Date of Award

2015

Document Type

Open Access Thesis

Department

Marine Science

Sub-Department

College of Arts and Sciences

First Advisor

Claudia Benitez-Nelson

Abstract

As the only gateway of material, particularly nutrients, from the Pacific to the Arctic Ocean, the biological and chemical transformations that occur within the Chukchi Sea are critical for understanding Arctic ecosystems. This study examines the biogeochemical cycling of the macronutrient phosphorus (P) relative to carbon and nitrogen in the eastern Chukchi Sea during the ICESCAPE’s mission. Sea ice and water column dissolved and particulate phosphorus samples were collected during two summer expeditions in 2010 (n=593) and 2011 (n=989). Despite being a landlocked marginal sea, the P pool present within the Chukchi Sea was substantially modified by biological processes with 30-40% of the total dissolved pool (TDP) comprised of organic P (DOP) and nearly 50% of total particulate P comprised of organic P forms. Surprisingly the offshore waters held significantly higher concentrations of P in all forms throughout the Chukchi Sea (TP2010 = 1.54 ± 0.64 μM, TP2011 = 1.58 ± 0.67 μM; ±1 standard deviation), suggesting coastal inputs of P were relatively small during our sampling. This increase offshore highlights the potential importance of sea ice melt in the addition of nutrients to the surface waters. Upon the examination of ice cores collected, this study suggests that the impact of sea ice melt depends heavily on whether the ice is clean or sediment-laden, as their particulate C:N:P ratios vary by over a factor of 10. The dissolved data also suggests the potential for N:P to be altered in favor nitrogen from 0.44 to 0.64, though overall concentrations would be diluted throughout the mixed layer.

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