A pond in the Arctic ice


Melting ice shelves are changing the chemistry of the Arctic Ocean.


A frozen melt pond and sea ice seascape at 86°04'N, 168°21'E on August 30, 2015.
A frozen melt pond and sea ice seascape at 86°04'N, 168°21'E on August 30, 2015.
A.R. Margolin

The Arctic melt pond shown in the photograph above is a sign of much greater changes afoot in the frozen north.

Over the past decade, the amount of material in the central Arctic Ocean that comes from ice shelves – such as nutrients, carbon, trace metals, and radium – has greatly increased. This increase is altering the water’s composition and could threaten local species.

A recent study published in Science Advances offered one of the first solid estimates of Arctic shelf flux, which is affected by shifts in permafrost thawing, river discharge and coastal erosion. All of these are changing in response to rapidly rising Arctic temperatures.

To make the estimate, MIT’s Lauren E. Kipp and her colleagues measured the distribution of radium isotopes, which leave a unique isotopic imprint in seawater. They obtained samples of surface water in 2015 from 69 stations ranging from the Chukchi Shelf to the North Pole.

When they compared their findings to a 2007 study they discovered a sharp increase in radium-228 concentrations of surface waters between 2007 and 2015.

This increase, the researchers argue, means that profound increases in nutrient, carbon, and trace metal balances must also be occurring.

  1. http://advances.sciencemag.org/content/4/1/eaao1302
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