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Dispatch 12: CDOM in the Arctic

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Cassie DeFrancesco

September 18, 2018

Location: 77° 0' N 140° 0' W

Weather: -6°C (21°F), Sunny, seas ice covered, West winds at 12 knots, seawater temperature -1.3°C (29.7°F)

Sea Ice: Variable from complete coverage to mostly covered.

Hey there! My name is Cassie DeFrancesco and I’ll be writing a guest dispatch for today! Hugo decided to run off and take a nap (oops, was I supposed to keep that a secret?) I’m a second-year masters student hailing from Peterborough, Ontario studying at Trent University. For those of you who haven’t heard of Trent before, it’s a tiny, quaint university that has about 8000 undergraduate and about 500 graduate students. It runs along the beautiful Otonabee river separating one side of campus from the other. My program, which is the Environmental and Life Science MSc. is quite multidisciplinary and encompasses many areas of science including biology, chemistry, geography, forensic science, and so on.

As for my master’s research project, I am studying coloured dissolved organic matter (CDOM) which Hugo mentioned briefly in the September 12th dispatch.  It is a smaller fraction of dissolved organic matter that absorbs UV and visible light. An even smaller fraction of CDOM can fluoresce light as well. You can think of dissolved organic matter as anything that can pass through a teabag. You can’t see any particulates in your mug, but you see a slight change in colour. That is the dissolved portion of the matter. CDOM is particularly abundant near the surface of the Arctic Ocean and because of its UV absorbing properties, it creates a barrier protecting the organisms below from the Sun’s harmful rays.

We are interested in how CDOM and the fluorophore components that make up CDOM (those parts that fluoresce light) are differing with a changing Arctic Ocean. We know that the Arctic Ocean makes up 1% of the global ocean volume but is supplied with ~11% of the global riverine freshwater. As the Arctic sea ice is retreating and the summer minimum extent is becoming ever smaller, we are also experiencing thawing permafrost and an increased amount of freshwater to the ocean. For these reasons, it is important to better understand the fate of terrestrial organic matter within the rapidly changing Arctic Ocean. We will determine if there are more terrestrial components reaching the ocean (from areas such as river run off), or if there is more of a marine signal, meaning that the components are originating from within the ocean over a ten-year time period. This is important to understand especially with the environment changing at such an increased rate.

Thanks for reading about my research, I think Hugo just woke up from his nap, so I’ll hand this back over to him!

Last updated: October 7, 2019

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