Water Quality in the Apalachicola-Chattahoochee-Flint River Basin, Georgia, Alabama, and Florida, 1992-95

|| Table of contents || References ||

Glossary

Ammonia

A compound of nitrogen and hydrogen (NH₃) that is a common by-product of animal waste. Ammonia readily converts to nitrate in soils and streams.

Aquatic guidelines

Specific levels of water quality which, if reached, may adversely affect aquatic life. These are nonenforceable guidelines issued by a governmental agency or other institution.

Aquifer

A water-bearing layer of soil, sand, gravel, or rock that will yield usable quantities of water to a well.

Atmospheric deposition

The transfer of substances from the air to the surface of the Earth, either in wet form (rain, fog, snow, dew, frost, hail) or in dry form (gases, aerosols, particles).

Background concentration

A concentration of a substance in a particular environment that is indicative of minimal influence by human (anthropogenic) sources.

Base flow

Sustained, low flow in a stream; ground-water discharge is the source of base flow in most places.

Basic Fixed Sites

Sites on streams at which streamflow is measured and samples are collected for temperature, salinity, suspended sediment, major ions and metals, nutrients, and organic carbon to assess the broad-scale spatial and temporal character and transport of inorganic constituents of streamwater in relation to hydrologic conditions and environmental settings.

Basin

See Watershed.

Bed sediment

The material that temporarily is stationary in the bottom of a stream or other water course.

Benthic invertebrates

Insects, mollusks, crustaceans, worms, and other organisms without a backbone that live in, on, or near the bottom of lakes, streams, or oceans.

Carbonate

Rock or sediment composed of more than 50 percent carbonate minerals such as limestone or dolomite.

Clastic

Rock or sediment composed principally of broken fragments that are derived from preexisting rocks which have been transported from their place of origin, as in sandstone.

Combined sewer overflow

A discharge of untreated sewage and stormwater to a stream when the capacity of a combined storm/sanitary sewer system is exceeded by storm runoff.

Community

In ecology, the species that interact in a common area.

Concentration

The amount or mass of a substance present in a given volume or mass of sample. Usually expressed as microgram per liter (water sample) or micrograms per kilogram (sediment or tissue sample).

Denitrification

A process by which oxidized forms of nitrogen such as nitrate (NO₃^-) are reduced to form nitrites, nitrogen oxides, ammonia, or free nitrogen: commonly brought about by the action of denitrifying bacteria and usually resulting in the escape of nitrogen to the air.

Detect

To determine the presence of a compound.

Detection limit

The concentration below which a particular analytical method cannot determine, with a high degree of certainty, a concentration.

Dieldrin

An organochlorine insecticide no longer registered for use in the United States. Also a degradation product of the insecticide aldrin.

Discharge

Rate of fluid flow passing a given point at a given moment in time, expressed as volume per unit of time.

Drinking-water standard or guideline

A threshold concentration 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.

Effluent

Outflow from a particular source, such as a stream that flows from a lake or liquid waste that flows from a factory or sewage-treatment plant.

EPT richness index

An index based on the sum of the number of taxa in three insect orders, Ephemeroptera (mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies), that are composed primarily of species considered to be relatively intolerant to environmental alterations.

Eutrophication

The process by which water becomes enriched with plant nutrients, most commonly phosphorus
and nitrogen.

Fertilizer

Any of a large number of natural or synthetic materials, including manure and nitrogen, phosphorus, and potassium compounds, spread on or worked into soil to increase its fertility.

Flood plain

The relatively level area of land bordering a stream channel and inundated during moderate to severe floods.

Fumigant

A substance or mixture of substances that produces gas, vapor, fume, or smoke intended to destroy insects, bacteria, or rodents.

Ground water

In general, any water that exists beneath the land surface, but more commonly applied to water in fully saturated soils and geologic formations.

Habitat

The part of the physical environment where plants and animals live.

Headwaters

The source and upper part of a stream.

Herbicide

A chemical or other agent applied for the purpose of killing undesirable plants. See also Pesticide.

Index of Biotic Integrity (IBI)

An aggregated number, or index, based on several attributes or metrics of a fish community that provides an assessment of biological conditions.

Insecticide

A substance or mixture of substances intended to destroy or repel insects.

Intensive Fixed Sites

Basic Fixed Sites with increased sampling frequency during selected seasonal periods and analysis of dissolved pesticides for 1 year. Most NAWQA Study Units have one to two integrator Intensive Fixed Sites and one to four indicator Intensive Fixed Sites.

Intolerant organisms

Organisms that are not adaptable to human alterations to the environment and thus decline in numbers where human alterations occur.

Intensive Fixed Sites

Basic Fixed Sites with increased sampling frequency during selected seasonal periods and analysis of dissolved pesticides for 1 year. Most NAWQA Study Units have one to two integrator Intensive Fixed Sites and one to four indicator Intensive Fixed Sites.

Karst

A type of topography that results from dissolution and collapse of
carbonate rocks such as limestone and dolomite, and characterized by closed depressions or sinkholes, caves, and underground drainage.

Load

General term that refers to a material or constituent in solution, in suspension, or in transport; usually expressed in terms of mass or volume.

Macroinvertebrate

An animal that is large enough to be seen without magnification and has no backbone or spinal column.

Main stem

The principal course of a river or a stream.

Median

The middle or central value in a distribution of data ranked in order of magnitude. The median is also known as the 50th percentile.

Micrograms per liter (µg/L)

A unit expressing the concentration of constituents in solution as weight (micrograms) of solute per unit volume (liter) of water; equivalent to one part per billion in most streamwater and ground water. One thousand micrograms per liter equals 1 mg/L.

Milligrams per liter (mg/L)

A unit expressing the concentration of chemical constituents in solution as weight (milligrams) of solute per unit volume (liter) of water; equivalent to one part per million in most streamwater and ground water. One thousand micrograms per liter equals 1 mg/L.

Nitrate

An ion consisting of nitrogen and oxygen (NO₃^-). Nitrate is a plant nutrient and is very mobile in soils.

Nonpoint source

A pollution source that cannot be defined as originating from discrete points such as pipe discharge. Areas of fertilizer and pesticide applications, atmospheric deposition, manure, and natural inputs from plants and trees are types of nonpoint source pollution.

Nonselective herbicide

Kills or significantly retards growth of most higher plant species.

Nutrient

Element or compound essential for animal and plant growth. Common nutrients in fertilizer include nitrogen, phosphorus, and potassium.

Occurrence and distribution assessment

Characterization of the broad-scale spatial and temporal distributions of water-quality conditions in relation to major contaminant sources and background conditions for surface water and ground water.

Organic compound

A compound containing at least one carbon-carbon bond (C--C) or one carbon-hydrogen bond (C--H).

Organic detritus

Any loose organic material in streams--such as leaves, bark, or twigs--removed and transported by mechanical means, such as disintegration or abrasion.

Perched ground water

Water in an isolated, saturated zone overlying a layer of material with low hydraulic conductivity and separated from the main body of ground water by unsaturated sediment or rock. Perched ground water has a perched water table.

Pesticide

A chemical applied to crops, rights of way, lawns, or residences to control weeds, insects, fungi, nematodes, rodents or other "pests".

pH

The logarithm of the reciprocal of the hydrogen ion concentration (activity) of a solution; a measure of the acidity (pH less than 7) or alkalinity (pH greater than 7) of a solution; a pH of 7 is neutral.

Phenols

A class of organic compounds containing C₆H₅OH and its derivatives. Used to make resins, weed killers, and as a solvent, disinfectant, and chemical intermediate. Some phenols occur naturally in the environment.

Phosphorus

A nutrient essential for growth that can play a key role in stimulating aquatic growth in lakes and streams.

Phthalates

A class of organic compounds containing phthalic acid esters [C₆H₄(COOR)₂] and derivatives. Used as plasticizer in plastics. Also used in many other products (such as detergents, cosmetics) and industrial processes (such as defoaming agents during paper and paperboard manufacture, and dielectrics in capacitors).

Point source

A source at a discrete location such as a discharge pipe, drainage ditch, tunnel, well, concentrated livestock operation, or floating craft.

Polychlorinated biphenyls (PCBs)

A mixture of chlorinated derivatives of biphenyl, marketed under the trade name Aroclor with a number designating the chlorine content (such as Aroclor 1260). PCBs were used in transformers and capacitors for insulating purposes and in gas pipeline systems as a lubricant. Further sale for new use was banned by law in 1979.

Polycyclic aromatic hydrocarbon (PAH)

A class of organic compounds with a fused-ring aromatic structure. PAHs result from incomplete combustion of organic carbon (including wood), municipal solid waste, and fossil fuels, as well as from natural or anthropogenic introduction of uncombusted coal and oil. PAHs include benzo(a)pyrene, fluoranthene, and pyrene.

Preemergence herbicide

Herbicide applied to bare ground after planting the crop but prior to the crop sprouting above ground to kill or significantly retard the growth of weed seedlings.

Postemergence herbicide

Herbicide applied to foliage after the crop has sprouted to kill or significantly retard the growth of weeds.

Recurrence interval

The average time interval between occurrences of a hydrologic event, such as a flood, of a given or greater magnitude.

Runoff

Excess rainwater or snowmelt that is transported to streams by overland flow, tile drains, or ground water.

Sanitary sewer overflow

A discharge of untreated sewage resulting from clogged sewer pipes or inoperative pumping stations. Untreated sewage overflows from manholes and leaky pipes into nearby streams rather than backing up into homes or businesses.

Selective herbicide

Kills or significantly retards growth of an unwanted plant species without significantly damaging desired plant species.

Semivolatile organic compound (SVOC)

Operationally defined as a group of synthetic organic compounds that are solvent-extractable and can be determined by gas chromatography/mass spectrometry. SVOCs include phenols, phthalates, and Polycyclic aromatic hydrocarbons (PAHs).

Surface water

An open body of water, such as a lake, river, or stream.

Suspended sediment

Particles of rock, sand, soil, and organic detritus carried in suspension in a water column, in contrast to sediment that moves on or near a streambed.

Synoptic sites

Sites sampled during a short-term investigation of specific water-quality conditions during selected seasonal or hydrologic conditions to provide improved spatial resolution for critical water-quality conditions.

Tile drain

A buried perforated pipe designed to remove excess water from soils.

Total concentration

Refers to the concentration of a constituent regardless of its form (dissolved or bound) in a sample.

Trace element

An element found in only minor amounts (concentrations less than 1.0 milligram per liter) in water or sediment; includes arsenic, cadmium, chromium, copper, lead, mercury, nickel, and zinc.

Upland

Elevated land above low areas along a stream or between hills; elevated region from which rivers gather drainage.

Volatile organic compounds (VOCs)

Organic chemicals that have a high vapor pressure relative to their water solubility. VOCs include components of gasoline, fuel oils, and lubricants, as well as organic solvents, fumigants, some inert ingredients in pesticides, and some by-products of chlorine disinfection.

Watershed

The portion of the surface of the Earth that contributes water to a stream through overland run-off, including tributaries and impoundments.

Wetlands

Ecosystems whose soil is saturated for long periods seasonally or continuously, including marshes, swamps, and ephemeral ponds.

Yield

The mass of material or constituent transported by a river in a specified period of time divided by the drainage area of the river basin.

U.S. Geological Survey Circular 1164

|| Table of contents || References ||