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Research Spending & Results

Award Detail

Awardee:SKIDMORE COLLEGE
Doing Business As Name:Skidmore College
PD/PI:
  • Margaret Estapa
  • (207) 944-6707
  • mestapa@skidmore.edu
Award Date:01/08/2014
Estimated Total Award Amount: $ 122,570
Funds Obligated to Date: $ 122,570
  • FY 2013=$122,570
Start Date:01/01/2014
End Date:03/31/2016
Transaction Type:Grant
Agency:NSF
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.050
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Rapid, Autonomous Particle Flux Observations in the Oligotrophic Ocean
Federal Award ID Number:1406552
DUNS ID:020670741
Parent DUNS ID:020670741
Program:Chemical Oceanography
Program Officer:
  • Henrietta Edmonds
  • (703) 292-7427
  • hedmonds@nsf.gov

Awardee Location

Street:815 North Broadway
City:Saratoga Springs
State:NY
ZIP:12866-1632
County:Saratoga Springs
Country:US
Awardee Cong. District:20

Primary Place of Performance

Organization Name:Skidmore College
Street:815 N. Broadway
City:Saratoga Springs
State:NY
ZIP:12866-1632
County:Saratoga Springs
Country:US
Cong. District:20

Abstract at Time of Award

Particles settling to the deep ocean remove carbon and essential trace elements for biological processes from the surface ocean and contact with the atmosphere over short time scales. Currently available technology is only able to resolve this flux at timescales of 24 hours to a few days and the methods are both labor- and time-intensive. Given the limited spatial and temporal scale of these flux measurements, it has been difficult to determine the processes that control the fate of particulate organic carbon (POC). Scientists from Woods Hole Oceanographic Institution will use an optical, transmissometer-based method to obtain particle flux observations from autonomous, biogeochemical profiling floats. Initially, a laboratory-based sensor calibration experiment will be carried out to determine the detection limit of the system and evaluate its sensitivity to particle size. This will be followed by a field effort wherein data obtained from the floats will be compared against direct sampling from sediment traps. Lastly, the system will be deployed for about a year in the North Atlantic during which data will be returned via satellite from the biogeochemical float. This year long deployment will be the first of its kind to collect nearly-continuous, hourly-resolution proxy measurements of particle flux. The data is expected to yield new insights into the factors that influence variability in POC export. A potentially transformative aspect of this proposal will be the broad application of a newly developed method that cuts labor and ship costs while generating high resolution data. Broader Impacts: Given the components for this system are readily commercially available means others in the science community have the opportunity to use this technology to make similar measurements. One postdoc would be supported and trained as part of this project. In addition, undergraduate students will be involved in the research via the Woods Hole Oceanographic Institution Summer Student Fellow and Minority Fellow program.

Publications Produced as a Result of this Research

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Durkin, C. A., M. L. Estapa, and K. O. Buesseler "Observations of carbon export by small sinking particles in the upper mesopelagic" Marine Chemistry, v.175, 2015, p.. doi:10.1016/j.marchem.2015.02.011 


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.

            Carbon-containing particles are produced from CO2 by tiny organisms in the surface ocean.  A small fraction of these particles sink into the deep ocean, ultimately removing CO2 from the atmosphere in a process termed “the biological pump”.  A shifting balance among physical motions of the water, chemical reactions, and the activities of ocean life determines whether and how much of the sinking carbon is ultimately sequestered in the deep ocean.  These processes affecting sinking carbon are most variable and hardest to measure at depths between roughly 100 and 1000 meters, sometimes called “the twilight zone”.  Our challenge is to expand the number of particle flux observations in the twilight zone, something that has proven elusive with ship-based “snapshots” that have lengths of, at most, a few weeks.  In this project we employed a type of optical sensor to measure the flux of sinking particles using self-sufficient, robotic profiling floats.  New developments in data interpretation, sensor operation, and platform control allow us to make measurements at fast time resolution, similar to the rapid changes that can occur in the natural processes that affect sinking carbon in the ocean.  The sensors and floats that we have used are simple, robust, and commercially-available, which allows these tools to be adopted by other researchers in many areas of the ocean.

            The project has two main goals:  First, we have quantified the flux of sinking carbon (i.e., the amount of carbon sinking through an area of the ocean during a given time period) by comparing the optical sensor observations to fluxes measured simultaneously with the established, but more labor-intensive method of using rain gauge-like sediment traps.  Second, we have tested how much rapid export “events” contribute to total sinking carbon fluxes in the open ocean by using profiling floats to measure the flux of sinking carbon as well as measurements of dissolved oxygen, temperature, salinity, particles, and photosynthesis pigments. 

            During this project, we conducted experiments in the laboratory to determine the detection limit of the optical flux sensor, and to determine whether many small particles give the same sensor response as fewer, larger particles of the same mass.  We also performed a series of five comparisons of sediment traps to optical flux sensors in conjunction with monthly Bermuda Atlantic Time-series Study (BATS) cruises, taking advantage of the timeseries measurements and the context provided by the 25-year record of sinking carbon flux at that site.  Finally, we used measurements, transmitted by two profiling floats allowed to operate on their own in the northwest Atlantic Ocean, to interpret sinking carbon fluxes over a year-long period in the context of physical and biological events occurring in the ocean during the deployments.

            Broader impacts of this project include the close involvement of two early-career researchers, and the training of one undergraduate student to work with profiling float data and conduct original research.  The project has enhanced research infrastructure by utilizing profiling floats developed through an academic-private sector collaboration.  These floats are now being used in a variety of other projects around the world, contributing both to our understanding of the ocean and to the competiveness of U.S.-produced oceanographic equipment.  The use of commercially-available, off-the-shelf technology for field observations has ensured th...

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