Water Quality Glossary

Aeration
Any process where a substance becomes permeated with air or another gas. The terms is usually applied to aqueous liquids being brought into intimate contact with air by spraying, bubbling or agitating the liquid.
AHD
Australian Height Datum. Level datum measured in metres.
Algae
Comparatively simple chlorophyll-bearing plants, most of which are aquatic and microscopic in size.
Alkalinity
The quantitative capacity of aqueous media to react with hydroxyl ions. The equivalent sum of the bases that are titratable with strong acid. Alkalinity is a capacity of an aqueous system.
Anthropogenic
Produced or caused by humans.
Benthos
The sum total of organisms living in, or on, the sediments of aquatic habitats.
Bioaccumulation
General terms describing a process by which chemical substances are accumulated by aquatic organisms from water directly or through consumption of food containing the chemicals.
Biochemical Oxygen
The decrease in oxygen content in mm/L of a sample of demand (BOD) water in the dark at a certain temperature over a certain period of time, which is brought about the bacterial breakdown of organic matter. Usually the decomposition has proceeded so far that after 20 days that no further change occurs. The oxygen demand is measured after 5 days (BOD5), at which time 70% of the final value has usually been reached.
Concentration
The quantifiable amount of chemical in the surrounding water, food or sediment.
Criteria (water quality)
Scientific data evaluated to derive the recommended limits for water uses.
Conductivity
Concentration of major salts or major ions in solution.
Cumulative
Brought about, or increased in strength, by successive additions at different times or in different ways.
Detection limit
The smallest concentration or amount of a substance that can be reported as present with a specified degree of certainty by a definite, complete analytical procedure.
Dissolved oxygen
The amount of oxygen in solution (in a water body)
Diurnal Daily.
Diurnal cycling Having a period of variation of one day.
Effluent
A complex waste material (eg liquid industrial discharge or sewage) that may be discharged into the environment.
Euphotic zone
Surface waters to a depth of approximately 80-100 m; the lit region that extends virtually from the water surface to the level at which photosynthesis fails to occur because of reduced light penetration.
Eutrophic
Abundant in nutrients and having high rates of productivity frequently resulting in oxygen depletion below the surface layer of a water body.
Eutrophication
Enrichment of waters with nutrients, primarily phosphorus, causing abundant aquatic plant growth.
Evapotranspiration
The combined loss of material from a given area during a specified period of time by evaporation from the soil or water surface and by transpiration from plants.
Flocculation
  1. The process by which suspended colloidal or very fine particles coalesce and agglomerate into well-defined hydrated floccules of sufficient size to settle rapidly.
  2. The stirring of water after coagulant chemicals have been added to promote the formation of particles that will settle.
Hydrograph
Graphical representation of either surface stream discharges or water-level fluctuations in wells.
Ingestion
The swallowing or taking in of food materials.
Invertebrates
Animals lacking a dorsal column of vertebrae or a notochord.
Leachate
Water that has passed through a soil and that contains soluble material removed from that soil.
Leaching
The downward movement of a material in solution through soil.
Littoral zone
The interface region between the land of the draining basin and the open water of lakes.
Macrophyte
A member of the macroscopic plant life, especially of a water body.
Macroscopic
Large enough to be observed by the naked eye.
Metabolism
The sum of all chemical processes occurring in an organism or living cell.
Organism
Any living animal or plant; anything capable of carrying on life processes.
Osmosis
Diffusion of a solvent through a semi-permeable membrane into a more concentrated solution, tending to equalise the concentrations on both sides of the membrane.
Oxidation
The combination of oxygen with a substance, or the removal of hydrogen from it or, more generally, any reaction in which an atom loses electrons.
Oxygenation
The process of adding dissolved oxygen to a solution.
Parameter
A measurable or quantifiable characteristic or feature.
Pathogen
An organism capable of eliciting disease symptoms in another organism.
Pelagic
Term applied to organisms of the plankton and nekton which inhabit the open water of a sea or lake.
Pesticide
A substance or mixture of substances used to kill unwanted species of plants or animals.
pH
Value taken to represent the acidity or alkalinity of an aqueous solution. It is defined as the negative logarithm of the hydrogen ion acidity of the solution.
Photosynthesis
The conversion of carbon dioxide to carbohydrates in the presence of chlorophyll using light energy. General equation:
 
	CO2 + 2H2O => (CH2O) + O2 + H2O
Precipitation
  1. The formation of solid particles in a solution. Generally, the settling out of small particles.
  2. The settling-out of water from cloud, in the form of rain, hail, snow, etc.
Respiration
The chemical reactions from which an organism derives energy, usually this requires the consumption of free oxygen and the production of carbon dioxide.
Redox
The measurement of the reduction-oxidation potential of a solution. Similar to a pH measurement which gives an indication of athe acid/base status of a solution, ie indicates the hydrogen ion activity, a redox measurement serves instead to determine the reduction-oxidation status of a solution, ie indicates the electron activity. The growth of micro-organisms is highly dependent on the redox level of the medium in which they exist. Thus, anaerobic micro-organisms require a low redox potential where they are found whilst aerobic micro-organisms require a high redox potential.
Salinity
The level of dissolved salts in a water body expressed in parts per thousand.
Species
Generally regarded as a group or organisms that resemble each other to a greater degree than members of other groups and that form a reproductively isolated group that will not normally breed with members of another group.
Steady state or Dynamic Equilibrium
The state at which the competing rates of uptake and elimination of a chemical within an organism or tissue are equal. An apparent steady state is reached when the concen- tration of a chemical in tissue remains essentially constant during a continuous exposure.
Stratification
Pertaining to the formation of layers.
Suspension
A system in which very small particles (solid, semi-solid, or liquid) are more or less uniformly dispersed in a liquid or gaseous medium.
Tolerance
The ability of an organism to withstand adverse or other environmental conditions for an indefinitely long exposure without dying.
Turbidity
Presence of suspended and colloidal substances of various origins.
Turbulence
Unorganised movement in liquids and gases resulting from eddy formation.
Uptake
A process by which materials are absorbed and incorporated into a living organism.
(from Australian and New Zealand Environmental and Conservation Council)

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