sail-world.com
 
 
News Home Cruising Photo Gallery Video 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



2014 Detroit Cup - Sam Gilmour leads by Dobbs Davis, Detroit, Michigan




Audi Hamilton Island Race Week: Riding the AC45 - VIDEO by Crosbie Lorimer, Hamilton Island










America's Cup: Five Challengers sign-on for 35th Match by Richard Gladwell/Sail-World.com/nz,


Volvo Ocean Race CEO Knut Frostad talks Time and Money (Part II) *Feature by Rob Kothe and the Sail-World team,


















AWT Quatro Desert Showdown at Punta San Carlos by American Windsurfing Tour,
















America's Cup: Rod Davis - Time for a change after ten years with team *Feature by Richard Gladwell/Sail-World.com/nz,








Maxi yacht rendezvous this September in Sardinia by International Maxi Association,






Sevenstar Round Britain and Ireland - Swish smash 5th World Record
Leaderboards take shape at the Nanjing Youth Olympic Games 2014
IFDS Worlds - Hot competition on first day of racing
Challenging Conditions - CORK OCR
IFDS World Championship - Day 1 for the US Sailing Team
2014 Melges 20 World Championship - Countdown begins
2014 Nanjing Youth Olympic Games - Day 3
America's Cup: Team NZ wish Davis well with new team *Feature
Fisher's View: Sailing perfection at Hamilton Island- Day 3
Roble and Wilson still number one match racers in the U.S.
2014 Formula Kite World Championship Day 1
IFDS World Championship - Day 1 images by Jude Robertson
Volvo Ocean Race: Forget the f-word - Team SCA profiled
52 Super Series - Fleet grows, 2015 dates revealed
420 and 470 Junior Europeans - Teams from 9 nations on the podium
IFDS Worlds - Former president presented with ISAF awards medal
Nanjing Youth Olympic Games - Improvements aplenty in Byte CII fleets
America's Cup: New Zealand loses top coach to Artemis Racing
Volvo Ocean Race 2014-15 CEO Knut Frostad talks (Part I) *Feature
Sevenstar Round Britain and Ireland Race Day 9 - Swish on record pace
2014 CORK Olympic Classes Regatta - Day 3   
2014 Nanjing Youth Olympic Games - Day 2   
2014 IFDS World Championship: Opening Ceremony images   
Opera House Cup - Images by Ingrid Abery   
Teams descend upon Cowes for inaugural J/111 World Championships   
Hamilton Island Race Week: Everywhere there's smiley people   
IFDS World Championships - US Paralympic hopefuls ready for racing   
Sopot Match Race - Poland's Tour debut deemed a triumph   
Vineyard Race celebrates 80th running of the East Coast classic   
Nanjing Youth Olympic Games: Young sailors begin racing on Lake Jinniu   
AWT Quatro Desert Showdown - Victory for Morgan Noireaux   
Sevenstar Round Britain and Ireland Race - Day 8: Test of endurance   
Bart's Bash: Over 2300 entered from 588 yacht clubs - Join here   
Halifax ready to welcome the world at 2014 IFDS World Championships   
RC44 World Championship title to Bronenosec + Video   
Audi Hamilton Island Race Week: Day 2 Images by Crosbie Lorimer   
IFDS Worlds - Gary Jobson to attend opening ceremonies   
Melges 32 U.S. National Championship - Dalton DeVos crowned champion   
2014 Nanjing Youth Olympic Games trailer   
2014 Chicago Grand Slam - Canfield wins   


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.
XLXL NEW US
LocalAds   DE  ES  FR  IT