target trace elements, including Fe, Al, Ca, Cd, Co, Cu, K, Mn, Na Ni, P, Pb, Ti, V, and Zn; (2) To measure particle-size distributions of aerosol trace elements, aerosol Fe fractional solubility and speciation, organic/inorganic ligands including oxalate and ammonium, and marine biogenic tracers including methanesulfonate and non-sea-salt sulfate and to understand better trace element solubility and processes affecting them; (3) To quantify total atmospheric fluxes of trace elements by both dry deposition and wet deposition processes, contributing to understanding trace element distributions in seawater. Aerosol samples collected on the GP17-ANT cruise will be analyzed for concentrations, composition and mineralogy by utilizing inductively coupled plasma mass spectrometry (ICPMS), synchrotron-based X-ray absorption spectroscopy (XAS) and scanning electron microscopy (SEM). Air mass back trajectory-based cluster analyses will be performed for different air mass provinces impacting the study region. Iron solubility and speciation in aerosol samples will be measured using UV/VIS spectrophotometry and synchrotron-based XAS. Ion chromatography will be utilized to determine water-soluble organic and inorganic species of marine origins. Trace elements in size-segregated aerosols and precipitation will be measured. Atmospheric deposition models will be used to calculate the deposition fluxes to the Amundsen Sea. 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.