Water Quality

Glossary
acid mine drainage (AMD) water draining out of surface or subsurface mines that has an extremely low pH (i.e. high concentration of hydrogen ions) and often contains high concentrations of sulfur, aluminum, and heavy metals such as iron.

aquatic of or relating to water; living on or in water (as opposed to land or air).

alkalinity a measure of the amount of anions of weak acid in water and of the cations balanced against them.

biota living things such as plants, animals, and microorganisms.

buffer something that chemically or physically dampens changes in a system; a protective barrier.

benthic of or pertaining to the bottom, or "bed," of a body of water.

biodiversity the relationship between the number of species present in an area and the number of individuals within each of those species.

buffering capacity the ability of a solution to resist or dampen changes in pH upon the addition of acids or bases.

catchment area the area of land drained within a watershed.

composite the combined typical characteristics of several individuals within a group.

condensation the process by which a gas is cooled and converted into a liquid.

decompose to rot or decay; it is the same chemical reaction that occurs during combustion and respiration, 6 O₂ + C₆H₁₂O₆ 6 H₂O + 6 CO₂

degradation a decrease in quality; degrade (verb).

detritus fresh to partly decomposed plant or animal matter.

drainage basin see watershed.

drought a period during which there is a water shortage.

effluent anything that flows out of a source, such as sewage from a pipe.

EPT index an index of water quality based on the abundance of three pollution-sensitive orders of macroinvertebrates relative to the abundance of a hardy species of macroinvertebrate. It is calculated as the sum of the number of Ephemeroptera, Plecoptera, and Trichoptera divided by the total number of midges (Diptera: Chironomid).

equilibrium reactions reversible chemical reactions in which the rates of reaction in both directions are the same and thus create a dynamic balance.

eutrophication the positive feedback process by which nutrient enrichment of aquatic systems ultimately results in the death of fish and macroinvertebrates due to suffocation. During this process, elevated nutrient levels in streams cause increased growth of aquatic plants. These plants eventually die and accumulate on the streambed. Microbes that decompose these plants use oxygen, therefore the decomposition of the excess plant material leads to an increased consumption of oxygen dissolved in the water. The decrease in available oxygen can lead to the death of plant-eating aquatic organisms like fish and macroinvertebrates. The death of plant-eating organisms results in an even greater increase in plant biomass availble for decomposition by microbes. This ultimately leads to an even greater decrease in the amount of oxygen dissolved in the stream water.

evaporation the conversion of a liquid substance into a gaseous state.

groundwater water that seeps down through the soil and is located in underground reservoirs called aquifers.

headwater streams first- through third-order streams (see stream order); these are the small streams in the upper reaches of a watershed.

hydrosphere the area in which water exists; for the purpose of this module, this sphere includes all liquid water on Earth, such as rivers, lakes, and oceans, as well as all frozen water, such as glaciers, icebergs, and polar icecaps.

landform a feature of the land such as a forest, mountain, or developed area.

macroinvertebrates small, spineless creatures that are visible with the unaided eye; they include organisms such as crustaceans, mollusks, worms, and insects.

non-point-source pollutant a pollutant that cannot be traced back to one specific source, but instead comes from a general area, such as runoff from a parking lot.

nutrient an inorganic (i.e. non-carbon-based) element required by an organism for normal growth and activity.

organic matter carbon-containing residues of living (or formerly living) organisms.

oxidation the loss of one or more electrons by an atom, molecule, or ion.

parameter characteristic being measured or described.

parts per million (ppm) unit of measure most often used to describe the amount of a particular gas or compound in the air or water. It is the proportion of the number of molecules of the gas or compound out of a million (1,000,000,000) molecules of air or water.

pathogenic anything that causes disease.

pH a logarithmic scale ranging from 1 to 14 that identifies the acidity of a solution as the negative logarithm of the concentration of hydrogen ions in solution: pH = - log [H⁺]. Because the pH scale is logarithmic, each unit change represents a ten- fold change in the concentration of hydrogen ions.

photosynthesis the process by which green plants convert solar energy into chemical energy in the form of organic (carbon-containing) molecules, releasing oxygen as a by-product; 6 CO₂ + 6 H₂O + sunlight C₆H₁₂O₆ + 6 O₂.

planimeter a sheet of clear plastic covered with evenly-spaced dots that are calibrated to represent a unit of area. This tool is used to determine the area of a region from a map.

point-source pollutant a pollutant that can be traced back to one specific source, such as sewage from a pipe.

positive feedback the process by which the cause of a change is increased or amplified by its effect.

precipitation the process by which liquid or solid water (rain, sleet, snow, etc.) moves from the atmosphere to Earth's surface.

realistic based on or like reality, but not necessarily existing in the real world.

reduction the gain of one or more electrons by an atom, molecule, or ion.

remediation the process by which something is corrected.

remote sensing the act of collecting data about an object from a distance.

riffle portion of a stream characterized by fast-moving, turbulent, relatively shallow water flowing over a substrate of rocks of various sizes.

River Continuum Concept a model of changes that might take place in an aquatic ecosystem as water travels from headwater streams to larger rivers. As streams flow down through a watershed, their size increases and the influence of the surrounding forest decreases. The river continuum concept provides predictions of the ways in which biological communities might change in response to such habitat differences.

runoff precipitation that has drained through or over an area.

sediment small pieces of organic or inorganic material that are deposited on Earth's surface by wind, water, or ice.

sewage waste water from residential and commercial buildings.

Shannon Index of Species Diversity formula used to calculate species diversity:

where H = diversity index, s= number of species (or orders), i = species (or order) number, pI = proportion of individuals of the total sample belonging to the ith species (or order) (an explicit example of the use of this equation is located in the teachers' notes). The higher the value of H, the greater the probability that the next individual chosen at random from a sample of species containing N individuals will NOT belong to the same species as the previous one (i.e. the greater H, the greater the diversity of species within an area).

siltation the movement of silt - tiny particles of clay and sand into streams during erosion.

species diversity a calculation that relates the density of individuals of each species (or order) present in a habitat to the total number of species (or orders) in that habitat.

stream order a measure of the relative size of a stream. Each increase in stream order is an order of magnitude increase in size. The smallest tributaries are referred to as first-order streams, while the largest river in the world is a twelfth-order waterway.

substrate the materials, such as sand, gravel, or cobble, that make up the bottom, or "bed," of a body of water.

suspended solids small pieces of organic or inorganic material floating in a column of water.

topographic map a map that displays the natural features of an area, such as elevation and bodies of water.

tributary a stream that flows into, or "feeds," another stream.

trunk stream a major artery of a stream network; for example, the Missouri and Ohio Rivers are trunk streams in the Mississippi River Basin.

watershed an area of land that drains into a common reservoir such as a stream, river, lake, or ocean; also referred to as a drainage basin or catchment area.

yellow-boy ferric hydroxide (Fe(OH)₃) precipitate often found in acid mine drainage; named for its yellow to red appearance.

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