Since the passing of the Clean Air Act and the Clean Water Act in the early 1970's, air pollution and water pollution were largely considered two separate problems. However, there is now a better understanding of the link between these two environmental threats. Pollutants released into the air will eventually make their way back down to the earth's surface.
Some of the factors that determine how far pollutants can travel through the air include, the makeup of the pollutant, weather conditions (wind, temperature, humidity), type and height of emission source (smokestack, automobile tail pipe), and the presence of other chemicals in the air. Airborne pollutants fall to the earth's surface by wet deposition, or dry deposition. Airborne pollutants that deposit on the landscape can be transported into streams, rivers, and the Bay by runoff or through groundwater flow.
The Chesapeake Bay Program is at the leading edge of addressing the relationships between the air, land, and water quality. For example, computer models estimate that the primary nitrogen oxide (NOx) emissions airshed for the Bay is approximately 418,000 square miles, this is six and half times larger than the Chesapeake Bay watershed. This airshed shows that airborne nitrogen deposits to the Bay and its watershed from local emission sources, as well as from sources in places far away, such as Kentucky, Indiana, and Canada. Chesapeake Bay Program, using monitoring and modeling, estimates that a quarter of the total nitrogen load to the Bay comes from atmospheric deposition, with 75 percent of that load being deposited on land (and later transported to the Bay by surface water runoff and groundwater flow). The remaining 25 percent is deposited directly on the Bay.
Determining the impacts that air pollution can have on the Bay's water quality and living resources is significant because reductions in air pollution can potentially improve water quality. With this connection in mind, resource managers are beginning to factor air pollution into their decisions about water quality improvements.
What are the sources of air pollution?
Air pollution can be man-made or naturally occurring. The main sources of air pollution are: stationary and area sources, mobile sources, agricultural sources, and natural sources.
Stationary and Area Sources
A stationary source of air pollution refers to an emission source that does not move (i.e., utilities, chemical and manufacturing industries). Often stationary sources are defined as large emitters who release relatively consistent qualities and quantities of pollutants. The term area source is used to describe the many smaller stationary sources located together whose individual emissions may be low but whose collective emissions can be significant. Typically area sources are those that emit less than 25 tons per year of any combination of hazardous air pollutants, or less than 10 tons per year of any single hazardous air pollutant.
Mobile Sources
A mobile source of air pollution refers to a source that is capable of moving under its own power. In general, mobile sources imply on-road transportation. In addition, there is also a non-road or off-road category that includes gas-powered lawn tools and mowers, farm and construction equipment, recreational vehicles, boats, planes, and trains.
Agricultural Sources
Agricultural operations, those that raise animals and grow crops, can generate emissions of gases, particulate matter, and chemical compounds. For example, animals confined to a barn or area (rather than field grazing), produce large amounts of manure. Manure emits various gases, particularly ammonia into the air. This ammonia can be emitted from the animal houses, manure storage areas, or from the land after the manure is applied. In crop production, the misapplication of fertilizers, herbicides, and pesticides can potentially result in aerial drift of these materials.
Natural Sources
Natural sources of air pollution are sources not caused by people or their activities. An erupting volcano emits particulate matter and gases; forest and prairie fires can emit large quantities of pollutants; plants and trees emit hydrocarbons; and dust storms can create large amounts of particulate matter. Wild animals in their natural habitat are also considered natural sources of pollution given that there is a certain amount of natural pollution, it is very important to control the "excess" pollution caused by man’s activities.
What are the impacts of air pollution?
Pollution from atmospheric deposition which impact the Chesapeake Bay are nitrogen (NOx) and chemical contaminants. These pollutants dramatically impact the Bay watershed.
The effects of nitrogen can be seen in:
Acid Rain (acid deposition)-nitrogen oxides (NOx) is one of the key air pollutants that causes acid deposition, and results in adverse effects on aquatic and terrestrial ecosystems. Acid deposition increase the acidity of water and soils. Increases in water acidity can impair the ability of certain fish and aquatic life to grow, reproduce, and survive. Increases in soil acidity can impair the ability of some types of trees to grow and resist disease.
Smog- is a catchall term for a collection of pollutants ; it is ozone (formed by NOx), particulate matter, and humidity, all mixed together. Smog reduces how far and how clearly we can see through the air, an effect called visibility reduction or regional haze. General atmospheric conditions are that haze and ozone occur at the same time and the mix of the two is called smog.
Eutrophication- when excess nitrogen causes accelerated growth of algae. The algae blocks sunlight, needed for submerged aquatic vegetation to grow, when the algae dies it sinking to the bottom and decomposes in a process which depletes the water of oxygen.
Accumulation- nitrogen can filter down through the ground into drinking water sources, these nitrates contaminant the h20 we drink.
The effects of chemical contaminants can be seen in:
Bioaccumulation- chemical contaminants increase in concentration as it moves through the food chain. Example: an invertebrate eats contaminated algae, a small fish eats many contaminate invertebrates, a large fish eats many small fish, and humans eat the big fish which is now loaded with the chemical.
Chemical contaminant can accumulation and bind to the sediments they deposit on. When this happens, the chemical contaminants are moved wherever the sediments are moved. (erosion and dredging exacerbate this problem by moving the sediments into the water system were is can travel for miles).
Chemical contaminants can change a plant species composition, and make species more susceptible to disease, weather, and insect damage. Changes such as these challenge a specie's ability to reproduce and develop.
Persistent- chemical contaminants do not breakdown or diminish over time.
How does air pollution move?
Air transport is the term used to describe the mechanism by which air pollution moves from an emissions source to a receptor. A source is a location (i.e., smokestack, chimney, exhaust pipe) from which the pollutant emanates and a receptor is the place (i.e., soil, vegetation, waterbodies) where the pollutant is deposited. A receptor is adversely affected by polluted air: a receptor can be people, animals, vegetation, materials, and aquatic life. The wind is the transporter of pollutants from sources and receptors. If the wind carries the plume of pollution high enough in the air, it may travel for hundreds of miles before being brought to earth. This is known as long-range or long-distance transport.
Important terms to know:
Emissions:
"Emission" refers to pollution being released or discharged into the air from natural or man-made sources. Pollutants may be released directly into the air from a structural device (i.e., smokestack, chimney, exhaust pipe) or indirectly via volatilization or dispersal (i.e., aerosol spraying).
Atmospheric Deposition:
The process whereby airborne particles and gases are deposited on the earth's surface by wet deposition (precipitation) or by dry deposition (processes such as settling, impaction, and adsorption).
Wet Deposition:
Atmospheric deposition that occurs when precipitation (rain and snow) carries gases and particles to the earth's surface.
Dry Deposition:
Atmospheric deposition that occurs when particles settle to a surface, collide with and attach to a surface (adsorption) or are absorbed.
Loads:
The Bay receives pollution from many different sources. Each type of source adds to the total pollution "load" the Bay receives.
When air pollution deposits onto the Bay water surface, it’s called a "direct load" because it comes directly from the air to the water. When air pollution deposits onto the watershed (land) surface, it can be transported to the Bay water via runoff or groundwater flow. This is considered an "indirect load" because it has an intermediate stop before getting to the Bay.
How YOU Can Help:
By choosing to make energy efficient and conservation wise decisions you will not only help improve the health of the Bay, but also ensure your good health and save money.
- Turn off your engine if waiting more than 1 minute at the drive-through or to pick someone up (more fuel is wasted when idling than restarting).
- Stay alert in traffic. Take alternate routes ones with few stop signs and lights to eliminate idling.
- Warm up vehicle for one minute.
- Accelerate gently and evenly, and use your cruise control to maintain a steady speed.
- Use vehicle's flow through vents instead of air conditioning (which decreases fuel efficiency by 21%) or opening window.
- Check car's cooling system thermostat. If this is stuck open it can reduce engine efficiency by 7% ($3.20 a month).
- Keep car engine tuned. A poorly tuned car wastes 15% more fuel. Again more fuel equals more pollution and travel fewer miles.
- Properly inflate & align tires to save gas & to reduce wear on tires over time.
- Reduce the amount of miles you drive. Fewer mile driven equals less gas, which equals fewer polluting emissions created. Walk or ride a bike!
- Planning trips carefully which will result in reductions in the amount of nutrients and toxic substances entering the watershed.
- Purchase fuel efficient automobiles: you'll get farther on less gas and keep more $ in your pocket.
- Follow state guidelines on emissions testing & maintain any pollution-control devices. Car will be more efficient, use less gas, produce fewer emissions.
- Consider telecommuting for work.
- Use public transportation when available.
- Conserve electricity, including turning off lights when not in use and keeping your thermostat at regular temperatures in winter (68) and summer (80). If 1% of the nation's consumer switch to energy efficient appliances it would equal eliminating greenhouse gas emissions from 1.5 power plants.
- Participate in recycling programs AND purchase products that are packaged and/or made from recycled and recyclable materials.Recycling conserves energy which equals less power plant emissions equals less air pollution. It also conserves natural resources.
Consider using an electric lawn mower instead of a gas-powered one and use a rake to collect leaves - it's good exercise! Lawn and handheld gardening engines account for 10% of mobile source hydrocarbon emissions. Running a gas powered lawn mower for one hour equals the emissions released when driving your car 350 miles!!!!
