New Technology Could Revive Oceanic Dead Zones


In areas of oceans and lakes where aquatic life once thrived, scientists are now finding “dead zones” – low-oxygen areas choked with algal blooms.

Most of the world eats fish a dietary staple. As dead zones grow larger, the demand for fish will increase and the supply available to those who need it most will diminish more and more over time. Fish raised in laboratory-created low oxygen conditions showed extremely low sex hormone and were less likely to reproduce, or produced fewer fertilize eggs.

Marine dead zones are natural phenomena, but they’re affected by human pollution. Our fragile ecosystem can collapse or thrive, based on our actions. So, some industries and scientists have begun searching in earnest for ways to breathe new life into dead zones.

What causes dead zones?

Large-scale farming results in the runoff of fertilizer, pesticides, animal waste and fungicides into waterways. Through runoff, this tainted water increases the levels of nitrogen and phosphorus in water, eventually reaching the ocean.

Nitrogen and phosphorus occur naturally in water, but when runoff causes those levels to skyrocket, algae multiply, blanketing the water and preventing sunlight from reaching plants and marine life below the water line. The result is a rapid decrease in oxygen. While some animals may flee to more hospitable waters, plants – and stationary animals like clams – are stuck where they are.

Another contributor to oceanic dead zones is air pollution. The smog produced by burning gasoline and industrial emissions turns into rain and brings excessive nitrogen into the ocean. The overabundance of nitrogen and phosphorus creates optimum conditions for the formation of algal blooms.

When algal blooms die, bacteria that feed on the blooms further deplete oxygen levels, making the water even less conducive to supporting life.

How are we solving this problem?

The University of Wisconsin-Milwaukee and Veolia Water North America partnered for a study of Veolia’s patented Actiflo Carb technology. In an eight-week test-run, the technology cut phosphorus concentrations in wastewater and removed 75 percent of pharmaceuticals and personal care product residue from water. If able to be implemented on a broader scale, this clarification technology could be extremely helpful in reducing the occurrence of algal blooms.

The Baltic Marine Environment Protection Commission estimates 15,000 tons of phosphorus flows into the sea every year; the algal bloom in the Baltic is actually visible from space. The commission estimates that wastewater phosphorus levels would need to be reduced from 1.0mg/L to .50 mg/L for any noticeable improvement in the sea. And Veolia’s technology was able to reduce levels to .05 mg/L – a promising development for the Baltic Sea.

How can we prevent dead zones?

Because farm runoff is the top contributor to the formation of algal blooms, tougher regulations may be forthcoming regarding fertilizer use and animal waste disposal. But we can also make an impact on an individual level.

Homeowners can stop or reduce the application of phosphorus and nitrogen fertilizers to their lawns. While a green lawn is aesthetically pleasing, more polluted oceans are not. Yard debris and pet waste can also increase the presence of nitrogen and phosphorus in water, so proper disposal is important.

The next time you reach for a glass of clear, filtered water, think about what a precious resource water is, and what you can do to prevent algal blooms.