Geoengineering light could be a way to reduce toxic algae in the Finger Lakes

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ROCHESTER, NY (WROC) – Here is an interview with Professor Rebecca North, an assistant professor for the School of Natural Resources at the University of Missouri. Her and her students ran experiments to slow the spread of Harmful Algal Blooms (HABs) with some promising results. Here is the interview:

WE HAVE ISSUES WITH BLUE GREEN ALGAE LOCALLY, HOW ARE YOU WORKING TO SOLVE THIS PROBLEM? 

“We know that with a changing climate, we’re getting changes in light with our inland lakes and our oceans, so in lakes, I have two graduate students. One wrote a paper on how here in Missouri, at least in the reservoirs, we can see that light controls the production, the primary productivity in algae. How much oxygen they’re producing to help with the carbon balance. Then I have another graduate student do a more applied research project, and so often when we are trying to mitigate harmful algal blooms, we focus on controlling specific nutrients, specifically phosphorus and nitrogen. In this case, in some of these natural reservoirs, sometimes it’s difficult to minimize how much nutrients are coming in.” 

“Light is an unexplored area in controlling these algal blooms. You’ve seen maybe these in California, where shade balls were added to drinking water reservoirs or aquashade is another dye product that people will add. THis is another technique that we thought was more naturally based and that’s using glacial rock flour, so kind of like the beautiful turquoise lakes in the rocky mountains, that fine particulate material can be added to make the water darker, which algae need light and nutrients to grow. If you turn off their lights, then potentially you can stop their growth and then stop their production of toxins.”

“We found that it worked pretty well. We did it with these tanks outside, and by adding this glacial rock flour, we were able to reduce the amount of cyanobacteria, but it ended up being a little more expensive than we thought. It’s just one option of many to try to mitigate these harmful algal blooms in this changing climate.”

IF IT DARKENS THE WATER, THE WATER IS ABLE TO ABSORB MORE HEAT, SO WOULDN’T THAT NEGATE ANY COOLING EFFECTS IF THE DARKER WATER WARMS? 

“It wasn’t enough to heat up the water. We only ran the experiments for nine days, so it was not long term in that regard, but certainly just the counteraction between light and temperature are both important for algal growth. Yes, you don’t want to increase the temperature, but if you can cut out the light, but I think that has more of an impact than increasing the temperature of that algal growth.” 

I UNDERSTAND THAT IT IS A BALANCE OF LIMITING INPUTS WHILE MITIGATING THE ACTUAL BLOOMS. HAS THIS BEEN USED IN THE NATURAL WORLD? 

“We have not. That was the plan, we were going to do a whole lake experiment with a pond around here, but that ended up being so costly. With an assistant professor’s grant, we were unable to do that kind of experiment. We were surprised at how quickly it fell out of the water column. They added it and it disappeared within 12 hours, so we didn’t think it was feasible on a large scale like that, That is usually an advised next step on the lakes.”

WHERE DID YOU GET THE MATERIAL? 

“We got it commercially. We just googled glacial rock flour and there’s a company that gets it from some moraines in the western Rocky Mountains in Colorado. They usually sell it to gardeners exetra as a fertilizer, though it doesn’t actually contain a lot of phosphorus, we did measure that to make sure we weren’t adding phosphorus with changing the light, that didn’t seem to be the case. That is how it’s marketed and sold. We ordered bags of it. We did the experiment at the Kansas Biological Survey in Kansas. We shipped it all there.”

WHAT’S THE FUTURE FOR THIS? 

“We typically see blooms happen at the end of the summer, so August, September, so when things calm down as well.  Blooms also like really stable waters, so things that are not too windy or turbulent. Knowing when and where you expect to see the bloom and reacting to that with this. It did take into effect within 24 hours, so it could be kind of a quick response.”  

We saw the blooms in Toledo, Ohio in the case of Lake Erie, and that system is just too large to do anything like this on. The water currents would just take it away. It can only really be applied by small drinking water reservoirs or small contained systems.” 

ARE THERE ANY OTHER FUTURE PLANS? 

One of the things we are looking at is the role of light. One of our land use practices are to reduce erosion, which is great, and that also cuts out the nutrients, but in some cases it also makes the water clear. Maybe that’s not a overall net good thing. Maybe having a little bit of that dirt and turbidity in the water could help control blooms in terms of light control. 

IS THIS GEOENGINEERING?  

This definitely falls in the geoengineering category. We are manually adding something to lakes to change the environment. It would definitely fall into that category. We are hoping that this would be a non-invasive, non-toxic approach. 

ANYTHING YOU WOULD LIKE TO ADD? 

In the future with changing climate, we are going to have more of these harmful algal blooms. They are going to occur more often in more places, and potentially be more toxic. It’s important that we come up with some creative solutions to be able to solve this problem. 

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