What Goes Up... Goes Into the Bay

by Bob Maddox
       Many of Maryland’s citizens and visitors enjoy the recreational opportunities and culinary delights offered by the Chesapeake Bay. People who live in and visit the region enjoy boating, fishing, hunting, and eating a variety of seafood. Years ago, an advertisement for a local product touted the Chesapeake Bay area as “the land of pleasant living.”

The airshed of the Bay is six and a half times the size of its 64,000 square-mile watershed.

       The Chesapeake Bay is the largest estuary (an estuary is a semi-enclosed body of water that has a free connection with the open sea) in the United States, and is a complex ecosystem of many species of plants and animals that depend on good water quality to survive and function properly.

       The water quality of the Bay is in need of improvements if the ecosystem is to be considered healthy. Although improvements in water quality have been seen in the last 15 years, the Bay still has a great distance to go to recovery. Nutrients in high concentrations have been found in the water in several areas, resulting in harmful conditions, such as algal blooms and the Pfiesteria outbreak in 1997.

       Generally, agricultural, wastewater discharges, and industrial practices within the Bay’s watershed are thought of as the causes for the Bay’s poor health, for farming, sewage treatment plants, and agricultural byproducts are a significant source of the excess nutrients (nitrogen and phosphorus) and industry discharges are the origin of much chemical pollution that enters the Bay.

       These practices, however, are not the only causes of the problem. Another major stressor to the health of the Bay is the air pollution that can originate nearby, and as far away as Indiana, Canada, and Georgia. In fact, the airshed of the Bay is six and a half times the size of its 64,000 square-mile watershed.

       “People have to realize that air is part of the whole ecosystem,” says Fran Flanigan, executive director for Alliance of the Chesapeake Bay. “Air quality is a big actor in the health of the Bay.”

Nitrogen Pollution
       Years ago, water and air pollution were considered two separate problems. Only recently has research shown the close link between these environmental threats. For example, nitrogen oxides (NOx) are emitted when fossil fuels (coal, oil, gasoline, and natural gas) are burned. Emissions of NOx are created by automobiles, electric utility plants, factories, boats, lawn-cutting equipment, and construction equipment. The NOx eventually settle back to the surface and enter the water directly or are washed from soil and impervious surfaces during rain to a water source.

       Scientists estimate that about one-quarter of the nitrogen entering the Bay is from the air. These nitrogen compounds reach the surface through either dry deposition or wet deposition. Dry deposition is atmospheric deposition that occurs when particles settle to the earth’s surface and attach to a surface or are absorbed. Wet deposition is atmospheric deposition that occurs when rain or snow carries gases or particles to the earth’s surface.

       Excess nitrogen in the Bay’s water causes dense algal blooms which block out the sunlight needed by the submerged aquatic vegetation. It is the submerged vegetation, or bay grasses, that provides protection and habitat for fish and crabs. Also, when the algae dies and decomposes, it depletes the oxygen in the water needed by plants and animals.

Other Pollutants
       Nitrogen deposition is not the only impact on the Bay from air pollution. Fossil fuels are also a source of polycyclic aromatic hydrocarbons (PAHs). These harmful chemicals, or toxics, can enter water through fuel spills, urban runoff, and atmospheric deposition. PAHs cover a variety of chemicals. Several of these are known carcinogens and are potentially harmful to aquatic life.

       Coal burning used to be the main source of PAHs, but vehicle emissions are now the largest source. The number of vehicle miles driven has increased significantly over the past few decades and the trend is expected to increase unless states in the region incorporate transportation alternatives in their planning.

SUVs pollute more. They currently have less restrictive emission standards than regular passenger cars, and generally have lower fuel efficiency.

       The increased popularity of sport utility vehicles (SUVs) is also taking its toll on the health of the Bay. SUVs pollute more. They currently have less restrictive emission standards than regular passenger cars, and generally have lower fuel efficiency.

       “The amount of time people spend in their vehicles has a significant impact on the quality of air,” Ms. Flanigan explained. “It’s not only the number of miles traveled that harms the air, but also the type of vehicle people choose to drive. In the nineties, the trend was that many people bought sport utility vehicles and other vehicles that are not fuel efficient.”

       “What the region needs is better land use policies that help people get to where they need to go without having to get into their personal vehicles,” says Dan Pontious of the Baltimore Regional Partnership, a coalition of civic, environmental, and smart growth groups. “This will help limit the number of cars on the road and the amount of tailpipe emissions.”

       Restoring the health of the Bay will take the efforts of local and state governments, civic organizations, businesses, and individuals.

       “One thing individuals can do is get involved with their community associations and local governments,” says Pontious. “Persuade officials to provide public transit and plan their communities to become more pedestrian and bicycle friendly.”

       “Where it is already possible, people can make good transportation choices too,” explained Pontious. “They can use public transit in communities where it is provided. Or walk or bike short distances instead of driving.”

       To learn more about the ecology and water quality of the Chesapeake Bay, visit the Chesapeake Bay Program’s Web site at To find out which organizations are working to restore the Bay and preserve Maryland’s natural environment, visit 1000 Friends of Maryland’s Web site at To learn more about Maryland’s air quality, visit the Maryland Department of the Environment’s Web site at and click onto the Air Quality Homepage. The Web address for the Alliance for the Chesapeake Bay is, and their telephone number in Baltimore is 410-377-6270. The Web address for the Baltimore Regional Partnership is and the telephone number is 410-385-2910.


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This story was published on February 28, 2001.