Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem

[Sally Furniss]

[SIZE=+2]Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem[/SIZE]
<aui auinm="Geisz, H. N."> <aui auinm="Dickhut, R. M."> <aui auinm="Cochran, M. A."> <aui auinm="Fraser, W. R."> <aui auinm="Ducklow, H. W."> <aus display="Ducklow, H. W." search="Ducklow, Hugh W."> <aus display="Dickhut, R. M." search="Dickhut, Rebecca M."> <aus display="Cochran, M. A." search="Cochran, Michele A."> <aus display="Geisz, H. N." search="Geisz, Heidi N."> <aus display="Fraser, W. R." search="Fraser, William R."> <aug> <aul></aul></aug></aus></aus></aus></aus></aus></aui></aui></aui></aui></aui> <au> Heidi N. Geisz,^* </au><au> Rebecca M. Dickhut, </au><au> Michele A. Cochran, </au><au> William R. Fraser,^? and </au><au> Hugh W. Ducklow^? </au>
<aff></aff> Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, Polar Oceans Research Group, Sheridan, Montana 59749, and Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543
Received for review November 21, 2007
Revised manuscript received February 29, 2008
Accepted March 18, 2008
Abstract:
Persistent organic pollutants reach polar regions by long-range atmospheric transport and biomagnify through the food web accumulating in higher trophic level predators. We analyzed Ade[FONT=Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont]́[/FONT]lie penguin (Pygoscelis adeliae) samples collected from 2004 to 2006 to evaluate current levels of ∑DDT (p,p′-DDT + p,p′-DDE) in these birds, which are confined to Antarctica. Ratios of p,p′-DDT to p,p′-DDE in Ade[FONT=Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont]́[/FONT]lie penguins have declined significantly since 1964 indicating current exposure to old rather than new sources of ΣDDT. However, ∑DDT has not declined in Ade[FONT=Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont]́[/FONT]lie penguins from the Western Antarctic Peninsula for more than 30 years and the presence of p,p′-DDT in these birds indicates that there is a current source of DDT to the Antarctic marine food web. DDT has been banned or severely restricted since peak use in the 1970s, implicating glacier meltwater as a likely source for DDT contamination in coastal Antarctic seas. Our estimates indicate that 1−4 kg?y⁻¹ ΣDDT are currently being released into coastal waters along the Western Antarctic Ice Sheet due to glacier ablation.

http://pubs.acs.org/cgi-bin/abstract.cgi/esthag/asap/abs/es702919n.html

 

[Sally Furniss]

Re: Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem

W&M student finds DDT in penguins
The William and Mary graduate student is helping unlock the secrets of Antarctic ice.

By PATRICK LYNCH | 247-4534
May 6, 2008

GLOUCESTER POINT - DDT was banned in the U.S. in 1973, but a College of William and Mary graduate student has found that levels of the chemical remain steady in the tissues of penguins in Antarctica, where DDT was never used.

The powerful pesticide remains in use sparingly around the world, primarily where malaria is a threat. Alternative chemicals and concern about DDT's effect on animal and human health led to widespread bans in most countries.

But the chemical persists for decades in the environment. Now Heidi Geisz, a graduate student at William and Mary's Virginia Institute for Marine Science, has found that not only are DDT levels remaining stable in Antarctic penguins, but it appears that global climate change is melting glaciers and releasing DDT that had been locked in ice for years.

Geisz, whose research is being published in the journal Environmental Science and Technology, studied DDT levels in the tissues and eggs of Adelie penguins on the Antarctic Peninsula. She and other VIMS researchers also sampled DDT levels in glacial meltwater. Her research found not only that DDT levels are consistent with what they were years ago, but also that "new" DDT was finding its way into the penguins' diet. DDT that has broken down slightly over the years shows a different chemical signature from DDT that has not.

The chemicals Geisz found in the penguin carcasses and abandoned eggs she tested revealed itself as "new" DDT. The question then became, "Why are we seeing fresh DDT in these seabirds at this point in the game?" Geisz said. "It's not in the air, it's not in the water, it's not in the snow."

But it was in the ice.

Melting glaciers on the Antarctic Peninsula are releasing more DDT into the food web, said Rebecca Dickhut, Geisz's faculty adviser. Some regions of Antarctica have seen some cooling trends in recent decades, but the peninsula has seen rapid warming. It is where the massive Larsen-B ice shelf, larger than Rhode Island, separated and drifted from the continent in 2002.

DDT and many other persistent, toxic chemicals are found in Antarctica even though they were never used there. Geisz chose to study DDT because there are better historical records of its presence on the continent. DDT was carried there through the atmosphere, deposited in the ocean or on the ice and snow, and then absorbed by microbial organisms.

Those microbes are then eaten by krill, small shrimp-like crustaceans. And krill comprise most of the Adelie penguins' diet. DDT, like other chemicals, also accumulates in larger quantities in larger predators. If the glaciers were not melting, the chemicals would likely stay locked in the ice.

But, Dickhut said, "It's there and it's coming out."

Instead of the DDT that was introduced in the 1950s and 1960s breaking down in animal tissues for decades, this release of the chemical is essentially starting a new cycle of the pesticide's introduction to the ecosystem. The end result is that in penguin tissues, "the levels have not come down since the 1970s," Dickhut said.

Geisz said the DDT concentrations in the birds she studied are not high enough to be of great concern for the animals' health, but show up as a reminder of how the chemical persists over years, and how it moves through an ecosystem.

http://www.dailypress.com/news/local/williamsburg/dp-local_ddt_0506may06,0,3887595.story

 

[tropical]

Re: Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem

"Instead of the DDT that was introduced in the 1950s and 1960s breaking down in animal tissues for decades, this release of the chemical is essentially starting a new cycle of the pesticide's introduction to the ecosystem. The end result is that in penguin tissues, "the levels have not come down since the 1970s," Dickhut said."

It would be interesting to see where are the other 20.000 new kinds of pesticides further released in the biosphera :yinyang: