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06-22-2002, 11:04 AM
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Large 'dead zone' in Lake Erie waters worries scientists
06/14/02
Bill Sloat
Plain Dealer Reporter
Scientists call it a dead zone, an area deep in the heart of Lake Erie devoid of life.
Last summer, the worst dead zone since the early 1980s formed offshore between Ohio and Ontario, an ominous sign that the lake's environmental progress is shifting into reverse. Already there are abundant warnings that the dead zone will return again this summer and concerns that it may get larger.
From Our Advertiser
Next week, ships loaded with scientists and sophisticated monitoring equipment will begin exploring the lake, trying to discover what is threatening to undo years of steady environmental improvement.
The dramatic cleanup of the 240-mile-long Great Lake - once among the world's most polluted waterways - has long been considered one of the environmental movement's greatest achievements. Any reversal could devastate tourism and fishing economies prospering along the shoreline.
Scientists from the United States and Canada say they are baffled by what is happening. A recent U.S. EPA report says last year's dead zone in Lake Erie's central basin duplicated how "anoxia was prevalent in the late 1960s."
"However, it is unclear why this may be reappearing," the report says.
"What we're seeing in the lake is that phosphorous levels are going up, and they are going up faster than they should," said David Rockwell, an EPA researcher at the Great Lakes National Program Office in Chicago. "And last year, we had the most rapid depletion of oxygen that we have measured since 1983."
In 1983, about 90 percent of Lake Erie's central basin was devoid of oxygen, according to old records.
The EPA christened Lake Erie's oxygen-less area the "dead zone" last month, in a hardly noticed Internet document describing significant issues affecting the Great Lakes.
Already this spring, an EPA boat, the Lake Guardian, has found samples of water that is unusually cloudy with algae and other forms of floating plant life.
Too much algae is a sign that nutrients such as phosphorus and nitrogen are overabundant - a combination that eventually creates a barren region beneath the surface.
In effect, the nutrients enrich the lake to death.
A lake can die when its bottom becomes covered with too much decomposing plant matter, which consumes more and more oxygen as it rots. When the oxygen is gone, the suffocating swath becomes lifeless.
Oxygen deprivation takes place nearly every summer somewhere in the deep waters of central Lake Erie. The water remains anoxic until the upper layer of the lake cools in the fall, and mixing occurs.
The western basin is so shallow that its waters mix all year long. The eastern basin, the lake's deepest section, is not threatened with oxygen depletion because its much greater water volume can absorb the seasonal changes.
Gerald Matisoff, a Case Western Reserve University geo-chemist heading the U.S. side of the Lake Erie investigation, said the eight-boat flotilla of research vessels will crisscross the central basin in search of answers.
Scientists will gather thousands of water samples to more precisely measure the dead zone's boundaries, depths and development in June, July and August. By midsummer, the United States and Canada will have about 40 researchers from 17 universities studying the area like a scientific SWAT team.
"Back in the 1960s and 1970s, the lake had the same problems. We thought they were solved, and for the last 10 years we've been patting ourselves on the back," Matisoff said. "All of a sudden we've got a disturbing trend of degrading water quality. The question is: How come?"
Many scientists suspect that zebra mussels and other exotic species such as round gobies are starting to reshape Lake Erie's ecosystem in ways that scientists have yet to fathom, Matisoff said. Others theorize that the lake may be suffering from the effects of climate changes linked to global warming.
Another theory is that sewage treatment plants could be dumping excess wastes, said Murray Charlton, a scientist at Canada's National Water Research Institute. The lake should not be in decline after nearly $8 billion was spent on new sewage treatment plants since the 1970s. Laws were passed to restrict the use of phosphate laundry detergents. Farmers even changed tillage practices to reduce fertilizer runoff.
Those moves cut the flow of phosphates into the lake by more than half - from 24,000 tons a year to less than 11,000 tons.
Most puzzling to scientists are water-quality measurements taken by Canadian researchers the last two years near Niagara Falls, where the lake's waters exit. They show phosphorous levels leaving Lake Erie have "markedly exceeded the quantity entering" each year from sewage treatment plants, farms and other known sources.
By all prior calculations, Lake Erie should still be growing cleaner, Charlton said.
"I don't want to sound alarmist," Charlton said, "But we have no idea, really, what is going on."
Plain Dealer reporter Molly Kavanaugh contributed to this story.
Contact Bill Sloat at:
bsloat@plaind.com, 513-631-4125
News
» The Plain Dealer
» Newsflash
» Weather
» Traffic
» Obituaries
» Opinion
» Business
» Crime
» Politics
» Education
SPEAK UP!
» Discuss local news
» Log On to ChatXtra Now!
HomeTown
Local News,
Links & More!
Enter Town or Zip:
» Looking for a car?
FROM OUR ADVERTISERS
>> Adelphia Power Link 2 Months FREE
>> Win a years supply of pool chemicals
>> No Minimum Checking at DollarBank
» Advertise With Us
» More From The Plain Dealer
News
Large 'dead zone' in Lake Erie waters worries scientists
06/14/02
Bill Sloat
Plain Dealer Reporter
Scientists call it a dead zone, an area deep in the heart of Lake Erie devoid of life.
Last summer, the worst dead zone since the early 1980s formed offshore between Ohio and Ontario, an ominous sign that the lake's environmental progress is shifting into reverse. Already there are abundant warnings that the dead zone will return again this summer and concerns that it may get larger.
From Our Advertiser
Next week, ships loaded with scientists and sophisticated monitoring equipment will begin exploring the lake, trying to discover what is threatening to undo years of steady environmental improvement.
The dramatic cleanup of the 240-mile-long Great Lake - once among the world's most polluted waterways - has long been considered one of the environmental movement's greatest achievements. Any reversal could devastate tourism and fishing economies prospering along the shoreline.
Scientists from the United States and Canada say they are baffled by what is happening. A recent U.S. EPA report says last year's dead zone in Lake Erie's central basin duplicated how "anoxia was prevalent in the late 1960s."
"However, it is unclear why this may be reappearing," the report says.
"What we're seeing in the lake is that phosphorous levels are going up, and they are going up faster than they should," said David Rockwell, an EPA researcher at the Great Lakes National Program Office in Chicago. "And last year, we had the most rapid depletion of oxygen that we have measured since 1983."
In 1983, about 90 percent of Lake Erie's central basin was devoid of oxygen, according to old records.
The EPA christened Lake Erie's oxygen-less area the "dead zone" last month, in a hardly noticed Internet document describing significant issues affecting the Great Lakes.
Already this spring, an EPA boat, the Lake Guardian, has found samples of water that is unusually cloudy with algae and other forms of floating plant life.
Too much algae is a sign that nutrients such as phosphorus and nitrogen are overabundant - a combination that eventually creates a barren region beneath the surface.
In effect, the nutrients enrich the lake to death.
A lake can die when its bottom becomes covered with too much decomposing plant matter, which consumes more and more oxygen as it rots. When the oxygen is gone, the suffocating swath becomes lifeless.
Oxygen deprivation takes place nearly every summer somewhere in the deep waters of central Lake Erie. The water remains anoxic until the upper layer of the lake cools in the fall, and mixing occurs.
The western basin is so shallow that its waters mix all year long. The eastern basin, the lake's deepest section, is not threatened with oxygen depletion because its much greater water volume can absorb the seasonal changes.
Gerald Matisoff, a Case Western Reserve University geo-chemist heading the U.S. side of the Lake Erie investigation, said the eight-boat flotilla of research vessels will crisscross the central basin in search of answers.
Scientists will gather thousands of water samples to more precisely measure the dead zone's boundaries, depths and development in June, July and August. By midsummer, the United States and Canada will have about 40 researchers from 17 universities studying the area like a scientific SWAT team.
"Back in the 1960s and 1970s, the lake had the same problems. We thought they were solved, and for the last 10 years we've been patting ourselves on the back," Matisoff said. "All of a sudden we've got a disturbing trend of degrading water quality. The question is: How come?"
Many scientists suspect that zebra mussels and other exotic species such as round gobies are starting to reshape Lake Erie's ecosystem in ways that scientists have yet to fathom, Matisoff said. Others theorize that the lake may be suffering from the effects of climate changes linked to global warming.
Another theory is that sewage treatment plants could be dumping excess wastes, said Murray Charlton, a scientist at Canada's National Water Research Institute. The lake should not be in decline after nearly $8 billion was spent on new sewage treatment plants since the 1970s. Laws were passed to restrict the use of phosphate laundry detergents. Farmers even changed tillage practices to reduce fertilizer runoff.
Those moves cut the flow of phosphates into the lake by more than half - from 24,000 tons a year to less than 11,000 tons.
Most puzzling to scientists are water-quality measurements taken by Canadian researchers the last two years near Niagara Falls, where the lake's waters exit. They show phosphorous levels leaving Lake Erie have "markedly exceeded the quantity entering" each year from sewage treatment plants, farms and other known sources.
By all prior calculations, Lake Erie should still be growing cleaner, Charlton said.
"I don't want to sound alarmist," Charlton said, "But we have no idea, really, what is going on."
Plain Dealer reporter Molly Kavanaugh contributed to this story.
Contact Bill Sloat at:
bsloat@plaind.com, 513-631-4125