Posted by Caroline in Untagged
Imagine a vast septic tank that was continuously filled for 200 years without ever being cleaned out. This tank contains an enormous volume of smelly, black gunk — up to 12 feet deep in some spots — that harbors harmful bacteria and suffocates most life-forms.
Welcome to the creeks of Chesapeake Bay.
Decades of work by organizations such as the Chesapeake Bay Foundation and by government agencies have dramatically reduced the amount of pollution entering the bay through its tributaries. But the Chesapeake is still clogged with millions of tons of slimy black muck — full of harmful ammonia and phosphates — that foils attempts to restore water quality and diversity of life.
A husband-and-wife science team is trying to find a way to destroy the muck, and their hoped-for solution lies at the bottom of a septic tank.
Diana Muller, director of scientific monitoring at the South River Federation in Edgewater, Md., and Andrew Muller, a professor of oceanography at the U.S. Naval Academy in Annapolis, are exploring whether a sort of dietary supplement for septic systems can digest black muck from the creeks that feed the Chesapeake.
They are using a formula similar to that of Rid-X, a blend of bacteria and enzymes that digests the sludge that builds up in septic systems over time. The bacteria include two types of microbes, nitrosomonas and nitrobacter. Nitrosomonas oxidizes otherwise harmful ammonia (plentiful in the Chesapeake’s black muck) into nitrites; then the nitrobacter converts those nitrites into nitrates, which aquatic grasses and other plants can use for growth.
“Two hundred years of clear-cutting,” Andrew Muller said, explaining the origins of the black muck. “When you clear-cut all those trees and there’s nothing holding that soil, now you have huge storms that come through over time. That sediment gets mobilized and literally cuts deep inside streams as that material moves through. . . . These creeks have got anywhere between five to 12 feet thick of this muck. This is not normal for these environments.”
The black muck fuels algae blooms that result in a largely dead ecosystem. Instead of a clean, sandy bottom with aquatic grasses, invertebrates, fish and oysters, an infected creek becomes a wasteland of mud, stench, ammonia and a few species of anaerobic bacteria.
The bay’s smaller, tidal tributaries have been overlooked in bay cleanup efforts, Diana Muller said.
“It’s always been about the James River, the Rappahannock, the major tributaries, but these smaller ones have been completely ignored and not researched at all,” she said. “If we were to take a sample, [the black muck] would look like just this black, gelatinous, mayonnaisey, high-in-hydrogen-sulfide ooze. . . . The idea is that the good bacteria, nitrobacter and nitrosomonas, eat and literally digest all the organic matter in your septic system. So if we treat this like a septic system, it should digest the organic material. So you can see, that is exactly what it is starting to do.”
The black muck does indeed appear to be disappearing from two of three 40-gallon tanks of water and mud in a lab at the Naval Academy. Tank 1 serves as a control against which the others can be compared. Tank 2 has tubes that provide aeration through the bottom of the mud. Tank 3 is receiving both aeration and large amounts of helpful bacteria.
Preliminary data gathered daily by Midshipman Annie Folkie of Charlottesville, Va., indicate that by at least one measure, the combination of aeration and bacteria is working. Four months into the study, Tank 3 has less than half of the harmful phosphates per liter than the control tank has. Tank 2 isn’t far behind Tank 3.
A sniff from each tank tells a promising story. Mud from the control tank has an unpleasant stench. No odor was detectable from the tank that received bacteria and aeration.
In a time of stagnant government grants, tackling the entire bay’s muck problem is arguably too daunting for any organization. But the South River Federation’s mission is so geographically limited — the watershed of the South River, which flows into the bay south of Annapolis — that an intensive project focused on one small branch, Church Creek, makes sense. (The federation has six employees, hundreds of volunteers and an annual budget of $1 million.)
Black muck is one of many things afflicting the Chesapeake, said Tom Horton, a professor of environmental studies at Salisbury University.
“If you were to list your bay problems, [the black muck] certainly wouldn’t make the top three, but that’s because the top three are enormous,” Horton said. “But yeah, it’s significant. For a few reasons. One, a lot of these little [tributaries] have been ignored. And two, you have a lot of people there. If you can bring the crab harvest back there, then it makes a huge difference for people living around the bay. There really isn’t one magic bullet or even five magic bullets. This seems like a smart thing to try.”
Both types of bacterium that the Mullers are using are found in the bay but not normally at the high concentrations used in products such as Rid-X. They have not been genetically engineered; in other words, no corporation has an exclusive claim on their use or manufacture.
One scientist who is not involved in the project wonders how the method could be applied on a wider scale, given that the Chesapeake watershedincludes more than 150 major rivers and creeks, plus thousands of smaller tributaries. Its more than 11,000 miles of shoreline are a much more complicated system than those three experimental tanks.
“On the implementation side, how do you apply this product, and how much would it cost?” asked Jeffrey Cornwell, a research professor at the University of Maryland’s Center for Environmental Science.
“Aeration on such large scales can be quite difficult and expensive,” Cornwell said. “These experiments are fundamentally interesting and at a very early stage; a better assessment of the approach can be made after the work is published and consideration of costs and benefits are made.”
Diana Muller envisions a system of reusable flexible tubes that provide extra oxygen to the bacteria while they eat the black muck. Solar-powered generators would provide the needed electricity.
“It will be literally a half-mile of giant tubing laid six to 12 inches beneath the sediment,” she said. She estimated it would cost about $200,000 to clean up a half-mile of Church Creek. This compares favorably with the millions of dollars that it would cost to dredge out and remove the muck.
“The traditional approach would be dredging,” Horton said. “That’s hard, because where do you put [the muck]? How do you contain it? How much do you disrupt the bank [of the creek]? The idea of treating the problem in place is the way to go, if it can be done. Dredging has a lot of problems — permits required. I think it’s well-nigh impossible.
“You can quick-start — supercharge — the biological cycling by oxygenating the sediment. That’s a lot cheaper.”
If a bio-remediation project such as this worked, the dead zones in tidal creek areas might shrink. “You might see the return of some of your fish populations,” Andrew Muller said. “It also means you could start putting back those oyster populations.”
Oyster restoration has been a high-profile goal for improving the health of the Chesapeake. One oyster typically cleans seven to 10 gallons of water per day and converts excess nutrients into food for other species. But oysters are not the first step. The bivalves live on oxygenated water, which requires stream bottoms with the right balance of microbes and aquatic plants.
“That’s another part of the key to this,” Andrew Muller said. “Right now in many locations [the habitat is] just not healthy enough for oysters to get ahead of the curve. . . . They’re not really getting ahead to the point where they’re able to efficiently filter to make a huge difference. . . . This has huge implications for oyster restoration, blue crab populations, anything that seems either fixed or slow-moving.”
Dealing with the black muck is necessary to allow oysters to thrive.
“To actually improve the Chesapeake Bay in terms of restoration, what we need to do is remediate the tidal and the non-tidal areas to a point where we can reintroduce species like oysters,” Andrew Muller said. “We can’t do it backwards. We can’t put in oysters without cleaning the environment to a point where they can actually survive and thrive.”
“This is probably the only way you’re going to deal with this stuff,” Horton said, “short of waiting 300 years or so. I think they should probably go with it.”
Landers is a freelance writer in Charlottesville.
See the full article at the Washington Post: http://www.washingtonpost.com/national/health-science/husband-and-wife-scientists-take-on-black-muck-clogging-chesapeake-bay/2015/05/11/abc97194-e784-11e4-aae1-d642717d8afa_story.html