Large, hazardous algae blooms are cropping up more and more around the country. The green, foul-smelling slime can affect everything from small fishing ponds to rivers and reservoirs, even great lakes. And the events are so toxic they’ve been known to cause serious health risk including lung and kidney problems in humans and deaths in animals, but some scientists in Mississippi are working on a solution.
Some experts say a mix of farm runoff, wastewater, and rising temperatures are making algal blooms more and more likely. Over the past several years, hazardous blooms have erupted in places like Lake Erie choking the city of Toledo’s water supply for weeks. Along the Ohio River, a hazardous bloom stretched nearly 600 miles affecting three states. In Mississippi, a toxic bloom held parts of the Gulf Coast under siege for days last year leaving a swath of dead marine life in its wake.
“We rely a lot of our recreation, our tourism, our economic dollars come from freshwater water bodies," says Brook Herman, a scientist at the U.S. Army’s Engineer and Research Development Center in Vicksburg.
“Really the impact of HAB’s are wide ranging. We have anywhere from public health issues where there’s human illnesses, pet deaths, wildlife deaths. Threatened and endangered species are impacted. Tourism, which then impacts a lot of the economy the has really emerged from water resources.”
Traditionally, authorities have used chemicals like algaecides and herbicides to treat hazardous blooms, but those chemicals may not be able to work in large scale events.
"Some of the treatments or applications of chemicals, that’s great in smaller ponds," says Herman. "You can really knock that out. In large scale reservoirs or navigational pools, we’re really constrained with how much you can actually dump in or treat in terms of those areas.”
So how do you treat a toxic event without using chemicals?
The researchers think they may have found a potential answer, hydrodynamic cavitation, or micro-bubbles that destroy the algae as it reproduces.
"Once those cyanobacteria are basically rendered harmless, it’s almost a situation where they’re being killed," research microbiologist Catherine Thomas explains. "They’re inactive at that point and they just precipitate out of the water column.”
However, there’s a catch. Authorities would have to be very strategic with where they tried to use the process because creating those micro-bubbles may not be able to work on a large scale. That’s why the scientists are also trying to find ways to locate algal blooms early before they become large-scale events. The research is still in its initial phases, but the team says using imaging data from drones may be able to help assess the scale of a potential bloom.
But one of the best ways to stop a hazardous algae bloom from becoming a large-scale event is by preventing it in the first place.
Researcher Carina Jung has been conducting an experiment that places specialized iron sheets in water attracting contaminants that can then be filtered out.
“A lot of these waterways are impacted with nutrients that are very high, typically, phosphorus, nitrogen, and these allow the organisms to bloom," says Jung. "Currently, I’m using a zero valent iron mechanism where we can actually bind the phosphate to the iron. Then any rust water we can filter out with activated charcoal. So far, we are having very good success with it."
As algae blooms grow and spread, the scientists at the Corps of Engineers say they will continue to work to contain the problem.