Could pumping oxygen-rich surface water into the depths of lakes, estuaries, and coastal ocean waters help ameliorate dangerous dead zones? New work led by Carnegie’s David Koweek and Ken Caldeira and published open access by Science of the Total Environment says yes, although they caution that further research would be needed to understand any possible side effects before implementing such an approach.
When excessive nutrients from agriculture and other human activities wash into waterways, it can create a dangerous phenomenon called eutrophication. This can lead to low-oxygen dead zones called hypoxia.
“Low-oxygen dead zones are one of the most-pervasive problems plaguing both marine and freshwater systems around the world and a major problem for communities that depend on fishing,” Koweek said.
Efforts to fight hypoxia often focus on reducing agricultural runoff and on preventing nutrients from being overloaded into waterways. But this is a very slow process that involves changing farming practices, upgrading wastewater treatment facilities, and altering home fertilizer usage.
Koweek and Caldeira led a team that investigated a proposed technological remedy, called downwelling, which could complement nutrient-reduction programs. This involves pumping naturally more-oxygenated water from the surface down into the depths of the affected body of water.
“In theory, downwelling would create vertical mixing in the water, distributing oxygen and preventing hypoxic conditions from taking hold,” Koweek explained. “We wanted to test this idea and see if it would really work.”
The team built models to compare downwelling to the two most-commonly used technological techniques for preventing dead zones—bubbling oxygen from the bottom and spraying fountain water across the surface. Their models indicate that downwelling would be three to 100 times more efficient than bubbling and 10,000 to a million times more efficient than fountains.
They then did a field experiment at the Searsville Reservoir in Woodside, California, which demonstrated that downwelling could increase oxygen saturation in the immediate area surrounding the pumps by between 10 and 30 percent, enough to alleviate hypoxic stress for many marine organisms. However, this did not extend for more than a handful of meters beyond the vicinity of the pipes through which the surface water was pumped. This means that an extensive network would be necessary for any major effort to fight dead zones in an economically important or ecologically sensitive area.
According to the researchers, their work indicates that downwelling technology may show potential to scale up to larger areas in which annual dead zones create great ecological and economic distress, such as the Chesapeake Bay or the Gulf of Mexico. They estimate that the energy required to power the pumps could cost tens of millions of dollars each year. Operating downwelling pumps year-round in the Chesapeake could cost between $4 and $47 million; In the Gulf, the same could cost between $26 and $263 million.
But these price tags are relatively small compared to the costs of upgrades to wastewater treatment facilities and fertilizer-reduction programs that limit nutrient inputs to the water bodies. This suggests that downwelling technology could be used alongside longer-term plans to reduce nutrient pollution.
“Reducing nutrient pollution is the only way to eliminate hypoxia permanently,” Calderia said. “However, our work shows that downwelling is a technological solution that could mitigate the risk of low-oxygen dead zones while nutrient management strategies are put in place.”
The Latest Updates from Bing News & Google News
Go deeper with Bing News on:
Aquatic dead zones
- Another View: Iowa farmers help fight dead zone in Gulf of Mexicoon October 6, 2020 at 9:50 am
The Gulf of Mexico is hundreds of miles south of Iowa, but actions now being taken by the state’s farmers will, over a period of years, help to improve that body of water. The gulf is afflicted by ...
- With Activists Silenced, China Moves Ahead on Big Dam Projecton October 5, 2020 at 2:27 am
The expected resurrection of a controversial dam project along the Yangtze River in western China is the latest sign that the nation’s once-robust environmental movement is being muzzled by the ...
- Editorial Roundup:on October 4, 2020 at 9:32 am
That causes algae to grow like crazy, consuming all the oxygen in the water. The result is essentially a dead zone with no aquatic life in it. On Thursday, Iowa Secretary of Agriculture Mike Naig gave ...
- What happens to all of the dead leaves?on October 4, 2020 at 3:49 am
As I crunch over dead leaves into the shadows, I'm pulled farther in by the sound of rushing water, and soon a wide stream emerges to the left. I have never visited this seven-acre patch of woods ...
- Wastewater detrimental to coral reefs off Kahekilion October 3, 2020 at 5:00 pm
It is critical to understand that the wastewater effluent is entering the ocean where people swim and that the reef is degrading because of it — data from the Division of Aquatic Resources and ...
Go deeper with Google Headlines on:
Aquatic dead zones
Go deeper with Bing News on:
- Curious minds: the biggest mysteries about space answeredon October 4, 2020 at 2:33 am
All About Space and Space.com have teamed up with some of the brightest minds to answer your questions about the universe! Whether it's the mysteries of black holes or how stars are formed, our ...
- Sally’s Slow Movement and Complex Setup Made For Difficult Forecaston September 16, 2020 at 1:08 pm
This storm actually had “downwelling” instead. And that kept sea surface temperatures from cooling too much. I've been watching this buoy closely and I am a bit perplexed. The SST here ...
- Hotter oceans harm seabed life survival prospectson September 14, 2020 at 10:45 pm
The researchers, from Rutgers University in New Brunswick, call it the downwelling effect, and identify a paradox: as the area habitable by bottom-dwellers gets bigger, their ranges dwindle. The ...
- Meet the Explorerson June 4, 2019 at 9:20 am
Much of her research has been on the visual ecology of deep-sea animals, studying adaptations to both downwelling light and bioluminescence. Her work has been funded by the National Science Foundation ...
- Air pollution from China detectedon December 25, 2017 at 4:15 pm
At Donner Summit, night-time “downwelling,” where cooling air drops from the upper atmosphere, reveals pollutants carried from thousands of miles away, said Cliff. “It pushes out all of the ...