Large items of waste materials (such as appliances, furniture, large vehicle parts, trees, and stumps) that cannot be handled by normal procedures for processing municipal solid waste. …
A North American grassland vegetation in which different types of native perennial grass grow in tufts or clumps rather than forming a sod or mat. Dominant grasses include little bluestem ( Schizachyrium scoparium ) and buffalo grass ( Buchloe dactyloides ), which provide good forage for grazing animals (such as cattle and buffalo). Common throughout the western states. …
An artificial barrier on a slope, made, for example, from soil or agricultural waste, designed to reduce runoff and soil erosion. …
An object's ability to float, for example in the air or in water, because the medium it is in has a greater density. …
A layer of Cambrian rocks in British Columbia, Canada. It contains many unique fossils of a variety of soft‐bodied animals that have not been found elsewhere, and scientists are uncertain whether or not these are the ancestors of animals that are alive today. …
1 A disposal site for unwanted radioactive materials, where earth or water are used as a shield. 2 A piece of land where dead bodies are buried. Both are also known as a graveyard. …
1 A land management technique that involves setting fire to vegetation to clear it, encourage new growth and restore soil fertility. See also prescribed burn. 2 An area of land that has recently been burned. See also fire. …
1 A low woody perennial plant that has no distinct trunk but usually has several major branches. 2 An area of dense vegetation dominated by stunted trees or bushes. …
The unplanned conversion of vegetation dominated by grassland to one dominated by woody species, often as a result of overgrazing or invasion by aliens. …
The natural vegetation that grows on land that is left uncultivated for some time, and includes small trees, shrubs, grasses, sedges, and herbaceous plants. See also enriched fallow, fallow, shifting cultivation. …
An open area with tall, scattered bushes covering at least 40% of the area. …
A scenario for future patterns of activity which assumes that there will be no significant change in people's attitudes and priorities, or no major changes in technology, economics, or policies, so that normal circumstances can be expected to continue unchanged. …
A gaseous hydrocarbon that is extracted from natural gas or refinery gas, and is used as household fuel, a propellant, and a refrigerant. …
A narrow flat‐topped hill of resistant rock with very steep sides, found in an arid area where there is little vegetation. It is formed by the erosion of horizontal strata where remnants of a resistant layer protect the softer rocks underneath. …
The phenomenon by which a small change at one place in a complex system can have large effects elsewhere. For example, through teleconnection a butterfly that flaps its wings in Rio de Janeiro might ultimate cause the weather in New York to change. …
The decomposition of various types of organic matter by chemical reaction. One of the many forms of fermentation involved in putrefaction. …
A law named after a Dutch meteorologist Buys Ballot ( 1817 ? 90 ), who in 1857 defined the relationship between the pressure gradient and the Coriolis force. The simple rule of thumb is: in the northern hemisphere, if you stand with the wind blowing into your back, low pressure is always to your left and high pressure is always to your right; in the southern hemisphere the pattern is rever…
A facility where individuals or groups take recyclable material in return for payment. …
Fish and other marine life that is caught incidentally while fishing for something else. Unwanted bycatch is normally thrown back into the sea as a waste product, even if it is commercially valuable. Also known as incidental catch or incidental take. See also longline, non‐target species. …
A route or road that passes around a city or other congested area. …
Any material, other than the principal product, that is generated as a consequence of an industrial or biological process, and for which there is often no commercial market. …
The intermediate layer in a soil profile, beneath the A‐horizon and above the C‐horizon. The B‐horizon is dominated by the deposition (illuviation) of material leached from the A‐horizon, so it is a zone of accumulation and enrichment. It contains little organic material, and is usually more compacted than the A‐horizon because clay washed down from the A‐horizon fills many of the void…
A method of logging in which timber is dragged by cable from where it is cut to a collecting point. See also ground‐lead logging, high‐lead logging. …
A naturally occurring, soft, bluish trace heavy metal that accumulates in the environment. Sources include smelter fumes and dust, some incineration products, phosphate fertilizer, municipal wastewater, and sludge discharges. It is also an industrial byproduct of the manufacture of zinc, copper, and lead. It corrodes galvanized pipes, and can be extremely toxic to humans and aquatic life. See also…
A silver‐white, soft ductile element, part of the alkali metal group. Used in photoelectric cells. The naturally occurring isotope is 133Cs but there are 15 other radioactive isotopes. …
See International Conference on Population and Development. …
1 A substance that is composed of, or contains, calcium carbonate, which typically causes an alkaline condition (pH greater than 7.0). 2 A species that accumulates calcium carbonate in its tissues. …
A plant that is adapted to growing on limestone or on soils that are derived from limestone and have a high calcium content. …
1 A soil forming process in which calcium carbonate accumulates in the lower horizons. This occurs mainly under grass or xerophytic shrub in subhumid, semi‐arid, and arid climates and produces neutral or basic soils. 2 Replacement of the hard body parts of an organism by calcium carbonate (for example in the form of a shell). …
A common rock‐forming mineral of calcium carbonate. It is crystalline, stable, one of the most common minerals, and a main ingredient of limestone. …
A chemical precipitate which is formed from the skeletons of corals and the shells of molluscs, and occurs as calcite, chalk, and limestone. It dissolves in water and so affects salinity and alkalinity, and at high concentrations it can make water hard. It is usually white, colourless, or light shades of grey, yellow, and blue, and is used in polishes and the manufacture of lime and cement. …
An alkaline metal that occurs naturally in the environment and accounts for 3.63% of the Earth's crust. It readily forms salts with various metals and halogens, and is an essential element (a minor element) for animals and humans. …
A large, steep‐sided, circular depression formed by the collapse of a volcanic crater. The caldera is usually much larger than the original vent of the volcano and has a relatively flat floor. …
A layer of calcium carbonate that has been deposited on or near the surface of a stony soil in an arid or semi‐arid area, by the evaporation of moisture in the soil. Also known as calcrete . …
A North American native grassland vegetation common throughout California, which was originally a mixture of short and tall bunch grasses. Much of the habitat has been lost through development and conversion, and in the areas that remain many of the native perennials have been replaced by introduced annuals. …
Undisturbed air in which there is no apparent motion. The lowest point on the Beaufort scale. …
A measure of energy. One calorie is equal to the total amount of heat that is required to raise the temperature of one gram of water by 1?C. …
The process of forming icebergs, in which pieces of a glacier or ice sheet break off when the ice meets the ocean. …
A single layer of cells between the woody part (xylem) and the bark (phloem) of a tree, where the growth takes place. These are the growth rings that can be counted to determine the age of the tree. See also dendrochronology. …
The first geological period of the Palaeozoic era, ranging from 570 to 510 million years ago, during which marine life (particularly invertebrates) evolved and spread widely. The oldest fossils of organisms with mineralized skeletons date from the Cambrian. See also Burgess shale. …
The common name for the huge increase in the number and diversity of life forms in the Earth's oceans that started during the Cambrian period. …
The disguise that a species of animal develops (through natural selection) that enables individuals to hide from predators by blending in with their surroundings, usually through the colour and pattern of their skin or fur. See also countershading, cryptic coloration. …
An instrument for measuring how long the Sun shines at a particular place, based on a glass sphere which focuses the Sun's rays to burn a hole through a graduated card. It is the most common sunshine recorder in use outside the United States. …
An artificial waterway that has been built for navigation, water supply, land irrigation, or drainage. …
Engineering works that straighten and/or deepen a natural channel to improve navigability, or that artificially force a river to flow along a particular course (often within a concrete channel) to speed the flow and/or reduce flooding. …
A group of more than 120 different diseases in which abnormal cells divide and grow rapidly and uncontrollably, producing tumours that can be malignant and often invade surrounding cell tissue. See also carcinoma. …
Species of plants and animals that are considered (by the US Fish and Wildlife Service or the National Marine Fisheries Service) to be candidates for listing (and thus protecting) under the Endangered Species Act. …
The roof‐like cover formed by the leafy upper branches and crowns of the tallest trees in a forest. In tropical forests, the canopy may be 50 metres or more above the ground. See also overstorey. …
The progressive reduction of space between the crowns of trees in a forest as they spread laterally, increasing canopy cover. …
A large, narrow valley or gorge with deep sides that is cut by a river. …
A layer of clay or other impermeable material that is spread over the top of a closed landfill or hazardous waste site in order to seal it, and thus prevent the infiltration of rainwater and minimize the leaching of pollutants into adjacent soil and rock. Also known as cover material . …
The suitability of a particular area of land for a given type and intensity of use, without permanent damage, which reflects factors such as site conditions (particularly climate, soils, geology), broader socioeconomic factors (including political, social, and economic constraints), and land management practices. …
The total amount of sediment that a river can transport, which is determined by both discharge and particle size. …
An approach to air pollution control, introduced in the Kyoto Protocol, that is based on the trading of emissions allowances between countries, within a total allowance that is strictly limited or capped. See also emissions allowance, emissions trading. …
The process by which water moves through very small spaces between particles in soil. It is caused by attraction (capillary forces) between the liquid and the particles. This process allows water to be drawn upwards in the soil. …
In rock or soil, the zone of porous material just above the water table that remains more or less saturated with water, because of capillary action. …
Water that is held within a soil by surface tension in and on soil particles, and in the pore spaces between particles. It can move in any direction within the soil, by capillary action. See also field capacity. …
Any form of wealth, resources, or knowledge that is available for use in the production of more wealth. …
The total investment that is needed to complete a project and make it commercially operable, such as the cost of building a new factory or engineering scheme. …
An economic system that is based on private enterprise, in which the means of production are owned privately and resources are exchanged through market processes. Also known as capitalist economy . Contrast Marxism, socialism. See also market economy. …
The breeding and raising of endangered species of animals in captivity (for example, in a zoo), where they can be protected and cared for, as part of a living collection, before being released into the wild in an attempt to prevent their extinction. See also selective breeding, reintroduction. …
Keeping small numbers of animals in protective isolation, to ensure that they breed successfully before being released. …
A procedure for estimating the size of a biological population, based on the distinctive marking and subsequent recapture or sighting of individuals. Also known as mark?recapture . …
The hard case or shell that covers the body of animals such as turtles or crabs. Contrast plastron. …
A class of insecticides derived from carbamic acid, which is less toxic and more biodegradable than many organophosphate insecticides. …
An organic chemical compound that contains only carbon, hydrogen, and oxygen and supplies energy to organisms. Examples include starch, glucose, and cellulose. …
An air pollution control device that uses activated carbon to absorb volatile organic compounds from a stream of gas, which are later recovered from the carbon. …
A rock, sediment, or aerosol that contains carbon. …
A water treatment system that removes contaminants from groundwater or surface water by adsorption, by forcing the water through tanks that contain activated carbon, which attracts the contaminants. …
The process by which plants take in (assimilate) carbon dioxide. …
A mineral that is mostly found in limestones and dolomites (such as calcite). The term is also used to describe sedimentary rocks that are largely composed of carbonate minerals. …
The hardness in water that is caused by bicarbonates and carbonates of calcium and magnesium. See also hard water. …
A common type of chemical weathering of rock by weak carbonic acid that is created from carbon dioxide dissolved in rainwater. This can be very significant in areas of limestone and dolomite. …
The balance of the exchanges (incomes and losses) of carbon between different reservoirs of carbon in the carbon cycle, which shows whether particular reservoirs (such as oceans or forests) are operating as sources or sinks for carbon dioxide. …
In greenhouse gasemissions trading, this is a credit granted to a particular country that counts towards their emission targets as agreed in the Kyoto Protocol. …
The natural biogeochemical cycle through which carbon circulates through the biosphere, atmosphere, and hydrosphere. This involves abiotic and biotic parts of interconnected cycles on land, sea, and the atmosphere. In the atmosphere carbon is found as carbon dioxide (CO2), which plants use in the process of photosynthesis to manufacture carbohydrates. Plants can then be consumed by herbivores and …
A method of dating organic material that is applicable to material of up to at least 40?000 years old. It uses the known rate of disintegration of the carbon‐14 atom as a basis for determining the age of a sample, based on the principle that the ratio of 14C/12C is directly related to the age of the sample. Also known as radiocarbon dating . …
A naturally occurring, heavy, colourless, odourless gas, which is a part of the ambient air, accounting for 0.035% of the Earth's atmosphere, by volume. It is produced by respiration, decomposition of organic substances, and the combustion of fossil fuels and biomass (particularly forest fires). It dissolves in water to form carbonic acid, is the principal greenhouse gas (it accounts for 80% of al…
The increased plant growth or rise in net primary production in natural or agricultural systems that is or would be promoted by an increase in the concentration of carbon dioxide in the atmosphere. …
A non‐metallic element that occurs in many inorganic compounds and all organic compounds, and is one of the most widely distributed elements on Earth. It occurs in combination with other elements in all plants and animals, and is a basic building block of life. Carbon occurs in four basic forms in nature?in the pure form as graphite and diamonds; as calcium carbonate in carbonaceous rocks such a…
A chemical process by which carbon from the atmosphere is assimilated into organic compounds and made available to organisms through food chains. See also photosynthesis. …
The rate of movement of carbon between different pools or reservoirs in the carbon cycle. …
a measure of the environmental impact of a particular human activities, based on the amount of natural resources they consume and the amount of greenhouse gases they produce. It is measured in units of carbon dioxide such as tons per year, for comparative purposes. …
The weak acid that is formed when carbon dioxide (CO2) is dissolved in water. …
A period of geological time during the Palaeozoic era, dating from about 360 to 290 million years ago, during which extensive coal measures were deposited. …
There are three naturally occurring isotopes of carbon: 12C or carbon‐12 (which accounts for 98.9 of all the carbon), 13C or carbon‐13 (about 1.1%) and 14C or carbon‐14 (negligible amount). Changes through time in the absolute and relative amounts of the carbon isotopes can be measured in ice cores and lake sediments, and these provide indicators or proxy measures of long‐term climate chan…
An approach to limiting the emission of carbon dioxide that is based on storing it (for example in carbon sinks), or using it in ways that prevent its release into the air. …
A colourless, odourless, non‐irritating but highly toxic gas that is produced by the incomplete combustion of hydrocarbon fuels, incineration of biomass or solid waste, or partially anaerobicdecomposition of organic material. Much comes from vehicle exhausts. It is a criteria pollutant which affects human health by interfering with the ability of blood to carry oxygen to cells, tissues, and orga…
The ratio between the amount of carbon and nitrogen in a particular soil or organic material, which affects fertility and suitability for composting. …
The total amount of carbon that is stored, cycling, or otherwise available for use in biogeochemical cycles. …
Any of the locations within the carbon cycle at which carbon compounds are stored, including the atmosphere, oceans, vegetation and soils, and reservoirs of fossil fuels. …
The long‐term natural storage of carbon in forests, soils, oceans, or underground in oil and gas reservoirs and coal seams. There have been initiatives to reduce the amount of carbon that is in the atmosphere by increasing the number and size of carbon sinks, in order to slow down global warming. …
A geochemical reservoir (sink) that can absorb or sequestercarbon which has been released from another part of the carbon cycle, thus removing it from the flowing part of the cycle for a period of time. Examples include soils, peat, large forests (which store organic carbon), and ocean sediments (which store calcium carbonate). One of the flexibility measures introduced in the Kyoto Protocol for d…
Any part or reservoir of the carbon cycle that releases carbon to some other part of the cycle. Examples include the burning of fossil fuels, decomposition of organic waste, and burning of trees or other vegetation. …
The carbon that is naturally stored in vegetation, decomposing organic matter, soils, and wood products. …
A tax or surcharge on the sale of fossil fuels (oil, coal, and gas) that varies according to the carbon content of each fuel, and is designed to discourage the use of fossil fuels and reduce emissions of carbon dioxide. …
A colourless, non‐flammable, toxic liquid compound that was once widely used as an industrial raw material, as a solvent, and in the production of CFCs. It is highly carcinogenic, and its use has been banned or strictly regulated in most countries since 1995 , under the Montreal Protocol. Also known as tetrachloromethane . …
A naturally occurring carbonisotope that is produced in the atmosphere by cosmic ray bombardment and has a half‐life of 5700 years. It is useful for the absolute dating of samples up to 40?000 years old. See also radiocarbon dating. …
The amount of recoverable fossil fuel and biomass that can be used to produce fuel. …
Any substance that produces cancer, by causing changes in the DNA of cells. See also mutagen, teratogen. …
A type of cancer that occurs in particular types of tissue. …
A toxic material that certain plants are able to produce as a defence against their own predators. …
A strategy for sustainable development that was published in 1991 by the IUCN, jointly with the United Nations Environment Programme and the World Wide Fund for Nature. …
A flesh‐eating animal (predator or carrion eater). …
A species of parrot ( Conuropsis carolinensis ) that was the only parrot species native to the eastern USA. It lived in old forests along rivers, and was found from the Ohio Valley to the Gulf of Mexico. By the early 1890s it had become extinct as a result of shooting by farmers (who saw it as a pest), over‐collecting (for its colourful feathers), and destruction of its native habitat. …
Wet woodland that grows on soils with permanently high water levels and is usually dominated by alder or willow trees. …
A person or animal that carries a specific infectious agent and is a potential source of infection. See also disease vector. …
The decaying flesh of a dead animal that is used as food by animals that scavenge. …
The maximum number of individuals (people or animals) that can be supported by a particular ecosystem (or area) on a sustainable basis without degrading it. Global carrying capacity refers to the total number of people which the Earth and its environmental systems can support on a sustainable basis. There are no clear‐cut answers to the question of what the Earth's carrying capacity really is; p…
A scientist and writer whose book Silent Spring ( 1962 ) looks at the effects of insecticides and pesticides on populations of songbird throughout the USA. See also bioaccumulation. …
An international agreement arising from the United Nations Framework Convention on Biological Diversity, that came into force in January 2000 , and is designed to protect biodiversity from the potential risks posed by living modified organisms that result from biotechnology. See also biosafety. …
A consortium of producers of a single product who agree to limit production to keep the price of the product high. …
Sharing a car to a destination in order to reduce fuel use, pollution, and travel costs. …
1 A small waterfall or series of small waterfalls. 2 A sudden downpour. …
Any crop that is grown for sale in a market, to agents, or directly from the farm. See also subsistence farming. …
The pipe that provides the walls of oil, gas, or water wells. …
A thick‐walled container, usually made from lead, that is used to transport radioactive material. Also known as a coffin . …
Any person suffering physical and/or psychological damage that kills, injures, or leads to material loss. …
The process by which a living cell or organism breaks down complex organic molecules to smaller ones, producing energy and waste matter. Also known as destructive metabolism . See also metabolism. …
Fish (such as eels) that spend most of their lives in freshwater rivers and lakes, but migrate downstream to the sea in order to breed. Contrast anadromous. …
Increasing the rate of a chemical or biochemical reaction by the addition of a catalyst. …
An inorganic substance that increases the rate of a chemical or biochemical reaction without being consumed or chemically changed in the process. …
A device fitted to the exhaust systems of motor vehicles which uses a catalytic agent (tiny quantities of metals such as platinum) to stimulate chemical reactions that remove pollutants from the exhaust gases. The process reduces emissions of noxious gases such as nitrogen oxides, unburnt hydrocarbons, and carbon monoxide and replaces them with less harmful emissions, either by oxidizing them into…
A pollution control device that oxidizesvolatile organic compounds by using a catalyst to promote the combustion process. …
A sudden, severe event that causes unusually large‐scale losses (including deaths, injuries, damage to property, and financial loss), beyond normal expectation. Examples include extensive damage cause by flooding, hurricanes, or large fires. Also known as disaster . See also emergency. …
An interpretation of features of the Earth's surface (including rocks, fossils, and landforms) as the product of sudden, cataclysmic upheavals, particularly caused by major floods (neptunianism) or volcanic activity (vulcanism). This view was popular during the 19th century, but it was challenged and eventually replaced by uniformitarianism. …
A sedimentation area that is designed to remove pollutants from runoff before it is discharged into a stream or pond. …
1 A sequence of soils in a landscape that are of similar age and have developed from similar parent material in the same climate, but which have different properties because of variations in relief and in drainage. Also known as toposequence . 2 A series of volcanic craters. …
An ion that has a positive charge. See also anion. …
The chemical exchange of cations that takes place between plant roots and the water, minerals, and organic matter within a soil. …
A measure of the ability of the colloids in a soil to attract and retain cations, which is usually expressed in terms of milliequivalents per 100 grams of soil (mEq 100?g-1). This capacity is highest in soils that contain a lot of humus and clay. …
A US non‐profit anti‐environmentalthink‐tank based in Washington, DC that seeks to promote traditional American principles of limited government, individual liberty, free markets, and peace within public policy debates. …
The growth of flowers on the large branches and trunk of a tree. …
Sodium hydroxide. A strongly alkaline substance that is used in the manufacture of soap, paper, aluminium, and a range of sodium compounds. …
A hollow chamber in rock, which is accessible from the surface, is large enough for a person to enter, and has usually been formed by natural processes. …
Any hollow or hole, such as a hole in a tree, that is regularly used by species of wildlife (particularly birds) for nesting, roosting, and reproduction. …
In the atmosphere, the height of the lowest layer of clouds when the sky is broken or overcast. …
The projection onto the sky of the Earth's equator, which is 90? from each of the Earth's celestial poles. …
The points in the sky that are above the Earth's North and South poles. …
The smallest unit of living matter that is able to grow and reproduce independently, of which all living organisms are composed. Cells contain DNA (information store), ribosomes (protein synthesis), and mechanisms for converting energy into usable forms. There are two main types of cell, prokaryotic and eukaryotic. See also cytoplasm, genome, nucleus. …
The process by which two identical cells are formed from one. …
A technique of joining two cells from different species to create one hybrid cell, in order to combine some of the genetic characteristics of each original. …
The outer membrane of a cell, which separates it from the surrounding environment. The term is used particularly to refer to the plasma membrane. …
The process by which a cell breaks down organic compounds (such as sugar) in order to release the energy it needs to perform work. This process may be aerobic or anaerobic, depending on the availability of oxygen. …
A colourless, solid carbohydratepolymer that is made from the simple sugar glucose, and is the most abundant compound on Earth that is manufactured by living things. …
A tough permeable layer that surrounds the cells of a plant. …
A temperature scale that is used internationally and was devised by the Swedish astronomer Anders Celsius ( 1701 ? 44 ). In it water freezes at 0?C and boils at 100?C. The equation for converting temperature from Fahrenheit to Celsius is ?C = 5/9 (?F ? 32), so that 100?C is equal to 212?F. Previously known as Centigrade . …
1 To bind or join together. 2 Any material that hardens to act as an adhesive. 3 A building material made of limestone and clay, which is mixed with water and sand or gravel to make concrete and mortar. …
The grains of a sedimentary rock that have been bonded together by substances such as calcium carbonate, silica, oxides of iron and aluminium, or humus. …
The current geological era, after the Mesozoic era, from about 65 million years ago to the present, during which the modern continents formed and modern animals and plants evolved. The Cenozoic is subdivided into the Tertiary and Quaternary periods. …
1 A count of all of the individuals in a specified area over a specified time interval or at a particular point in time. 2 The act or process of counting all individuals within a specified area and estimating population density or a total population for that area. …
An economic system (like those in most communist countries, such as China) in which investment and production are coordinated by a central government body rather than by market forces. …
A geographical area that has high levels of genetic or species diversity. See also biodiversity. …
A geographical area that has a relatively high number of locally endemic species. See also endemic. …
A geographical area in which a taxon originated, which may or may not correspond with the centre of diversity for that taxon. …
The force that causes a body moving in a curve to move away from the centre of the curve. Contrast centripetal force. …
A drainage pattern that is the opposite of a radial drainage pattern, in which the rivers drain in towards the centre of a basin, like the spokes of a wheel. …
The force that causes a moving object to follow a curved path rather than continue on a straight line. The force is directed towards the cenrtre of the curve. Contrast centrifugal force. …
See Comprehensive Environmental Response Compensation, and Liability Act. …
See Comprehensive Environmental Response, Compensation, and Liability Information System. …
A plant in the grass family Gramineae, which produces seeds (grain) that are edible. Examples include wheat, oats, barley, rye, rice, and maize. …
See Community Environmental Response Facilitation Act. …
In the context of pollution control, this is an important part of the Clean Development Mechanism agreed by the Kyoto Protocol. It is the process by which an accredited body gives written assurance of the emission reductions that have been achieved, which can be confirmed by independent third parties, and which then allows the emissions reduction to become a separate commodity for emissions tradin…
A unit of greenhouse gas reductions that has been achieved and has been subjected to certification under the Clean Development Mechanism agreed by the Kyoto Protocol. See also credit, emissions reduction unit. …
A covered hole or pit in which untreated sewage is stored. …
Any member of the order of marine mammals that includes whales, dolphins, and porpoises. …
A colourless, liquid hydrocarbon that is found in petroleum and is used as an indicator of fuel efficiency for diesel oils. …
1 A general term for any self‐sustaining process. 2 A nuclear reaction in which the fission of nuclei produces neutrons that then split other nuclei and the process becomes self‐sustaining. …
A soft, white organic sedimentary rock, the purest form of limestone, which is made of very pure calcium carbonate derived from the shells and skeletons of marine micro‐organisms. …
A type of grassland that grows in thin calcareous soils over chalk bedrock. …
1 A waterway, such as a stream, river, or canal, that contains moving water (continuously or periodically) and has a definite bed and banks. Also known as a watercourse . 2 A narrow seaway, such as the English Channel. …
A ridge of coarse gravel that is deposited on the bed of rivers with steep slopes, where flow velocity decreases, for example where a steep tributary stream flows into the main river. …
An engineering scheme that is designed to stabilize a river channel to increase flow speeds, reduce bank erosion, and/or protect against flooding. This might involve decreasing channel roughness (for example by lining the channel with smooth artificial bed and banks), widening and/or deepening the channel (by dredging), or shortening the channel (by straightening it and cutting off meander bends).…
The shape of a river channel when viewed from above or on a map. There are three main patterns, which are straight, meandering, and braided. …
The volume of water that is temporarily stored in a river channel and its floodplain while it flows towards an outlet (such as a lake, reservoir, or estuary). …
The breakdown of predictability, or a state of disorder in a complex system in which patterns exist but they are complicated, not truly random, and difficult to discover. …
The study of complex systems that exhibit discontinuous change, with a focus on irregular and complex behaviour which is only partially predictable. …
An aridbiome in California that is dominated by broadleaved, evergreen, drought‐resistant shrub, associated with the climate of hot dry summers and mild wet winters. …
Any recognizable trait, feature, or property of an organism. …
An ecological pattern in which two species having overlapping niche requirements differ more when they live together than when they live apart. The difference is usually morphological (such as head size) and is caused by competition and adaptation to local conditions (such as the size of available prey). …
Any one of the four categories that are used to define hazardous waste in North America: corrosivity, ignitability, reactivity, and toxicity. …
The natural pattern of distribution and abundance of populations, species, and habitats in the absence of human impact. …
Species that are special to or especially abundant in a particular situation or biotope, which can usually be easily identified. …
The process of determining the scale and nature of a release of a pollutant, which helps to determine appropriate ways of dealing with it and cleaning it up. …
An area of land that has relatively uniform vegetation, geology, hydrology, and topography. …
A very dark grey porous form of carbon that is made by incomplete burning of wood or bone. …
The combination of nutrients in a form that is easy for plants to absorb, chemically bound to a carbon‐based substance. …
The process of chemically binding a metal to another substance, which is used to increase absorption of mineralnutrients (such as calcium and magnesium), to remove toxic substances (such as lead and arsenic), and to prevent the precipitation of metals (copper). …
Any element, chemical compound, or mixture of elements and/or compounds. …
A chemical that is used for some purpose, particularly to reduce or remove pollutants from water. …
The force that holds atoms together in a molecule or crystal. …
The combination of two or more elements in defined amounts. …
Using pesticides and herbicides to control pests and unwanted plant species. …
Details of the properties of each element can be found online at http://www.lenntech.com/Periodic-chart-elements/alphabetic.htm …
An emergency created by an accidental release or spill of hazardous chemicals that threatens the safety of workers, residents, the environment, or property. …
Energy that is stored in chemical compounds and released as a result of chemical reactions. …
A stable chemical reaction or series of reactions in which the concentrations of all substances remain constant through time. …
In risk assessment, particularly in the USA, these are particular chemicals that are identified for evaluation, to determine whether they pose a risk to people or the environment. …
In risk assessment, particularly in the USA, these are chemicals identified as possibly posing a risk to people and the environment, which are further investigated. …
A measure of the amount of oxygen that is required to oxidize all of the organic and inorganic compounds in a particular waterbody. Biological oxygen demand only measures the oxygen used in breaking down the biodegradable material. See also biochemical oxygen demand. …
The separation of a chemical into different media or states. Many metals, for example, are more likely to partition to sediments than remain in groundwater. …
The introduction of chemical contaminants into air, water, or soil. …
A change in one or more chemical elements or compounds which results in a new compound. …
The result of a chemical reaction between two or more materials, such as corrosive materials attacking a metal. …
Any chemical that is released into the environment through human activities (such as industrial waste, vehicle emissions, and pesticides) that can damage or kill plants and animals. …
A shorthand way of representing an element, using a one‐ or two‐letter symbol. For example, sodium chloride is represented in chemical symbols as NaCl (Na is sodium and Cl is chlorine). …
The production of complex chemical compounds from simpler ones, for commercial or research purposes. …
1 The use of chemicals or chemical processes to treat waste materials. 2 The use of chemicals to control unwanted vegetation. See also herbicide. …
The use of chemical agents to kill, injure, or incapacitate the enemy during a conflict. …
Any chemical substance that can be used to kill or injure people, animals, and plants. A weapon of mass destruction. …
The breaking down of rocks and minerals as a result of chemical reactions with the surrounding air and water. The most common processes are oxidation, carbonation, and hydrolysis, and decomposition is usually fastest in hot, humid climates. Contrast mechanical weathering. See also weathering. …
The study of the properties, composition, and structure of matter. …
An organism that uses inorganiccarbon (carbon dioxide or carbonates) as a source of energy for the synthesis of organic matter. See also autotroph, photoautotroph. …
The ability to sense changes in the concentration of chemicals in the environment. …