Lynchpin Scholar and ex Oceano PhD candidate, Nick Roden – Research Article
Journal of Geophysical Research: Oceans
10.1002/2016JC012008
Carbon cycling dynamics in the seasonal sea-ice zone of East Antarctica
Nicholas P. Roden1,2,3, Bronte Tilbrook2,3, Thomas W. Trull2,3, Patti Virtue1,3, and Guy D. Williams1,3
1Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia, 2CSIRO Oceans and
Atmosphere, Hobart, Tasmania, Australia, 3Antarctic Climate and Ecosystems Cooperative Research Centre, University of
Tasmania, Hobart, Tasmania, Australia
Abstract
The carbon cycle of the seasonally ice covered region of the southwest Indian Ocean sector of
East Antarctica (308–808E, 608–698S) was investigated during austral summer (January–March 2006). Large
variability in the drivers and timing of carbon cycling dynamics were observed and indicated that the study
site was a weak net source of carbon dioxide (CO2) to the atmosphere of 0.861.6 g C m22 during the
ice-free period, with narrow bands of CO2 uptake observed near the continental margin and north of the
Southern Antarctic Circumpolar Current Front. Continuous surface measurements of dissolved oxygen and
the fugacity of CO2 were combined with net community production estimates from oxygen/argon ratios to
show that surface heat gain and photosynthesis were responsible for the majority of observed surface water
variability. On seasonal timescales, winter sea-ice cover reduced the flux of CO2 to the atmosphere in the
study area, followed by biologically driven drawdown of CO2 as the ice retreated in spring-summer
highlighting the important role that sea-ice formation and retreat has on the biogeochemical cycling of the
region.
Key Points:
_ Large variability in the biological and
physical drivers of carbon cycling
dynamics was observed
_ The East Antarctic seasonal ice zone
was a weak net source of CO2 to the
atmosphere during the ice-free
period
_ Seasonally integrated estimates of
net community production were as
high as 6.4 mol C m22, but on
average were found to be
1.360.9 mol C m22