Ontario targets phosphorus from runoff as algal bloom season begins


As summer starts, Canada is reminded of its continuing struggle with blue-green algae. But in Ontario, The Thames River Phosphorus Reduction Collaborative is installing and testing technologies that intercept and remove phosphorus from agricultural runoff to protect against the growth of harmful algal blooms in the Thames River and Lake Erie.

In June, cities such as Fredericton, N.B., already issued advisories about the risks of skin, eye and throat irritation, or more serious health effects such as gastrointestinal illness, that can occur if toxins from blooms are consumed. Likewise, the North Bay Parry Sound District Health Unit says algal blooms have also been found at two spots on Lake Nipissing.

Elsewhere in Atlantic Canada, a new report by researchers at both Dalhousie University and the Canadian Healthy Oceans Network revealed that 64% of individual eelgrass beds in 180 bays across Atlantic Canada are at risk of seagrass decline from blue-green algae nitrogen loading. Prince Edward Island’s eelgrass beds, in particular, suffer most from agriculture runoff, which is the target of the new Ontario-based project led by the Ontario Federation of Agriculture and the Great Lakes and St. Lawrence Cities Initiative.

Seven test sites are underway or nearly set to begin as part of The Thames River Phosphorus Reduction Collaborative to explore new ways of preventing harmful algal blooms.

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At the Oxford One Farm test and demonstration site, researchers will examine the feasibility and efficiency of using leftover material from metal refining, commonly known as slag, to reduce phosphorus loadings from agricultural field tiles to open watercourses.

“A cartridge containing clean pea gravel and slag, which have been approved by government as low-risk substances, will be inserted into three tiles of different diameters to test and compare the filter sizes and maintenance requirements,” project leaders explained.

At least two of the sites will be testing for differences in phosphorus runoff between solid and liquid manure applications, as well as the different topography of the land.

Still in the commissioning stage is a test site in London, ON, where researchers will test processes from Muddy Rivers Technologies based in Delta, B.C. They hope to dissolve phosphorus from a stream that flows primarily through agricultural land. 

“The process involves using electricity to slowly dissolve lava rock with the resulting iron, magnesium, aluminum and calcium ions binding to phosphate ions in the water to form a solid material that can be removed,” project leaders explained.

A similar test site is underway at the Chatham-Kent Boudreau Pump Station, where researchers will be led by Waterloo Biofilter. While the project involves a series of different experiments, one involves the use of electricity to dissolve an electrode, releasing iron ions that bind with phosphorus dissolved in the water.

On the Chippewa First Nation Lands, The Thames River Phosphorus Reduction Collaborative will work with ESSRE Consulting Inc. and Silt Sock Environmental. A municipal drain outlet that services about 70 acres on several farms provides a flow of tile water to be filtered for phosphorus removal. The fields receive commercial fertilizers and the testing will be on phosphorus that runs into the system.

Project progress photos that detail work to protect against the growth of harmful algal blooms in the Thames River and Lake Erie. Photo Credit: The Thames River Phosphorus Reduction Collaborative.

“An underground tank containing lava rock and sponge materials takes water from an underground municipal drain,” project leaders explained. “As the water rises through the tank, phosphorus is absorbed, and the outflow of water empties into an open municipal drain.” 

Follow the progress of the various projects here.


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