Award Abstract # 1736906
US GEOTRACES PMT: Shipboard determination of key dissolved trace elements

NSF Org: OCE
Division Of Ocean Sciences
Recipient: UNIVERSITY OF HAWAII
Initial Amendment Date: July 10, 2017
Latest Amendment Date: January 20, 2023
Award Number: 1736906
Award Instrument: Standard Grant
Program Manager: Henrietta Edmonds
hedmonds@nsf.gov
 (703)292-7427
OCE
 Division Of Ocean Sciences
GEO
 Directorate for Geosciences
Start Date: November 1, 2017
End Date: September 30, 2023 (Estimated)
Total Intended Award Amount: $438,766.00
Total Awarded Amount to Date: $438,766.00
Funds Obligated to Date: FY 2017 = $438,766.00
History of Investigator:
  • Mariko Hatta (Principal Investigator)
    mhatta@hawaii.edu
  • Christopher Measures (Co-Principal Investigator)
Recipient Sponsored Research Office: University of Hawaii
2425 CAMPUS RD SINCLAIR RM 1
HONOLULU
HI  US  96822-2247
(808)956-7800
Sponsor Congressional District: 01
Primary Place of Performance: University of Hawaii
1000 Pope Road
Honolulu
HI  US  96822-2347
Primary Place of Performance
Congressional District:
01
Unique Entity Identifier (UEI): NSCKLFSSABF2
Parent UEI:
NSF Program(s): Chemical Oceanography
Primary Program Source: 01001718DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 9150, 9198
Program Element Code(s): 167000
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.050

ABSTRACT

This project will provide shipboard measurements of the dissolved trace elements aluminum (Al), iron (Fe), and manganese (Mn) during an Alaska to Tahiti cruise that will sail as part of the US GEOTRACES Pacific Meridional Transect (PMT). The PMT expedition is part of the international GEOTRACES program designed to improve understanding of global ocean biogeochemical cycles. The growth of microscopic oceanic plants in surface waters depends on the availability of certain trace elements (particularly dissolved Fe). In addition, the distribution of this and other trace elements record current and past chemical and biological processes in the ocean. The PMT cruise track includes multiple unique oceanic conditions and thus the results of the work will provide important insight into diverse global ocean processes. For broader scientific impact, results will be incorporated into models that address the current and future role of the ocean in global processes. Assessing the distribution of trace elements in the Clarion-Clipperton Fracture Zone, along the cruise track, will also provide an important baseline for this region where seabed mining of manganese nodules is planned. Educational outreach will take place with a mid-cruise stop in Hilo, Hawaii to engage local students with visits to the ship. Direct exposure to a working oceanographic research vessel together with a post-cruise follow up visit will provide students with a unique opportunity to discuss the findings from the expedition directly with the scientists engaged in the project.

To develop the data sets required for new understanding of the relative importance of trace element input processes in establishing oceanic chemical distributions, seawater samples from the entire water column will be collected using a custom designed sampling package at 41 locations during the 62-day cruise. The northern part of the cruise track originates in a region where very low concentrations of dissolved Fe in surface waters limit plant growth. Further to the south, increased atmospheric deposition of mineral dust blown from the continents will be traced by measuring the dissolved Al concentration in surface waters. The addition of this dust also adds dissolved Fe. Potential additional inputs of Fe from coastal regions will be identified by coincident increases in dissolved Mn concentrations. The project will compare and correlate variations in Al, Fe, and Mn to quantify and identify distinct addition processes along the cruise track. By using shipboard flow injection analysis to provide near real-time measurements for these trace elements, the potential exists to modify sampling strategies for maximum scientific return. The shipboard results will also help identify any sampling contamination problems that are a constant risk when collecting these low-level trace elements. Altogether, the shipboard analysis of these essential elements is an essential activity to ensure success of the GEOTRACES PMT.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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Chmiel, Rebecca and Lanning, Nathan and Laubach, Allison and Lee, Jong-Mi and Fitzsimmons, Jessica and Hatta, Mariko and Jenkins, William and Lam, Phoebe and McIlvin, Matthew and Tagliabue, Alessandro and Saito, Mak "Major processes of the dissolved cobalt cycle in the North and equatorial Pacific Ocean" Biogeosciences , v.19 , 2022 https://doi.org/10.5194/bg-19-2365-2022 Citation Details
Jenkins, W.J. and Hatta, M. and Fitzsimmons, J.N. and Schlitzer, R. and Lanning, N.T. and Shiller, A. and Buckley, N.R. and German, C.R. and Lott, D.E. and Weiss, G. and Whitmore, L. and Casciotti, K. and Lam, P.J. and Cutter, G.A. and Cahill, K.L. "An intermediate-depth source of hydrothermal 3He and dissolved iron in the North Pacific" Earth and Planetary Science Letters , v.539 , 2020 https://doi.org/10.1016/j.epsl.2020.116223 Citation Details
Marsay, Chris M. and Landing, William M. and Umstead, Devon and Till, Claire P. and Freiberger, Robert and Fitzsimmons, Jessica N. and Lanning, Nathan T. and Shiller, Alan M. and Hatta, Mariko and Chmiel, Rebecca and Saito, Mak and Buck, Clifton S. "Does Sea Spray Aerosol Contribute Significantly to Aerosol Trace Element Loading? A Case Study From the U.S. GEOTRACES Pacific Meridional Transect (GP15)" Global Biogeochemical Cycles , v.36 , 2022 https://doi.org/10.1029/2022GB007416 Citation Details

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

This project constructed a map of the dissolved trace elements aluminum (Al), iron (Fe), and manganese (Mn) at 41 locations in the Pacific Ocean during a 62-day research cruise from Alaska to Tahiti (from September 18th to November 24th, 2018) as part of the US GEOTRACES Pacific Meridional Transect (PMT). The PMT research cruise is part of the international GEOTRACES program which is designed to improve understanding of global ocean biogeochemical cycles by mapping the distribution of a variety of reactive trace elements. For example, the growth of microscopic oceanic plants in surface waters depends critically on the availability of, amongst other things, dissolved Fe. In addition, the distribution of Fe and other trace elements records current and past chemical and biological processes in the ocean. The PMT cruise track was designed to include multiple unique oceanic hydrographic conditions and thus the results of this work provide important insights into diverse global ocean processes. By using a shipboard flow injection analysis system to provide near real-time measurements of these trace elements, it allows shipboard personnel to modify sampling strategies thus allowing unexpected discoveries to be further investigated resulting in maximum scientific return. The shipboard results also help identify any sampling contamination problems that are a constant risk when collecting these low-level trace elements.

The dissolved Al distribution which is not a required element by oceanic plants serves as an effective oceanographic tracer. Its distribution in the ocean records the chemical signature of mineral dust that has been blown over the oceans from the continents and then deposited by rain or gravitational settling into the surface ocean. Since this acts as a tracer for lithogenic material inputs, it also records where dissolved Fe coming from mineral dust is also added to the ocean.  The dissolved Al can also be used to examine the dispersion of mining effluent as well as sediment resuspension processes that can occur along the edges of the ocean.

Intellectual Merit: The basin-wide data set of dissolved trace elements during the GEOTRACES project will significantly improve our understanding of how global ocean biogeochemical cycles operate.  The dataset will be used to improve and constrain coupled ocean/atmosphere nutrient and carbon cycling models and permit more accurate prediction of the role played by atmospheric dust deposition in providing biogeochemically important trace elements to the surface ocean and the mechanisms by which they are transferred to the interior of the ocean.

Broader Impacts: A graduate student benefited from participation in the GEOTRACES project that brought technologies and scientists from different institutions together creating a collaborative cohort that will outlast the specific project.  Additionally, using our local contacts we developed a collaboration with several faculty members from the University of Hawaii at Hilo and arranged a visit and tour of the ship during its port call in Hilo for their students.  The GEOTRACES project also provided an initial survey of background chemical conditions in the water column of the Clarion-Clipperton Fracture Zone between 15ºN to 5 ºN, which is a region scheduled for the seabed mining of manganese deposits.  The United Nations law of the sea requires a baseline assessment (physical, geochemical, biological) of this area before mining commences, as it will likely produce large-scale sediment resuspension during mining and will produce detritus from shipboard processing of nodules.

 


Last Modified: 01/27/2024
Modified by: Mariko Hatta

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