Lynchpin Scholar and ex Oceano PhD candidate, Nick Roden – Research Article

Journal of Geophysical Research: Oceans



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



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





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


_ 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