sail-world.com
 
 
News Home Video Gallery Photo Gallery
Sail-World.com : Glaciers contribute essential nutrient to North Atlantic Ocean
Glaciers contribute essential nutrient to North Atlantic Ocean


'Close-up of the outlet of the ‘N’ glacier outflow. The meltwater exiting the base of the glacier is extremely turbid, with high suspended sediment loads from interaction with the bedrock and sediments beneath the glacier'    Ben Gready, University of Alberta

All living organisms depend on iron as an essential nutrient. In the ocean, iron’s abundance or scarcity means all the difference as it fuels the growth of plankton, the base of the ocean’s food web.

A new study by biogeochemists and glaciologists at Woods Hole Oceanographic Institution (WHOI) identifies a unexpectedly large source of iron to the North Atlantic – meltwater from glaciers and ice sheets, which may stimulate plankton growth during spring and summer. This source is likely to increase as melting of the Greenland ice sheet escalates under a warming climate.

The study was published online in Nature Geoscience on March 10, 2013.

'There’s only been one other study looking at the amount of iron that’s being released in meltwater runoff itself,' says Maya Bhatia, a graduate of the MIT/WHOI Joint Program in Oceanography and Applied Ocean Sciences and Engineering, and the study’s lead author, 'and that had reported high nanomolar concentrations. So to find iron in concentrations several orders of magnitude higher – in the micromolar range – was very surprising.'

The research team collected samples from sites at three land-terminating glaciers on the western margin of the Greenland ice sheet. The primary glacial outflow sampled in this study was ‘N’ glacier, above -  Sarah Das - WHOI  
Iron from wind-blown dust and river runoff fuels annual plankton blooms in the world’s ocean. Ice sheets and glaciers are now also thought to contribute iron from sediments on the bottom of calved icebergs and glacially-derived dust. Until now, meltwater runoff from glaciers and ice sheets was considered too dilute to carry much iron, although previous research has shown a strong correlation between the plankton blooms and the runoff from Greenland ice sheet.

'Glacial runoff has only recently been considered a potentially important source of nutrients that are useable, or bioavailable, to downstream ecosystems,' says Bhatia. 'We believe our study now adds iron to that list of nutrients, and underscores the potential for a unique but as-yet-undetermined chemical impact from increasing ice sheet meltwater runoff.'

During the course of two expeditions to the Greenland ice sheet in May and July 2008, Bhatia and her colleagues collected samples from sites at several land-terminating glaciers on the western side of the Greenland ice sheet. The glaciers’ meltwater empties into a large lake, which eventually drains into an estuary system before reaching the open ocean. Their study reports levels of dissolved iron orders of magnitude higher than previously found for Greenland glacial runoff rivers. When the WHOI team extrapolated their findings to calculate the contribution of iron from the entire ice sheet, they estimated its value to be within the range of that from dust deposition in the North Atlantic, which is believed to be the primary source of bioavailable iron to this ocean. This value is only an order of magnitude lower than the estimated annual contribution of iron from rivers worldwide.

Research area: During the course of two expeditions to the Greenland ice sheet in May and July 2008, Bhatia and her colleagues collected samples from sites at three land-terminating glaciers. The meltwater from these glaciers travels through a flood plain and eventually drains into Qasigiatsigit Lake, before finally emptying into the fjord. -  Maya Bhatia - WHOI  
When an ice sheet or glacier melts, most of the water doesn’t simply run off the surface of the ice sheet. Instead it first drains to the bedrock below the ice sheet through cracks and conduits called moulins and then exits in large runoff rivers.

'A lot of people think of a glacier and an ice sheet as a big block of ice,' says Bhatia, 'but it’s actually quite a porous, complicated system underneath a glacier, with lots of moulins and crevasses leading to the bottom. Once you get into the bottom, there are large tunnels that these waters are passing through.' The more time the water spends in contact with the bedrock and sediments beneath the glacier, the more nutrients it picks up, including iron.

The WHOI team says further research is needed to determine how much of this iron actually reaches the open ocean, as their study followed the meltwater from the edge of the glaciers to the large lake they empty into. For this study, the team assumed that the amount of iron filtered out as the water moves through estuaries before reaching the marine environment would be roughly the same for glacial systems as it is for river systems.

Field assistant Ben Gready measures the electrical conductivity of the ‘N’ glacier outflow. By making this measurement at different times of the season, scientists can compare concentrations of dissolved nutrients in meltwater passing through the subglacial environment. Early in the melt season, the network of tunnels and chasms under the glacier is less efficient at draining meltwater, extending the meltwater’s contact with sediments and bedrock, thus picking up more dissolved nutrients. -  Matt Charette, WHOI  
The researchers hope to do more work to confirm the study’s numbers by sampling over a larger geographical area. Additional research could also confirm whether this influx of iron is in a form that can be easily utilized by phytoplankton and therefore stimulates primary production in the ocean.

'We don’t have enough historical measurements to say that this iron contribution is an increase over past conditions, but if it is working the way we think it is, the contribution would be greater as meltwater discharge increases,' Bhatia says. 'It is interesting to think that, as ice sheets melt, there are biogeochemical considerations beyond changing sea level.'

Maya Bhatia is currently a postdoctoral fellow in the Department of Microbiology and Immunology at the University of British Columbia in Vancouver, BC, Canada. Her co-authors include Elizabeth B. Kujawinski, Department of Marine Chemistry and Geochemistry; Sarah B. Das, Department of Geology and Geophysics; Crystaline F. Breier, Department of Marine Chemistry and Geochemistry; Paul Henderson, Department of Marine Chemistry and Geochemistry; and Matthew A. Charette, Department of Marine Chemistry and Geochemistry, all of WHOI.

This research was supported by the WHOI Clark Arctic Research Initiative, the National Science Foundation, the WHOI Ocean and Climate Change Institute, and an AGU Horton Hydrology Grant.

The study’s lead author, Maya Bhatia, second from left, spent seven weeks on the southwestern margin of the Greenland ice sheet in the spring/summer 2008 with her colleagues: WHOI marine chemist Liz Kujawinski, far left, field assistant Ben Gready, second from right, from the University of Alberta, and WHOI marine chemist Matt Charette, far right. Other colleagues included glaciologist Sarah B. Das, and chemistry research associates Crystaline F. Breier and Paul Henderson, all from WHOI. -  Matt Charette, WHOI  

The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit the WHOI website.


by Woods Hole Oceanographic Institution

  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=107457

8:03 PM Wed 13 Mar 2013GMT


Click here for printer friendly version
Click here to send us feedback or comments about this story.







News - USA and the World

Rolex China Sea Race 2014 - nip and tuck for IRC honours by RHKYC and Guy Nowell, Sail-World Asia, Hong Kong










America's Cup Book Review: Winging It - Oracle Team USA's comeback *Feature by Richard Gladwell Sail-World.com/nz,




























HUD Vision: An interview with Afterguard Marine’s Alex Moret *Feature by David Schmidt, Sail-World USA Editor, Seattle














America's Cup: Expected de Ridder penalty should be reduced *Feature by Richard Gladwell/Sail-World.com/nz, Auckland, NZ














Volvo Ocean Race - Maersk Line named shipping partner
Congressional Cup - Victory for Taylor Canfield and crew
SSV Oliver Hazard Perry joins America's Tall Ship fleet + Video
2014 Halifax – Saint-Pierre Ocean Race
Oyster Regatta Antigua - Glorious conditions prevail on final day
WWA Pro Card Qualifier - Pro Cards earned at Freedom Wake Park
Christmas Caribbean Rally - Top class sailors to compete
Earth Day boater tips
Anna Tunnicliffe - from CrossFit to Extreme 40's
Charleston Race Week - Photos by Chris Howell
Image Gallery: Stratis SL33 flies on the Waitemata
Audi Melges 20- Sperry Topsider Charleston Race Week - Light final day
Clipper Round the World Yacht Race - PSP Logistics prepares for USA
ISAF Sailing World Cup Hyères - Crème of the crop to compete
Congressional Cup: Luna Rossa makes podium in first event
Int 14 World Championships 2015 launch new event website
International Optimist Regatta Clinic and Team Race - Register now!
Congressional Cup: World top rankers finish that way in Long Beach
Sperry Top-Sider Charleston Race Week Day 3 finale
America's Cup: Gino Morrelli outlines the new AC62 design
Doyle Sails New Zealand signs Andrew Brown as One Design Manager   
America's Cup: Dean Barker's Blog - A sail with the Duke and Duchess *Feature   
29er World Youth Sailing Week Easter regatta - Day 1 and 2 overall   
C Thomas Clagett Jr Memorial Clinic/Regatta - Entries start to roll in   
50th Congressional Cup: See the delayed coverage and media conferences   
Clipper Race 10 Day 27: Closing stages - Qingdao to San Francisco   
Canfield, Williams, Bruni, Swinton in Congressional Cup final four   
Sperry Top-Sider Charleston Race Week - Day 2   
Audi Melges 20 Charleston Race Week - Perfect conditions in Charleston   
Oyster Regatta Antigua - Full on ocean conditions for day 3   
PWA World Tour - A taste of things to come at La Torche + Video   
Women's International Match Racing Series kicks off in June   
Melges 32 Audi Tron Sailing Series - Action shots by Max Ranchi   
Clipper Round the World Yacht Race - Frustrating conditions   
Man rescued after falling overboard in Pacific taken to hospital   
Sperry Top-Sider Charleston Race Week 2014 - Youth leading Melges 20   
Congressional Cup - Canfield leads toward Congressional Cup sailoffs   
Sperry Top-Sider Charleston Race Week 2014 - Perfection for Day 1   
America's Cup: Coutts claims ISAF Jury on a crusade, backs Kiwi report *Feature   
Clipper Round the World Yacht Race - Will light winds hamper progress?   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph contact the photographer directly.
X6XL WAS US