The goal of this project was to determine how carbon cycles in the Arctic Ocean. We studied a form of carbon that is radioactive, called ¹⁴C. By measuring the amount of ¹⁴C in the water, we can tell how fast the carbon cycles in the surface and deep waters.  The reason this is important is because the Arctic is warming quickly, and the cycling of carbon and some other elements are being disrupted from their normal patterns.  We seek to know how carbon is cycling now, so that we can predict how it will change as warming increases.  We studied the most abundant form of organic carbon in the seawater, called dissolved organic carbon (DOC), and a product of incomplete combustion on land, called black carbon (BC). We aspired to understand the timescales of DOC and BC cycling in the Arctic Ocean, which receives the highest amount of DOC from rivers per unit volume than any other ocean on Earth.

Opportunities were presented for graduate students, academic staff members and two undergraduate students to perform research in the lab and in the field. A postdoctoral fellow (Brett Walker) collected samples onboard the CLIVAR cruise A16N in 2013 from a site just south of Iceland. A graduate student from the University of Stolkholm collected a depth profile of samples for DOC ¹⁴C and sent them to UCI for analysis. Specialist Sheila Griffin participated on the R/V Healy cruise from Dutch Harbor-to-Canadian Basin in 2012 to collect water samples in the Beaufort Sea and northern coast of Alaska. These individuals, and two undergraduate students (Chris Glynn and Danielle Glynn) and a graduate student (Alysha Coppola), analyzed these samples for ¹⁴C at the UCI Keck Carbon Cycle AMS laboratory. We are all involved in writing up the results for publication in peer-reviewed journals.

We attempted to determine the transit time of DOC from the northern North Atlantic to the deep Canadian Basin using ¹⁴C. We also attempted to understand the contribution of BC to the DOC pool in the Arctic Ocean. The impact of this research on the development of our understanding of DOC cycling in the Arctic is in two areas. First, DOC appears to increase in ¹⁴C age by several hundred years as deep water flows from the eastern basin to the western basin. This information is important for our understanding of how DOC cycles in the Arctic Ocean. Second, BC in a surface water sample from the coast of Alaska has an extremely old ¹⁴C age (14000 14C years), much older than those from the Beaufort Sea (1800–3000 ¹⁴C years), indicating a very old riverine source of BC.

Graduate student Alysha Coppola developed a revised method for isolating DOC from seawater as a part of her doctoral thesis and is publishing her results in Marine Chemistry (Coppola et al. in revision, Marine Chemistry, 2015). She measured 10-liter surface water samples collected on the Healy cruise and found concentrations of 1.6–2.6 μM at the three sites in the Canadian Basin, which made up 6–9% of the DOC. Studies are ongoing to determine the source of BC to the surface Arctic Ocean.

This grant supported the work of one graduate student, a postdoc and two undergraduate students and provided hands-on experience that helped prepare them for careers as scientists and educators. PI Druffel assisted high school teachers in their development of science curricula.  She also served on the advisory board for FCOSEE (Florida Center for Ocean Science Education Excellence COSEE) to assist in developing web-based educational classes at the college level.  She also participates in teaching a short course at UCI on “Radiocarbon in Ecology and Earth System Science” during summers. 

Last Modified: 09/14/2015
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