Research Features

Sara Zeidan

Sara is currently a first year graduate student at the University of Ottawa studying Earth Sciences with a specialization in Chemical and Environmental Toxicology under the supervision of Dr. Brett Walker.

Radiocarbon and stable carbon isotopic measurements of dissolved inorganic carbon (DIC) in Baffin Bay

The oceans store around half of the carbon dioxide (CO2) emitted into the atmosphere from fossil fuels as dissolved inorganic carbon (DIC), holding ~38,000 GtC and making it the largest marine carbon reservoir. The Arctic Ocean is a region that is both chemically and ecologically sensitive, and little is known about the impacts of climate change on the marine carbon cycle of this region and on atmospheric CO2). Baffin Bay is an ocean basin that feeds cold, fresh surface water into the Labrador Sea, critical for deep water formation and the ‘engine’ driving global deep ocean circulation. The residence time of water in Baffin Bay remains an area of scientific debate, with estimated ventilation times ranging from 77 to 1,450 years.
DIC samples collected throughout Baffin Bay will be measured for 14C and 13C, both powerful tools used to constrain physical oceanographic parameters and better understand the marine carbon cycle. Based on these measurements we hypothesize that 1) Estimated residence time of deep water in Baffin Bay will be less than 1,450 2) Bomb and anthropogenic 14C signatures will have penetrated these deepest Baffin Bay waters 3) Dual 14C, 13C tracer approach will quantify Atlantic, Arctic and Pacific water end member contributions to Baffin Bay deep water. Seawater samples were collected by a CTD rosette system on CCGS Amundsen in July 2019 throughout Baffin Bay. Samples were poisoned with saturated HgCl2, and will be extracted and analyzed by accelerator mass spectrometry (AMS) at the University of Ottawa. This work will provide a greater understanding of the Arctic marine carbon cycle, further constrain the physical circulation of Baffin Bay, and quantify the amount of sequestered anthropogenic carbon.

David Zal

David is a recent graduate from the University of Ottawa with a BAC Honours in Environmental Science. He is currently working as a Research Assistant for Professor Ian Clark, with plans to further his education by perusing a Masters degree in earth sciences.

Source and age of CO2 emissions in the riparian zone adjacent to farm fields

The carbon cycle is comprised of 3 main reservoirs: the atmosphere, oceans and the terrestrial biosphere, in which carbon cycles through. This study looks at the contribution of soil respiration to the carbon cycle. The soil cores were collected outside of Ottawa from farm fields and the adjacent riparian zone. The atmosphere currently holds around 800 gigatons of carbon which equates to around 400 ppm of CO2. It is crucial to understand respiration of sequestered carbon which is released as CO2 back into the atmosphere. As this allows for the calculation of a rate at which the sequestered carbon is released as CO2 by respiration.

“I truly enjoy doing research, as there are so many questions one can ask and so many possibilities to answer them, while learning something new each and every day.”

The objectives of this project are to 1) determine the age of CO2 that is being released from agricultural soils to the atmosphere, 2) determine the impact that dredging of the riparian zone has on CO2 emission of the soil and 3) determine whether dredging of the riparian zone releases older CO2 gas. It is predicted that the sites that have not been disturbed will release less and younger CO2 in comparison to disturbed sites. The microcosm incubations of soil form depth profiles show respiration of carbon sequestered subsequent to and older than 1963, with the respired CO2 from the soil cores becoming older with depth. The stable isotope, 13C, demonstrates that all of this carbon originates from C3 vegetation. Further research will better define the age of soil emissions and source of CO2 respired.