MATSEC IM Environmental Science key terms

The continuous movement of elements such as carbon, nitrogen and phosphorus between living organisms, the atmosphere, water, soil and rocks, driven by biological, geological and chemical processes.

A reservoir such as a forest, soil, ocean or peatland that absorbs and stores more carbon than it releases, slowing the build-up of carbon dioxide in the atmosphere.

The natural warming of Earth's surface caused by gases in the atmosphere that absorb outgoing infrared radiation and re-emit it downwards, keeping the planet far warmer than it would otherwise be.

The fraction of incoming solar radiation reflected back to space by a surface; bright surfaces such as snow or pale limestone have high albedo, dark surfaces such as forest or asphalt have low albedo.

A body of rock or sediment that is porous and permeable enough to store and transmit usable quantities of groundwater, recharged by rainfall infiltrating from the surface.

The downward movement of water from the ground surface into soil and rock voids, which replenishes soil moisture and groundwater and is reduced where surfaces are sealed by concrete or asphalt.

Terrain formed on soluble rock, typically limestone, where water dissolves the rock to create features such as sinkholes, caves, dry valleys and an almost absent surface drainage network.

The removal of topsoil by wind or water faster than it can form, often after vegetation is cleared or land is left bare, leading to loss of fertility and sedimentation downstream.

The conversion of unreactive atmospheric nitrogen gas into ammonia or related compounds by bacteria such as Rhizobium in root nodules, by cyanobacteria and by lightning, making nitrogen available to living things.

A region of the stratosphere, roughly fifteen to thirty-five kilometres up, where ozone concentrations are highest; it absorbs most of the harmful ultraviolet radiation reaching Earth from the Sun.

A community of organisms interacting with each other and with their non-living surroundings - air, water, soil and climate - exchanging energy and matter as a functioning unit.

The position an organism occupies in a food chain, defined by how many energy-transfer steps separate it from the primary producer at the base.

The rate at which producers such as plants, algae and phytoplankton convert solar energy into organic matter through photosynthesis, forming the energy base of nearly all ecosystems.

A network of interconnected food chains showing the many feeding relationships among organisms in a community, which is a more realistic picture than a single linear chain.

The maximum population of a species that a given habitat can support indefinitely without degrading the resources on which that population depends.

A species whose influence on its community is disproportionately large relative to its abundance; its removal causes major changes in ecosystem structure and in the survival of other species.

A species that occurs naturally in one restricted geographic area and nowhere else; islands such as Malta hold many endemics that are especially vulnerable to habitat change.

The variety of life at all levels: genetic variation within species, the number of different species, and the range of habitats and ecosystems present in a given area.

The gradual, directional change in the species composition of a community over time, from colonising pioneer species towards a more stable mature community, as conditions such as soil depth and light change.

A low, open scrub habitat of dry limestone areas in Malta and the Mediterranean, with thin soil and drought-tolerant shrubs such as thyme, together with annuals that flush after autumn rain.

A dense scrub community of evergreen shrubs and small trees, typical of the Mediterranean and of sheltered Maltese valleys and slopes, usually taller, denser and more shaded than garigue.

The breaking up of a continuous habitat into small, isolated patches by roads, buildings or farmland, which reduces gene flow and makes species more vulnerable to local extinction.

An estimate of the land and sea area needed to supply a population with the resources it consumes and to absorb the waste it produces, expressed in global hectares.

A description of how birth and death rates change as a country develops: both fall from high to low levels, passing through a stage of rapid population growth before numbers stabilise.

Nutrient enrichment of a water body, usually by nitrate and phosphate from fertiliser, sewage or livestock, causing algal blooms, oxygen depletion and the death of fish and invertebrates.

The build-up of a substance, such as a heavy metal or pesticide, in the tissues of an individual organism over its lifetime, because it is absorbed faster than the body can excrete it.

The increase in concentration of a persistent substance at each successive trophic level, so that top predators carry much higher body burdens than the organisms they feed on.

Airborne particles with a diameter under ten micrometres, released by combustion, traffic and dust, which can penetrate deep into the lungs and are linked to respiratory and heart disease.

The removal of dissolved salts from seawater or brackish water, usually by reverse osmosis, to produce fresh water; the process is energy-intensive and leaves a concentrated brine waste stream.

An engineered waste disposal site where refuse is compacted and covered, with a clay or plastic liner and leachate collection to limit pollution of soil and groundwater.

The low-density, often unplanned outward spread of built-up areas into surrounding countryside, increasing car dependence, sealing land and consuming agricultural or natural habitat.

A formal procedure that predicts the likely environmental effects of a proposed project before it is approved, and sets out mitigation and monitoring requirements for the decision-makers.

The idea that where there is a threat of serious or irreversible environmental damage, lack of full scientific certainty should not be a reason for postponing cost-effective measures to prevent it.

The principle that those who cause pollution should bear the full cost of preventing, controlling and remedying it, rather than passing that cost on to society or to the environment.

Development that meets the needs of the present without compromising the ability of future generations to meet their own needs, balancing economic, social and environmental goals.

The priority order for managing waste: prevent it first, then reuse, then recycle, then recover energy from it, and send it to landfill only as a last resort.

A European Union network of protected areas made up of Special Areas of Conservation designated under the Habitats Directive and Special Protection Areas designated under the Birds Directive.

An economic model in which materials are kept in use for as long as possible through repair, reuse and recycling, so that waste and demand for new raw materials are minimised.