The State of Canada's Environment — 1996

Glossary of Selected Terms - A

A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z
Sources for definitions

abiotic: Refers to all physical elements of an ecosystem, including, for example, climate, soil, water, geology, physiography, ice, and nonliving organic matter like peat (E.B. Wiken and A.M. Turner, State of the Environment Directorate, Environment Canada, personal communication).

absorption: The incorporation of a substance into a solid or liquid body (Demayo and Watt 1993). See also adsorption.

acidic deposition: (includes acid rain and other forms of acidic precipitation) Refers to deposition of a variety of acidic pollutants (acids or acid-forming substances) on biota, land, or waters of the Earth's surface. Deposition can be in either wet forms (e.g., rain, fog, or snow) or dry forms (e.g., gas or dust particles).

acid mine drainage: Low- pH drainage water from certain mines, usually caused by the oxidation of sulphides to sulphuric acid (Demayo and Watt 1993). Mine drainage can also contain high concentrations of metal ions.

acute toxicity: Severe biological harm or death produced in an organism by a substance within a short time after exposure (Demayo and Watt 1993). See also chronic toxicity.

adsorption: Surface retention of solid, liquid, or gas molecules, atoms, or ions by a solid or liquid. Adsorption onto suspended or bottom sediments is an important process in the removal of pesticides and other organic compounds from the water column of rivers, lakes, and oceans (Demayo and Watt 1993). See also absorption.

aerosols: Minute mineral particles suspended in the atmosphere, onto which water droplets or crystals and other chemical compounds may adhere. Both natural processes and human activities emit aerosols. Aerosols also affect the energy balance between Earth and its atmosphere by absorbing, scattering, or reflecting solar radiation back to space (Environment Canada 1995).

agroecosystem: An ecosystem managed for the purpose of producing food, fibre, and other agricultural products, comprising domesticated plants and animals, biotic and abiotic elements of the underlying soils, drainage networks, and adjacent areas that support native vegetation and other wildlife (University of Guelph 1994).

air contaminant: Any solid, liquid, gas, or odour or a combination of any of them that, if emitted into the air, would create or contribute to air pollution (Government of Canada 1988).

air pollution: A condition of the air, arising wholly or partly from the presence therein of one or more air contaminants, that endangers the health, safety, or welfare of persons, interferes with normal enjoyment of life or property, endangers the health of animal life, or causes damage to plant life or property (Government of Canada 1988).

algal bloom: See bloom.

alien: (also known as exotic, introduced, or nonnative) Refers to any organism that enters an ecosystem beyond its normal range through deliberate or inadvertent introduction by humans. Includes genetically modified organisms (living modified organisms) that result from biotechnology (Federal-Provincial-Territorial Biodiversity Working Group 1995).

allowable annual cut: The amount of timber that is permitted to be cut annually from a specified area (Natural Resources Canada 1994). The allowable annual cut is used to regulate the harvest level to ensure a long-term (i.e., sustainable) supply of timber.

ammonia nitrogen: Nitrogen in the form of ammonia (NH₃). See also nitrogen fixation.

anadromous: Characterizes migrating fish growing in the sea and ascending freshwater streams to spawn (Demayo and Watt 1993).

analogue: In climate change studies, researchers look for past situations that had similar characteristics to present or future scenarios. These are called climate analogues (Environment Canada 1995).

anoxia: The absence of oxygen, which is necessary to sustain most life. In aquatic ecosystems, this refers to the absence of dissolved oxygen in water (Environment Canada et al. 1988).

anthropocentric: (also known as homocentric) Any human-oriented perspective of the environment, but usually used to emphasize a distinction between humans and nonhumans (Meffe et al. 1994). For example, assessing a forest in terms of its potential timber value would be an exclusively anthropocentric perspective. See also biocentric.

anthropogenic: Refers to influences that originate from humans (Wildlife Advisory Council 1993).

antifouling agents: Various chemical substances added to paints and coatings to combat mildew and crustaceous formations, such as barnacles, on the hulls of ships.

aquaculture: The marine or freshwater cultivation of finfish or shellfish (Wildlife Advisory Council 1993).

aquatic: Pertains to both marine and freshwater ecosystems.