Acid deposition A complex chemical and atmospheric phenomenon that happens when emissions of sulfur and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere (often far from the original sources), form sulfuric and nitric acids, and are deposited on earth in either a wet or dry form. The wet form, often called "acid rain," can fall as rain, snow, or fog. The dry forms are acidic gases or particulates. In high enough concentrations, acid deposition can damage surface waters by altering pH, vegetation such as forests or agricultural crops, and buildings. More Information Rainfall Learn More. See also Atmospheric deposition.
Acid rain The wet form of acid deposition.
Adaptation Changes in an organism's structure, function, behavior, or activities that help it adjust to its environment.
Administrative hearing A formal hearing, contesting a governmental agency's intent to issue (or deny) a permit, that takes place before a hearing officer from the agency. A hearing can be requested by a permit applicant or other affected individual, once the agency's notice of intent to issue (or deny) has been made public.
Administrative order A governmental agency's legal document ordering that corrective action be taken or an environmentally harmful or dangerous activity be stopped.
Administrative record All the information collected by a governmental agency about a particular action (including public comments), on which it bases its decision.
Administrative rule The rules that are developed by a governmental agency, once the legislature has passed a particular law, set guidelines and specific regulations for enforcing that law.
Adsorption The adhesion of gas molecules, liquid, or dissolved solids to a surface.
Aerobic Life or processes that occur only in the presence of oxygen.
Agricultural exemption An exemption from environmental-permit requirements for agricultural activities, including farming and forestry operations, provided the operations do not impede or divert surface-water flows.
Agricultural pollution The liquid and solid wastes from farming, including stormwater runoff, leaching of pesticides and fertilizers into groundwater, erosion, dust from plowing, animal manure and carcasses, and crop residues.
Airborne particulates The total suspended particulates found in the atmosphere as solid particles or liquid droplets. Their chemical composition varies widely, depending on the location and time of year. Such particulates include windblown dust, emissions from industrial processes, smoke from burning coal and wood, and vehicle exhaust.
Air pollution The presence of any substances in air that do not disperse and that can, in high enough concentrations, harm humans or other animals, vegetation, or materials. Pollutants can include almost any natural or artificial substance capable of being airborne as solid particles, liquid droplets, and gases, or a combination of these forms. Generally, air pollutants fall into two major groups: (1) those emitted directly from identifiable sources and (2) those produced in the air when two or more primary pollutants interact, or that react with normal atmospheric constituents. Excluding pollen, fog, and dust, which are of natural origin, about 100 pollutants have been identified and fall into the following major categories: solids, sulfur compounds, volatile organic chemicals, nitrogen compounds, oxygen compounds, halogen compounds, radioactive compounds, and odors. In Florida, air pollution is most serious in urban areas. Federal and state laws have set limits on certain air pollutants. More Information Air Quality Index
Air pollution episode A period of abnormally high levels of air pollutants, often caused by low winds and temperature inversions that can cause illness and death.
Air-quality index (AQI) An index in which measured levels of selected pollutants are converted into an index number, which is then translated into a single descriptive word (such as "fair," "average," or "poor"). More Information Air Quality Index
Alga (plural algae) A simple, rootless plant that grows in sunlit water, giving the water a highly colored appearance, often green.
Algae bloom A sudden spurt of algal growth that occurs because of high nutrient levels and warm waters. Large amounts of algae can affect water quality by lowering the level of dissolved oxygen in the water. Fish kills often result.
Alkaline Sometimes water or soils contain an amount of alkali (strongly basic) substances sufficient to raise the pH value above 7.0 and be harmful to the growth of crops.
Ambient monitoring system Monitoring program with fixed station networks and intensive surveys and producing chemical, physical, and biological analyses. Ambient monitoring deals with conditions in the aquatic environment--streams, lakes, bays, estuaries, and oceans. By contrast, effluent (discharge) monitoring involves sampling and analysis of wastewater.
Amphibian A cold-blooded, scaleless vertebrate-such as a frog, toad, or salamander-that usually begins life as a tadpole in water and, after changing form, develops lungs and becomes a terrestrial air breather.
Anadromous fish Migratory species such as sturgeon and shad. Born in fresh water, they spend most of their lives in estuaries and ocean waters, and return to fresh water to spawn.
Anaerobic Life or processes that occur in, or are not destroyed by, the absence of oxygen.
Aquatic nuisance species Water-borne plants or animals that pose a threat to humans, agriculture, fisheries, and/or wildlife resources. See also Exotic species; See also Hydrilla; See also Non-indigenous species.
Aquatic plant Any plant growing in or closely associated with water.
Aquifer An underground geological layer (stratum), or group of layers, that holds water which can be fresh, brackish, or saline. Florida has numerous aquifers: the Floridan, Biscayne, Sand and Gravel, and Chokoloskee Aquifers; as well as undifferentiated, unnamed aquifers; surficial aquifers; and intermediate aquifers.
Aquifer Resource Index Provides current groundwater conditions compared to historical records to inform the media, residents and local government with a gauge of the groundwater levels in their area. This gauge helps with understanding the severity and cycles of drought and recovery. More Information Aquifer Resource Indicator
Army Corps of Engineers (ACOE) The federal agency that administers the Section 404 permit program on dredging or filling navigable waters, including wetlands.
Artesian well A well from which water naturally flows from an underground aquifer because of subterranean pressure.
Artificial Reef Principle purpose is to increase recreational fishing opportunities, scuba diving sites, and to repair or mitigate damage to ocean habitat such as coral reefs. More Information Artificial Reef
Atmospheric Deposition The delivery of pollutants from the atmosphere to either land or water. Sometimes called "air deposition." More Information Atmospheric Chemistry and Deposition
Automated Surface Observing System (ASOS): The Automated Surface Observing Systems (ASOS) program is a joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), and the Department of Defense (DOD). The ASOS systems serve as the nation's primary surface weather observing network designed to support weather forecast activities and aviation operations and, at the same time, support the needs of the meteorological, hydrological, and climatological research communities. More information Weather
Background level In air pollution control, the concentration of air pollutants in a definite area during a fixed period, before a source of emission under control is started up or stopped. In toxic substances monitoring, it refers to the average level in the environment.
Backpump To pump water to a higher elevation, often used to refer to backpumping water from agricultural fields into a body of water.
Backwater A body of water in which the flow is slowed or turned back by an obstruction such as a bridge or dam, an opposing current, or the movement of the tide.
Bacterium (plural bacteria) A microscopic living organism found in soil, water, or air. While mostly beneficial, some bacteria can harm humans, animals, and plants. Bacteria can aid in pollution control by breaking down organic matter found in sewage, or by consuming oil or other water pollutants. More Information Bacteria
Barrier island A narrow, sandy coastal island built through wave action and separated from the mainland. Such islands form a barrier that protects the shore from the open sea. They are easily flooded during storms or high water, and are constantly in the process of being created, shifted, or destroyed by wind and waves.
Base flow The sustained low flow of a stream, usually groundwater inflow to the stream channel.
Basin A depression of the earth in which sedimentary materials accumulate, usually over a long period. Also refers to a drainage basin, a large area of land from which water drains into streams and rivers. See also Watershed.
Bathymetry The measurement of the depth of large bodies of water (oceans, seas, ponds and lakes). The measurement of water depth at various places in a body of water. Also the information derived from such measurements. (NALMS) More Information Bathymetry. See also Topography.
Bayhead A freshwater hardwood swamp dominated by bay trees, which have evergreen, leathery, broad leaves.
Beach drift See Littoral drift.
Beach re-nourishment A maintenance or restoration project that dredges sand onto an eroded beach. This expensive process must be repeated periodically as the sand continues to erode. If sand of a different composition and density is brought in from other areas, re-nourishment may affect aquatic habitats.
Benthic A term that describes both organisms and processes that occur in, on, or near, a lake's bottom sediments. More Information Benthic and Sediment
Benthic invertebrates Insects, mollusks, crustaceans, worms, and other organisms without a backbone that live in, on, or near the bottom of lakes, streams, wetlands or oceans. Benthic invertebrates provide an essential source of food for young and adult fish, wildlife and other animals. See also Macroinvertabrates.
Berm A narrow, artificially created hill that contains a water body.
Best Management Practices (BMP) An agricultural practice that has been determined to be an effective, practical means of preventing or reducing nonpoint-source pollution. BMPs include the best structural and non-structural controls and operation and maintenance procedures available. BMPs can be applied before, during and after pollution-producing activities, to reduce or eliminate the introduction of pollutants into receiving waters.
Bioaccumulation Toxic substances that increase in concentration in the tissues and organisms of living organisms as they breathe contaminated air, drink contaminated water, or eat contaminated food. These substances are very slowly metabolized or excreted.
OR
The net accumulation of a substance by an organism as a result of uptake from all environmental sources. As an organism ages it can accumulate more of these substances, either from its food or directly from the environment. Bioaccumulation of a toxic substance has the potential to cause harm to organisms, particularly to those at the top of the food chain. The pesticide, DDT, is an example of a chemical that bioaccumlates in fish and then in humans, birds, and other animals eating those fish.
Bioassay Using living organisms to measure the effect of a substance, factor, or condition by comparing before-and-after data.
Biochemical oxygen demand (BOD) The amount of dissolved oxygen, expressed in milligrams per liter that is required by an ecosystem for biological respiration and chemical reactions. It is a measure of the amount of organic material in water. High BOD means that less oxygen is available for aquatic animals and usually indicates poor water quality. See also Impaired Waters.
Biodegradable The ability of a substance or material to break down rapidly through natural conditions and processes, including the action of bacteria, insects, and fungi.
Biodiversity (or biological diversity) Biodiversity exists on a number of levels. Genetic diversity is the diversity in the gene pool of an entire species, that is, all the genes present in all its individuals. This diversity allows at least some individuals to survive extreme environmental changes that threaten the survival of a species. If too few genes remain in the gene pool, inbreeding results and a species is more likely to become extinct. Species diversity is the number of different interdependent species living in a particular ecosystem. On a larger scale, ecosystem diversity is the number of different interconnected ecosystems that exist in a particular region. All these different levels of biodiversity contribute to global biodiversity, the diversity of life on the entire planet.
Biological integrity The health of a particular ecosystem, characterized by the number and variety of species present, as well as a system's stability and capacity to sustain itself over a long period.
Biological productivity The measurement of how much of the Sun's energy is being converted into plants and animals (or biomass). Productivity varies for each ecosystem; systems such as wetlands and estuaries, which shelter the greatest numbers of plants and animals, are the most productive.
Biological waste Any solid or liquid waste that can cause disease or infection, including laboratory waste, waste containing human blood and body fluids, diseased or dead animals, and other materials that can transmit pathogens. Also called biohazardous waste.
Biomass The amount of living matter, in the form of organisms, present in a particular habitat, usually expressed as weight-per-unit area.
Biomass conversion The process of converting biomass into energy. Because it stores the sun's energy through plant photosynthesis, biomass is a form of indirect solar energy. The energy can be released by burning wood, garbage, or other organic material; or by creating synthetic fuels from manure, crops, garbage, or plant oils.
Bioremediation The restoration of all or some of an ecosystem or area's biological functions.
Biosphere The portion of Earth and its atmosphere that can support life.
OR
A term that includes all of the ecosystems on the planet along with their interactions; the sphere of all air, water, and land in which all life is found.
Biota See Biomass.
Biotic community A naturally occurring assemblage of plants and animals that live in the same environment and that are mutually self-sustaining and interdependent.
Biotic index The measurement of an ecosystem's biodiversity.
Black water (1) Surface water that is dark in color because it contains high levels of colored organic acids such as tannic acid, or (2) domestic wastewater that contains animal, human, or food wastes.
Bloom See Algae bloom.
BOD See Biochemical oxygen demand (BOD).
Botanical pesticide A pesticide whose active ingredient is a plant-produced chemical such as nicotine or pyrethrin. While some of these compounds can be extremely toxic, generally they break down quickly compared with many other pesticides.
Bottomland hardwoods Hardwood-forested freshwater wetlands adjacent to surface waters in the southeastern United States. They contain plants typical of seasonally flooded floodplains and are especially valuable for wildlife breeding and nesting.
Brackish water Water that has a salinity intermediate between seawater and freshwater (containing from 1,000 to 10,000 milligrams per liter of dissolved solids).
Breakwater A natural or artificial barrier that breaks the force of waves.
Bubble In Florida's aquifers, a formation of fresh water that lies above areas of salt water. It is also called a lens. Bubbles are particularly vulnerable to saltwater intrusion if the fresh water is pumped out.
Buffer The space next to an environmentally sensitive area required to protect it from human activities, so that its biological function and stability as an ecosystem are preserved. Some restrictions on future development are usually imposed in a buffer.
Bulkhead An artificial retaining wall used to stabilize a shoreline. More Information Shoreline Morphology
Buttressing The swelling at the base or along the exposed roots of certain trees, such as cypress and gum, that grow in a wetlands environment.
Capital Improvement Projects (CIP) The CIP is designed by a County to meet infrastructure needs in six facility types: parks, solid waste, stormwater, transportation, water and wastewater. More Information CIP
Carbon dioxide (CO2) A colorless, odorless, poisonous gas resulting from fossil-fuel combustion and the breakdown of organic matter. It is an essential part of the Earth's atmosphere and a major greenhouse gas that may be contributing to global warming. Carbon dioxide levels have increased substantially since the Industrial Revolution-particularly in the last few decades as fossil-fuel use and the large-scale burning of tropical rainforests have increased.
CCCL See Coastal Construction Control Line.
Channelization Straightening and deepening streams so water will move faster. Because channelization increases water flow, flooding is reduced, but the practice destroys habitats, lowers the water table, and interferes with an area's ability to assimilate wastes.
Chemical oxygen demand (COD) A measure of the oxygen required to oxidize all organic and inorganic compounds in water. See also Water Quality Index (WQI).
Chlorinated hydrocarbons (organochlorines) A high-risk group of persistent, broad-spectrum insecticides and chemicals that pass up the food chain and accumulate in fatty tissue. They attack the nervous system and are suspected carcinogens and mutagens. Chemicals in this category-many of which have been banned or restricted, or are being considered for further restrictions-include DDT, aldrin, benzene, kepone, heptachlor, methoxychlor, dicofil, dieldrin, heptachlor, chlordane, lindane, endrin, mirex, hexachloride, toxaphene, and trichloroethylene.
Chlorination Adding chlorine to drinking water, sewage, or industrial waste to disinfect or to oxidize undesirable compounds.
Chlorophyll a The measurement of a water body's algae levels and trophic state. Chlorophyll is a green pigment found in plants that carry out photosynthesis. See also Water chemistry.
Clean Air Act Contains many provisions to protect the outdoor air quality in the United States by setting national ambient air quality standards to protect public health. See also Air Quality Index.
Clean Water Act Uses a variety of regulatory and non-regulatory tools to sharply reduce direct pollutant discharges into waterways and manage polluted runoff by setting water quality standards for all contaminants in surface waters.
Coastal Construction Control Line (CCCL) A line defining a coastal construction zone, mandated by the 1985 Florida legislature. Within the zone, local governments must adopt construction codes that allow buildings to withstand 110-mile-an-hour hurricane winds.
Coastal strand A thin strip of fragile, wind-pruned, woody vegetation along high-energy coastlines, coastal strand is an important type of upland beach and dune habitat that contains many rare or endangered plants and animals. Coastal strand is rapidly vanishing because it is considered ideal for development.
Coastal wetlands Tidal coastal areas such as mangrove swamps and salt marshes that are extremely valuable ecologically. These areas contribute directly to the high biological productivity of coastal waters by providing nursery and feeding areas for shellfish and finfish, as well as habitat for birds and other animals. They also reduce flooding and sedimentation, absorb nutrients, hold water for groundwater recharge, and provide significant evapotranspiration-an important part of the hydrological cycle.
Coastal zone Coastal waters and adjacent lands that exert a measurable influence on the uses of the seas and their resources and biota.
COD See Chemical oxygen demand.
Coliform Bacteria found in the intestinal tracts or feces of humans and other warm-blooded animals (called fecal coliform). Their presence in water indicates fecal pollution and potentially dangerous bacterial contamination by disease-causing organisms such as streptococcus. More Information Bacteria
Coliform index A water-purity rating based on a count of fecal bacteria.
Colonial birds Birds such as pelicans, cormorants, and herons that nest in large colonies in the marshes and islands adjacent to Florida's surface waters. More Information Birds
Composting A solid waste management technique of accumulating organic matter and then allowing natural biological decomposition to occur. The material breaks down in the presence of oxygen to form humus-like material that can be used to improve soil. See also Organic Fertilizer.
Conditional permit See Permit
Conservation The planned management of resources, especially natural resources, to prevent their exploitation, destruction, or neglect.
Conservation easement A legal document granting a right or interest in real property to preserve land or water in its natural state.
Consistency The requirement of Florida's 1975 Local Government Comprehensive Planning Act that local governments make land-use decisions that are consistent with their comprehensive plans and with state plans.
Consumptive-use permits See Permit
Continental shelf The gently sloping part of the ocean floor that lies between the shoreline and an abrupt change in slope that occurs farther out to sea.
Coral reef The complex marine ecosystem associated with living coral. See also Artificial Reefs.
Corridor See Habitat system.
Criteria pollutants (CAP) A group of air and water pollutants regulated by the EPA under the Clean Air Act and Clean Water Act on the basis of criteria that includes information on health and environmental effects. Criteria pollutants include particulates, some metals, organic compounds and other substances attributable to discharges.
Critical habitat An area containing important habitats, such as feeding and nesting areas, that are essential to preserving a formally protected species.
Cross-Florida Barge Canal Proposed in 1962 by the U.S. Army Corps of Engineers, this 110-mile-long canal would have crossed the state from west to east, from Yankeetown to Palatka, destroyed much of the Oklawaha River, and penetrated the Floridan Aquifer. Numerous citizen and environmental groups effectively opposed the canal, which was halted in 1971 by a citizens' suit and an executive order from President Richard Nixon, and formally de-authorized by Congress in 1990.
Cultural eutrophication The accelerated rate at which water bodies become eutrophic, or die, because of human-caused nutrient pollution.
Cumulative impact The total effect of a number of human activities on the environment. While each one alone may not have a noticeable effect, in combination with others their impact can be significant.
Datum (plural data) Information (either facts or figures) from which conclusions can be drawn.
Datum plane A horizontal plane to which ground elevations or water surface elevations are referenced. See also Stage; See also Water level.
Decomposition The process of breaking down matter into simpler compounds by bacterial, fungal, or chemical action.
Degradable Able to be broken down into a simpler form using chemical, physical, or biological means.
Detention pond A pond to collect and temporarily store stormwater runoff. Pollutants are allowed to settle out, and the water is then gradually released to surface waters.
Dew Point A measure of atmospheric moisture. It is the temperature that air must be cooled in order to reach saturation (assuming air pressure and moisture content are constant). A higher dew point indicates more moisture present in the air.
Dichlorodiphenyltrichloroethane (DDT) One of the nine critical pollutants, was commonly used as an insecticide after World War II and is now banned in the U.S. and Canada. DDT and its metabolites are toxic pollutants with long-term persistence in soil and water. They concentrate in the fat of wildlife and humans and may disrupt the human body's chemical system of hormones and enzymes. DDT caused eggshell thinning in a number of fish-eating birds and is associated with the mortality of embryos and sterility in wildlife, especially birds.
Direct discharger A municipal or industrial facility that introduces point source pollution through a defined system.
Discharge: Any release or unloading of a substance or materials from a pipe, or other emission source. The addition of any pollutant to the waters within the state or to any disposal system from a point source.
Dissolved oxygen (DO) The oxygen freely available in water that is vital to the existence of fish and other aquatic life. It is considered the single most important indicator of a water body's ability to support desirable aquatic life. Secondary and advanced waste treatment systems are usually designed to protect DO in waste-receiving waters. More Information Dissolved Oxygen or Water Quality Index (WQI) Learn More
Dissolved solids See Total dissolved solids.
Disturbed lands Areas where native vegetation has been removed, usually by human causes. These areas are especially vulnerable to invasions of exotic plants.
Diversity index A measure of the diversity of species contained in a sample; a greater diversity of species usually indicates lower levels of pollution, while fewer species existing in large numbers usually indicate higher levels of pollution. In surface waters, macroinvertebrates are used as a measure of diversity.
Draft permit See Permit
Drainage basin The land area drained by a river; a subdivision of a watershed. More Information General Information Page-Watersheds
Drainfield An area of land used as a filter. Water flow is directed over a drainfield to remove impurities, for example, in a septic system.
Drawdown Lowering a lake's water level so that all or part of the bottom is exposed. As a result, thick organic sediments that destroy habitat for aquatic life are oxidized and consolidated, and the lake is then refilled with cleaner water. Drawdowns are much less expensive than pumpdowns, in which water must be mechanically pumped out to lower the lake level.
Dredge To excavate, create, or alter a water body. Dredging destroys habitats and causes silting that can harm aquatic life. Further environmental damage can occur if the dredging stirs up heavy metals or other hazardous substances in bottom sediments. See also Maintenance dredging.
Dredge and fill To excavate a low-lying area such as a wetland, containing muck or other highly organic soils, and then fill the area with material such as sand or gravel, suitable as a base for a road or building.
Drinking water supply standard A threshold concentration for a constituent or compound in a public drinking-water supply, designed to protect human health. As defined here, standards are U.S. Environmental Protection Agency regulations that specify the maximum contamination levels for public water systems required to protect the public welfare; guidelines have no regulatory status and are issued in an advisory capacity.
Drought An extended period without rain: technically, a period in which rainfall is 70 percent below average for three weeks or longer.
Ecological stability The state of an ecosystem in which its structure and function stay approximately the same for long periods.
Ecology The relationship of living things to each other and their environments, or the study of such relationships.
Ecosystem The interaction of a biological community and its environment, considered collectively. Each ecosystem is made up of biotic and abiotic (living and nonliving) components.
Effluent Treated or untreated wastewater flowing out of a treatment plant, sewer, or industrial outfall into a water body.
Emission inventory A listing, by source, of the amount of air pollutants discharged into a community's atmosphere that is used to set emission standards.
Emission standard The maximum amount of an air-polluting discharge legally allowed from a single source, mobile or stationary.
Emissions trading A U.S. Environmental Protection Agency policy under the federal Clean Air Act Amendments that allows a plant with several facilities to decrease pollution at some while increasing it at others, as long as the overall results are equal to or better than previously existing limits. Complexes that substantially reduce their emissions can "bank" their pollution "credits" or sell them to other industries.
Endangered species A formal federal and state designation for animals or plants in immediate danger of extinction because of human-induced or natural changes in their environments.
Environment All the external conditions-physical and biological-that affect an organism's life, development, and survival in its ecosystem.
Environmental externalities The indirect costs to society that result from long-term, residual environmental effects such as pollution, after existing environmental standards have been complied with. These costs are important in competitive bidding. If not accounted for, they allow low-cost bidders who omit them to win contracts, accrue large profits that do not go to those affected, and cause long-term environmental damage.
Environmental impact statement (EIS) Under the federal National Environmental Policy Act (NEPA), this detailed document must be produced to describe the environmental effects of a large-scale project, activity, or legislative proposal. Federal agencies planning a large-scale project must also prepare an EIS, which describes both the positive and negative effects of the project and lists alternative approaches.
Environmental Protection Commission of Hillsborough County Created in 1967 by a special act by the Florida Legislature and consists of five different divisions: Air, Environmental Resources Management, Waste, Water and Wetlands. Their primary responsibility is to conduct pollution complaint investigations and deals with permitting issues.
Ephemeral stream A stream or part of a stream that flows only after precipitation, and whose channel is always above the water table.
Erosion Wearing away land surfaces by wind or water through the processes of weathering, dissolution, abrasion, corrosion, and transportation. While erosion is a natural process, it can be accelerated by poor land management practices.
Estuaries Regions between rivers and near-shore ocean waters where tides and rivers mix fresh and salt water. Habitat quality in these areas depend on how much fresh water flows into them, how good in quality that water is, how often it flows in, and how long it flows. These variables establish salinity levels, which in turn dictate the kinds of plants and animals that live there. Estuaries can include bays, river mouths, tidal marshes, and the sheltered waters between barrier islands and the mainland. The estuarine zone is very productive biologically because of its high nutrient levels. It shelters and feeds many marine species, birds, and other wildlife.
Ethylene dibromide (EDB) A toxic and carcinogenic chemical used as an agricultural fumigant and in some industrial processes. It has been banned in the United States for most agricultural uses. A number of Florida's rural drinking-water wells are contaminated with the chemical.
Eutrophic (noun eutrophication) The aging process by which a water body evolves into a bog or marsh and eventually fills in and disappears. In later stages, the levels of nutrients such as nitrogen and phosphorus released by the decaying organic matter increase, and the amount of dissolved oxygen in the water decreases. This shift favors the development of plant over animal life.
Evapotranspiration The part of the hydrologic cycle in which water vapor is returned to the atmosphere through the processes of evaporation from soil and surface waters, and transpiration from plant leaves.
Exotic species A plant or animal species that is not native to a geographic area or ecosystem. Because they may have no natural pests once they are placed in a new location, many exotic species reproduce prolifically and replace native species or the habitats that support those species. Controlling Florida's exotic plants (such as melaleuca, Brazilian pepper, and water hyacinths) and exotic animals (such as the fish tilapia and wild hogs) costs millions of dollars annually. See also Aquatic nuisance species; See also Non-indigenous species.
Exploitation Using natural resources strictly for human benefit, without considering factors such as long-term environmental damage, resource depletion, or other important considerations.
Exploratory well A well drilled in unproved or semiproved territory to ascertain the presence of a particular deposit such as oil or minerals.
Extinct No longer in existence. Plants and animals become extinct because of factors such as habitat alteration or destruction, overhunting or overfishing, competition from exotic species, or destruction by humans because of competition with human needs (such as livestock predators).
Fauna The entire animal life of a particular region or geological period.
Fecal coliform See Coliform.
Fertilizer A substance needed for plant nutrition, such as phosphorus, nitrogen, and potassium.
Field study Ecological research done in real (as opposed to artificial laboratory) environments.
Fire ecology The study of natural communities such as pine flatwoods and scrub that have adapted to naturally occurring fires every three to ten years. Fire-adapted species that would become extinct without fires to maintain their habitats include red-cockaded woodpeckers, bluebirds, fox squirrels, gopher tortoises, and many kinds of trees, shrubs, and wildflowers.
First flush A form of nonpoint source pollution, the first flush is the first inch of stormwater runoff containing the most pollution. The pollution content of urban stormwater in the first inch usually exceeds that of untreated sewage.
Fish kill A variety of factors, including microorganisms, lack of dissolved oxygen, rapid changes in temperature or salinity, and others can result in serious stress to fishes and in fish death. People are advised not to swim or gather fish for consumption in an area where dead fish are present.
Fisheries independent monitoring A Florida Fish and Wildlife Conservation Commission monitoring program that collects fisheries information by sampling the abundance of young, juvenile fishery species in several bays and estuaries throughout the state. Fish are caught and sampled by Fish and Wildlife Research Institute (FWRI) scientists, rather than depending on fishermen and seafood dealers for fishery data. Fishery independent monitoring data provides trends in abundance for most fishery species. More Information Fisheries Independent Monitoring
Flatwoods The most common plant community in Florida, flatwoods are dominated by longleaf pine, slash pine, and saw palmettos. They are often temporarily flooded in the summer and burn naturally from lightning strikes. Flatwoods contain many fire-dependent species.
Flocculation The process in which solid clumps in water or sewage are made to increase in size by biological or chemical action so they can be separated from the water.
Floodplain The low-lying area bordering a stream, river channel, or lake that is inundated during high water.
Flora The entire plant life of a particular region or geological period.
Florida Department of Environmental Protection The lead agency in state government for environmental management and stewardship. The Department is divided into three primary areas: Regulatory Programs, Land and Recreation and Planning and Management.
Florida Fish and Wildlife Conservation Commission Exercises the regulatory and executive powers of the State of Florida with respect to wild animal life and fresh water aquatic life. The research arm of the Commission is called the Fish and Wildlife Research Institute.
Florida Lake Management Society The Florida Chapter of the North American Lake Management Society (NALMS) which promotes understanding of and comprehensive lake management while assisting in local lake protection.
Florida Lakewatch A volunteer citizen lake monitoring program that facilitates "hands-on" citizen participation in the management of Florida lakes through monthly monitoring activities.
Florida Sea Grant A partnership program with the Florida Board of Education and National Oceanic and Atmospheric Administration, uses academic research, education and extension to create a sustainable coastal economy and environment. See also National Sea Grant College Program.
Flow See Stream flow.
Food chain A series of nutritional steps that pass energy through an ecosystem through a series of organisms, starting with plants. Organisms low on the food chain are eaten by the organism on the next level. The chain ends with predators. Pollutants that enter the food chain can pass up the chain, bioaccumulating in the tissues and organs of animals at the top of the chain.
Fragmentation The division of ecosystems and habitats into smaller and smaller pieces because of human activities. Individual specimens and populations become isolated, can no longer move about to meet their basic habitat needs, find new territories, or mate. Isolated populations become subject to inbreeding, which can eventually cause reproductive failure or vulnerability to disease.
Fresh water Water that generally contains less than 1,000 milligrams per liter of dissolved solids. Usually, more than 500 mg/L of dissolved solids is undesirable for drinking water and many industrial uses.
Fungus (plural fungi) A group of organisms, including molds, mildews, and yeasts, that lacks chlorophyll (i.e., does not carry out photosynthesis).
Gage height See Stage.
Gaging station A particular site on a stream, canal, lake, or reservoir where systematic observations of hydrologic data are obtained.
Game fish Species of fish caught for sport, such as trout or bass. Many of these species show more sensitivity to environmental changes than so-called rough fish.
Geographic Information Systems (GIS) A computerized system for combining, displaying, and analyzing geographic data. GIS produces maps for environmental planning and management by integrating physical and biological information (soils, vegetation, hydrology, living resources, and so forth) and cultural information (population, political boundaries, roads, bank and shoreline development, and so forth). See also Spatial Data.
Global warming A projected increase in the global mean temperature of as much as five degrees Fahrenheit that may occur by the end of the 21st century, caused by the increase in greenhouse gases that trap heat in the Earth's atmosphere. These include carbon dioxide, methane, chlorofluorocarbons, and nitrous oxides. Global warming may have a variety of consequences, including climate change and a sea-level rise from melting polar ice caps.
Greenhouse effect The warming of the Earth's atmosphere that may be taking place, caused by the buildup of carbon dioxide and other gases in the atmosphere since the Industrial Revolution of the late 1800s. The buildup of these "greenhouse gases" may be allowing the sun's rays to heat the planet but prevent a counterbalancing loss of heat. As a result, global temperatures may rise as much as five degrees Fahrenheit by the end of the 21st century, possibly resulting in global climate changes, altered weather patterns, the melting of the polar ice caps and glaciers, and a rise in sea levels that would flood many populated areas.
Greenhouse gases Gases such as carbon dioxide, methane, chlorofluorocarbons, and nitrous oxides that accumulate in the atmosphere and may be contributing to global warming. These gases are generated mainly by human activities, as follows: energy use, 56%; agriculture, 21%; refrigeration and cooling systems, 15%; natural causes, 7%; and industry, 1%. See also Hydrochlorofluorocarbons.
Green Revolution The period beginning in the 1940s and culminating in the 1960s with the production of high-yield agricultural varieties. The widespread use of these varieties, however, can encourage monocultures that are vulnerable to disease and that need more water, fertilizer, and pesticides than traditional crops.
Groin A barrier built on a beach at right angles to the water's edge and entering the sea. It reduces local erosion by holding back the currents that tend to carry sediments along the beach, but deprives downshore areas of sand.
Groundwater Water usually found in porous layers, or aquifers, below the Earth's surface. Groundwater can be fresh, brackish, or saline. Ninety percent of Florida's drinking water comes from groundwater. These underground supplies, however, can easily be polluted by agricultural or industrial chemicals, hazardous waste spills, landfills, leaking underground storage tanks, or saltwater intrusion.
Groundwater flow The underground pathway by which groundwater moves from areas of recharge to areas of discharge.
Habitat The place where an organism, population, or community of animals, plants, or microorganisms lives, as well as its surroundings, both living and nonliving. Habitat includes the basic needs of all living things: food, water, shelter, and space. Animal and plant populations shrink and disappear because the habitats that supply their basic needs are destroyed or altered, and they cannot adapt to other habitats. As a result, they cannot reproduce or raise their young. Since 1950, Florida has lost many of its native habitats, including almost half of its wetlands, one-fourth of its forests, and most of its tropical hardwood hammocks, scrub, and coastal habitats.
Habitat system A broad view of habitat as the entire complex of factors that animals and plants need for long-term survival. These can include other animals, natural forces, or particular territories (which, for animals such as the Florida panther or black bear, can be hundreds of square miles). Habitat needs vary depending on the season, the available food, breeding activities, and need for shelter. Encroaching urban and agricultural development creates "islands," isolating wildlife populations that historically were contiguous. These fragmented populations may then die out because they lack food, shelter, or reproductive opportunities, or because their gene pool is not large enough to protect against the weakening effects of inbreeding.
Half-life (1) Biological half-life is the time required for a pollutant to lose half its effect on the environment. For example, the half-life of the pesticide DDT in the environment is 15 years. (2) The time required for half the atoms of a radioactive element to undergo decay. For example, the half-life of radium is 1,580 years; plutonium, 26,000 years. (3) The time required to eliminate one-half of a total dose from the body.
Hammock In Florida, an area often higher than its wetter surroundings, characterized by hardwood forests of broad-leafed evergreens such as oaks, sweetgums, hickories, palms, and hollies.
Hardwood Any tree, usually broad leafed and deciduous, that has compact, heavy wood, such as oak, maple, walnut, hickory, locust, and sweetgum.
Harvesting A euphemism for killing or collecting that takes place under a management plan when a species in a particular area becomes a nuisance, or is stressed or diseased because of overpopulation and accompanying food shortages. Also refers to a commercial use, such as pine-tree harvesting.
Hazardous substance Any substance that threatens human health and/or the environment. Hazardous substances are typically toxic, corrosive, ignitable, explosive, or chemically reactive. The U.S. Environmental Protection Agency also lists other hazardous substances that may not have these characteristics.
Hazardous waste Byproducts of society that can be hazardous to human health or the environment, and that usually possess at least one of the four characteristics of hazardous substances.
Headwaters The source and upstream waters of a stream or river, such as a lake or wetland.
Health advisory An alert for pollution or other conditions that can harm humans if they are exposed.
Heavy metals Metallic elements with high atomic weights, such as mercury, chromium, cadmium, arsenic, and lead. They can damage or kill living things even in low concentrations. Heavy metals can accumulate in the food chain and in sediments at the bottom of water bodies, where they can be stirred up by dredging.
Herbaceous A plant with little or no woody tissue that dies down at the end of a growing season.
Herbicide A chemical substance that controls or destroys plants, weeds, or grasses. About half the pesticides sold each year in the United States are herbicides.
Herbivore An animal that feeds on plants.
HCFCs See Hydrochlorofluorocarbons.
HFCs See Hydrofluorocarbons.
Human health advisory Guidance provided by U.S. Environmental Protection Agency, State agencies or scientific organizations, in the absence of regulatory limits, to describe acceptable contaminant levels in drinking water or edible fish.
Humidity See Relative Humidity.
Hydric soil A soil that in its undrained condition is saturated, flooded, or pooled long enough during the growing season to develop anaerobic conditions that favor the growth and regeneration of hydrophytic vegetation (plants adapted to wet areas).
Hydrilla An exotic weed that is an aquatic nuisance species which can grow from the bottom of the waterbody to the surface inhibiting water flow, recreation and can alter water chemistry levels.
Hydrocarbons Organic chemical compounds consisting mainly of carbon and hydrogen. They often occur in petroleum, natural gas, coal, and bitumens. This group of compounds includes the naturally occurring hydrocarbons produced by plankton, as well as many petroleum-based products like gasoline and motor oil. Chlorinated hydrocarbons, a subclass of hydrocarbons, are human derived and generally toxic.
Hydrochlorofluorocarbons (HCFCs) Recently developed substitutes for chlorofluorocarbons (CFCs). While chemically related to CFCs, they do less damage to the ozone layer in the Earth's upper atmosphere. HCFCs are still potent greenhouse gases, however, and thus far from being a perfect replacement for CFCs.
Hydrofluorocarbons (HFCs) Recently developed substitutes for chlorofluorocarbons (CFCs). HFCs, because they contain no chlorine, do not damage the ozone layer in the Earth's upper atmosphere.
Hydrograph A graph showing stage, flow, velocity, or other property of water with respect to time.
Hydrologic cycle The global cycle of water movement from the atmosphere to Earth and back. Water in the atmosphere that condenses and precipitates as rain, snow, or ice falls to Earth. Some evaporates into the atmosphere from surface waters. Plants also take up water through their roots and then transpire water vapor into the atmosphere through their leaves. The combined process of evaporation and transpiration is referred to as evapotranspiration. Water also seeps into the ground and recharges aquifers, and eventually resurfaces to evaporate again. Because water is extremely stable at a molecular level, we are using the same water that has flowed through the hydrologic cycle for millions of years. See also Hydrology.
Hydrology The science that deals with water as it occurs in the atmosphere, on the surface of the ground, and underground. More Information Hydrology
Hydroperiod The cyclical frequency of water in a particular area. Certain plants such as cypress need seasonal flooding to reproduce.
Hydrophytic vegetation Plant life growing in water or in a place that is at least periodically deficient in oxygen because of high water levels. More Information Vegetation
Hypereutrophic A water body in an accelerated state of eutrophication, caused by an increase in nutrient levels that encourages rapid plant growth. It is usually caused by human activities such as stormwater runoff containing large quantities of fertilizers.
Hypoxia Low levels of dissolved oxygen in water, which usually result in fish kills and decrease plant growth.
Impaired water Condition of the quality of water that has been adversely affected for a specific use by contamination or pollution. More Information Impaired Waters
Inbreeding In an animal species, breeding between the same or closely related stocks which reduces genetic diversity and can cause undesirable recessive characteristics to appear.
Incidental catch The capture and killing in fishing equipment of animals that are not targeted, such as dolphins and turtles. Also called bycatch. Incidental catches of sea turtles can be prevented by using special turtle excluder devices (TEDs).
Incidental taking The destruction of individuals in a species that results from, but is not the purpose of, an otherwise legal activity.
Index of Biotic Integrity An aggregated number, or index, based on several attributes or metrics of a fish community that provides an assessment of biological conditions.
Indicator species In biology, an organism, species, or community whose characteristics show the presence of specific environmental conditions. For example, canaries were used in mines to indicate the presence of dangerous gases. The birds would die at low levels of exposure and thus warn the miners of dangerous conditions. Other indicators are used to demonstrate the presence of a healthy ecosystem. For instance, the red-cockaded woodpecker is considered an indicator species for a healthy, mature pine forest ecosystem because it nests only in pines 70 years old or older. See also Keystone Species.
Injection well A well that injects wastewater fluids into underground formations. Florida has five classes of injection wells, which are used to dispose of treated municipal effluent, stormwater, and industrial and hazardous wastes.
Intermittent wetland A wetland that dries up periodically.
Invasive plant species See Aquatic nuisance species; See Exotic species.
Inversion An atmospheric condition caused by a layer of warm air that prevents cooling air trapped beneath it from rising. This stops pollutants from rising and dispersing, and can cause an air pollution episode.
Invertebrate An animal without a backbone, such as an insect, spider, mollusk, or jellyfish.
Isolated wetland A wetland not connected by a river or lake to other bodies of surface water.
Jetty A pier or wall built out into a body of water to control currents.
Jurisdictional wetlands Wetlands whose uses are strictly controlled by a governmental agency.
Karst Water-soluble limestone, dolomite, and gypsum beds in which water has dissolved underground cavities, producing fissures, sinkholes, underground streams, and caverns. Florida has numerous karst formations.
Keystone species A species whose niche (occupation) in its ecosystem is vital to the survival of many other species. The disappearance of keystone species thus leads to a series of extinctions in an ecosystem.
Lagoon (1) A shallow artificial pond where sunlight, bacterial action, and oxygen work to purify wastewater, store wastewater, or store spent nuclear fuel rods; or (2) a shallow, naturally formed body of water with little tidal circulation, often separated from the sea by coral reefs or sandbars. Because of their shallow, warm water and abundant food sources, lagoons are hatcheries and nurseries for most sea life. Most wastes that enter them are not flushed out to sea, and thus lagoons are extremely vulnerable to pollution.
Lake Natural or enhanced natural impoundment of water formed by various geological, tectonic, and physicochemical processes including, but not limited to glaciation; meander isolation (e.g., oxbow lakes); land subsidence; spring upwellings, and subterranean erosion and consequent surface collapse (e.g., sinkhole lake). Contrast with reservoirs. See also Reservoir.
Lakewatch See Florida Lakewatch.
Land acquisition programs The Florida Department of Environmental Protection purchases environmentally sensitive lands through the Florida Forever program in order to restore damaged environmental systems, for water resource management, increase public access and increase protection of land by acquisition and conservation.
Land Cover The ecological status and physical structure of the vegetation on the land surface. More Information Land Cover
Land development regulations (LDRs) For Florida counties and cities, regulations that are consistent with and that implement local comprehensive plans required under Florida's Growth Management Act.
Land Use The primary or primary and secondary uses of land, such as cropland, woodland, pastureland, etc. The description of a particular land use should convey the dominant character of a geographic area, and thereby establish the types of activities which are most appropriate and compatible with primary uses. More Information Land Use
Landfill Generally, a land disposal area for waste. (1) A sanitary landfill is a land disposal site for nonhazardous solid wastes in which the waste is spread in layers, compacted, and covered at the end of each day. (2) Secure chemical landfills are disposal sites for hazardous waste. They are chosen to minimize the release of hazardous substances into the environment. No known technology exists, however, to prevent a landfill from leaking eventually.
Land trust A nonprofit corporation established by the members of a community to buy and protect environmentally important areas, and to help local governments make land acquisition decisions.
LDRs See Land development regulations.
Leachate The liquid that results when water seeps through landfill wastes, agricultural pesticides, or fertilizers. It contains a mix of suspended and dissolved materials that can be hazardous or toxic. Leaching may occur in industrial operations, farms, feedlots, and landfills. It can pollute surface water, groundwater, or soil.
Lens See Bubble.
Level of service standards Standards used to measure the adequacy of public facilities addressed in local comprehensive plans, covering such facilities as roads, sewer, solid waste, drainage, potable water, parks and recreation, and mass transit. Local governments are required to plan to meet the future demand for the facilities and services of the population they project, without falling below the levels of service they themselves have set. See also Watershed Management Plans.
Limestone A sedimentary rock consisting chiefly of calcium carbonate, primarily in the form of the mineral calcite.
Limiting factor A condition whose absence or concentration may affect a species or population's ability to grow or survive.
Limnology The study of the physical, chemical, meteorological, and biological characteristics of fresh water.
Liner A relatively impermeable barrier designed to prevent leachate from leaking into the soil below or next to a landfill. Liner materials include plastic and dense clay.
Littoral zone The shallow zone along the shoreline of a body of water, containing rooted plants that provide important habitat for other aquatic species.
Littoral drift The process by which sand is constantly carried along Florida's coasts by wave action.
Load An amount of water, sediment, nutrients, pollutants, heat, etc. that is introduced into a receiving water. Loading may be either of anthropogenic origin (pollutant loading) or natural (natural background loading). See also Total Maximum Daily Load (TMDL).
Macroinvertebrate Bottom-dwelling aquatic invertebrate animals large enough to be seen with the naked eye. They consist mainly of insects, shrimp, crayfish, clams, snails, and worms. The analysis of the quantity and type of macroinvertebrate species is used as an indicator of water quality. Polluted areas tend to have large numbers of only a few macroinvertebrate species that can tolerate decreased oxygen levels, while non-polluted areas tend to have smaller numbers of many different kinds of macroinvertebrate species. More Information Macroinvertebrate Learn More
Maintenance dredging The periodic removal of shoals or sediments from existing navigational channels associated with deep water and commercial shipping. Dredging destroys habitat in the areas dredged as well as the land areas where the dredging spoil is placed.
Mammals Warm-blooded animals, excluding birds, that have hair, produce live young, and nurse their young.
Mangrove swamp A type of coastal wetland found mainly in the southern half of the state, dominated by white mangrove, red mangrove, or black mangrove. Mangroves, a tropical species, are very hardy-having become adapted to a harsh environment where water and salinity levels fluctuate. Freshwater flows bring nutrients into the system and reduce salt stress. Mangrove swamp sediments contain little or no oxygen, but special pores in the tree's exposed roots allow them to "breathe." These species grow densely in sheltered, brackish coastal areas; provide important food, nesting, and nursery habitats for numerous species, including fish, crabs, and shrimp; and buffer the shoreline from storm erosion.
Maximum contaminant level (MCL) As mandated by the 1974 federal Safe Drinking Water Act, the maximum permissible level of a contaminant in water delivered to any user of a public drinking-water system. See also Total Maximum Daily Loads; See also Safe Drinking Water Standards.
Mean high water The average height of all high waters recorded at a given place over a period of time. See also Water level.
Mean low water The average height of all low waters recorded at a given place over a period of time. See also Water level.
Mercury A heavy metal that can accumulate in the environment, mercury is extremely toxic if breathed or swallowed. It is used in exterior latex paints as a mildew inhibitor as well as in pesticides, batteries, and various industrial processes. In humans it can cause central nervous system damage, liver and kidney damage, and fetal abnormalities. Mercury contamination has been found in surface waters and fish throughout Florida, with the highest levels being found in parts of South Florida. The contamination has also been found in panthers, predators at the top of their food chain. While studies are now being conducted, the cause of the contamination is not yet known. Possible sources include municipal solid waste incinerators and the burning of sugarcane wastes.
Mesic Related to conditions of moderate moisture or water supply. Used to describe organisms occupying moist habitats.
Mesotrophic Lakes with moderate quantities of nutrients, found in areas with more fertile soils, or where nutrients from stormwater runoff flow into lake water.
Metadata Information that describes the content, quality, condition, and other characteristics of data. More Information Metadata
Microbes Microscopic organisms such as algae, animals, viruses, bacteria, fungi, and protozoa, some of which can cause disease.
Mitigation Creating, enhancing, or restoring wetlands to compensate for those on a particular site that will be destroyed for development. Most mitigation projects to create wetlands do not succeed because of a lack of maintenance and follow-up. Forested wetlands such as bayheads, which are particularly complex ecosystems, have never been successfully created or duplicated by humans. Other forested wetlands take many years to mature. Wetlands restoration and enhancement projects are generally more successful. Under the 1984 Warren S. Henderson Wetlands Protection Act, the Florida Department of Environmental Protection is required to consider any proposed mitigation in deciding whether to issue or deny a wetlands dredge-and-fill permit application.
Mitigation banking A relatively new practice that allows developers to trade off the impacts of development on wetlands by buying conservation easements to protect valuable habitats elsewhere, rather than on site. While such banking helps preserve the large, interconnected tracts of land that provide habitat for many species, it also allows the destruction of smaller wetlands that may be very important to the survival of other species.
Mitigation ratio The ratio of the wetlands that will be created, restored, or enhanced to the wetlands that will be destroyed, established by the government agencies with jurisdiction over a particular wetland.
Mollusks Invertebrates such as clams, oysters, slugs, snails, and snails. Octopus and squid, which have interior shells, are also mollusks.
Moisture Water diffused in the atmosphere or the ground.
Monitoring Repeated observation, measurement, or sampling at a site, on a scheduled or event basis, for a particular purpose. See also Fisheries independent monitoring; See also Water quality monitoring.
Mouth The place where a stream discharges to a larger stream, a lake, or the sea.
Muck soil Earth made from decaying plant materials. Most of South Florida, as well as large areas around Lakes Okeechobee and Apopka, contains muck soils that have been drained and used for agriculture.
Mulch A layer of material such as wood chips, straw, or leaves placed around plants to hold moisture, prevent weak growth, protect plants, and enrich the soil. More Information Vegetation
National Ambient Air Quality Standards (NAAQS) Standards established by U.S. Environmental Protection Agency that apply for outside air throughout the country.
National Oceanic and Atmospheric Administration (NOAA) A federal agency, NOAA's mandate is to conserve and manage wisely the nation's coastal and marine resources, and describe and predict changes in the Earth's environment to ensure sustainable economic opportunities. NOAA administers the National Sea Grant College Program, National Underseas Research Program, National Marine Fisheries Service, National Coastal Resources Research and Development Institute, National Weather Service, and others. More Information Weather
National Pollutant Discharge Elimination System (NPDES) A permit program established by the U.S. Environmental Protection Agency that controls water pollution by regulating point sources that discharge pollutants into waters of the United States. See also Total Maximum Daily Load (TMDL).
National Sea Grant College Program A nation-wide partnership with public and private sectors combining research, education, and technology transfer for public service. A national network of universities meeting changing environmental and economic needs of people, industry, and government in coastal, ocean, and Great Lakes States. Administered by National Oceanic and Atmospheric Administration. See also Florida Sea Grant.
National Weather Service (NWS) Provides weather, hydrologic, and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas, for the protection of life and property and the enhancement of the national economy. More Information Weather
Native species Species native to a particular geographic area. Because they are part of an ecosystem where everything is interdependent, these species are adapted to local foods, soil and weather conditions, and pests and diseases. Native plants, for example, need less water, fertilizer, and pesticides than species not adapted to that particular location.
Natural pesticides Pesticides derived from naturally occurring compounds. Although they can be very toxic, they often break down more quickly and produce fewer hazardous metabolites than synthetic chemicals.
Natural resource A material or energy resource not made by humans that is used to meet human needs.
Navigable waters Traditionally, waters deep and wide enough for navigation by all, or specified sizes of, vessels. Some interpretations state that the vessel can be as small as a canoe or reed boat. Navigable waters in the United States come under federal and state jurisdiction and are included in certain provisions of the federal Clean Water Act.
Nitrate A nitrogen-containing compound that can exist in the atmosphere or as a dissolved gas in water. Nitrates are found in fertilizers, and human and animal wastes. Nitrate pollution of drinking water is increasing, especially in states like Florida where fertilizers are commonly used and groundwater deposits are relatively shallow and vulnerable to pollution. Nitrites can combine to form toxic nitrosamines, which are mutagenic, teratogenic, and carcinogenic. Nitrates can harm humans and animals; they are especially dangerous to infants. Because they limit the body's ability to carry oxygen to the cells, they can cause brain damage and death.
Nitrogen A biologically important nutrient essential to plant growth, which exists in solid, gaseous, and liquid states. More Information Water Quality > Nutrient Chemistry
Nitrogen loading See Nutrient loading.
Nitrogen oxides (NOx) Nitrogen oxides, a product of gasoline combustion and fertilizer use, are a major greenhouse gas and also contribute to acid deposition.
Non-indigenous species Those species found beyond their natural ranges or natural zone of potential dispersal. See also Aquatic nuisance species; See also Exotic species.
Non-point source pollution Surface-water pollution sources that come from smaller sources in developed urban and agricultural areas. These sources are so numerous and widespread that they are difficult to identify individually. The pollutants-which include oils, greases, and other petroleum products; nitrogen and phosphorus from fertilizers and animal wastes; pesticides; garbage; heavy metals; fecal matter; and silt and sand-are usually carried off the land into surface waters by stormwater runoff. The first inch of stormwater runoff (the first flush) contains the most pollutants. Non-point source pollution also includes freshwater pollution, the salinity changes that result when fresh water is flushed into a saline area such as an estuary or lagoon. See also Total Maximum Daily Load.
Nuisance species Undesirable plants and animals, commonly called exotic species.
Nutrients Elements or compounds essential as raw materials for organism growth and development, such as carbon, nitrogen, and phosphorus. More Information Nutrient Chemistry
Nutrient chemistry See Water Chemistry.
Nutrient loading The quantities of nutrients, mainly nitrogen and phosphorus, in water. These can come from decaying organic matter or from stormwater runoff containing fertilizers. Generally, higher levels of nutrients accelerate plant growth, increasing the speed with which water bodies fill in. More Information Nutrient Chemistry Learn More
Nutrient sufficiency An agricultural technique that provides nutrients only in amounts that plants can use, thus reducing surface-water and groundwater pollution.
Oceanography The study of the ocean, embracing and integrating all knowledge pertaining to the ocean's physical boundaries, the chemistry and physics of sea water, and marine biology.
Oligotrophic Deep, clear lakes with low nutrient supplies that contain little organic matter and have a high dissolved-oxygen level.
Ordinary high-water mark (OHW) The mark found along the bed and banks of a stream, where the presence of water is so common and long-standing that the soil and vegetation are distinctly different from that of the adjacent upland. It is used to define state-owned sovereignty lands.
Organic fertilizer Organic materials-including manures, compost, and green crops such as legumes-that are plowed into the soil. These materials add plant nutrients, hold moisture, and reduce soil erosion. See also Composting.
Organic matter Material derived from living or once-living plants or animals.
Outer Continental Shelf (OCS) The relatively shallow submerged lands adjacent to the United States.
Outfall The place where effluent is discharged.
Overland flow The flow of rainwater or snowmelt over the land surface toward stream channels. After it enters a stream, it becomes runoff.
Oxygen demand The quantity of oxygen used by an aquatic system during a given period.
Ozone (O3) A gaseous form of oxygen found in the atmosphere. In the troposphere (the layer that extends from the Earth's surface to as much as 12 miles up), ozone is a chemical oxidant and a major component of photochemical smog. Here it is produced through the complex chemical reactions of