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UD researcher seeks clues to curing annual Chesapeake Bay dead zone

Each summer in Chesapeake Bay, huge algal blooms, fueled by nutrient pollutants, blossom and die. Their remains sink to the bottom and are quickly devoured by bacteria that monopolize the Bay’s stores of dissolved oxygen, stressing or suffocating entire communities of marine life, such as clams, oysters and sponges.

“Restoration efforts in recent decades have helped improved water quality and ecological conditions in the Chesapeake Bay. However, the extent and severity of [the dead zone] has not improved as expected,” said Deb Jaisi associate professor of plant and soil science at the University of Delaware.

This past summer, in 2011, the Chesapeake received its worst report card yet from EcoCheck, a partnership between NOAA and the University of Maryland Center for Environmental Science, despite concerted efforts to reduce the amount of nutrients released into the bay through human activities.

The U.S. Environmental Protection Agency has named phosphorous as one of two major nutrient pollutants (along with nitrogen) contributing to the annual “dead zone.” Phosphorous is an essential element for life. It is found in every cell in the human body and nearly every food we eat. Humans, plants, and animals consume and excrete it. However, as with many things, too much phosphorous can be deadly.

Jaisi believes that a hidden record of phosphorous concentrations lies buried in the Bay floor. By decoding that record, he hopes to learn how concentrations have changed over time, and potentially pinpoint when and how a nutrient found in the bay for centuries became a pollutant capable of threatening the health of the entire bay.

Oak Ridge Associated Universities, a consortium of PhD-granting institutions, and the University of Delaware have awarded matching grants to support this research.

UD researcher seeks clues to curing annual Chesapeake Bay dead zone
UD plant and soil science professor Deb Jaisi is examining how phosphorous contributes to Chesapeake Bay dead zone.(Photo courtesy: University of Delaware/Kathy F. Atkinson)

Something of a molecular detective, Jaisi plans to examine sediment cores provided by oceanography professor and eminent scholar David Burdige of Old Dominion University for traces of excess phosphorous that have settled on the bay floor year after year. Each source of phosphorous, from various fertilizers, to sewage treatment discharges, has its own atomic structure, similar to a fingerprint.

This summer, Jaisi will be installing a thermo-chemical element analyzer to help identify these fingerprints. Assuming he can get his lab up and running by mid-summer, he hopes to have some answers by the end of the year.

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The first signs of trouble — depleted dissolved oxygen in the depths of the bay — began to show in the 1930s. By the 1950’s the dead zone started making annual appearances and has grown larger with each passing summer.

Because the Chesapeake Bay watershed is 64,000 square miles — nearly the size of the country of Cambodia — the problems and solutions likely originate far beyond the bay shores.

While half of the phosphorous in the bay comes from terrestrial sources, the U.S. Geological Survey estimates that nearly 10,000 metric tons of phosphorous enters the Bay through the watershed each year. Sources can include excess fertilizers applied to farmland, discharges from sewage treatment plants, and leaching from septic systems. One third of Delaware lies in the Bay’s watershed, so its farms, sewage treatment plants and septic systems contribute to the problem.

While Pennsylvania, Maryland, Virginia, and the District of Columbia have been attempting to improve the health of the Bay for thirty years, the EPA widened the approach in 2010. It required other states in the Chesapeake Bay watershed to submit plans to curb nutrient pollution. Delaware, New York, and West Virginia each completed the second phase of planning this spring and are preparing to implement new anti-pollution measures.

For Delaware, “it’s not just about trying to improve the bay 100 miles away. It’s about trying to improve waterways in our own state.” said Delaware Department of Natural Resources and Environmental Control Secretary Collin O’Mara.

Because nutrients enter the bay from so many sources, O’Mara says that DNREC has had to enlist the help of local municipalities and industrial partners. “To achieve a healthy Chesapeake Bay is going to take the efforts of everyone from the local government to the county government, to the businesses and the farmers. We are going to have to work together so the bay can heal itself.”

O’Mara says the efforts will include upgrading wastewater treatment plants, improving storm water practices, and examining industrial sources of nutrient pollution.

However, 70 percent of Delaware’s nutrient runoff comes from agricultural activities, so individual farmers play a key role, says O’Mara. A cost-sharing program will encourage farmers to plant “cover crops” — ones that grow alongside desired crops and take up excess nutrients.

Doing more to reduce pollution in Chesapeake Bay will require significant financial investments, at a time when states are struggling to balance their budgets.

“The economic climate is tough, but efforts to clean up the Chesapeake Bay have been taking place for 20 to 30 years. We can’t delay implementation of additional pollution control measures because of costs,” said Nicholas DiPasquale, director of the Chesapeake Bay Program at the Environmental Protection Agency. “We must also consider the economic and non-economic benefits that will result from these efforts.”

Both DiPasquale and O’Mara point out that Delaware can expect some returns from these investments.

Improving storm water controls, using low-impact development techniques, and installing rain gardens will reduce flooding and the costs of responding to flood damage, says DiPasquale.

“If we’re able to improve the waterways to the point where more fish survive, it’s better for everyone,” said O’Mara.

Much of the seafood caught off the coasts of Delaware, Maryland, New Jersey, and the Carolinas started life in the waters of the Chesapeake. The success of Atlantic coastal fisheries—and the many livelihoods they support—depends directly on the health of the bay.

DiPasquale says he has started to see some success stories.

Numbers of striped bass, or rockfish, an important commercial and recreational sp that lives in the Chesapeake Bay and its tributaries dwindled in the 1980s, but since then the fish has recovered.

“We think we are starting to see the resilience of the bay restored,” said DiPasquale. “When you look at long term trends, you can see improvements in the health of the watershed, but we’re not there yet.”