acid deposition
The falling of acids and acid-forming compounds from the atmosphere to the earth’s surface. Commonly known as acid rain, a term that refers to the wet deposition of droplets of acids and acid-forming compounds.
air pollution
One of more chemicals in high enough concentrations in the air to harm humans, other animals, vegetation, or materials. Excess heat is also considered a form of this. Such chemicals or physical conditions are called air pollutants.
atmospheric pressure
Force or mass per unit area of air, caused by the bombardment of a surface by the molecules in air.
EPA
Responsible for managing federal efforts to control air and water pollution radiation and pesticide hazards, environmental research, hazardous waste and solid waste disposal.
industrial smog
Type of air pollution consisting mostly of a mixture of sulfur dioxide, suspended droplets of sulfuric acid formed from some of the sulfur dioxide, and suspended solid particles.
ozone (O3)
Colorless and highly reactive gas and a major component of photochemical smog. Also found in the ozone layer in the stratosphere.
ozone depletion
Decrease in concentration of ozone in the stratosphere.
ozone layer
Layer of gaseous ozone in the stratosphere that protects life on earth by filtering out most harmful ultraviolet radiation from the sun.
PANs
Peroxyacyl nitrates; group of chemicals found in photochemical smog.
particulates
Also known as suspended particulate matter (SPM); variety of solid particles and liquid droplets small and light enough to remain suspended in the air for long periods. About 62% of the SPM in outdoor air comes from natural sources such as dust, wild fires, and sea salt. The remaining 38% comes from human sources such as coal–burning electric power and industrial plants, motor vehicles, plowed fields, road construction, unpaved roads, and tobacco smoke.
photochemical smog
Complex mixture of air pollutants produced in the lower atmosphere by the reaction of hydrocarbons and nitrogen oxides under the influence of sunlight. Especially harmful components include ozone, peroxyacyl nitrates (PANs), and various aldehydes.
primary pollutant
Chemical that has been added directly to the air by natural events or human activities and occurs in a harmful concentration.
secondary pollutant
Harmful chemical formed in the atmosphere when a primary air pollutant reacts with normal air components or other air pollutants.
smog
Originally a combination of smoke and fog but now used to describe other mixtures of pollutants in the atmosphere.
stratosphere
Second layer of the atmosphere, extending about 17–48 kilometers (11–30 miles) above the earth’s surface. It contains small amounts of gaseous ozone (O3), which filters out about 95% of the incoming harmful ultraviolet radiation emitted by the sun.
sulfur dioxide (SO2)
Colorless gas with an irritating odor. About one–third of the SO2 in the atmosphere comes from natural sources as part of the sulfur cycle. The other two–thirds come from human sources, mostly combustion of sulfur–containing coal in electric power and industrial plants and from oil refining and smelting of sulfide ores.
temperature inversion
Layer of dense, cool air trapped under a layer of less dense, warm air. It prevents upward– flowing air currents from developing. In a prolonged inversion, air pollution in the trapped layer may build up to harmful levels.
troposphere
Innermost layer of the atmosphere. It contains about 75% of the mass of earth’s air and extends about 17 kilometers (11 miles) above sea level.
urban area
Geographic area containing a community with a population of 2,500 or more. The number of people used in this definition may vary, with some countries setting the minimum number of people at 10,000–50,000.
volatile organic compounds (VOCs)
Organic compounds that exist as gases in the atmosphere and act as pollutants, some of which are hazardous.
biomimicry
Process of observing certain changes in nature, studying how natural systems have responded to such changing conditions over many millions of years, and applying what is learned to dealing with some environmental challenge.
conservation
Sensible and careful use of natural resources by humans. People with this view are called conservationists.
conservation biology
Multidisciplinary science created to deal with the crisis of maintaining the genes, species, communities, and ecosystems that make up earth’s biological diversity. Its goals are to investigate human impacts on biodiversity and to develop practical approaches to preserving biodiversity.
conservationist
Person concerned with using natural areas and wildlife in ways that sustain them for current and future generations of humans and other forms of life.
cultural eutrophication
Overnourishment of aquatic ecosystems with plant nutrients (mostly nitrates and phosphates) because of human activities such as agriculture, urbanization, and discharges from industrial plants and sewage treatment plants.
environmental justice
Fair treatment and meaningful involvement of all people, regardless of race, color, sex, national origin, or income, with respect to the development, implementation, and enforcement of environmental laws, regulations, and policies.
eutrophication
Physical, chemical, and biological changes that take place after a lake, estuary, or slow– flowing stream receives inputs of plant nutrients—mostly nitrates and phosphates—from natural erosion and runoff from the surrounding land basin.
hazardous waste
Any solid, liquid, or containerized gas that can catch fire easily, is corrosive to skin tissue or metals, is unstable and can explode or release toxic fumes, or has harmful concentrations of one or more toxic materials that can leach out. These substances offspring during reproduction. They are usually byproducts of manufacturing processes.
industrial solid waste
Solid waste produced by mines, factories, refineries, food growers, and businesses that supply people with goods and services.
municipal solid waste (MSW)
Solid materials discarded by homes and businesses in or near urban areas.
nondegradable pollutant
Material that is not broken down by natural processes. Examples include the toxic elements lead and mercury.
nonpoint sources
Broad and diffuse areas, rather than points, from which pollutants enter bodies of surface water or air. Examples include runoff of chemicals and sediments from cropland, livestock feedlots, logged forests, urban streets, parking lots, lawns, and golf courses.
open dump
Fields or holes in the ground where garbage is deposited and sometimes covered with soil. They are rare in developed countries, but are widely used in many developing countries, especially to handle wastes from megacities.
oxygen-demanding wastes
Organic materials that are usually biodegraded by aerobic (oxygen–consuming) bacteria if there is enough dissolved oxygen in the water.
point source
Single identifiable source that discharges pollutants into the environment. Examples include the smokestack of a power plant or an industrial plant, drainpipe of a meatpacking plant, chimney of a house, or exhaust pipe of an automobile.
primary recycling
Process in which materials are recycled into new products of the same type—turning used aluminum cans into new aluminum cans, for example.
primary sewage treatment
Mechanical sewage treatment in which large solids are filtered out by screens and suspended solids settle out as sludge in a sedimentation tank.
recycle
To collect and reprocess a resource so that it can be made into new products; one of the three R’s of resource use. An example is collecting aluminum cans, melting them down, and using the aluminum to make new cans or other aluminum products.
reduce
To consume less and live a simpler lifestyle; one of the three R’s of resource use.
secondary recycling
A process in which waste materials are converted into different products; for example, used tires can be shredded and turned into rubberized road surfacing.
secondary sewage treatment
Second step in most waste treatment systems in which aerobic bacteria decompose as much as 90% of degradable, oxygen–demanding organic wastes in wastewater. It usually involves bringing sewage and bacteria together in trickling filters or in the activated sludge process.
septic tank
Underground tank for treating wastewater from a home in rural and suburban areas. Bacteria in the tank decompose organic wastes, and the sludge settles to the bottom of the tank. The effluent flows out of the tank into the ground through a field of drainpipes.
sludge
Gooey mixture of toxic chemicals, infectious agents, and settled solids removed from wastewater at a sewage treatment plant.
toxic waste
Form of hazardous waste that causes death or serious injury (such as burns, respiratory diseases, cancers, or genetic mutations).
waste mangement
Managing wastes to reduce their environmental harm without seriously trying to reduce the amount of waste produced.
waste reduction
Reducing the amount of waste produced; wastes that are produced are viewed as potential resources that can be reused, recycled, or composted.
water pollution
Any physical or chemical change in surface water or groundwater that can harm living organisms or make water unfit for certain uses.
integrated waste management
Variety of strategies for both waste reduction and waste management designed to deal with the solid wastes we produce.
reuse
To use a product over and over again in the same form. An example is collecting, washing, and refilling glass beverage bottles. One of the 3 Rs.
sanitary landfill
Waste disposal site on land in which waste is spread in thin layers, compacted, and covered with a fresh layer of clay or plastic foam each day.
solid waste
Any unwanted or discarded material that is not a liquid or a gas.