Radium isotopes and radon-222 as tracers of sediment-water interaction in Arctic coastal and lacustrine environments
Dabrowski, Jessica S.
MetadataShow full item record
Arctic marine and lacustrine systems are experiencing rapid warming due to climate change. These changes are especially important at the interface between sediments and surface waters because they are hotspots for biogeochemical transformations such as redox reactions, nutrient consumption and regeneration, organic matter leaching and degradation, and mineral weathering. Radium isotopes (223Ra, 224Ra, 226Ra, 228Ra) and radon-222, naturally occurring radioactive isotopes produced in sediments, are well-suited as tracers of nutrients, trace metals, and organic matter cycling processes at the sediment-water interface. In this thesis, I have applied radon-222 and the quartet of radium isotopes to study fundamental processes in subarctic lakes and on the Arctic continental shelf. First, radon-222 is used to quantify groundwater discharge into a shallow, tundra lake on the Yukon-Kuskokwim Delta in Alaska in summer of 2017. Radon-derived groundwater fluxes were then paired with methane (CH4) measurements to determine delivery rates of methane into the lake via groundwater. Groundwater CH4 fluxes significantly exceeded diffusive air-water fluxes from the lake to the atmosphere, suggesting that groundwater is an important source of CH4 to Arctic lakes and may drive observed CH4 emissions. Higher CH4 emissions were observed compared to those reported previously in high latitude lakes, like due to higher CH4 concentrations in groundwater. These findings indicate that deltaic lakes across warmer permafrost regions may act as important hotspots for methane release across Arctic landscapes. Then, the quartet of radium isotopes is used to study the impacts of storms and sea ice formation as drivers of sediment-water interaction on the Alaskan Beaufort shelf. The timeseries presented in this study is among the first to document the combined physical and chemical signals of winter water formation in the Beaufort Sea, made possible by repeat occupations of the central Beaufort shelf. Radium measurements are combined with inorganic nitrogen and hydrographic measurements to elucidate the episodic behavior of winter water formation and its ability to drive exchange with bottom sediments during freeze-up.
Submitted in partial fulfillment of the requirements for the degree of Master of Science in Chemical Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 2020.
Suggested CitationThesis: Dabrowski, Jessica S., "Radium isotopes and radon-222 as tracers of sediment-water interaction in Arctic coastal and lacustrine environments", 2020-09, DOI:10.1575/1912/26239, https://hdl.handle.net/1912/26239
Showing items related by title, author, creator and subject.
Total molybdate reactive and unreactive phosphorus concentrations from sediment extracts from sediment samples collected during cruises in the Arctic Ocean, California Margin, and Equatorial Pacific from 1992-1998 Paytan, Adina; Defforey, Delphine (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: firstname.lastname@example.org, 2020-07-02)Total molybdate reactive and unreactive phosphorus concentrations from sediment extracts from sediment samples collected during cruises in the Arctic Ocean, California Margin, and Equatorial Pacific from 1992-1998. For ...
The sediments of the western Gulf of Mexico. I. The continental terrace of the western Gulf of Mexico : its surface sediments, origin, and development. II. Chemical studies of sediments of the western Gulf of Mexico Stetson, Henry C.; Trask, Parker D. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1953-05)In 1947 the Woods Hole Oceanographic Institution organized an expedition to investigate the bottom sediments and oceanography of the northwest Gulf of Mexico. The Geological Society of America contributed to the support ...
An analysis of Atlantic Water in the Arctic Ocean using the Arctic Subpolar Gyre State Estimate and observations Grabon, Jeffrey S. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2020-09)The Atlantic Water (AW) Layer in the Arctic Subpolar gyre sTate Estimate (ASTE), a regional, medium-resolution coupled ocean-sea ice state estimate, is analyzed for the first time using bounding isopycnals. A surge of AW, ...