Interdisciplinary investigations into the role of sea ice as moderator of and platform for biogeochemical cycles in Arctic and Antarctic waters

Leader: Mats Granskog                                                  Start of the project: 2005
Research group: Global change                                     End of the project:  2008

Project is funded by Academy of Finland

Overview

Sea ice plays an important role in Earths climate, and a considerably less well known role in the biogeochemical cycles and air-ocean-land interactions in ice covered seas. The exact role of sea ice as moderator of sea-air interactions and fluxes of gases through the sea-air boundary layer are poorly understood. In this context the physical properties of the sea ice and snow cover may strongly affect the oceanic flux of gases (e.g. carbon dioxide) to the atmosphere. Also the chemical processes during the formation of sea ice and the sea ice associated ecosystems may provide mechanisms for gas fluxes through the sea ice into the atmosphere.


In coastal areas in the Arctic Ocean and surrounding seas (e.g. Hudson Bay and Baltic Sea) with considerable river runoff, the sea ice cover may indirectly affect the transport and retention of land derived substances, which may be of importance in the context of pollution, eutrophication and productivity of the coastal zone. Most likely sea ice covered coastal areas support less productivity (in winter) which appears to result in unmodified transport of river borne substance due to lack of modifying processes. In addition the circulation in ice-covered waters is altered by the presence of ice, and result in more effective transport of river runoff to the open sea than in areas that remain ice-free. With a predicted change in climate large coastal areas presently with ice cover may remain ice-free for a longer period or entirely, and this may considerably alter the conditions in the coastal zone.
Research icebreaker Polarstern (Germany) in the Arctic
Coring sea ice samples at the edge of a melt-pond on a multi-year sea ice floe in the Arctic.
Photo: Mats Granskog







The project aims

The main aim of the project is to investigate how sea ice affect biogeochemical cycles in ice covered seas. The main interest is in organic matter (especially carbon), which plays a fundamental role in the climate system. Oceans are the largest reservoir and currently sink for excess carbon the atmosphere and therefore the oceans play a very important role in controlling the atmospheric CO2 content.  Polar sea play an important but yet not fully understood role in the oceanic cycling of carbon. Sea ice is usually considered as a simple barrier for ocean-atmosphere exchange; however, some special features of the sea ice might actually make sea ice an active component in marine carbon cycling.

Field work on sea ice will be conducted in the Canadian Arctic (2005/6 and 2008; during the ArcticNet and CFL-IPY  programs), in the Baltic Sea and in Antarctic waters (2007). These will be undertaken onboard ice breaking research ships so that we can access these harsh environments.

Together with our collaborators we intend to collect and analyze sea ice samples from a variety of environments, especially to characterize the organic material within the sea ice, and examine how it responds to e.g. biological activity and sunlight. Of especial interest is how organic material in the sea ice responds to exposure of ultraviolet light. This is potentially an important pathway in the transformation of organic material to inorganic species, e.g. nutrients that will become available for biota, or organic carbon is transformed into CO2 by photo-oxidation. The sea ice might be a unique platform for these processes, because during sea ice formation all dissolved material in seawater is concentrated into brine channels, where also the biological activity of sea ice occurs. This is a really concentrated system, where also carbon cycling and other processes may operate at high efficiency, compared to the diluted environment in seawater.


Research icebreaker Polarstern (Germany) in the Arctic
Research icebreaker Polarstern (Germany) in the 
Arctic.Photo: Mats Granskog
In the larger context the results can be used to understand better the response of the Arctic and subarctic and Antarctic marine environments to global change. The loss of sea ice will strongly affect any processes that occur in these waters, and a fundamental understanding of these processes are still lacking. In order for us to understand the implications of e.g. an ice-free Arctic Ocean, we need to know how the system currently operates.

Participants/Cooperation

Principal investigator Dr Mats Granskog

Key national collaborators are:

• Dr. Hermanni Kaartokallio , Finnish Marine Research Institute
• Prof. Harri Kuosa , Helsinki University
• Dr. Anssi Vähätalo, University of Helsinki

Key international collaborators are:

• Prof. David Thomas , School of Ocean Sciences, University of Wales-Bangor, UK
• Dr. Klaus Meiners, Antarctic Ecosystems and Climate CRC , Hobart, Australia
• Prof. Tim Papakyriakou , University of Manitoba, Canada
• Dr. Colin Stedmon, NERI, Denmark

International projects we participate in:

• ArcticNet network in Canada
• Circumpolar Flaw Lead (CFL) system study - project in the Canadian Arctic

Recent Publications

Granskog, M., H. Kaartokallio, H. Kuosa, D.N. Thomas and J. Vainio. 2006. Sea ice in the Baltic Sea - A Review. Estuarine Coastal and Shelf Science, 70, 145-150. doi: 10.1016/j.ecss.2006.06.001 Copyright Elsevier Ltd. 2006. Download pdf .

Kuparinen, J., Kuosa H., Andersson, A., Autio, R., Granskog M.A., Ikävalko, J., Kaartokallio, H., Karell, K., Leskinen, E., Piiparinen, J., Rintala, J-M., Tuomainen, J. 2007. Role of sea-ice biota in nutrient and organic material cycles in the northern Baltic Sea, Ambio, 36, 149-154. doi: 10.1579/0044-7447(2007)36[149:ROSBIN]2.0.CO;2;Download pdf .

Useful links

Sea ice for beginners (AWI)

More information

Postdoctoral researcher Mats Granskog
Arctic Centre, University of Lapland
firstname.surname@ulapland.fi