The Distribution of Dissolved Barium Along the U.S. Geotraces North Atlantic Transect: Impact of Biogeochemical Processes, Circulation and Phase Association

• Main Author: Grissom, Karen Renee
• Format: Text
• Language: unknown
• Published: The Aquila Digital Community 2015
• Subjects: North Atlantic; Dissolved Barium; GEOTRACES; paleo-productivity; Oceanography
• Online Access: https://aquila.usm.edu/masters_theses/118; https://aquila.usm.edu/context/masters_theses/article/1129/viewcontent/auto_convert.pdf

During the last four decades, since the completion of the GEOSECS program, there has been a growing interest in the biogeochemical cycle of barium (Ba) due to its potential as a proxy for interpreting the geologic record. The typical barium distribution exhibits removal in the upper water column and regeneration at depth, consistent with its classification as a bio-intermediate element and similar to the nutrient-like profiles of silicic acid and alkalinity. To better constrain the uses of Ba, trace element clean samples were collected during the North Atlantic US GEOTRACES cruises. The cycling of barium in the North Atlantic region was found to be a complex interaction of biological activity and chemical equilibrium combined with an overprinting of ocean circulation. The key findings indicated a feedback of processes in the eastern Atlantic that moved dissolved barium from the surface layer to an environment where further enrichment of barium could enhance barite precipitation. The results demonstrated primary productivity can compensate for iron limitations during adsorption of dissolved barium to ferric oxyhydroxide through an increase in pH. There was evidence of a hydrothermal Ba input from the Mid-Atlantic Ridge and a near surface maximum along the continental slope of North America from a submarine groundwater discharge. Lastly, the error in the biogenic barium calculation from assuming a two phase model for particulate barium were assessed and showed the error from using an estimated Ba/Al ratio was prevalent, but minor, yet the error from excluding other phases was an order of magnitude larger.