The State of Canada's Environment — 1996

Glossary of Selected Terms - O

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Sources for definitions

ocean dumping: The deliberate disposal at sea from ships, aircraft, platforms, or other anthropogenic structures, including disposal by incineration or by any other thermal degradation, of any substance, or the disposal of any substance by placing it on the ice in any area of the sea (Government of Canada 1988).

old-growth forest: (also known as ancient forest) A stand of mature and overmature trees relatively uninfluenced by human activity (Natural Resources Canada 1994). The stand can contain multiple layers of tree canopies and various species of trees, a significant number of which are huge and long-lived. Such a forest also usually has many large, standing dead trees and numerous logs lying about the forest floor.

organic compounds: Compounds based on carbon and usually also containing hydrogen, with or without oxygen, nitrogen, or other elements (Wells and Rolston 1991). Organic originally meant "of plant or animal origin," and it is still sometimes used in this way. For example, "organic waste" can mean food scraps, manure, sewage, leaves, etc.; "organic fertilizer" can mean manure; "organic deposits" can mean peat or other plant material in soil; "organic nutrients" can mean nutrients derived from decayed plant material. However, now that organic compounds are routinely created by people, the word "organic" is also used to refer to synthetic organic compounds, as in "organic pollution" (which can include toxic human-made organic compounds). See also organochlorine compounds.

organic matter: Plant, animal, or microorganism matter, either living or dead.

organochlorine compounds: (also known as chlorinated organic compounds, chlorinated organics, or organochlorides) Chlorine-containing organic compounds, which may contain oxygen and other elements, such as phosphorus. The term includes many pesticides and industrial chemicals (Wells and Rolston 1991). Examples are dioxins and furans, PCBs, DDT, dieldrin, HCB, and HCH. Many of these kinds of compounds tend to be persistent, meaning that they do not break down easily in ecosystems.

ozone (o3): A pungent, faintly bluish gas composed of three atoms of the element oxygen. In the lower 10 km of the atmosphere, it occurs as a pollution product formed by combining nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight (Greater Vancouver Regional District 1994). In this portion of the atmosphere, it is also a greenhouse gas (Environment Canada 1995). Above 20 kilometres, it is produced naturally and serves to protect the biosphere from damaging ultraviolet radiation. See also ground-level ozone and stratospheric ozone.