Arctic Ocean sea-ice is decreasing and the water at the sea surface is getting warmer and fresher. These changes may be affecting the accumulation of carbon dioxide in the atmosphere and in the ocean. The carbon cycle is complex because there are many processes that control the amount of carbon dioxide in the Arctic Ocean. Plant growth, oxygen use by organisms, ice cover, temperature, and ocean circulation all contribute to differences in the amount of carbon dioxide in the water and the exchange of carbon dioxide with the atmosphere. As ice cover in the Arctic Ocean decreases, scientists think the water will absorb more anthropogenic (human originated) carbon dioxide from the atmosphere. As carbon dioxide levels increase, this will lead to the ocean becoming more acid (lower pH) because carbon dioxide forms carbonic acid when it dissolves in water. The lower pH water can affect the food web by slowing the growth of shell-forming organisms. Despite these important issues, not much is known about the carbon cycle in the central Arctic Ocean basins. Nearly all measurements have been made close to the Arctic coasts during the low ice summer period, when water for samples are more accessible to scientists. With this National Science Foundation support we will combine forces with another National Science Foundation project and use the Canadian icebreaker Louis S. St-Laurent to reach the under-studied central Arctic Ocean. These data will be made available to the public and other researchers. The project also supports operation of an ocean acidification exhibit for University of Montana’s science museum so we can better share our results with the public. A post-doctoral researcher, research technician, and two undergraduate students will be supported on the project. The specific activities on this project are focused on a field effort in fall 2018 that includes shipboard measurements and deployments on moorings and ice-tethered profilers. A shipboard underway partial pressure of carbon dioxide (pCO2) measurement system will be installed on the icebreaker. The goal of these measurements is to map sea surface pCO2 over a broad region to quantify air-sea CO2 fluxes. Sensors for pCO2, pH, and dissolved oxygen will be deployed on the Woods Hole Oceanographic Institution time-series moorings and ice-tethered profilers. Three moorings will be deployed with a subsurface profiler that measures conductivity, temperature, depth, and dissolved O2. Our sensors are deployed at 35 m depth, just below the subsurface float. These data are used to examine short- and long- term carbon cycle variability in the Canada Basin. Sensors for pCO2 and O2 will also be deployed just under the ice surface on two ice-tethered profilers. These sensors record variability near the ice interface that is not possible with the deeper subsurface moorings. A post-doctoral researcher will lead the data quality control and interpretation and will work with other Arctic scientists to facilitate use of the data in their studies.

This project will allow for the continuation of a sea surface pCO2, pH, and dissolved O2 observing network, funded previously by the NSF Arctic Observation Network (AON) program. In the summer of 2018, researchers will recover three bottom-tethered moorings that have been previously established within the Beaufort Gyre as part of the Beaufort Gyre Observation System (BGOS) in 2017. Additionally, two or three Ice-Tethered Profilers (ITP) will be deployed. One researcher will conduct the research onboard CCG Ship Louis S. St-Laurent that houses the Warsilla bubbler system used for the removal of heavy pack sea ice over the mooring sites.

All logistics will be organized by the researcher and paid through the grant.