Jessica Fitzsimmons

Jessica Fitzsimmons

Associate Professor

Chemical Oceanography: Trace metal biogeochemistry, nutrients, pollutants, colloids, isotopes, hydrothermal vents, polar oceanography

  jessfitz@tamu.edu

  (979) 845-5137

  Eller O&M 403A

Research

The Fitzsimmons Lab values diverse perspectives, talents, and identities that we consider essential to broadening the scientific and societal impact of our science. However, unfortunately we are not accepting new graduate students for 2024-2025. Interested parties are always welcome to contact jessfitz@tamu.edu with a copy of your CV for more information.

  • Trace metal biogeochemistry
  • Colloids and metal speciation
  • Metal stable isotopes
  • Hydrothermal vent biogeochemistry
  • Polar Oceanography
  • Inductively-Coupled Plasma Mass Spectrometry
  • Analytical chemistry
  • Inorganic Chemical Oceanography

Fitzsimmons is a chemical oceanographer interested in the biogeochemical cycling of trace metals in the ocean. Trace metals are important to study because they can act as (1) nutrients for marine organisms, (2) anthropogenic pollutants, and/or (3) tracers for oceanographic processes. Metals such as iron, copper, manganese, zinc, cadmium, and nickel are required nutrients for photosynthesizing plankton (phytoplankton), who sit at the base of the marine food web and contribute to the removal of carbon dioxide from the atmosphere. However, trace metals are present in very low concentrations in seawater, and as a result some metals (iron being the best example) have been shown to limit the growth of phytoplankton in more than a third of the global surface ocean. We know that phytoplankton are an integral part of the global carbon cycle and heavily influence the feedback cycles of earth's climate both today and during the geologic past. Thus, trace metals play an important role in global carbon cycling and thus global climate, making it important topic of study study in the face of modern climate change.


The Fitzsimmons group studies the distribution, physicochemical speciation, and isotope ratios of trace metals in seawater in order to better understand the cycles and biological usage of metals in the water column. We are a sea-going group, collecting our samples at sea and then analyzing them back in the laboratory. Our primary analytical tool is inductively coupled plasma mass spectrometry (ICP-MS), which is housed in the Williams Radiogenic Laboratory at Texas A&M. However, biogeochemistry is by its very name an interdisciplinary field, and thus we evaluate all trace metal processes in close cooperation with other labs measuring the biological, geologic, and physical parameters of our study regions, which frames our interpretation in the context of the global ocean system.

Selected Publications

  • Lanning, NT, Jiang, S, Amaral, VJ, Mateos, K, Steffen, JM, Lam, PJ, Boyle, EA, and Fitzsimmons, JN. (2023) Isotopes illustrate vertical transport of anthropogenic Pb by reversible scavenging within Pacific Ocean particle veils. Proceedings of the National Academy of Sciences, 120 (23): e2219688120. https://doi.org/10.1073/pnas.2219688120.
  • Sieber, M, Lanning, NT, Bian, X, Yang, S-C,Takano, S, Sohrin, Y, Weber, T, Fitzsimmons, JN, John, SG, and Conway, TM. (2023) The importance of reversible scavenging for the marine Zn cycle evidenced by the distribution of zinc and its isotopes in the Pacific ocean. Global Biogeochemical Cycles, 128 (4), e2022JC019419. doi: 10.1029/2022JC019419.
  • Fitzsimmons, JN and Conway, TM. (2023) Novel insights into marine iron biogeochemistry from iron isotopes. Annual Reviews of Marine Science, 15: 383-406. doi: 10.1146/annurev-marine-032822-103431. (invited)
  • Sieber, M, Lanning, NT, Bunnell, ZB, Yang, S-C, Marsay, CM, Landing, WM, Buck, CS, Fitzsimmons, JN, John, SG, and Conway, TM. (2023) Biological, physical, and atmospheric controls on the distribution of cadmium and its isotopes in the North Pacific Ocean. Journal of Geophysical Research-Oceans 37, e2022GB007441, doi: 10.1029/2022GB007441.
  • Hicks, TL, Shamberger, KEF, Fitzsimmons, JN, Jensen, CC, DiMarco, SF. (2022) Tropical cyclone-induced coastal acidification. Nature Communications Earth & Environment, 3(297). doi: 10.1038/s43247-022-00608-1.
  • Williford, T, Amon, RMW, Benner, R, Kaiser, K, Stedmon, C, Bauch, D, Fitzsimmons, JN, Gerringa, LJA, Newton, R, Hansell, DA, Granskog, MA, Jensen, LT, Laglera, LM, Pasqualini, A, Rabe, B, Reader, H, Rutgers van der Loeff, M, Yan, G. (2022) Spatial complexity in dissolved organic matter and trace elements driven by hydrography and freshwater input across the Arctic Ocean during 2015 Arctic GEOTRACES expeditions. Journal of Geophysical Research – Oceans, 127 (11), e2022JC018917. doi: 10.1029/2022JC018917.
  • John, SG, Kelley, RL, Bian, X, Y, S-C, Fu, F, Smith, MI, Lanning, NT, Liang, H, Pasquier, B, Seelen, E, Holzer, M, Conway, TM, Fitzsimmons, JN, and Hutchins, DA. (2022) The biogeochemical balance of oceanic nickel cycling. Nature Geoscience, 15: 906-912. doi: 10.1038/s41561-022-01045-7.
  • Marsay, CM, Landing, WM, Umstead, D, Till, CP, Freiberger, R, Fitzsimmons, JN, Lanning, NT, Shiller, AM, Hatta, M, Saito, M, Chmiel, R, Buck, CS. (2022) Does sea-spray aerosol contribute significantly to aerosol trace element loading? A case study from the US GEOTRACES Pacific Meridional Transect (GP15). Global Biogeochemical Cycles, 36, e2022GB007416. doi: 10.1029/2022GB007416.
  • Jensen, LT, Cullen, JT, Gerringa, L, Bauch, D, Middag, R, Sherrell, RM, and Fitzsimmons, JN. (2022). A refinement of the processes controlling dissolved copper and nickel biogeochemistry: insights from the pan-Arctic. Journal of Geophysical Research: Oceans Special Issue on Arctic Ocean, 127, e2021JC018087. doi: 10.1029/2021JC018087.
  • Chmiel, R, Lanning, NT, Laubach, A, Lee, J-M, Fitzsimmons, JN, Hatta, M, Jenkins, WJ, Lam, PJ, McIlvin, M, Tagliabue, A, Saito, MA. (2022). Major processes of the dissolved cobalt cycle in the North and equatorial Pacific Ocean. Biogeosciences, 19, 2365-2395. doi: 10.5194/bg-19-2365-2022.
  • Lopez, AM, Fitzsimmons, JN, Adams, HM, Dellapenna, TM, and Brandon, AD (2022). A time-series of heavy metal geochemistry in sediments of Galveston Bay estuary, Texas, 2017-2019. Science of the Total Environment, 806 (3): 150446. doi: 10.1016/j.scitotenv.2021.150446.
  • Zhang, R, Jensen, LT, Fitzsimmons, JN, Sherrell, RM, Lam, PJ, Xiang, Y, and John, SG. (2021) Iron isotope biogeochemical cycling in the western Arctic Ocean. Global Biogeochemical Cycles, 35, e2021GB006977. doi: 10.1029/2021GB006977.
  • Jensen, LT, Lanning, NT, Marsay, CM, Buck, CS, Aguilar-Islas, A, Rember, R, Landing, WJ, Sherrell, RM, and Fitzsimmons, JN (2021). Biogeochemical cycling of colloidal trace metals in the Arctic cryosphere. Journal of Geophysical Research: Oceans, Special Issue on Arctic Ocean. 126, e2021JC0177394. doi: 10.1029/2021JC017394.
  • Lopez, AM, Brandon, AD, Ramos, RC, Fitzsimmons, JN, Dellapenna, TM, and Adams, HM (2021) Lead geochemistry of sediments in Galveston Bay, Texas. Environmental Advances, 4: 100057 doi: 10.1016/j.envadv.2021.100057.
  • Hoffman, CL, Schladweiler, C, Seaton, NCA, Nicholas, SL, Fitzsimmons, JN, Sherrell, RM, German, CR, Lam, PJ, and Toner, BM (2020). Diagnostic morphology and solid-state chemical speciation of hydrothermally derived particulate Fe in a long-range dispersing plume. ACS Earth & Space Chemistry, Special Issue on Marine Particles. 4: 1831-1842. doi: 10.1021/acsearthspacechem.0c00067.
  • Jensen, LT, Morton, P, Twining, BS, Heller, MI, Hatta, M, Measures, CI, John, SG, Zhang, R, Sherrell, RM, and Fitzsimmons, JN (2020). A comparison of marine Fe and Mn cycling: U.S. GEOTRACES GN01 Western Arctic case study. Geochimica et Cosmochimica Acta. doi: 10.1016/j.gca.2020.08.006.
  • Jenkins, WJ, Hatta, M, Fitzsimmons, JN, Schlitzer, Lanning, NT, R, Shiller, A, Buckley, NR, German, CR, Lott III, DE, Weiss, G, Whitmore, L, Casciotti, K, Lam, PJ, Cutter, GA, Cahill, KL (2020). An intermediate-depth source of hydrothermal 3He and dissolved iron in the North Pacific. Earth and Planetary Science Letters, 539: 116223. doi: 10.1016/j.epsl.2020.116223.
  • Charette, MA, Kipp, LE, Jensen, LT, Dabrowski, JS, Whitmore, LM, Fitzsimmons, JN, Williford, T, Ulfsbo, A, Jones, E, Bundy, RM, Vivancos, SM, Pahnke, K, John, SG, Xiang, Y, Hatta, M, Petrova, M, Heimburger-Bovaida, L-E, Bauch, D, Newton, R, Pasqualini, A, and more than 40 other authors listed alphabetically (2020). The Transpolar Drift as a source of riverine and shelf-derived trace elements to the Central Arctic Ocean. Journal of Geophysical Research: Oceans, 125: e2019JC015920. doi: 10.1029/2019JC015920.
  • Kadko, D, Aguilar-Islas, A, Buck, C, Fitzsimmons, JN, Landing, WJ, Shiller, A, Till, CP, Bruland, KW, Boyle, EA, and Anderson, RF (2020). Sources, fluxes, and residence times of trace elements measured during the U.S. GEOTRACES East Pacific Zonal Transect. Marine Chemistry, 222: 103781. doi: 10.1016/j.marchem.2020.103781.
  • Hayes, CT, Fitzsimmons, JN, Jensen, LT, Lanning, NT, Hatta, M, McGee, D, and Boyle, EA. (2020) A Lagrangian view of trace elements and isotopes in the North Pacific. Journal of Geophysical Research: Oceans, 125, e2019JC015862. doi: 10.1029/2019JC015862.
  • Jensen, LT, Wyatt, NJ, Landing, WM, and Fitzsimmons, JN. (2020) Assessment of the stability, sorption, and exchangeability of marine colloidal metals. Marine Chemistry, 220: 103754. doi: 10.1016/j.marchem.2020./103754.
  • Carvalho, F, Fitzsimmons, JN, Couto, N, Gorbunov, M, Kohut, J, Oliver, MJ, Sherrell, RM, and Schofield, O (2020) Testing the Canyon Hypothesis: Evaluating light and nutrient controls of phytoplankton growth in penguin foraging hotspots along the West Antarctic Peninsula. Limnology & Oceanography, 65:455-470. doi: 10.1002/lno.11313.
  • Zhang, R, Jensen, LT, Fitzsimmons, JN, Sherrell, RM, and John, SG. (2019) Dissolved cadmium and cadmium stable isotopes in the western Arctic Ocean. Geochimica et Cosmochimica Acta, 258: 258-273. doi: 10.1016/j.gca.2019.05.028.
  • Jensen, LT, Wyatt, NJ, Twining, BS, Rauschenberg, S, Landing, WM, Sherrell, RM, and Fitzsimmons, JN (2019). Biogeochemical cycling of dissolved zinc in the Western Arctic (GEOTRACES GN01). Global Biogeochemical Cycles, 33. doi: 10.1029/2018GB005975.
  • Cheize, M, Planquette, H, Fitzsimmons, JN, Pelleter, E, , Sherrell, RM, Lambert, C, Bucciarelli, E, Sarthou, G, Boutorh, J, Le Goff, M, Liorzou, C, Cheron, S, Viollier, E, Gayet, N. (2019) Contribution of resuspended sediments to the dissolved trace metal pool: An experimental study. Chemical Geology, 511: 389-415. doi: 10.1016/j.chemgeo.2018.10.003.
  • Boiteau, RM, Till, CP, Coale, T, Fitzsimmons, JN, Bruland, KW, and Repeta (2019), D. Patterns of iron and siderophore distributions across the California Current System. Limnology & Oceanography, 64: 376-389. doi:10.1002/lno.11046.
  • Kadko, D, Aguilar-Islas, A, Bolt, C, Buck, CS, Fitzsimmons, JN, Jensen, LT, Landing, WM, Marsay, CM, Rember, R, Shiller, AM, Whitmore, LM, Anderson, RM. (2019) The residence time of trace elements determined in the surface Arctic Ocean during the 2015 US Arctic GEOTRACES expedition. Marine Chemistry, 208: 56-69. doi:10.1016/j.marchem.2018.10.011
  • Fitzsimmons, JN, John, SG, Marsay, CM, Hoffman, C, Nicholas, S, Toner, BM, German, CR, and Sherrell, RM. (2017) Iron persistence in a distal hydrothermal plume supported by dissolved-particulate exchange. Nature Geoscience, 10: 195-201. doi: 10.1038/ngeo2900

    See publications prior to 2019 on Google Scholar.

Education

Ph.D. Chemical Oceanography, MIT/WHOI Joint Program, 2013.

B.A. Chemistry, Biology with a concentration in Marine Science, Boston University, 2008.

Awards

2023 – Texas A&M College of Arts & Sciences Research Impact Award for Associate Professors

2021 – International Association of the Physical Sciences of the Oceans (IAPSO) Early Career Award in the Chemical Ocean Sciences

2020 - Texas A&M College of Geosciences Dean’s Distinguished Award for Faculty Service

2019 – National Academy of Sciences, Gulf Research Program, Early-Career Fellowship

2014 – Rossby Award for Best Dissertation in the MIT Programs in Atmospheres Oceans & Climate

2009-2012 – NSF Graduate Research Fellowship

2006 – Ernest F. Hollings Scholarship & Internship, NOAA

Links

Link to CV

Link to Google Scholar page

Courses

OCNG 251 – Oceanography

OCNG 453 – Hydrothermal Vents & Mid-Ocean Ridges

OCNG 640 – Chemical Oceanography

OCNG 641 – Inorganic Aquatic Geochemistry

Additional Information

Current Students:

1. Janelle Steffen (Ph.D. student)

2. Shelby Gunnells (Ph.D. student)

3. Yerim Kim (Ph.D. student)

4. Kristie Dick (Ph.D. student)

5. Teagan Bellitto (Ph.D. student)

Active Projects: 

1. U.S. GEOTRACES GP17-ANT: Dissolved concentrations, isotopes, and colloids of the bioactive trace metals. NSF Chemical Oceanography 2123333. $1,202,652; $410,163 TAMU portion. (10/21 – 9/25). Lead-PI: Tim Conway (USF). Co-PIs: Jessica Fitzsimmons (TAMU) and Seth John (USC).

Student: Teagan Bellitto and Yerim Kim

The GP17-ANT project is part of the International GEOTRACES Program, which seeks to constrain the sources, sinks, and distributions of trace elements and their isotopes across the global ocean. The GP17-ANT program will explore the Amundsen Sea near Antarctica, which hosts multiple glaciers including the Thwaites Glacier, which is one of the fastest melting glaciers flowing from the West Antarctic Ice Sheet. GP17-ANT aims to use chemical tracers to understand the impact of glacial melt, benthic sediment fluxes, dust fluxes, circulation, and biological utilization for setting the distributions of trace elements in the Amundsen Sea. Specifically, the Fitzsimmons lab’s roles in GP17-ANT is to measure the concentrations of multiple dissolved trace metals (iron, zinc, copper, cadmium, nickel, manganese, and lead) and their partitioning into soluble and colloidal size fractions to understand the relative contributions of iron from deep water, benthic, and glacial melt sources, in order to develop a greater understanding of how iron is modified by various input and output fluxes within the Amundsen Sea, before it is delivered to anemic phytoplankton in the greater Southern Ocean.

 

2. U.S. GEOTRACES GP17-OCE: Dissolved concentrations, isotopes, and colloids of the bioactive trace metals. NSF Chemical Oceanography 2049241. $1,177,457; $456,770 TAMU portion. (4/21 – 3/25). Lead-PI: Jessica Fitzsimmons (TAMU). Co-PIs: Tim Conway (USF) and Seth John (USC).

Management and implementation of the U.S. GEOTRACES GP17 section: South Pacific and Southern Ocean. NSF Chemical Oceanography 2023206. $1,951,183; $502,824 TAMU portion. (10/20 – 9/23).

Lead-PI: Ben Twining (Bigelow). Co-PIs: Jessica Fitzsimmons and Christina Wiederwohl (TAMU) and Greg Cutter (ODU).

Students: Kristie Dick and Yerim Kim.

The GP17-OCE project is part of the International GEOTRACES Program, which seeks to constrain the sources, sinks, and distributions of trace elements and their isotopes across the global ocean. The GP17-OCE program will explore the South Pacific and Southern Oceans. GP17-OCE, which sails from Tahiti to Antarctica and back to Chile, South America, aims to use chemical tracers to understand the sources and sinks of trace metals to the massive and ever-important South Pacific Ocean, which is some of the most nutrient-limited water in the world but also home to critical biogeochemical gradients and carbon sequestration zones. Specifically, the Fitzsimmons lab’s roles in GP17-OCE is to measure the concentrations of multiple dissolved trace metals (iron, zinc, copper, cadmium, nickel, manganese, and lead) and their partitioning into soluble and colloidal size fractions to understand the relative contributions of iron from dust, hydrothermal vents, sediments, Antarctica, water mass circulation, and the marine ecosystem, in order to develop a greater understanding of how metal inventories are affected by oceanic processes.

3. Accelerating Thwaites Ecosystem Impacts for the Southern Ocean (ARTEMIS). NSF GEO-NERC 1941308. $1,864,037; $252,830 TAMU portion. (8/21 – 7/25).

Lead-PI: Tish Yager (UGA). Co-PIs: Rob Sherrell (Rutgers), Patricia Madeiros (UGA), Pierre St-Laurent (VIMS), Sharon Stammerjohn (UC-Boulder).

Student: Janelle Steffen

This project will investigate the biogeochemical impacts of glacial melt from the Thwaites glacier, Amundsen Sea, Antarctica, which is one of the fastest melting glaciers flowing from the West Antarctic Ice Sheet. The physical melting processes are being studied by the International Thwaites Glacier Collaboration (ITGC), including an ongoing oceanographic field program (TARSAN). ARTEMIS aims to use trace metal, nutrient, organic matter, and microorganism measurements to understand the impact of glacial melt on the coastal ecosystem and the regional carbon cycle. Specifically, the Fitzsimmons lab’s roles in ARTEMIS are to examine iron speciation (colloids) along the cruise transect and employ iron isotope measurements to understand the relative contributions of iron from deep water, benthic, and glacial melt sources, in order to develop a greater understanding of how iron is modified along the Antarctic coastal current.

4. Characterization of the water column environment in relation to the testing of a prototype deep-sea mining vehicle in the eastern Clarion Clipperton Zone (CCZ), Pacific Ocean. The Metal Company, formerly known as DeepGreen Metals, Inc. $3,893,109; $1,011,435 TAMU portion.

Lead-PIs: Jeff Drazen (University of Hawaii) and Jessica Fitzsimmons (TAMU). Co-PIs: Mariko Hatta and Chris Measures (University of Hawaii) and a host of others.

Student: Shelby Gunnells

This is a project funded by The Metals Company to study the water column ecosystem of the NORI-D exploration region in the CCZ, both during baseline studies pre-mining and after mining trials. This project is an interdisciplinary collaboration, and our part will be to study the chemical oceanography of the CCZ water column, including oxygen, macronutrients, micronutrient and contaminant trace metals in the dissolved and particulate phases, pH/DIC/alkalinity, dissolved and particulate organic carbon, and total suspended solids. We are also interested in identifying the best tracers for deep-sea mining impacts, both by sensors and by more sensitive chemical measurements, as well as experiments outlining the longer-term transformations of mining discharged chemicals in the water column.

5. Hydrothermal Estuaries: What sets the hydrothermal flux of Fe and Mn to the oceans? National Science Foundation, OCE-1851078. $1,658,407; $399,558 TAMU portion (6/1/19 – 5/31/25).

Lead-PI: Chris German (WHOI). Co-PIs: Brandy Toner (Minnesota), Chip Breier (UTRGV), Guangyu Xu (APL-UW).

Student: Kristie Dick

This project will fill a critical knowledge gap in understanding the impact of hydrothermal venting on ocean chemistry by combining state-of-the-art plume modeling, AUV-based water column surveys, and GEOTRACES-quality marine biogeochemistry. We will conduct our work at the Endeavor Segment of the Juan de Fuca Ridge, which is one of few locations on Earth where one can effectively model the track of a dispersing hydrothermal plume over the critical 1-100 km length scale that determines the ultimate flux of metals such as Fe and Mn into the ocean interior. We will complete GEOTRACES-quality soluble, colloidal, dissolved, and particulate metal analyses, complemented by He isotope, Fe-binding ligand and siderophore, POC, DOC, and dissolved oxygen analyses to determine the biotic and abiotic processes involved in setting these critical ocean fluxes of micronutrient metals.

6. Iron isotopes in seawater using multi-collector ICP-MS.
Student: Janelle Steffen
The Williams Radiogenic Lab at Texas A&M was funded by the National Science Foundation and Texas A&M for the acquisition of a new high-resolution, multi-collector ICP-MS instrument, the ThermoFisher Scientific Neptune Plus. This instrument will be used for the analysis of stable iron isotopes in seawater, which can be used to trace the source of iron to the ocean, as well as track any isotope-fractionating that iron is undergoing in seawater. Samples from three ocean regions/projects are archived in the lab for analysis: (1) soluble and colloidal-filtered seawater from the 4000-km long, East Pacific Rise hydrothermal plume in the South Pacific Ocean, (2) dissolved samples from West Antarctic Peninsula continental shelf, and (3) dissolved and colloidal seawater from the central California Current.

7. Heavy metal contaminants and lead isotopes in waters and sediments of Galveston Bay, Texas.

Students: Yerim Kim (and previously Mandy Mulcan Lopez University of Houston)

This is a project funded by the Galveston Bay Estuary Program (Texas Commission on Envionrmental Quality) in collaboration with Alan Brandon (University of Houston) and by the Texas A&M University T3 Triad program and College of Geosciences High Impact Learning Program in collaboration with Oceanography faculty Franco Marcantonio, Gerardo Gold, Shari Yvon-Lewis, Katie Shamberger, and Kristen Thyng, Civil Engineering faculty Jim Kaihatu and Bella Chu, and Texas A&M Galveston faculty Antonietta Quigg. We are investigating heavy metal and organic pollutant inputs and estuarine acidification in Galveston Bay with seasonal cruises each year. The 2017-2018 cruises captured the effects of Hurricane Harvey on Galveston Bay, while 2019 cruises captured the effects of the Deer Park ITC fire/spill, with additional cruises into the San Jacinto and Trinity Rivers. Graduate and undergraduate students have all participated in these day cruises and sample analyses of the water column, air, sediment, and oyster samples. Fitzsimmons lab students have measured heavy metals in the waters, sediments, and oysters of Galveston Bay and aim to use lead (Pb) isotopes to track sources of heavy metals to different parts of the Galveston Bay estuary.

Past Projects:

1. U.S. GEOTRACES Pacific Meridional Transect (PMT), National Science Foundation, OCE-1737167; $580,976; $464,498 TAMU portion. (11/2017 – 10/2023). Lead PI: Jessica Fitzsimmons (TAMU); Co-PI Claire Till, Humboldt State University.
Student: Nate Lanning (2018-2023, Ph.D.) – Now a postdoc at Masschusetts Institute of Technology.
This is a project to measure the dissolved and colloidal micronutrient metal concentrations of a suite of eight metals (Fe, Mn, Zn, Cu, Cd, Ni, Pb, and Sc) across the Northern and Southern Central Pacific Ocean along 152°W as a part of the International GEOTRACES Program (Section GP15). We aim to determine the input and output fluxes of metals in this dynamic ocean basin, as well as how the size partitioning of the dissolved metal phase determines its fate with respect to scavenging and biological uptake. The cruise section goes from Seattle, WA, to Tahiti and took place from September-November 2018.

2. U.S. Arctic GEOTRACES, National Science Foundation, OCE-1434493; $497,314; $326,183 TAMU portion (1/2015 – 12/2019). Lead PI: Jessica Fitzsimmons (TAMU); Co-PI Robert Sherrell, Rutgers University.
Student: Laramie Jensen (2015-2020, Ph.D.) – Now a postdoc at University of Washington, Cooperative Institute for Climate, Ocean, and Ecosystem Studies.
This was a project to measure the dissolved and colloidal micronutrient metal concentrations of a suite of eight metals (Fe, Mn, Zn, Cu, Cd, Ni, Pb, and Sc) across the Western Arctic Ocean as a part of the International GEOTRACES Program (Section GN01). We aimed to identify which polar and biological processes, many of which are already undergoing fundamental changes as a result of climate warming, control the inputs and fate of essential micronutrient metals in the Arctic Ocean. This cruise went in and out of Dutch Harbor, Alaska and took place in Fall 2015. The archived data product can be found at BCO-DMO (Dataset 817259), and we have many publications describing our conclusions.

3. Physicochemical speciation of dissolved iron, National Science Foundation, OCE 1558722 $468,081; $198,737 TAMU portion. (9/2014 – 8/2018). Lead-PI Mark Wells, University of Maine; Co-PI: Jessica Fitzsimmons (TAMU).
Student: Kimber De Salvo Anderson (2016-2018, M.S.)
This was a project to develop a new method of flow-field flow fractionation coupled to inductively-coupled plasma mass spectrometry in order to measure the size distribution and chemical composition of marine colloidal iron. Colloidal iron (the portion of dissolved iron falling into the size range of 3-200 nm) makes up a large component of the marine dissolved iron inventory, yet its reactivity and biogeochemical fate is oftentimes more like particulate than dissolved iron. Resolving the relative sizes and composition of the different species that compose the colloidal iron pool is an important step toward understanding the chemical transformations that modulate dissolved iron distributions in the open ocean. This project included several short cruises to coastal Maine. The archived data product can be found at BCO-DMO (Project 805258).

4. Imaging and chemical composition of marine colloidal iron in Galveston Bay.
Student: Laramie Jensen (2015-2020, Ph.D.) – Now a postdoc at University of Washington, Cooperative Institute for Climate, Ocean, and Ecosystem Studies.
This was a project in collaboration with Brandy Toner at the University of Minnesota to use high resolution imaging techniques to image and measure the fine-scale chemical composition of marine colloidal iron. We explored transmission electronic microscopy techniques as well as synchrotron imaging and speciation techniques such as Scanning Transmission X-ray Microscopy (STXM) at the Advanced Light Source in Berkeley, CA. Samples were collected opportunistically from Galveston Bay, ultrafiltered to collect their colloidal content, and preserved for imaging. This application pushes the spatial resolution of these cutting-edge imaging techniques but will provide much needed information on the associations of metals and organic compounds within the dissolved phase, as it is these associations that control the bioavailability and scavenging fate of marine metals.

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