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It's no surprise we've done a pretty good job of polluting our rivers, contaminating our oceans and baking our glaciers into oblivion.
What might come as a surprise is that some of the lakes that seem to be the most pristine aren't all that pristine at all. Some of the bodies of water that seem about as remote as they get are being affected by the nastiness we put in the air. And it's not the sort of nastiness you might expect.
We all know about our carbon footprint, that specter that makes us feel guilty every time we drive to the grocery store and drop some grapes from Chile into our plastic bag. Now, it turns out, we need to be worried about our nitrogen footprint. If you have any doubt, all you have to do is take a hike into Rocky Mountain National Park and dip you're feet in the water of an icy-cold alpine lake.
What seem to be some of the purest bodies of water, tucked high in the Rockies, are getting greener, and not in a good way. They're getting greener in a yucky, slimy, algae kind of way.
A report in a recent edition of Science finds that some high alpine lakes are being swamped with nitrogen from the atmosphere, caused by pollution from cars, factories, feed lots and fertilizer. The nitrogen is essentially fertilizing lakes that aren't used to being fertilized, causing a growth of algae and threatening to harm the fish at the top of the food chain.
In addition to our carbon footprint, researchers say, human activity leaves a more subtle nitrogen footprint that is affecting natural systems around the world, even in some of the remotest places on earth.
“It's part of a global phenomenon,” says James Elser, life sciences professor at Arizona State University, the lead author of the report.
The increase in nitrogen has caused so-called “dead zones” each summer in the Gulf of Mexico and around the country. These dead zones, algae blooms consumes the available oxygen and starves aquatic life off the coast. Researchers say a similar phenomenon is occurring in alpine and subalpine lakes in Rocky Mountain National Park, as well as at remote lakes in Sweden and Norway. Parts of the world that seemed far-removed from human impacts are being affected by what has been a doubling of nitrogen released into the earth's atmosphere since the Industrial Revolution.
“This is as serious a problem (as global carbon levels),” says co-author Jill Baron, ecosystem ecologist for the US Geological Survey's Natural Resource Ecology Laboratory Colorado State University. “What we have is nitrogen that's up in the atmosphere with the prevailing winds and it comes down in rain and snow. It's fertilizing places that have never seen it before.”
It turns out, those remote mountain lakes have gotten along just fine without nitrogen for as long as they've been around. Nitrogen is a powerful fertilizer, though, and adding it to the aquatic systems has wreaked havoc on them.
Where does all this nitrogen come from? Well, from a lot of the same places that produce carbon. Nitrogen is released into the atmosphere from tailpipes, industrial operations, cattle manure and artificial fertilizer. High-alpine lakes have historically been low in nitrogen. When nitrogen pollutes the lakes, it causes microscopic phytoplankton to become deficient in phosphorus, which is needed for the plants to grow properly. That can mean more—but less nutritious—algae in the lakes for the animal plankton to feed on. When the fish eat the animal plankton, they don't get the proper food either.
“It's junk food for fish,” Elser says. “It'slike expecting a teenager to grow by just eating marshmallows.”
The algae bloom can also contribute to greenhouse gases, Baron says. The additional plant growth often ends up dying, floating downstream and putting more carbon into the atmosphere.
“We have disrupted the global nitrogen cycle and few ecosystems if any are immune from this,” says Baron, who will address the upcoming climate talks in Copenhagen. “Even very low amounts of this nitrogen that comes out of the sky can cause major changes to protected ecosystems. ... One of the nice things that I think we have in our grasp is our ability to reverse it. None of this is permanent.”
David Frey can be reached through his Web site, www.davidfrey.me.
What might come as a surprise is that some of the lakes that seem to be the most pristine aren't all that pristine at all. Some of the bodies of water that seem about as remote as they get are being affected by the nastiness we put in the air. And it's not the sort of nastiness you might expect.
We all know about our carbon footprint, that specter that makes us feel guilty every time we drive to the grocery store and drop some grapes from Chile into our plastic bag. Now, it turns out, we need to be worried about our nitrogen footprint. If you have any doubt, all you have to do is take a hike into Rocky Mountain National Park and dip you're feet in the water of an icy-cold alpine lake.
What seem to be some of the purest bodies of water, tucked high in the Rockies, are getting greener, and not in a good way. They're getting greener in a yucky, slimy, algae kind of way.
A report in a recent edition of Science finds that some high alpine lakes are being swamped with nitrogen from the atmosphere, caused by pollution from cars, factories, feed lots and fertilizer. The nitrogen is essentially fertilizing lakes that aren't used to being fertilized, causing a growth of algae and threatening to harm the fish at the top of the food chain.
In addition to our carbon footprint, researchers say, human activity leaves a more subtle nitrogen footprint that is affecting natural systems around the world, even in some of the remotest places on earth.
“It's part of a global phenomenon,” says James Elser, life sciences professor at Arizona State University, the lead author of the report.
The increase in nitrogen has caused so-called “dead zones” each summer in the Gulf of Mexico and around the country. These dead zones, algae blooms consumes the available oxygen and starves aquatic life off the coast. Researchers say a similar phenomenon is occurring in alpine and subalpine lakes in Rocky Mountain National Park, as well as at remote lakes in Sweden and Norway. Parts of the world that seemed far-removed from human impacts are being affected by what has been a doubling of nitrogen released into the earth's atmosphere since the Industrial Revolution.
“This is as serious a problem (as global carbon levels),” says co-author Jill Baron, ecosystem ecologist for the US Geological Survey's Natural Resource Ecology Laboratory Colorado State University. “What we have is nitrogen that's up in the atmosphere with the prevailing winds and it comes down in rain and snow. It's fertilizing places that have never seen it before.”
It turns out, those remote mountain lakes have gotten along just fine without nitrogen for as long as they've been around. Nitrogen is a powerful fertilizer, though, and adding it to the aquatic systems has wreaked havoc on them.
Where does all this nitrogen come from? Well, from a lot of the same places that produce carbon. Nitrogen is released into the atmosphere from tailpipes, industrial operations, cattle manure and artificial fertilizer. High-alpine lakes have historically been low in nitrogen. When nitrogen pollutes the lakes, it causes microscopic phytoplankton to become deficient in phosphorus, which is needed for the plants to grow properly. That can mean more—but less nutritious—algae in the lakes for the animal plankton to feed on. When the fish eat the animal plankton, they don't get the proper food either.
“It's junk food for fish,” Elser says. “It'slike expecting a teenager to grow by just eating marshmallows.”
The algae bloom can also contribute to greenhouse gases, Baron says. The additional plant growth often ends up dying, floating downstream and putting more carbon into the atmosphere.
“We have disrupted the global nitrogen cycle and few ecosystems if any are immune from this,” says Baron, who will address the upcoming climate talks in Copenhagen. “Even very low amounts of this nitrogen that comes out of the sky can cause major changes to protected ecosystems. ... One of the nice things that I think we have in our grasp is our ability to reverse it. None of this is permanent.”
David Frey can be reached through his Web site, www.davidfrey.me.
