THE BIOGEOCHEMICAL CYCLING OF DISSOLVED AND COLLOIDAL TRACE METALS IN THE WESTERN ARCTIC OCEAN

• Main Author: Jensen, Laramie Thaniel
• Other Authors: Fitzsimmons, Jessica, Amon, Rainer, Marcantonio, Franco, Santschi, Peter
• Format: Thesis
• Language: English
• Published: 2021
• Subjects: GEOTRACES; trace metals; biogeochemistry; Arctic Ocean; colloids; oceanography; geosciences; analytical chemistry; mass spectrometry; Arctic; Chukchi Shelf; Chukchi; Phytoplankton; Sea ice
• Online Access: https://hdl.handle.net/1969.1/192332

The Arctic Ocean is characterized by broad continental shelves, large river inputs, sea ice coverage, and limited exchange with other major ocean basins. This provides a unique environment in which to examine the distribution of trace metal micronutrients such as Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb. Many trace metals are essential micronutrients for phytoplankton in the surface ocean, serving as metal centers for important metabolic reactions such as photosynthesis, nitrogen fixation, and carbon uptake. The distribution and behavior of these metals are relatively unexplored in the Arctic Ocean. However, this dataset collected within the international GEOTRACES program presents an opportunity to explore elemental cycling and size speciation on an unprecedented spatial scale in the Western Arctic Ocean. It also bridges together the overall dissolved, colloidal, and soluble size distribution of these trace metals. The colloidal size fraction (here defined between 0.003 μm or 0.02 μm and 0.20 μm) is an operationally defined component of the dissolved phase (<0.20μm) that may be more bioavailable to phytoplankton and represents an intermediary between the soluble and the more refractory particulate phase. Our methodology allows us to combine and exploit the characteristics of multiple trace metals at once to expand our understanding of the biogeochemical processes governing the Arctic Ocean. Overall, this work defined the unique behavior of trace metals in the Arctic Ocean. First, we outline our methodology, including the under-explored effects of storage on filtration and sorption to bottle walls, important tenets of the trace metal field. We then spend the next three chapter outlining the unique cycling of different metals within the Western Arctic Ocean. First, we first examined the dissolved biogeochemical cycling of Zn, an essential micronutrient that often cycles with major macronutrients such as silicate. This study illuminated the role of the Chukchi Shelf as a major factor controlling the distribution of ...