The process of assigning activities, costs, or facilities to particular people, or of designating certain resources for particular purposes. …
1 Not indigenous, introduced. Can be used to describe flora, fauna, or people. 2 In geology, a deposit that originated elsewhere than its current position. Contrast autochthonous. …
The study of the relative growth of a part or aspect of an organism (for example, its shape or length) relative to the growth of the whole organism, either for growth of an individual (ontogenetic allometry) or by comparing related organisms of different sizes (phylogenetic allometry). …
An allelochemical that can be produced by a species and influences the behaviour or growth of another species. See also semiochemical. …
Similar organisms which could cross breed but don't because of geographical separation. Contrast sympatric. …
1 In the UK, a small plot of land rented by local people (usually from the local authority) on which they can cultivate food and flowers. 2 In the USA, the area of land designated for use by a prescribed number of livestock for a prescribed period of time. Also known as a range allotment . …
Two or more different physical forms in which a particular element exists. For example, carbon has two allotropes, diamond and graphite. …
The existence of two or more forms (allotropes) of the same element. …
The volume or acreage of timber that can be harvested each year from a particular area of forest, defined by the objectives of management. …
The amount of wood that may be harvested annually or periodically from a particular area of forest over a stated period of time, defined by the objectives of management. …
The level of use of rangeland that is sustainable, defined by the objectives of management. To maintain a range in good to excellent condition, use of 40 to 50% of the annual growth is often allowed; less use will be allowed if the aim is to restore overgrazed land. …
Composed of or relating to alluvium, or caused by or related to river action. Also known as riverine . Compare colluvial. …
A mass of sediment that builds up at a point on a stream course where there is a sudden decrease in gradient (for example, in a mountain canyon). Adjacent alluvial fans are commonly found in arid and semi‐arid environments, and they can coalesce to form a bajada. …
A river that flows through alluvium, that it can move and refashion, as opposed to a bedrock river that flows through or over solid rock. …
Soil that has developed on alluvium that has recently been deposited, with as yet little or no modification of the original material by soil‐forming processes. …
Loosely compacted sediment that is deposited by a river, which can include particles ranging in size from clay, silt and sand, to gravel. Stones and boulders are often worn by the water into rounded shapes. Also known as an alluvial deposit . Contrast colluvium. See also alluvial fan, alluvial plain, floodplain. …
A stand of forest in which trees of different ages are found growing together. See also even‐aged stand, uneven‐aged stand. …
1 A high mountain. 2 Relatively flat area of grazing land in a mountain environment, that is covered by snow during winter but free from snow in the summer. …
Process of radioactive decay in which the nucleus of an atom emits an alpha particle. …
The diversity of species within a particular area or ecosystem, expressed by the number of species (species richness) present there. A measure of biodiversity. Also known as local diversity . See also beta diversity, gamma diversity. …
A helium nucleus given out by some radioactive substances during alpha decay. Alpha particles cannot penetrate very far into materials, even soft tissue, but if they enter the body (by inhalation or through a wound) they can cause great biological damage. …
Emission of alpha particles from a material that is undergoing nuclear transformation. See also radiation. …
Relating to or growing above the tree line in high mountain areas, higher than about 1500 metres above sea level, where it is too cold for trees to grow. The term is also used to describe things that are typical of high mountain areas, or related to or found in them. …
An approach to farming that reflects traditional practices such as using organic rather than chemical fertilizers and pesticides, increased use of crop rotations, reduced tillage of the soil, greater use of renewable energy sources and of intermediate technology, compared with modern high‐energy, chemical‐dependent agribusiness. Also known as alternative farming . Contrast conventional agricu…
An approach to pollution control or the reduction of environmental risk that is based on setting targets but allowing those responsible to choose amongst a variety of different methods for achieving them, rather than command and control regulations that define standards and specify how to meet them. …
Any non‐traditional crop that can be grown in an area to diversify crop rotations (and thus increase soil fertility and productivity) and increase income. …
Energy that is produced from sources other than fossil fuels, which includes sources such as compressed natural gas, solar, hydroelectric, or wind energy. …
A non‐petroleum (not gasoline or diesel) fuel, in liquid or gas form, that is used to power vehicles and produces less pollution. Examples include biofuels or alcohol fuels (such as ethanol and methanol), mineral fuels, natural gas, hydrogen, and fuel cells. …
Technology that has been developed or is used to reduce the generation of hazardous waste, promote recycling, or develop alternative disposal methods. …
An instrument that indicates the altitude of an object above a fixed level, usually sea level. Pressure altimeters use an aneroid barometer with a scale graduated in altitude instead of pressure. …
A high plateau in south‐eastern Peru and western Bolivia, at an elevation of about 3500?m. …
1 In general, any period of high temperature. 2 Often used to refer specifically to a period of time in the mid‐Holocene, between about 4000 and 8000 years ago, when the climate was generally warmer (particularly during summer) than before or since. This period is also known as the hypsithermal or Climatic Optimum . …
Height above sea level or ground level. Also known as elevation . …
A vertical pattern of migration in which populations that breed in the alpine or subalpine zones during the summer move to lower levels in winter, to avoid harsh climate and snow cover, and then return to the higher level the following spring. See also alp. …
The pattern of variation of plant and animal species relative to elevation, in response to vertical differences in climate (particularly temperature and precipitation). …
A category of clouds which have a cumulus shape and are found at medium altitude, about 2400?6100 metres (8000?20?000 feet). They are composed mainly of water droplets, and consist of grey‐white sheets or soft, rounded patches, which are usually larger and darker than those in cirrocumulus and smaller than those in stratocumulus. Altocumulus are associated with weather changes, and often appear …
A type of cloud that is found at medium altitude, about 2400?6100 metres (8000?20?000 feet), and generally consists of uniform grey sheets or layers that are lighter than nimbostratus but darker than cirrostratus. The cloud may be striated, fibrous, or uniform, and it may be composed of ice crystals and well as water droplets. Altostratus often cover the whole sky, and they often arrive ahead of a…
Unselfish concern for the welfare of others, usually other people. Many animals also display forms of altruistic behaviour. …
Aluminium potassium sulphate. A white or colourless crystalline compound that is used to dress leather, and as a pigment in dyes. Also known as potash alum . …
A naturally occurring, light, metallic element that is silver‐grey in colour, conducts heat and electricity, is easy to weld, and is resistant to corrosion. It is the third most abundant element in the Earth's crust, and is used in alloys with copper, zinc, manganese, and magnesium. It is a very versatile metal with a wide variety of uses, including utensils, vehicle and airplane bodies, buildin…
A compound that is used in sewage treatment and for the purification of drinking water. It causes dirt and other particles to clump together and fall to the bottom of settling basins. It is also used in the paper industry and as a fire‐proofing agent. …
The Amazon Basin of South America. It covers an area of 5.8 million square kilometres of Peru, Colombia, and Brazil, and is dominated by grassland, wetland, shrubland, lakes, and tropical forests. …
The fossilized resin of conifer trees. It is hard, translucent, yellowish to brownish in colour, and used for the manufacture of ornamental objects including jewellery. …
Surrounding environmental conditions, such as pressure, temperature, or humidity. …
The permissible upper limit for a pollutant in ambient air, established by the state or federal government, that serves as a target in local air quality improvement or protection programmes. It is based on the maximum acceptable average concentrations of air pollutants during a specified period of time. The primary standard protects public health, and the secondary standard protects public welfare…
The general level of any particular substance or pollutant in the environment, expressed as an average over a suitably long time and large area. …
A measure of the concentration of a particular substance or pollutant within the immediate vicinity of an organism, which can be related to the maximum amount of possible exposure. …
The useful or desirable features of a place, that provide non‐monetary benefits to those who use it but which are not necessary for its use. An amenity can be natural (such as an attractive location or accessible woods or water) or made by people (such as a swimming pool or garden). …
Gardening or cultivation for leisure or aesthetics rather than for commercial reasons. Also known as hobby farming . …
Planting trees and shrubs for non‐commercial purposes, for example to make a landscape more attractive rather than to produce a crop for sale. …
Any resource that is valued for non‐monetary characteristics, such as its beauty or uniqueness. For example, attractive natural scenery can inspire creativity and promote well‐being. …
The non‐monetary, intangible value of goods or services. …
An organic compound that contains both an amino group (NH2) and a carboxyl group (COOH). Amino acids are the building blocks of protein molecules in living things. There are 20 common amino acids that can be combined to form proteins. …
A method of absolute dating of organic materials that is based on the chemical change that amino acids undergo. This is dependent on both time and temperature. …
A colourless gas with a strong smell. It is a compound of nitrogen and hydrogen that is formed naturally when bacteria decompose nitrogen‐containing compounds such as manure, and is used to manufacture fertilizers and nitrogen‐based compounds. Ammonia is extremely soluble in water and it reacts with nitrogen oxides to form ammonium nitrate in soils and streams. See also nitrogen cycle. …
The adsorption of ammonium ions by clay minerals, which makes them insoluble and non‐exchangeable. …
The biochemical process in which ammonia is produced by micro‐organisms through the decomposition of organic matter. …
An ion derived from ammonia; the primary form in which nitrogen is applied in fertilizers. …
A colourless, crystalline salt that is used in explosives, fertilizers, and veterinary medicine. …
A chemical compound that is used as a fertilizer. It is quite acidic, and will raise the pH of a soil. …
A cold‐blooded, smooth‐skinned vertebrate animal of the class Amphibia that can live on land or in water but which returns to the water to breed. They usually hatch as aquatic larvae, breathe by means of gills, and metamorphose to an adult form with air‐breathing lungs. Examples include frogs, toads, and salamanders. See also herpetofauna. …
A gentle local wind that blows up a hillslope when the sloping ground has been warmed by the sun. Also known as an upslope wind . Compare katabatic wind. …
The process by which a living cell or organism constructs the proteins, carbohydrates, and fats which form tissue and store energy. Also known as biosynthesis or constructive metabolism . See also metabolism. …
Fish that mature and spend their adult life in the sea but swim upriver to reproduce in freshwater spawning grounds. Examples include salmon and striped bass. Contrast catadromous. …
A condition in which there are low levels of red blood cells or red blood cells that are deficient in haemoglobin. Can be due to iron deficiency or loss of blood and causes tiredness. …
An organism (such as bacteria) that does not need oxygen to respire. The opposite is an aerobe. …
Organisms or processes that do not require oxygen, or which oxygen would damage. Also known as anoxic . Contrast aerobic. …
A process commonly used in the treatment of municipal waste that uses anaerobic organisms (without air) to reduce the organic matter in wastes. Also known as anaerobic digestion . …
Composting based on anaerobic decomposition. Contrast aerobic composting. …
The breakdown of organic matter caused by anaerobicmicro‐organisms in an oxygen‐free environment. …
Similar in structure, appearance, or function but not in origin or development. See also climatic analogue. …
1 The structure of an organism or one of its parts. 2 The study of those structures. …
A weather front in the atmosphere, along which warmer air rises rapidly over a layer of cold air. Ana‐fronts are very active, and are associated with uplift, condensation, and pronounced weather changes. See also kata‐front. …
Any organism, population, or species from which another organism, population, or species is descended. …
A forest that is typically older than about 250 years with large trees, dense canopies, and great diversity of wildlife. In North America this is described as old growth forest. …
Woodland in Britain that originated before ad 1600 and has had a continuous cover of trees since then. Ancient woodland can also be secondary woodland, which might have previously been cleared for underwood or timber production. …
A fine‐grained, intermediate, volcanic rock characterized by feldspars which formed by the ejection of lava in continental areas. Named after the Andes mountains in South America. …
An order of deep, texturally‐ light volcanic soils that contain iron and aluminium compounds. …
Possessing both masculine and feminine characteristics. See also hermaphrodite. …
An instrument that is used to measure wind speed (some can also measure wind direction). There are two main types, the rotating‐cup anemometer and the pressure‐tube anemometer. …
An instrument that is used to measure atmospheric pressure based on variations in the height or thickness of a sealed metal box from which most of the air has been evacuated. The box has a flexible top that rises or falls in response to changes in atmospheric pressure; variations in the height or thickness of the box are recorded on a pressure scale. …
Any of the flowering seed plants having their seeds enclosed in an ovary which matures into a fruit. Contrast gymnosperm. …
The angle at which any ray or wave meets a surface, such as the angle at which the Sun's rays strike the Earth's surface. …
The steepest angle in which unconsolidated sediment will lie without sliding down. It is an important measure in determining the stability of a slope and its susceptibility to mass movement. …
The slope at which unconsolidated sediment will start to slide, which is slightly greater than the angle of repose (because of friction). …
A unit of length equal to 10?10 metres that is used to measure wavelengths and intermolecular distances. It has been replaced by the nanometre (nm): 1?? = 0.1?nm. …
The tendency of a spinning body or mass of air or water to continue to spin. …
An unconformity in which the bedding planes of the rocks above and below are not parallel to each other. This occurs, for example, where older underlying beds have undergone alteration and been eroded prior to deposition by younger overlying beds. …
See Alaska National Interest Land Conservation Act. …
Any member of the animal kingdom, which comprises all multicellular organisms that obtain energy, actively acquire their food and digest it internally, have well‐developed nervous systems, have cells organized into tissues, and reproduce sexually. This includes multicellular marine organisms, worms, insects, spiders, crustaceans, fish, amphibians, reptiles, birds, and mammals. …
The characteristic assemblage of animals that is associated with a particular ecosystem. …
In taxonomy, the animal kingdom. See also animal. …
The taxonomic kingdom (Animalia) that comprises all living or extinct animals. Also known as zoological kingdom . …
The belief that animals have rights similar to those afforded to humans, and that those right need to be respected and protected. …
The capture and reuse of methane produced from the decomposition of animal waste, before the manure or fertilizer is spread on fields. Recovery technologies include the anaerobic digester, and machines that use the methane to produce energy. …
A measure of the surface charge of an anion, expressed in equivalents of exchangeable ions per unit weight of the solid. …
Having different properties in different directions. For example, variations in hydraulic properties of groundwater in an aquifer. Contrast isotropy. …
The greenhouse gases whose emissions are regulated by the Kyoto Protocol (as defined in Annex A) in order to reduce global warming and slow down climate change. The gases are carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulphur hexafluoride. …
The list of industrialized countries and economies in transition that have their greenhouse gas emissions capped under the Kyoto Protocol (as listed in Annex B). The Protocol also defines legally binding obligations on each country to reduce their emissions by set amounts within a defined period of time. For example, most European countries are required to decrease their emissions by 8% (relative …
Countries that committed themselves specifically to the aim of reducing their emissions of greenhouse gases to 1990 levels by the year 2000. The list, which appears in Annex I to the United Nations Framework Convention on Climate Change, includes all the countries in the Organisation for Economic Cooperation and Development, plus countries designated as economies in transition. By default other co…
The countries listed in Annex II to the United Nations Framework Convention on Climate Change that have a special obligation to help developing countries with financial and technological resources required to reduce greenhouse gas emissions and curb global warming. This includes all 24 original member countries of the Organisation for Economic Cooperation and Development plus the European Union. …
A plant that completes its life cycle (germination, growth, flowering and fruiting, then death) in a single growing season and so has a lifespan of 1 year. See also biennial, perennial plant, seasonal plant. …
The yearly cycle of changes in the climate system and related environmental systems, caused by variations in the amount of solar radiation that reaches the Earth as it orbits the Sun. …
The amount of new biomass produced by a plant per year, usually measured as above‐ground production. …
Flow records that are used in flood frequency analysis, which include only the highest discharge each year (the annual maximum). Contrast partial duration series. …
A pasture consisting of introducedforage species that have been planted to grow for only one year or season. Contrast permanent pasture. …
A type of drainage pattern in a river system. It develops on a dome where concentric outcrops of rocks with different resistance to erosion are exploited by river erosion. …
The difference between a particular measurement (for example of weather elements such as temperature or precipitation) and the mean or expected value. …
Lacking oxygen or oxygen‐free. See also anaerobic. …
The interaction of two or more substances with opposing effects which partially or wholly cancel each other out, or (for organisms such as bacteria) where the growth of one inhibits that of the other. Contrast synergism. …
The fifth largest and by far the coldest of the seven continents. It is centred on the South Pole, located mostly within the Antarctic Circle, covered with ice (which in places is more than 2000 metres thick) and surrounded by sea ice, particularly during the winter. The outer limits of Antarctica are defined by the Antarctic Convergence. It is, in effect, a cold desert, with an average annual pre…
The area of land and sea that lies south of latitude 66?S, around Antarctica. …
A large ocean current that is driven by the wind and flows completely around Antarctica from west to east. …
A sharp change in the physical characteristics of the Atlantic, Indian, and Pacific oceans between latitudes 48? and 60?S. Here, warmer waters moving south from the mid‐latitude oceans meet and mix with colder waters moving north from Antarctica, and there is a steep temperature gradient within the ocean water which effectively isolates life in the Southern Ocean (i.e. the area within the Antarc…
The seasonal depletion of ozone over much of Antarctica. See also ozone hole. …
A biogeographical realm in the southern hemisphere, which contains a variety of ecosystems from temperate forest and grassland in New Zealand to tundra and ice sheets in Antarctica. …
An international treaty that is designed to preserve the unique environment of Antarctica by limiting development there. It was signed in 1959 by the seven countries (Norway, France, Australia, New Zealand, Chile, Great Britain, and Argentina) which claim sovereign rights over the continent, plus twelve other countries, and it dedicated the whole continent to peaceful scientific investigations. …
The degree of wetness of the soil at the beginning of a period of runoff, usually expressed as the total inch‐depth‐equivalent of water stored in the soil. Also known as antecedent soil water . …
A river network in which an initial pattern, established in the geological past, has been preserved while the area has been uplifted. Rates of river downcutting must have been higher than rates of uplift for this to occur. …
The period before the Biblical flood (described in Genesis, Chapter 7). …
Living or growing on flowers, as certain insects do. …
A hard, black coal that burns slowly with little flame or smoke but gives off intense heat, formed at the later stages of the coal cycle by the folding and hardening of sedimentary strata containing bituminous coal. This is the most highly metamorphosed form of coal, containing 92 to 98% of fixed carbon. …
Relating to the period during which humans have existed on Earth. …
Human‐centred. Based on the belief that only humans have value and thus they have a privileged position in nature, that the environment exists only for the benefit of humans, and that nature has no rights. Also known as homocentric . Contrast ecocentric. …
A worldview that sees humans as the source of all value, since the concept of value itself is a human creation, and that sees nature as of value merely as a means to the ends of human beings. See also ecocentrism, human exceptionalism paradigm. …
Made by humans or resulting from human activities. …
A member of the group of primates (suborder Anthropoidea) that comprises monkeys, apes, and humans. …
The study of human cultural variations, including language, biology, and society. See also ethnography. …
The attribution of human motivation, characteristics, or behaviour to non‐human things, which leads to the treatment of animals, gods, inanimate objects, or natural phenomena as if they have human feelings and emotions. …
A chemical produced or synthesized by living micro‐organisms (such as yeast) that destroys or inhibits the growth of other organisms, especially bacteria. Used to treat or prevent infections by inhibiting the growth of bacteria and fungi that produce disease. …
A special protein that is produced by the immune system within an organism in response to an invading foreign antigen (such as bacteria, dust, or pollen). …
A substance or agent that opposes the action of carcinogens. …
A common type of fold in rock. It takes the form of a symmetrical fold, arched upward in the middle, in which the rocks at the centre are usually the oldest. Contrast syncline. …
A series of small‐scale anticlines and synclines which may be small enough to be viewed in outcrop. …
A large area of high atmospheric pressure around which the winds blow clockwise in the northern hemisphere (and anticlockwise in the southern hemisphere) and which usually results in calm, fine weather. Also known as a high . …
A remedy designed to relieve, prevent, or counteract the effects of a poison, usually by eliminating it, neutralizing it, or absorbing it. …
A substances that the body regards as foreign, which results in the production of antibodies. …
The collective name for prehistoric and historic artefacts, objects, structures, ruins, sites, and monuments that have some cultural or scientific significance and are considered to be older than 100 years. …
US legislation that protects ruins or objects of antiquity on federal lands. …
A group that is known for either pushing an agenda contrary to the environmental movement, or for engaging in efforts to undermine the effectiveness of the environmental movement. Examples from the USA include think‐tanks such as the Cato Institute, Heartland Institute, Heritage Foundation, legal groups such as the Mountain States Legal Foundation, and front groups such as the Climate Council, C…
An effect that leads to less equity and more inequality. …
The three‐dimensional mosaic within a habitat that is created by the non‐overlapping territories of dominant ants. This in turn has a significant influence on the diversity and species composition of other organisms, including plants, vertebrates, and invertebrates. …
The top part of a cumulonimbus cloud which spreads horizontally outward in the vicinity of the tropopause and looks like a blacksmith's anvil. …
The point in the Earth's orbit when it is farthest from the sun (152.5 million kilometres), which occurs on the 3rd or 4th of July each year. The opposite is perihelion. …
Totally dark. Also known as disphotic . Contrast photic. …
Beekeeping in order to produce honey. Contrast bombiculture. …
In exposure assessment, the amount (dose) of a substance that is in contact with the parts of an organism (such as the skin, lung tissue, or gastrointestinal track) through which it can be absorbed. …
A wingless insect of a group that is believed never to have had wings in its evolutionary past. Contrast pterygote. …
The cultivation of marine or freshwater food fish or shellfish, such as oysters, clams, salmon, and trout, and the farming of aquatic plants, under controlled conditions to be sold for human consumption. Also known as fish farming, mariculture, or pisceculture . …
A person who is trained to live in underwater installations and to conduct, assist in, or be a subject of scientific research. …
A tank, pool, or building in which living aquatic animals and plants are kept under controlled conditions for pleasure, study, exhibition, or as a form of ex situ conservation. …
An agroforestry system that combines trees with fish farming. See also aquaculture. …
The living resources of aquatic habitats, which include fish, invertebrates, and amphibians. …
A long channel or raised bridge‐like structure built to transport water from a remote source, usually by gravity. See also interbasin transfer. …
Containing water, dissolved in water, or composed mainly of water. …
The extent to which a substance will dissolve in water. …
An effectively impermeable layer of rock that confines an aquifer, preventing the water in it from moving upward or downward into adjacent strata. Examples include shale and some igneous rocks. See also perched aquifer. …
A body of permeable and/or porousrock that is underlain by impermeable rock and is saturated with water (groundwater) or transmits water underground, which can be extracted for use by humans, most commonly by drilling wells. See also aquiclude, aquitard, artesian well, confined aquifer, perched aquifer. …
Withdrawing groundwater from an aquifer faster than it is naturally replenished. Also known as groundwater mining or overdraft . …
The withdrawal of groundwater from an aquifer, over a period of time, at a rate that exceeds the rate of natural recharge. …
The less permeable beds in a rock sequence, that may be permeable enough to transmit water but not permeable enough to allow water to be abstracted from wells within them. …
1 Land that is suitable for cultivation. 2 A farming system in which crops (such as cereals) are raised, rather than livestock. …
Air‐breathing arthropod such as spiders and mites, that has a body made of two segments (except mites) and four pairs of legs. …
A very large freshwaterlake (formerly the world's fourth largest lake) on the border between Kazakhstan and Uzbekistan in Central Asia. Since the 1960s the lake has been drying up and shrinking as a result of a loss of water due to the diversion of river flow to a major irrigation project designed to make the area self‐sufficient in cotton, and to increase rice production. The surface area of th…
A formal process for resolving disputes, in which there are strict rules of evidence, cross‐examination of witnesses, and a legally‐binding decision made by the arbitrator that all parties must obey. …
A collection of specimen trees from which seeds and cuttings can easily be gathered as part of a living collection. …
The cultivation and management of trees. See also silviculture. …
A virus that is transmitted by an arthropod (such as a mosquito or tick), which includes encephalitis, yellow fever, and dengue fever. …
A period of geological time extending from about 3.9 to 2.5 billion years ago (the start of the Proterozoic), during which the Earth's crust formed. The earliest part of Precambrian time. Rocks of this age contain fossils of single‐celled organisms, which are the earliest forms of life on Earth. …
US legislation that provides for recovery, protection, and preservation of significant cultural resources that will be irreparably lost or destroyed by alteration of terrain from any federal construction project or federally licensed activity or programme. …
All remaining physical evidence of past human occupation, other than historical documents, which can be used to reconstruct life styles of ancient cultural groups. This includes skeletons, sites, monuments, artefacts, environmental data, and all other relevant information. …
Any place that contains physical evidence of past human activity, and which provides scientific, cultural, or historical evidence relating to the history of that place. …
The study of past human cultures through the analysis of material remains (as fossil relics, artefacts, and monuments), which are usually recovered through excavation. …
The original form or body plan from which a group of organisms develops. …
The area lying above 66.5? North that is dominated by the Arctic Ocean but also includes large land areas in Canada, Russia, Greenland, Scandinavia, Iceland, and Alaska. Some of the land areas, including most of Greenland, are permanently covered in ice and pack ice is common throughout the Arctic Ocean. Climate in this high latitude zone is extreme, with short cool summers and long cold winters. …
A very cold and dry air mass that generally forms north of the Arctic Circle but moves southwards, cooling the areas it passes over. …
A weather front that develops at the boundary between the very cold dense arctic air mass that is associated with the cold arctic anticyclone, and the warmer polar air mass. …
A persistent thin mist that lies over the Arctic during the winter months, possibly associated with by the long‐range transport of air pollutants that originate in mid‐latitude countries. …
A very cold zone of high atmospheric pressure that originates over the Arctic Ocean. …
A *National Wildlife Refuge that covers about 80?000 square kilometres in north‐eastern Alaska, in the North Slope region. The area has been protected since 1960 , but the refuge was expanded in 1980 under the Alaska National Interest Lands Conservation Act. …
The ice‐covered waters that surround the North Pole, which are largely covered with solid ice or with ice floes and icebergs. …
1 A type of strip mining that is practiced on relatively flat land, which involves cutting a trench through the overburden in order to expose the deposit of mineral or ore to be removed. The overburden is placed on un‐mined land adjacent to the cut, and the mineral or ore is then removed. A second cut is then made parallel to the first, the overburden from which is deposited in the first cut. Th…
An area of public land in the USA where management is directed towards the protection of fish and wildlife, important historic, cultural, or scenic values, or other natural systems or processes. See also Fragile or Historic Lands. …
An area of protected countryside in the UK, designated under the National Parks and Access to the Countryside Act 1949 on the basis of attractive landscape, in which development is tightly controlled. …
Any source of air pollution that is released over a relatively small area but is not a point source. Sources include vehicle exhausts, houses and small businesses. Similar to a non‐point source. See also emission source. …
Species that respond badly if the patch size of their habitat decreases. …
Medium‐grained sandy clasticsedimentary rocks, such as sandstone, with particles ranging in size from 0.06 to 2.0 millimetres. …
A long, sharp, knife‐edged ridge with a serrated top, formed when glaciers erode adjacent cirques on the opposite sides of a mountain ridge. See also col, horn. …
Fine‐grained clasticsedimentary rocks, such as siltstones and marls, made of clay and silt particles smaller than 0.06 millimetres. …
A natural, colourless, odourless, inertgas that is the third most abundant constituent of dry air (it comprises 0.93% of the Earth's atmosphere). …
A desert type (order) of soil that develops in an arid region, with little or no organic content but significant amounts of calcium carbonate (gypsum) and other deposited salts. With little if any vegetation growing on the soil surface, there is no surface litter, no humus, and no dark organic layer in the A‐horizon. There is a relatively deep B‐horizon where soluble compounds accumulate which…
A measure of the lack of moisture in a place, based on the level of water deficit. In equation form the index is 100???water deficit/potential evaporation. …
An area with a dry climate which cannot support the growth of trees, woody plants, or most crops (without irrigation), and with a biome in which only drought‐resistant vegetation naturally survives. …
A pattern of growth that increases at a constant rate over a specified time period, such as 1, 2, 3, 4 or 1, 3, 5, 7. Contrast exponential growth, geometric growth. …
A major group of unsaturated hydrocarbons, such as benzene or toluene, which have a specific type of benzene ring structure and are added to gasoline to increase octane. Some are toxic; all have a strong but not unpleasant odour. Also known as arene . …
An incomplete ecological succession that has not reached the natural climax stage, usually as a result of human disturbance or alteration which is reflected in subclimax and plagioclimax vegetation. …
A Swedish physicist and chemist ( 1859 ? 1927 ) who predicted that the release of carbon dioxide into the atmosphere would lead to global warming, and estimated the magnitude of the greenhouse gas effect. …
A small, deep gully or channel with steep or vertical walls and a flat floor, which is eroded into the surface of a dry desert by an intermittent stream. The bed is usually dry, and the arroyo contains streamflow only after rain. …
A heavy metal element that occurs naturally in the Earth's crust and fossil fuels, which bioaccumulates and is highly toxic and carcinogenic to humans. It is used in the production of glass, enamels, ceramics, oil, cloth, linoleum, electrical semiconductors, pigments, fireworks, pesticides, fungicides, veterinary pharmaceuticals, and wood preservatives. …
An object made by humans, usually for a practical purpose, which has been preserved and can be studied to learn about the period it was made and used. …
An aquifer in which groundwater is confined between two impermeable layers (aquitards), under hydrostatic pressure, which is significantly greater than atmospheric pressure and forces the water to flow out of an artesian well, boreholes or springs, so long as the aquifer is constantly recharged. Also known as confined aquifer . …
A well sunk in an artesian aquifer, from which groundwater is naturally forced to the surface by hydrostatic pressure so the well is free flowing. See flowing well. …
A member of the phylum Arthropoda, which is by far the largest in the animal kingdom and includes many different invertebrates with an exoskeleton such as arachnids (spiders, mites) insects (bees, ants, moths) and crustaceans (shrimps, crabs). …
A chemical that is added to soil to increase fertility and enhance crop production. …
Adding water to an aquifer to restore groundwater. …
Establishing a new forest by planting seedlings or by direct seeding, often after deforestation. Contrast natural regeneration. …
The process by which humans breed animals and cultivate crops to ensure that future generations have specific desirable characteristics, by exploiting the process of natural selection. Breeders select the most desirable variants in a plant or animal population, and then selectively breed them with other desirable individuals. Examples include particular plants that are resistant to disease, high y…
An engineered wetland, often constructed to treat sewage or other organic wastes. …
A group of naturally occurring fibrous minerals that can be spun and woven. They are strong, do not corrode or burn, and good at insulating heat and electricity, and are used for insulation, construction and brake linings. Asbestos minerals separate into fibres that can cause air and water pollution, and cause cancer or asbestosis when inhaled by humans. In the US their use in construction and man…
Measures used to control the release of dangerous fibres from materials that contain asbestos, or remove them completely. These include removal, enclosure, and encasement. …
A lung disease in humans, associated with chronic exposure to asbestos and inhalation of asbestos fibres, that results from scarring of the lung tissues by the fibres. The disease makes breathing progressively more difficult and can be fatal. …
A mode of reproduction, common among lower animals, micro‐organisms, and plants, in which offspring are created by a single parent so they inherit only the genes of that parent. …
1 The mineral content of a product that remains after complete combustion, which consists mainly of minerals in oxidized form. See also fly ash. 2 Volcanic dust that erupts from a volcano, and either flows out (as a pyroclastic flow) or forms a cloud. …
A steep‐sided volcano composed of fine volcanic ash erupted from the volcano. …
An approach to the control of radiation in order to protect public health and the environment, based on keeping radiation emissions and exposures to levels set as far below regulatory limits as is reasonably possible. …
The direction in which a slope or feature faces, usually expressed in terms of points on a compass. For example, an aspect of 90? is due east, 180? is due south and 315? is north‐west. See also azimuth. …
A vapour or gas that can cause unconsciousness or death due to a lack of oxygen (suffocation). Chemical asphyxiants like carbon monoxide (CO) reduce the ability of the blood to carry oxygen; those like cyanide interfere with the way the body uses oxygen. …
Analysis of a specific chemical, microbe, or biological response. See also bioassay, limit of detection. …
A group of plants and/or animals that is indicative of a particular environment. See also community. …
Anything owned by an individual or group that has a value, whether financial or otherwise. …
The total amount of greenhouse gas that each country is allowed to emit during the first Commitment Period of the Kyoto Protocol, taking into account certified emissions reductions acquired via the Clean Development Mechanism. Also known as emissions budget . …
The process by which organisms take in and convert nutrient substances for growth, reproduction, or repair. …
