Maine’s marshlands are rich with blue carbon muck, the state’s most ecologically valuable soil. Photo: Rob Vincent, EPA
Carbon Sequestration: One More Reason to Appreciate Muck
By Kevin McKeon, Maine Master Naturalist
Muck is the stuff we feel seeping between our toes and up around our ankles while wading in seldom-visited areas along the shores of ponds. It’s the same stuff we cringed at as children but now feel a soothing, spa-like joy wading out for a warm summer’s swim. The type of muck we are most familiar with near our swimming holes is called gyttja, Swedish for “oozy mud,” consisting mostly of a mixture of decaying leaves and sticks, mud, and very small mineral particles called silt and clay.
Estuaries — the most environmentally rich wetlands in the world — hold what is probably the world’s most valuable muck, often referred to as blue carbon, so called due to the enormous quantities of carbon contained in these coastal ecosystems by the decomposition of seagrass meadows and salt marshes held under the “blue” estuarial waters. In Maine, this valuable muck is found in over 157,500 acres of tidal marshes. These areas support salt hay and seagrass plants that photosynthesize atmospheric carbon dioxide into plant tissue. The continual dieback and regrowth eventually forms this blue carbon, reaching depths of over 6 feet, which can sequester carbon for thousands of years, but unfortunately is little recognized for this valuable facet to Earth’s carbon cycle. The Smithsonian Environmental Research Center says that Maine marshes are roughly 10 times more effective at storing carbon on a per-acre basis than Maine forestland.
Another type of muck is called marl, or “marly muck” — a clay-rich soil with various amounts of fine-grained minerals. Some of us gardeners are familiar with a type of marl called greensand, a fertilizer many organic gardeners use that contains a high content of a green mineral called glauconite that is rich in potassium, helping our gardens with flower and fruit production. The only operational greensand mine in the world is in Sewell, NJ (also home to Barnsboro Inn, Jersey’s oldest tavern).
Probably the most intriguing muck in our area can be found at the bottom of Deering Pond, the centerpiece of Mousam Way Land Trust’s Hall Environmental Reserve in Springvale, easily accessed via the trails encircling the pond: The Rail Trail, Vigue Trail, and Carpenter Trail. Sanford’s renowned ecologist/conservationist, Dr. Bud Johnston, mentored many students in and around this ancient body of water during his tenure as professor of biology and environmental studies at Nasson College. He and his students even designed and built a small barge, using it as a floating laboratory. One of Dr. Bud’s studies is available online. The type of muck formed by centuries of extremely slowly decomposing organic matter at this peat-bog pond is called dy, an acidic, organic-rich but nutrient-poor peat mud. Dr. Bud’s measurements revealed the depth of this dy, under about 15 feet of water, to be more than 90 feet! Adjacent to the pond and memorialized by a trailside kiosk lies the remains of the famous Sunken Rail Car, entombed about 14 feet deep within the dy.
These mucks are worlds unto themselves, holding active life and age-old secrets within. These soils provide habitats for a plethora of creatures and are the basis for a landscape’s food chain. Microscopic remains of pollen grains, diatoms, and sponge spicules give valuable paleoenvironmental evidence of historic water quality and environmental changes over the centuries. Mucks form a critical habitat for various aquatic life forms, from microscopic diatoms to insect larvae, snails and mussels, which provide the primary lower-tropic food source for their ecosystems.
Core extraction studies of muck’s historic accumulations of entombed pollen, pesticides, and toxic metals reveals clues to controlling nutrient levels and thus the management of algae blooms, pollution levels, and water quality control. Unnatural additions like fertilizer runoff and acid rain can result in chemical imbalances that can accelerate the release of methane gas — a potent greenhouse gas; knowing mucks’ composition can aid mitigation of such events. Muck and peat soils are excellent carbon sequesters, with peat wetlands and marshlands being especially highly valued as carbon repositories.
A 2017 Harvard study of muck concluded that “multiple episodes of cosmic impact,” i.e., active meteorite bombardment, occurred in the Bering Strait area about 129,000 to 11,700 years ago. So, we’re never really sure of what the muck oozing between our toes might be holding — a yucky feel or a soothing relaxing mud bath — but it could be cosmic!
Blue carbon: https://mousamwaylandtrust.org/2019/12/25/blue-carbon-and-seagrass/
Dr. Bud’s study: https://mousamwaylandtrust.org/2019/11/04/the-natural-history-of-deering-pond/
Sunken Rail Car: https://static1.squarespace.com/static/624efffd8ef1885fd8ab5ca1/t/660083e771268751580c43e0/1711309800537/NL-2019-1&2.pdf
Harvard study: https://dash.harvard.edu/server/api/core/bitstreams/7312037e-ab30-6bd4-e053-0100007fdf3b/content
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