Collaborative Research: Sinking Rates and Nutritional Quality of Organic Matter Exported from Sea Ice; the Importance of Exopolymeric Substances
Available data concerning the sinking rates of ice algae are highly divergent, while the characteristics of particles formed from other large organic pools in sea ice have received little study. As an initial step to remedy this situation, funds are provided to study the role of exopolymeric substances (EPS), produced by ice algae, in particle formation. The importance of EPS to particle coagulation and sinking rate is well established for temperate water columns. In sea ice, EPS comprise 20-70% of total particulate organic carbon, but their role in the sinking rate and composition of particles exported from sea ice is poorly understood. Based on previous studies, the PIs predict both positive and negative effects of EPS on particle sinking rate depending on EPS quantity. EPS also is predicted to increase the ratio of carbon to nitrogen (C:N) in the organic matter, which serves as a nutritional indicator.
The researchers will use established techniques to measure the sinking rates of particles released from melted sea ice cores compared to observed exopolymeric substance concentration to help better determine arctic carbon budgets.
OUTCOMES: Found that chlorophyll concentrations were highest where light was most available and nutrient limitations are minimal with the highest concentrations in the lowest 10cm of the sea ice. Found that dissolved organic carbon was highest in the upper ice and did not change when chlorophyll declined, while particulate dissolved carbon does not decline when algae is exported.