By Megan May
At the end of a gravel road, tucked deep into the woods, bald cypress trees dot the shoreline of Bennett’s Mill Pond. Great blue herons wade in the shallows, searching for their next meal. It’s July in North Carolina, and time on the water would be the perfect way to enjoy some peace and quiet. But not today.
Haley Plaas pulls on a pair of rubber gloves. She lays on the dock and gently reaches her hand in. A mucus-like substance clings to her glove as she pulls back, leaving stringy threads on the water’s surface. While brilliant in color, the network of blue scum across the pond is dangerous cyanobacteria, a type of harmful algae.
Sometimes confused with aquatic plants like duckweed, cyanobacteria can vary from looking like green or blue-green opaque, thin mats to translucent paint or dye. Blooms pose a threat to the local environment — leading to fish kills, ecosystem damage, and drinking water contamination. They can also cause illness in humans and death among pets and wildlife.
Harmful algal blooms, often called HABs, occur naturally, but human activities increase their frequency and intensity.
HABs feed on nutrient runoff — anything from leaky septic tanks to fertilizers and industrial waste. While the U.S. South has dealt with this for years, it’s a growing global environmental issue exacerbated by climate change. Increased surface temperatures lead to warmer waters, and more extreme storms are followed by periods of drought. That combination is a perfect recipe for the algae — storms increase nutrient runoff into waterways, and then drought leads to stagnant, warm water.
While cyanobacteria directly impact water quality, less is known about how they affect air quality. Enter Plaas, a doctoral candidate in environmental science and engineering at the University of North Carolina Chapel Hill.
Harmful algal blooms emit cells and chemical compounds that travel as tiny atmospheric particles, called aerosols. Plaas has partnered with the Chowan Edenton Environmental Group, or CEEG, to deploy PurpleAir air sensors along North Carolina’s Chowan River, part of the Albemarle-Pamlico estuarine system. Their goal is to see if blooms correlate with poor air quality due to an increase in these aerosols, and generate a wealth of accessible data in areas that are underreported.
