Patterns of Distribution and Photooxidation of Fluorescent Dissolved Organic Material in the Arctic Ocean

Description/Abstract/Artist Statement

Thinner sea ice and increasingly ice-free summers in the Arctic Ocean have the potential to affect the rate of loss of fluorescent dissolved organic material (FDOM) via photooxidation. Photooxidation is the transformation of dissolved organic material to CO2 or lower molecular weight compounds and is a crucial part of the Arctic carbon cycle. Increased sunlight due to thinner ice and more open water could increase the rate of photodegradation, therefore, causing more rapid cycling of dissolved organic material. However, there is little data on this subject due to the challenges of sampling in the Arctic in the early spring. Between 2014 and 2018, six autonomous ice-tethered buoys were deployed in the Chukchi Sea into first-year sea ice. These buoys measured water temperature, light intensity, chlorophyll, and FDOM under the ice starting in the spring. A general pattern of higher concentrations of FDOM on the Chukchi shelf and lower concentrations on the shelf break and the deeper Canada basin were observed in all years. On the Chukchi Shelf, we observed a strong photooxidation trend beginning in July and ending in early September. In comparison, a much slower photooxidation rate was present on the Chukchi Shelf break. In the deep Canada Basin, there was no observed loss due to photooxidation. Higher photooxidation is expected on the Chukchi shelf as the FDOM pool consists of labile compounds from land and river runoff as well as material produced in situ by ice algae and phytoplankton. Material in the Canada Basin is older and often does not contain compounds that respond to photooxidation. With this work we hope to quantify the loss and recycling of DOM in the Arctic Ocean via the photooxidation pathway, leading to predictions for carbon cycling in the future Arctic.

Presenting Author Name/s

Mary LePere

Faculty Advisor/Mentor

Victoria Hill

Faculty Advisor/Mentor Department

Ocean and Earth Sciences Department

College Affiliation

College of Sciences

Presentation Type

Poster

Disciplines

Biogeochemistry | Oceanography

Session Title

Poster Session

Location

Learning Commons Lobby @ Perry Library

Start Date

3-25-2023 8:30 AM

End Date

3-25-2023 10:00 AM

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Mar 25th, 8:30 AM Mar 25th, 10:00 AM

Patterns of Distribution and Photooxidation of Fluorescent Dissolved Organic Material in the Arctic Ocean

Learning Commons Lobby @ Perry Library

Thinner sea ice and increasingly ice-free summers in the Arctic Ocean have the potential to affect the rate of loss of fluorescent dissolved organic material (FDOM) via photooxidation. Photooxidation is the transformation of dissolved organic material to CO2 or lower molecular weight compounds and is a crucial part of the Arctic carbon cycle. Increased sunlight due to thinner ice and more open water could increase the rate of photodegradation, therefore, causing more rapid cycling of dissolved organic material. However, there is little data on this subject due to the challenges of sampling in the Arctic in the early spring. Between 2014 and 2018, six autonomous ice-tethered buoys were deployed in the Chukchi Sea into first-year sea ice. These buoys measured water temperature, light intensity, chlorophyll, and FDOM under the ice starting in the spring. A general pattern of higher concentrations of FDOM on the Chukchi shelf and lower concentrations on the shelf break and the deeper Canada basin were observed in all years. On the Chukchi Shelf, we observed a strong photooxidation trend beginning in July and ending in early September. In comparison, a much slower photooxidation rate was present on the Chukchi Shelf break. In the deep Canada Basin, there was no observed loss due to photooxidation. Higher photooxidation is expected on the Chukchi shelf as the FDOM pool consists of labile compounds from land and river runoff as well as material produced in situ by ice algae and phytoplankton. Material in the Canada Basin is older and often does not contain compounds that respond to photooxidation. With this work we hope to quantify the loss and recycling of DOM in the Arctic Ocean via the photooxidation pathway, leading to predictions for carbon cycling in the future Arctic.