Iron key weapon in blue-green algae fight, U of A researchers say

U of A research conducted at Nakamun Lake, west of Edmonton, found that adding iron prevented toxic blue-green algal bloom and improved water quality.

• Further reading: Beating blue-green algae with iron

"Iron plays a very important role in lakes," said freshwater ecologist Diane Orihel, the lead author of the study published in Ecological Applications. "It can bind the nutrients that the algae rely on."

Researchers hoped to prove that the addition of iron would lock the minerals up at the bottom of the lake "and basically starve the algae of the nutrients they need."

Blue-green algae (cyanobacteria) was again found in lakes around Alberta this summer and the warning to avoid the blooms has become all too familiar to summertime lake-goers.

Algal blooms produce a toxin that can cause liver damage and serious illness for those who drink or come into contact with contaminated water.

Orihel conducted the research at Nakamun Lake, an hour west of Edmonton, as a PhD student with the University of Alberta.

To complete the experiment, she used 15 mescocosms, devices that resemble giant test tubes, to test water quality in different parts of the lake.

By testing the water before and after adding the mineral, the results showed that the iron treatment reduced phosphorus levels in the water and, as a result, lowered the amount of algae and the associated toxic bacteria.

The algae thrives in an environment that has high concentrations of certain nutrients, particularly phosphorus emitted from the sediment on the lake bottom.

The blooms are worsened by phosphorus added from fertilizer runoff and other pollutants.

"Our impact on the watershed of lakes has made harmful algal blooms more prevalent," Orihel said.  

Most lakes in Alberta are also naturally lacking in iron due to the province's natural geology.

Iron binds with the phosphorus in the water, preventing it from feeding algal blooms.

Prairie lakes are well suited to the treatment because they are alkaline lakes and the addition of iron will not disturb the natural pH balance. 

Orihel said the research revealed that higher doses made a greater difference, whereas small amounts of iron had very little effect. 

Blue-green-eyed monster

Orihel said the research is part of a global battle against algae.

"There is a great need for strategies to deal with harmful algal blooms," she said.

Cyanobacteria can produce toxins that cause respiratory and liver failure and harms humans as well as livestock and pets.

In lakes and coastal areas, the toxin also creates dead zones by robbing the water of essential levels of oxygen, preventing fish or other aquatic life from surviving.

The spread has become a problem for lakes around the world, hurting tourism and fishing. Satellite images show massive bodies of water covered in the blue green bacteria.

Previous research found adding iron to water helped in fight against the algal bloom, but this is the first study of its kind in Canada.

Rearchers have advocated for the use of other chemicals to fight algal blooms, but iron creates a compound that is already naturally occurring in lakes.

The University of Alberta researchers said this provides a greener alternative.