Author: Larry Warnberg (Larry_warnberg)
Thursday, January 29, 2009 - 11:49 am
Dead zones due to nitrogen pollution are expanding in many places, including Puget Sound in Washington State. As an oyster farmer for many years I was aware of the threat of nutrient pollution to the shellfish industry, and have promoted composting toilets as an important method to prevent such pollution while returning valuable nutrients to the soil where they belong. Finally, our Dept.of Ecology released a study about the problems created by nitrogen effluent, promising another analysis of potential solutions in 2010. Once more I will be offering the suggestion that composting toilets can be part of the solution.
Here is today's Seattle Times report on the new study:
By Lynda V. Mapes
Seattle Times staff reporter
To learn more and read the study: www.ecy.wa.gov/puget_sound/dissolved_oxygen_study.html
Discharge from sewage-treatment plants and rivers — the end repositories of pollutants rinsing off the land, including stormwater — are major sources of nitrogen pollution, a new state study has found.
Excess nitrogen can be a problem because it feeds algae blooms. When the algae dies, it decomposes and sucks oxygen out of the water that fish and other aquatic life need.
Nitrogen pollution is not a problem everywhere in Puget Sound, but in some areas, where water is shallow and embayments tight, with little water circulation, low levels of dissolved oxygen caused by excess nitrogen can be deadly.
So far scientists have found sewage-treatment-plant pipes contribute 80 to 90 percent of the nitrogen in some parts of Puget Sound during some parts of the year, according to the study.
Rivers, air deposition, sediments, septic systems and even the Pacific Ocean also pump nitrogen into Puget Sound.
The findings, reported by the state Department of Ecology, are just the first part of a long-term study, sampling waters from King to Mason counties. Next will come analysis of how water circulates in Puget Sound, how nitrogen is affecting the water quality and what to do about it.
The places in the study area that don't meet state water-quality standards are Carr, Case and Budd Inlets in south Puget Sound.
But whether or how discharge from rivers and sewage-treatment plants is involved in those low dissolved-oxygen levels is yet to be determined. Scientists need to learn how water circulates in the sound, and how the that, in turn, affects water quality.
Some steps have already been taken to combat nitrogen pollution. The sewage treatment plant in Olympia spent $37 million in 1994 to clean nitrogen from plant effluent from April to October, when sunlight and warmer water temperatures encourage algae growth.
Jan Newton, an expert with the University of Washington on dissolved-oxygen problems in Hood Canal, said the problem with nitrogen isn't how much of it there is, but where it is, and when it's present.
In a fast-flushing body of water with a complex seabed that causes mixing of layers of water, nitrogen is dispersed and mixed in the water column, rather concentrated, and available to feed algae. The time of year also matters. Colder months with less sunlight don't see much algae growth.
How a complex system such as Puget Sound, with its differing depths and circulation patterns can be best managed for water quality is something scientists are still working to figure out.
More study can help target places where the combination of nitrogen loads and local circulation patterns and weather combine to harm aquatic life.
When it's complete in 2010, the study may help target where and how to make smart investments in water-quality improvement, said Duane Fagergren of the Puget Sound Partnership, the new state agency created to protect and restore Puget Sound. Fagergren said.
"If we don't have oxygen, we don't have fish and we don't have shellfish, which naturally filter the water," Fagergren said. "We don't have much of anything."
Lynda V. Mapes: 206-464-2736 or email@example.com
Copyright © 2009 The Seattle Times Company
Tuesday, May 27, 2003 - 6:58 pm
Oceans in Peril
It has long been clear that the world's oceans are in trouble, its coastal waters increasingly polluted and its fish stocks in various stages of decline. Now comes the most shocking news in years: a report from two Canadian scientists that says the world's mechanized fishing fleets have managed in a mere 50 years to wipe out nine-tenths of the world's biggest and most economically important species of fish, including cod, halibut, tuna and swordfish.
Wednesday, August 24, 2005 - 8:41 am
Wave of Marine Species Extinctions Feared
By Juliet Eilperin
Washington Post Staff Writer
Wednesday, August 24, 2005; Page A01
BIMINI, Bahamas -- The bulldozers moved slowly at first. Picking up speed, they pressed forward into a patch of dense mangrove trees that buckled and splintered like twigs. As the machines moved on, the pieces drifted out to sea.
Sitting in a small motorboat a few hundred yards offshore on a mid-July afternoon, Samuel H. Gruber -- a University of Miami professor who has devoted more than two decades to studying the lemon sharks that breed here -- plunged into despondency. The mangroves being ripped up to build a new resort provide food and protection that the sharks can't get in the open ocean, and Gruber fears the worst.
Marine biologist Ellen K. Pikitch holds a baby lemon shark on the island of Bimini, where the species' habitat is shrinking because of development. (By Grant Johnson)
Some notable global marine species have become extinct in recent decades.
What Do You Think?
"At the end of my career, I get to document the destruction of the species I've been documenting for 20 years," he lamented as he watched the bulldozers. "Wonderful."
Gruber's sentiments have become increasingly common in recent years among a growing number of marine biologists, who find themselves studying species in danger of disappearing. For years, many scientists and regulators believed the oceans were so vast there was little risk of marine species dying out. Now, some suspect the world is on the cusp of what Ellen K. Pikitch, executive director of the Pew Institute for Ocean Science, calls "a gathering wave of ocean extinctions." Dozens of biologists believe the seas have reached a tipping point, with scores of species of ocean-dwelling fish, birds and mammals edging toward extinction. In the past 300 years, researchers have documented the global extinction of just 21 marine species -- and 16 have occurred since 1972.
Since the 1700s, another 112 species have died out in particular regions, and that trend, too, has accelerated since the mid-1960s: Nearly two dozen shark species are close to disappearing, according to the World Conservation Union, an international coalition of government and advocacy groups.
"It's been a slow-motion disaster," said Boris Worm, a professor at Canada's Dalhousie University, whose 2003 study that found that 90 percent of the top predator fish have vanished from the oceans. "It's silent and invisible. People don't imagine this. It hasn't captured our imagination, like the rain forest."