An air pollutant (such as acid mist or fluorides) which is not defined in the US Clean Air Act as either a criteria pollutant or a hazardous air pollutant, but for which emission standards exist for new sources. …
Uses for water that are identified in state water quality standards in the USA for which water quality must be protected. These include hydroelectric power generation, navigation, public water supply, fisheries, and recreation (such as swimming, boating, and fishing). …
The maximum volume of flow that an engineering structure is designed to handle, such as the number of vehicles using a road per day or the average daily flow of material into a water treatment plant. …
A common term for microbes that are developed through biotechnology and can degrade specific toxic chemicals in toxic waste dumps or in groundwater. …
The future condition of a particular resource (such as a forest or grassland) that is expected to result if the goals and objectives of resource management are fully achieved. …
The plant community that best meets the agreed objectives for a particular site, as defined in a land use or management plan. …
The release of atoms, molecules, or ions that are attached to solid surfaces. Contrast absorption. …
The mixing of water within a lake or reservoir in order to reduce or remove separate layers (for example of temperature or aquatic organisms). Contrast stratification. …
A convergent boundary between adjacent crustal plates that are moving towards each other, where crust is being destroyed by subduction. Usually associated with volcanoes and earthquake activity. Also known as destructive margin . See also plate tectonics, constructive plate boundary. …
The reduction or removal of the sulphur content of fuel in order to reduce air pollution. Also known as fuel desulphurization . …
The temporary storage of surface water in low areas such as puddles, bogs, ponds, and wetlands, from which it evaporates or flows overland towards a stream channel. Also known as depression storage . …
The period of time over which a particular material is stored temporarily in a particular way, such as the storage of water in a reservoir before being used or in a settling basin. …
A synthetic cleansing agent that, when added to water, helps to remove oil and dirt. See also surfactant. …
A process or event that is predictable because it is governed by definite rules of system behaviour which produce the same results each time. Contrast random, stochastic. …
To remove a poison or render safe through removal of a poison. …
Crystalline calcium carbonate that is found in ocean sediments and is usually derived from the weathering of carbonate rock. …
A sediment (such as detrital carbonate) that is produced by the mechanical breakdown of rock by weathering and erosion. …
An animal (such as an earthworm, maggot, or woodlouse) that feeds on dead and decaying organic matter from plants and animals. Also known as decomposer, deposit feeder, detritus feeder . See also decomposition. …
1 Organic debris from dead organisms, which is often an important source of nutrients in a food web. 2 Loose, unconsolidated particles or sediments that are formed by the weathering of rocks. …
An isotope of hydrogen that contains one proton and one neutron in its nucleus. …
A country that has evolved through the demographic transition and is technologically advanced, capital‐intensive, highly urbanized, and wealthy. These are usually industrialized countries such as European countries, Canada, the USA, Australia, Japan, New Zealand, and Russia. Compare developing country, more developed country, transitional nation. See also Annex I Countries, Annex B Countries. …
Any land that has been built on or substantially altered to benefit people, including development of settlements, factories, and roads. …
Any form of recreation requiring facilities that, in turn, result in concentrated use of the area. Examples include skiing (that requires ski lifts, car parks, buildings, and roads) and campgrounds (that require roads, picnic tables, and toilet facilities). Contrast dispersed recreation, informal outdoor recreation. …
A low‐income country with an economy that is largely based on agriculture, which may be going through the demographic transition, is often in the process of industrialization, and usually has few resources to spare to solve its own socio‐economic and environmental problems. Most developing countries are in the southern hemisphere. Also known as a less developed country or a Third World cou…
A process in which something changes by degrees to a different stage, particularly a more advanced stage. …
The statutory process land use planning system in the UK, through which a local authority determines whether a proposal for a large‐scale building development should be granted planning permission, and whether any particular conditions or restrictions should apply. …
The rights to develop land, as distinguished from ownership of it. Compare conservation easement. …
A well that is drilled with the intent of producing oil or gas from a reservoir that is known to be productive. …
The most recent continental glaciation, known as the Devensian in Britain and the Wisconsinan in North America, which began about 70?000 years ago, reached a peak about 18?000 years ago, and ended about 10?000 years ago. Ice sheets covered much of North America and Europe/Asia and sea surface temperatures were about 2?2.5?C below present ones. …
A period of geological time in the Palaeozoic era, dating from about 409 to 360 million years ago, during which fish were dominant and the first trees, insects, and vertebrates appeared. …
Small drops of moisture that form on cool surfaces at night, caused by the condensation of water vapour from the air. …
1 To remove some of the water in a sludge or slurry, in order to dry the sludge so that it can be handled and disposed. 2 ? To drain water from a tank or trench. 3 To extract groundwater by wells, electro‐osmosis, sumps and drains, or by exclusion. …
The temperature at which water vapour in air will condense on a cool surface and form drops (dew). Also known as condensation point or isobaric saturation point . …
The direct transfer of heat energy. Examples include condensation, evaporation, solar radiation, and the release of latent heat. Contrast adiabatic. …
The processes that take place in a sediment after deposition. These include compaction, cementation (lithification), dissolution, and recrystallization. …
A general term for unsorted, unstratified rock debris that is composed of a wide range of particle sizes and could be formed by a variety of different processes. …
A crystalline allotrope of carbon that is very hard (the hardest known substance) and durable. It is valued as a precious gem when it is cut and polished. …
A period of dormancy in insects and other invertebrates, during which growth or development is suspended. Roughly equivalent to hibernation. …
The deformation of the Earth's crust by tectonic forces, which gives rise to continents, mountains, and major geological features such as folds and faults, through the processes of warping, folding, and faulting. …
Microscopic single‐celled algae that grow in both fresh and saltwater. They produce silica skeletons that are often preserved in lake or marine sediments after death and are studied in palaeolimnology. There are more than 11?500 different species of diatoms, and they are a common form of marine phytoplankton and a primary food source for aquatic animals, especially filter‐feeding shellfish. Th…
A light, easily crumbled, silica‐rich material that is formed mainly from diatom remains and is used to filter out solid waste in wastewater treatment plants. Also known as diatomaceous earth. …
A fine muddy deep sea sediment that is formed mainly from the hard silica remains of diatoms. …
A flowering plant of the angiosperm group, which has a seed with two seed leaves (cotyledons). …
A form of petroleum that is used to fuel internal combustion engines. See clean fuel. …
The usual food and drink that an organism consumes. …
A synthetic oestrogen drug that was once widely prescribed to prevent miscarriages, and was used in feed for livestock and poultry. …
1 The process by which cells grow to become more specialized. 2 In tackling climate change under the Kyoto Protocol, the setting of different emissions reduction targets and timetables for individual countries, to allow for differing national circumstances. …
The bending of light around objects (such as cloud and fog droplets) which produces fringes of light and dark or coloured bands. …
A method of aeration that forces oxygen into sewage by pumping air through perforated pipes inside a holding tank. …
Radiation within the atmosphere that is scattered by tiny particles and travels in all directions, rather than travelling in a beam. …
The random movement of atoms, molecules, or ions from areas of higher to lower solute concentration, which tends to distribute them more uniformly. …
An enclosed composting system that includes a device to mix and aerate the waste materials in order to speed decomposition by aerobic bacteria. …
The biochemical decomposition of organic matter into mineral compounds and simple organic compounds that can be absorbed into the body of an organism or excreted from it. Bacteria decompose sewage in this way. …
To become weaker in strength or affect, for example thinning out a solution or making it less concentrated by adding a liquid, usually water. …
The process of reducing the concentration of a solute in solution, usually by mixing it with more solvent. …
The ratio between the concentrations of a solute in a solution before and after dilution. …
A molecular gas that is produced by phytoplankton in the surface waters of the ocean and escapes into the atmosphere. It might play a significant role in future climate change because oxidation of DMS creates a sulphate‐based aerosol that acts as cloud condensation nuclei, which might create more cloud cover and thus affect the Earth's heat balance. …
A freshwater lake or reservoir that has two mixing periods (turnovers) a year, usually in spring and autumn. See also mixing cycle. …
A situation in any open system (such as a company or the economy) in which an increase in the input of a particular resource, with other inputs fixed, results in smaller and smaller returns. …
Microscopic, single‐celled marine organisms which can be classified as plants or animals because some contain chlorophyll. They provide a major food source of plankton at the bottom of the marine food chain. See also red tide. …
An ancient terrestrial reptile that stood upright on its legs, did not fly or swim, and could be either carnivorous or herbivorous. Dinosaurs became extinct at the end of the Cretaceous Period, 65 million years ago. See also k?t boundary. …
A group of about 75 different chlorinated hydrocarbon compounds that are created in the production of pesticides, have no industrial use, are persistent and very toxic and carcinogenic, and are hazardous to human health. Exposure to dioxin affects humans in various ways, including disfiguring skin complaints, birth defects, miscarriages, and cancer. Dioxins are regularly released into the environm…
The angle between a geological surface in rock (such as a bedding plane or a fault) and the horizontal. See also inclination. …
Having a full set of genetic material consisting of paired chromosomes, one from each parent. …
A large order of insects with two wings, which includes flies, gnats, midges, and mosquitoes. …
A geological fault that involves vertical movement up and down the dip of the fault line. …
Protective action by a particular group of people, that is based on non‐violent, passive resistance (for example, using protest marches, picketing a site, or blocking roads) which forces opponents to defend their position. See also Chipko Movement, eco‐activism. …
Any form of air circulation (such as a land breeze) that is driven mainly by warm air rising and cold air sinking. …
An effect that occurs at the same time and place as the initial cause, without any other cause or factor being involved. Also known as primary effect . Contrast indirect effect. …
A method of treating wastewater that involves adding chemicals but not using sedimentation. …
Preferential selection that leads to a consistent change in how a particular character of a population changes through time, such as selection for larger eggs. Compare natural selection. …
An instruction that defines what is to be done or achieved, without necessarily specifying how. See also regulation. …
Radiation within the atmosphere that reaches the ground surface directly from the Sun, without being deflected or scattered. See also diffuse radiation. …
Water that flows through or over the ground directly into streams, rivers, and lakes. …
Economic values that are associated with the direct use of a natural resource. …
A hazard event (natural or induced) that seriously disrupts the normal functions of society and causes widespread human, material, or environmental losses which exceed the ability of the affected society to cope using only its own resources. See also catastrophe. …
A comprehensive approach to reducing the adverse impacts of particular disasters (natural or otherwise) that brings together in a disaster plan all of the actions that need to be taken before, during, immediately after, and well after the disaster event. These include mitigation, preparedness, emergency response, recovery, rehabilitation, and reconstruction. Also known as emergency management . …
A formal record of agreed roles, responsibilities, strategies, systems, and arrangements for managing a particular type of disaster in a particular place. Also known as contingency plan . …
An approach to disaster management that is based on reducing the likelihood of situations or events that leads to disasters, and increasing the capacity to deal with them effectively should they arise. …
A measure of the ability of a community to cope with the effects of a severe disaster and to recover afterwards. …
1 The rate of flow of surface water in a stream or canal, or of groundwater from an artesian well, a ditch, or a spring. Usually expressed in cubic metres per second (m3 s--1) (cumecs) or litres per second (L s-1). 2 Any substance (a gas, liquid or solid, or a micro‐organism) that is emitted, deposited, or allowed to escape from any activity. 3 To remove the electrical energy from something. …
Approval to discharge an agreed amount of a substance into the environment, such as a pollutant released into the air or into a stream. …
A major interruption or break in continuity. In geology, a sudden change in the physical properties of rocks within the Earth. …
A rate that is used to convert future costs or benefits to their present value, based on assumptions about how to discount or reduce the value of each in the future. See also cost?benefit analysis. …
Any disorder in the normal function of an organism, which can be genetic but is often caused by pathogenicbacteria, fungi, or viruses. …
A physical, chemical, or biological factor that causes disease. See also pathogen. …
The individual who contracts a particular disease. …
Any source that harbours disease‐causing organisms and could thus cause an outbreak of that disease. See also disease vector. …
The routes by which a particular disease is transmitted and spread, including direct contact, indirect contact, via droplets, orally, and by vectors. …
An organism that transmits a disease or a parasite without necessarily being affected itself. See also carrier, vector. …
A chemical or physical process that kills pathogenic organisms in water, air, or on surfaces. Examples are chlorine and ozone that are used to disinfect water supplies, wells, swimming pools, and effluent from sewage treatment. …
Populations that are fragmented or separated from one another by an area where the species is not present at all. …
1 The movement of organisms away from the places where they were born (natal dispersion) or where they breed (breeding dispersal). 2 An approach to containing oil spills, in which chemical detergents are used to break up the slick. …
A chemical agent that is used to break up concentrations of organic material, such as spilled oil. …
Forms of recreation (such as hunting, fishing, backpacking or scenic driving) that are usually low‐density and take place without facilities, not in a developed recreation site. Contrast developed recreation, informal recreation, concentrated recreation. …
Scattered individual homesteads in the countryside. A dispersed form of rural settlement. …
Scattering or spreading widely. See also dispersal. …
A computer model that is used to predict how pollutants disperse across an area, based on local environmental factors. See also point source. …
Common term for consumer products and packaging that are used once or a few times and then thrown away. …
1 To get rid of something. 2 The final placement or destruction of toxic, radioactive, or other wastes. See also waste disposal. …
A fee or tax that is paid by a producer of waste materials, which reflects the social cost of the pollution. Also known as throughput tax . …
Equipment and land that is used to receive waste and dispose of it, including landfills, surface impoundments, land farming, deep‐well injection, ocean dumping, or incineration. …
A well that is used for the disposal of waste into rocks beneath the ground surface. …
A form of camouflage in which colours and patterns disrupt the body shape and outline of an individual. …
The fraction of a river's load that is carried in solution. It is made up for the most part of ions of chloride, sulphate, bicarbonates, sodium, and calcium. It is estimated by measuring electrical conductivity and provides an indicator of salinity or hardness. Excessive amounts make water unfit to drink or use in industrial processes. Also known as dissolved solids, solution load, total dissolve…
The amount of oxygen that is dissolved in a given volume of water at a given temperature and atmospheric pressure, which is usually expressed in milligrams per litre(mg L-1), parts per million (ppm), or per cent of saturation. It is a widely used indicator of water quality, and adequate levels are necessary for fish and other aquatic life. Secondary wastewater treatment and advanced wastewater tre…
A process that is used to separate the components of a liquid mixture, by boiling the liquid and then condensing the vapour. It is used to purify water by removing inorganic contaminants, and in desalination to remove salt from water. …
Any activity or event (such as a forest fire or change in land use) that disrupts natural environmental systems and processes. …
1 Active during daylight hours. 2 Recurring every day or having a daily cycle. See also circadian rhythm. …
Movement or flow in different directions, such as winds or ocean currents. Contrast convergence. …
The evolution of two or more unique species from one ancestral species, through the separate evolution of isolated populations. Contrast convergent evolution. …
A boundary between adjacent lithosphericplates that are being pulled or pushed apart, and where new lithosphere is created, such as at mid‐oceanic ridges. Also known as divergent margin, constructive margin or constructive plate boundary . …
A change in direction. Planned diversions are used, for example, to direct part of a stream flow into a water supply system and to control the spread of hazardous material in order to contain risk. …
An artificial channel that intercepts and transports water from one place to another. …
The percentage of waste materials that are diverted from traditional disposal (such as landfill or incineration) to be recycled, composted, or reused. …
An international partnership of intergovernmental and non‐governmental organizations that was formed in 1991 to promote and facilitate scientific research on biodiversity. …
Variety, the presence of a wide range of variation in the qualities or attributes of the thing under discussion. See also biodiversity. …
A method of marine fishing in which some species (such as octopus, sea urchins, and sea cucumbers) are handpicked by divers, brought to the surface, placed in boats, and taken ashore for processing. …
One of the major subgroups within the plant kingdom, comprising a number of similar classes of plants. See also biological classification. …
Deoxyribonucleic acid, the genetic material that is found in all living organisms. It is the long molecule composed of carbon, nitrogen, and phosphorus that is in the nucleus of every cell, controls inheritance, and directs the development and functioning of all cells. The strand or string of DNA has a double helix structure so that the genetic instructions (gene code) of the cell are passed on wh…
The storage of DNA, for example to assist future medical research, allow individuals to trace the pattern of diseases in families, or create an archive of the genetic material of different organisms. …
Techniques that are used to detect the unique patterns in DNA, which operate like a genetic bar‐code and can be used to indicate the presence of a gene associated with a given trait. This has applications in forensic science, and in selecting breeding stock with favourable characteristics (such as disease resistance or rapid growth). …
The duplication of a DNA molecule by itself, in order to create new strands of DNA. …
A unit that is used to measure the amount of ozone in the atmosphere, based on thickness. 100 DU of ozone would form a layer 1 millimetre thick. …
Common name for the Mauritius dodo (Raphus cucullatus), a flightless bird that lived on the island of Mauritius and has been extinct since about 1660 because of over‐killing. It was about 1 metre high, lived on fruit, nested on the ground, and was captured and eaten by visiting sailors. …
A climate region near the equator that has low atmospheric pressure and light, shifting winds. Also known as equatorial low . See also Intertropical Convergence Zone. …
A closed depression in an area of karst, that is created by the solution and subsidence of limestone. …
1 A common rock‐forming mineral, composed of calcium?magnesium carbonate, that is crystalline and forms extensive beds as a compact limestone. See also karst. 2 A term also often used to refer to the sedimentary rock dolostone, but strictly speaking it applies only to those dolostones which contain more than 90% dolomite. …
1 The high, stable central part of an ice sheet, with low rates of accumulation and slow ice movement. 2 A round anticline from which the ground slopes downward in all directions. …
To breed a species for specific characteristics that humans value, or the species that is so bred. See also cultivate. …
A species in which the evolutionary process has been deliberately influenced by humans to meet their needs. Also known as cultivated species . …
Organic waste and wastewater that is produced by a household and carried from houses to treatment works by sewers. …
Water that is used for household purposes such as washing, food preparation, and bathing. …
The extent to which a particular species or organism exerts the most influence in a community because of its size, abundance, or cover. …
The tallest individuals or species in a stand of vegetation (such as a forest), which receive the greatest amount of sunlight. …
The view that humans are superior to other all other species, the Earth provides unlimited resources for humans, and that progress is an inherent part of human history. Contrast new environmental paradigm. …
An approach to resource management in which land and water are the main type of land use, and others are treated as of secondary importance. …
An approach to resource management that is based on the idea that although a given area of land may be capable of many uses, it will provide for one use better than any other, so the land is managed for the single purpose of maximizing that use to the exclusion of other uses where conflicts exist. …
The site from which individuals of an introduced species are taken in order to be introduced to another place (the receptor site). …
A type of weather radar that determines whether air (and thus weather) is moving toward or away from the radar. …
Temporarily inactive, such as a volcano that is no longer active but not known to be extinct. See also quiescence, torpor. …
The quantity of a chemical that is given to an organism or to which it is exposed, or the amount of ionizing radiation that someone or something has been exposed to. See also absorbed dose, administered dose, applied dose, human equivalent dose, LD50, potential dose. …
A measure of the amount of ionizing radiation that an individual person receives, which is based on the type of radiation, the amount of the body exposed, and the risk of exposure. Expressed in rem. …
A measure of the dose that is received per unit of time, expressed for example in milligrams per day (mg day -1). Also known as dosage . …
An indication of how an individual, or a population, is likely to be affected by a change in the amount, intensity, or duration of an exposure. Also known as dose effect . …
The quantitative relationship between the amount of exposure to a substance and the extent of toxic injury or disease that is produced in response to that exposure. …
An instrument that is used for measuring and registering the radiation dose a person has received or that something has absorbed. …
The twisted‐ladder shape that two linear strands of nucleotides assume when they are bonded together via their base pairs to form DNA. …
The time it takes, usually expressed in years, for a population to double in size. A population growing at 5% a year would double in 14 years, whilst a population growing at 1% a year would double in 70 years. Doubling time can be estimated by dividing the annual percentage population growth rate (r) into 70, i.e. doubling time = 70/r. The importance of doubling time as an indicator of rate of cha…
A severe, localized downward push of air from a thunderstorm or shower. Also known as downdraft . See also macroburst, microburst. …
In the same direction as the current or stream. Contrast upstream. …
The warping or bending downwards of the Earth's crust. …
The process by which surface water in the sea increases in density and sinks, usually along a coastline or where water masses converge in the oceans. Contrast upwelling. …
In the direction that the wind is blowing, with the wind. Contrast upwind. …
The draft version of an environmental impact statement that is made available to the public and other agencies for review and comment. …
An excavating machine that uses a bucket that is operated and suspended by means of cables, which allows the bucket to be dragged toward the machine for loading. …
An open channel (drainage ditch) or pipe that is used to move water such as surface runoff or wastewater from a factory downstream. …
1 A method of improving land quality by removing excess water from the soil, which decreases waterlogging. See also subsurface drainage, surface drainage. 2 The removal of water from land by streams and rivers, as part of the local water cycle. …
The area of land that is drained by a particular river within a drainage basin, defined by the drainage divide. …
The area of land that is drained by a river and its tributaries. The boundary of a basin is defined by the drainage divide, and the area within the divide is the drainage area. Also known as basin, catchment, water catchment, watershed, river basin . …
The length of river channel per unit of drainage area measured in kilometres per square kilometre (km km--2). It provides a measure of the concentration of streams in an area and thus a measure of the amount of dissection of the land surface. Contrast stream frequency. …
A ditch or open channel that is used to carry excess water or sewage downstream. See also surface drainage. …
A ridge of land that separates adjacent drainage networks. Also known as divide, hydrographic divide, interfluve, watershed . …
The network of river channels and tributaries that forms within a drainage basin. Also known as river network . …
The pattern displayed by a river network, as seen from the air or on a map, which is usually controlled by geology. The most common ones are dendritic, trellis, rectangular, annular, radial, centripetal, parallel, and deranged. …
A network formed by a main river and its tributaries. …
1 An area of land that is used as a filter for wastewater. 2 The part of a septic system where the wastewater is released into the soil. …
To decrease water level, such as in a storage tank or reservoir, or in groundwater around a well, by the extraction of water. See also cone of depression. …
A method of marine fishing that uses a bag dragged behind a vessel in order to scrape the bottom, usually to catch shellfish. …
The process of excavating, creating, or altering a water body such as a river, lake, or estuary, by scooping or sucking up sediment from the bed in order to deepen it. …
1 Sprayed or dusted material that does not settle on the target area but blows further away. 2 Sediment created by glacial activity, such as boulder clay or till. 3 Material that is transported by wind and deposited in heap, such as snowdrift. 4 A horizontal tunnel in an underground mine. 5 See genetic drift. …
A fishing net that can be several kilometres long and is suspended vertically from floats at a specific depth in the water. It is left to drift freely with the current to catch fish. …
Wood that is floating on the sea or has been washed ashore. …
Sowing seed in rows in the soil. Contrast broadcast seeding. …
Any source of raw or treated water that is, or may be, used by a public water system, or as drinking water by one or more individuals. …
A form of irrigation that uses a perforated pipe to deliver water one drop at a time directly to the soil around each plant, in order to eliminate runoff and soil erosion. Also known as trickle irrigation . …
Very light rain composed of very fine droplets formed by stratus clouds. …
A method of collecting recyclable materials in which individuals take them to a designated collection site. …
A prolonged, continuous but temporary period of very dry weather compared with the long‐term average for that place. A drought is different from a dry climate, which is usually associated with a region that is normally, or at least seasonally, dry. A drought is also drier and lasts much longer than a dry spell, which is usually defined as more than 14 days with no significant precipitation causi…
A long, elliptical hill usually composed of glacial till (but occasionally composed of solid rock), streamlined in the direction of ice movement, that was deposited beneath an advancing glacier. Usually found in a cluster (drumlin field). …
A group of drumlins which are aligned more or less parallel to one another (in the direction of ice movement). Also known as a drumlin swarm . …
The rate (9.8?C per kilometre) at which a rising parcel of dry air cools, by adiabatic expansion, and at which a sinking parcel of dry air warms. Contrast saturated adiabatic lapse rate. See also lapse rate. …
A method of controlling emission of air pollutants by spraying dry sodium bicarbonate into flue gas in order to absorb and neutralize acidicsulphur compounds. …
The fallout of gases, aerosols, and fine particles with no associated precipitation. This usually occurs relatively close to the emission sources of the gases. An important process in the formation of acid deposition. …
A method of farming in arid and semi‐arid areas without using irrigation, which relies on treating the land in ways that conserve moisture (including using a mulch). …
Frozen carbon dioxide that is used in cloud seeding. …
An area with an arid climate, with low precipitation and rainfall mainly in localized, brief, high‐intensity storms. …
A type of prairie that occurs on slopes and well‐drained uplands, and is often interspersed with areas of mesic prairie in valleys. …
A method of extracting geothermal heat from the Earth based on pumping water through hot rocks. …
A valley that has no river flowing through it. It would have been formed under a climate that is very different from today's (for example by meltwater at the end of the Pleistocene) and indicates previous erosion by water. …
A US‐based non‐profit conservation organization which is committed to conserving, restoring, and managing the country's wetlands, waterfowl, and wildlife. …
The physical property of being able to sustain large plasticdeformations without fracture, as occurs in metals that are capable of being hammered thin without breaking, or drawn into a thin shape such as a wire. See also malleable. …
A North American term for organic material (such as dead grass, leaves, conifer needles, and other plant parts) that is in various stages of decomposition on the floor of a forest. …
Enslavement, usually of worker ants by a rival species. …
An uncontrolled area where solid wastes have been left on or in the ground, sometimes illegally, without environmental controls. See also landfill. …
1 A bedform in an alluvial channel that forms at higher flow velocity than a ripple and which gradually moves downstream along the bed of the channel, much more slowly than the water flows. 2 A mound of sand that is built up by prevailing winds, in a desert or on a sandy beach. Also known as sand dune . …
The shape assumed by a sand dune, which depends on wind speed and direction, and the availability of sand. Examples include crescent‐shaped dunes (barchans), seif dunes, and star‐shaped dunes. …
The period of declining daylight between sunset and dark. Also known as twilight . See also dawn. …
General term for fine particles that are light enough to be suspended in air. …
An area in the Great Plains region of the USA that experienced prolonged drought and soil erosion in the late 1920s and 1930s, partly caused by dry weather but aggravated by over‐intensive farming practices. The area?which includes parts of Kansas, Oklahoma, Texas, New Mexico, and Colorado?has a long history of persistent droughts and had a natural vegetation of grass which protected the fine‐…
A strong miniature whirlwind that develops best on clear, dry, hot afternoons and throws up dust, litter, and leaves into the air. …
A strong wind that blows fine dust across the surface of a desert, which can significantly reduce visibility and adversely affect communications and agriculture. Contrast sand storm. See also haboob. …
Fine particles of ash, dust, and sulphur dioxide that are thrown up into the stratosphere by a volcanic eruption, and which can serve as condensation nuclei for the formation of sulphate aerosols. …
A disease of elm trees that is caused by a fungus (Ceratocystis ulmi) which is spread by a bark‐beetle. The disease is usually fatal, was first introduced to the UK in the 1930s, and since the 1960s has devastated the elm population of the UK. …
The obligation to avoid negligence, particularly to take reasonable care not to cause physical, economic, or emotional loss or harm to others. …
1 An embankment made of earth and rock, for example to prevent a spill from spreading or to prevent flooding. 2 A steeply inclined layer of intrusiveigneous rock, formed from cooling magma, that is relatively resistant to erosion and is discordant and cuts across existing layers. …