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Nabbing Nitrogen

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Citizen Stewards Volunteer Initiative: Nabbing Nitrogen Project

If you happened to be looking out over Portland Harbor on Sunday morning, July 10, 2016, you may have spotted several people behaving oddly. At precisely 10:10 a.m., 97 people stooped by the water’s edge and scooped up a small vial of water from Casco Bay. They were not praising Poseidon, they were Nabbing Nitrogen.
That was our “Nabbing Nitrogen” project to educate the public, provide the Maine Department of Environmental Protection (DEP) with data needed to begin regulating nitrogen, and provide a simple way for a “flash mob” of volunteers to assist us in doing science. Our goals were to collect a significant amount of simultaneous (or, as scientists say, “synoptic”) data, connect with users of the Bay, and shine the public spotlight on an issue too few understand.
On that particular morning, we experienced a heavy rain that followed a long dry spell. This made for ideal conditions for collecting data on a “storm event.” We collected and analyzed 90 samples, which Research Associate Mike Doan used to construct a map of nitrogen levels around Portland Harbor at this one point in time. He wasn’t surprised to find that nitrogen levels were higher than normal.
This reinforces our findings from other water quality sampling by Friends of Casco Bay that has shown that nitrogen pollution is most severe in areas that are close to shore, near river mouths, at sewer overflow pipes, and other locations where stormwater runoff reaches the Bay.
One of goals for Nabbing Nitrogen was to recruit new volunteers, boaters, and fishermen to join us in taking a regional snapshot of nitrogen levels. The most important takeaway from this project is that we have an amazing Casco Bay community of individuals who are ready and willing to get involved when we send out a call to action! We garnered so much public attention through our flash mob sampling that the Maine Public Relations Council awarded us with a Silver Arrow Award for this effort. The success of this “Nab” is leading us to continue to develop low-threshold opportunities for volunteers to help us collect meaningful data.
WMTW Meteorologist Sarah Long was one of the many volunteers who participated in this sampling event. You can see her coverage of the event here.

Why do we worry about too much nitrogen in Casco Bay?

Too much nitrogen can turn Casco Bay from a healthy blue to a slimy green. All living things need nitrogen to grow, but an overdose can trigger excessive growth of nuisance algae, reduce water clarity, and lower oxygen levels. This process also releases carbon dioxide, creating acidic conditions that can make it harder for clams and mussels to build and maintain their shells.
Nitrogen is an essential plant nutrient, critical for growing. In the ocean, nitrogen nurtures plant growth, from single-celled phytoplankton to large seaweeds. But too much nitrogen triggers excessive algae growth that can turn the Bay green. When the plants die, decomposing bacteria remove the oxygen from the water and release carbon dioxide, making the water more acidic.
Over the last 100 years, the amount of nitrogen available for plant growth has more than doubled, thanks to the invention of commercial fertilizers and the increase in the burning of fossil fuels. Human sewage, air pollution, and rainwater washing fertilizers and animal wastes off yards and farms add excess nitrogen to our coastal waters.
In recent summers, we can see large mats of green algae in Back Cove in Portland and Mill Cove in South Portland. Those carpets of ‘green slime’ could smother anything trying to live underneath them. In South Portland, we also found that the mud beneath the algal mats was more acidic.
Loss of eelgrass, brown foam, and the changing chemistry of Casco Bay all have been blamed on too much nitrogen.
Too much nitrogen in the shallow water can impact eelgrass, the nursery of the sea. Large phytoplankton blooms, fertilized by the excess nitrogen, can make the water murky, limiting the sunlight that can reach these seagrasses. This can be of concern because of how important eelgrass is to a healthy ecosystem. Eelgrass anchors sediments in place, helps to prevent erosion, dampens wave action, which protects the shoreline, and most importantly, provides hiding places for juvenile marine animals.

What can you do about stormwater pollution, excess nitrogen, and acidification?

  • Learn more about about stormwater pollution, excess nitrogen, and acidification
  • Do not use fertilizer on your yards and practice BayScaping to minimize the need for lawn chemicals
  • Keep rainwater from running off your driveway and yard by planting rain gardens and using permeable pavement
  • Support efforts by your municipality to reduce nitrogen-laden sewage overflows into the Bay
  • Support our work with the Maine Department of Environmental Protection to set responsible limits on nitrogen discharges into coastal waters