98-percentile - The value of a ranked distribution above (or below) which 98 per cent of values in the distribution lie, depending on application.
Acid Sensitive - Surface water and soils that due chiefly to their low calcium concentration, have little or no resistance to acid inputs.
Acidification - Continuing loss of capacity to neutralise acid inputs indicated by declining alkalinity and increasing hydrogen ion concentration (i.e., the decrease in pH of water or soil resulting from increases in acidic anion inputs such as sulphate).
Aerosols - Airborne solids or liquids, with a typical size between 0.01 and 10 μm. Aerosols may be of either natural or anthropogenic origin. Aerosols may influence climate in two ways directly through scattering and absorbing radiation, and indirectly through acting as condensation nuclei for cloud formation or modifying the optical properties and lifetime of clouds.
Afforestation - Establishment of a new forest by planting of non-forested land.
Alert Threshold - The concentration of a pollutant, notified to the public, beyond which there is a risk to human health from brief exposure.
Algae - Simple aquatic plants that may be attached or free floating (planktonic) and occur as single cells, colonies, branched and unbranched filaments.
Algal Bloom - Dense growth of planktonic algae or most commonly Cyanobacteria (blue-green bacteria formerly classified as algae) in nutrient enriched lakes causing discoloration of the water.
Ammonia (NH3) - A simple form of nitrogen primarily originating in waste discharges. It can be toxic to fish under certain circumstances and is a source of nitrogen for plants and algae.
Amphibian - Vertebrates, including frogs, with an aquatic larval stage followed by a terrestrial adult stage.
Anthropogenic - Produced as a result of human activities.
Aquaculture - The farming of aquatic species such as fish and shellfish under controlled conditions.
Aquifer - A rock unit that will yield water in a usable quantity to a well or spring. A geological formation through which water can percolate, sometimes very slowly for long distances.
Atmospheric Deposition - Pollution from the atmosphere associated with dry deposition in the form of dust, wet deposition in the form of rain and snow, or as a result of vapour exchanges.
Attenuation - The reduction in magnitude/intensity/concentration of a substance dispersed in a gaseous or liquid medium.
Benthic Organism (benthos) - An organism that lives on or near the bottom of a river, lake or ocean.
Bioaccumulative Substance - A substance that builds up in tissue of living organisms as a result of direct exposure to polluted water, air or soil, or through consumption of contaminated food.
Biochemical Oxygen Demand (BOD) - A measure of the potential oxygen consumption of decaying organic matter in water. It is a widely used measure of organic pollution in rivers and in effluents discharged to water.
Biodiversity - Word commonly used for biological diversity and defined as assemblage of living organisms from all habitats including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part.
Biomass - The weight of biological matter. Standing crop is the amount of biomass (e.g. algae) in a waterbody.
Biota - The flora and fauna of an area.
Biotoxins - Substances produced by certain organisms that are toxic or otherwise injurious to other organisms.
Black Smoke - The fraction of total suspended particulates in air determined from the blackness measurement of the stain produced by passing the air through standard filter paper.
Blanket Bog - An area, often very extensive, of acid peatland, found in constantly wet climates, characteristic of broad flat upland areas, which develops where drainage is impeded and the soil is acid.
Bonamiasis - A disease that affects native oysters (Ostrea edulis) caused by infection by the parasite Bonamia ostreae.
Calcareous Grassland - Grassland occurring on well-drained, lime-rich soils that are dominated by a suite of calcicole (lime-loving) grass and broadleaved herbaceous plants.
Calcicole Plants - Plants which grow best on calcareous soils.
Callows - Areas of fen peat periodically inundated by floodwater.
Carbon Dioxide (CO2) - A naturally occurring gas which is also a by-product of burning fossil fuels and biomass, land-use changes and industrial processes. It is the principal anthropogenic greenhouse gas that affects the earth’s radiative balance. It is the reference gas against which other greenhouse gases are measured and therefore has a Global Warming Potential of 1.
Carbon Sequestration - The uptake of carbon containing substances, in particular carbon dioxide.
Carcinogen - A substance that causes or is believed to cause cancer in humans.
Catchment Area - The area from which a major river system or lake derives its water (i.e., the area drained by a river system).
Cetacean - A marine mammal belonging to the taxonomic order Cetacea, which includes all whales, dolphins and porpoises.
CFCs (Chlorofluorocarbons) - A range of compounds of chlorine, fluorine and carbon implicated mainly in the destruction of stratospheric ozone but also in enhancing the greenhouse effect.
Chemotherapeutics - Specific chemicals such as antibiotics that are used to treat disease.
Chloroform - Trichloromethane (CHCl3) which may be produced as a by-product of the chlorination of water supplies especially when organic matter is present in the water being chlorinated.
Chlorophyll - The green pigment found in algae and higher plants which is involved in photosynthesis.
Coral Reef - A Reef formed by the growth of coral which is the hard calcareous substance secreted by marine animals (polyps) for support and habitation.
Cryptosporidium - A coccidian protozoan parasite that infects vertebrates such as sheep and cattle. It can infect humans and is a particularly dangerous parasite when its oocysts enter public water supply systems due to, for example, cattle slurry contamination.
Decibel (dB) - The unit of measurement of sound intensity.
Deforestation - The removal of trees in an area.
Demersal Fish - Fish such as cod, whiting, plaice, haddock, skates and rays, that spend most of their time swimming near the seabed. It usually refers to the adult stage of the species.
Diffuse Source Pollution - Pollution that arises from diffuse areas in a catchment such as fields adjacent to a river or stream during heavy rainfall when surface runoff occurs.
Dioxins - A collective name given to a group of 75 closely related chemical compounds known as polychlorinated dibenzodioxins (PCDDs). Dioxins can form during combustion of organic materials containing chlorine, as undesirable by-products during chemical manufacture and bleaching operations.
Dissolved Oxygen (DO) - A measure of the concentration of oxygen in a liquid, such as water or wastewater, usually expressed in mg/l or per cent saturation.
Dolomitisation - The process by which an original calcium carbonate rock is converted into a double calcium-magnesium carbonate rock.
Drumlin - A low hill of glacial boulder clay, considered to have been fashioned beneath an ice-sheet.
Ecclesiastical Remains - Remains of, or relating to, the Christian Church or its clergy.
Eco-Efficiency - Aims at breaking the link (decoupling) between economic growth, environmental degradation and use of natural resources. Indicators of eco-efficiency represent the use of nature in society and the economy.
Ecology - The study of the relationship among organisms and between those organisms and their non-living environment.
Ecosystem - A community of interdependent organisms together with the environment they inhabit and with which they interact, and which is distinct from adjacent communities and environments.
Eco-Audit - A generic term that includes several procedures in use at present, such as Environment Proofing, Green Accounting and at company level, Environmental Management Systems such as ISO 14001 or EMAS.
Eco-Tourism - Eco-tourism is responsible travel to fragile, pristine and usually protected areas that strives to be low impact and (usually) small scale. It helps educate the traveller, provides funds for conservation, directly benefits the economic development and political empowerment of local communities and fosters respect for different cultures and human rights.
Effluent - Liquid wastes.
Endocrine Disrupting Chemical - A chemical that disrupts the endocrine system and the organs that respond to hormonal signals.
Environmental Assessment - The preparation of an environmental report, the carrying out of consultations, the taking into account of the environmental report and the results of the consultations in decision-making.
Erosion - Wearing away of earth or rock by the effects of rain, wind, sea or rivers or by the action of toxic substances.
Eutrophic - Greek for well nourished. Applied to waterbodies with high nutrient concentrations leading to large algal standing crops.
Eutrophication - The enrichment of water by nutrients, especially compounds of nitrogen and/or phosphorus, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms present in the water and to the quality of the water concerned.
Evapotranspiration - The combined processes of evaporation and transpiration. It can be defined as the sum of water used by vegetation and water lost by evaporation.
Faecal Coliforms - Harmless bacteria which serve as indicators of the presence of human and animal faeces in waters.
Fauna - Animals.
Fen - An area of waterlogged peat which, unlike bog, is alkaline or only slightly acid.
Fiscal Instrument - A financial tool or mechanism by which certain practices may be encouraged, e.g. via incentives or discouraged via levies or taxes or controlled via regulation. The purpose is to influence economic behaviour to follow an ecologically benign path.
Flora - Plants.
Flue-Gas Desulphurisation - The removal of sulphur from the flue gases in combustion activities.
Fouling - In an aquatic context, fouling is the growth of microbial, plant or animal life on the hulls of boats, on piers, platforms and other structures, which leads to increased resistance to water flow and increased susceptibility to corrosion and damage.
Fugitive Emissions - Emissions that occur through leakage, evaporation or other uncontrolled losses.
Geographical Information System (GIS) - A set of integrated techniques for storing, retrieving, transforming and displaying spatially referenced thematic data in map form.
Geomorphology - The study of the form and development of the Earth, and especially of its surface and physical features, and of the relationship between these features and the geological structures beneath.
Green Accounting - Accounting methods which take into consideration positive or negative impacts on the environment and natural resources.
Greenhouse Effect - Enhanced warming of the atmosphere due to the reduction in outgoing solar radiation resulting from increased concentrations of gases, in particular, CO2.
Greenhouse Gases - Gaseous constituents of the atmosphere that absorb/trap infrared (thermal) radiation which is mainly emitted by the Earth’s surface and thereby influence the Earth's temperature.
Groundwater - Water that occupies pores and crevices in rock and soil, below the surface and above a layer of impermeable material.
Habitat - The dwelling place of a species or community, providing a particular set of environmental conditions (e.g. forest floor,sea shore).
Haemoglobin - A substance in red blood cells that carries oxygen around the body.
Hazardous Waste - Defined in the Waste Management Act 1996 as any waste which appears on the hazardous waste list or is prescribed as a hazardous waste and which displays one or more of the properties of hazardous waste listed in the Waste Management Act 1996.
HCFCs (Hydrochlorofluorocarbons) - Compounds which have been substituted for CFCs as the latter become phased out by international agreement.
Heath - An area of open uncultivated land, typically an acid soil with characteristic vegetation of heather, gorse and coarse grasses.
Hydrograph - A graph showing variation of stage (depth) or discharge of water in a stream over a period of time.
Hypertrophic - Applied to water bodies which are excessively nourished, extremely productive.
Insoluble - Does not dissolve.
Integrated Pollution Control (IPC) - A system of licensing which covers all emissions to air, water and land, including noise/odour and is intended to minimise the impact on the environment by taking account of pollution that may be transferred from one environmental medium to another. IPC is based on Best Available Technology Not Entailing Excessive Cost (BATNEEC). The implementation of the Integrated Pollution Prevention Control (IPPPC) Directive will replace this system of licensing in an advanced form.
Integrated Pollution Prevention and Control (IPPC) - Council Directive 96/61/EC prescribes IPPC as an EU-wide licensing and enforcement regime for specified activities aimed at preventing/reducing pollution and providing a high level of protection for the environment as a whole. It will supersede IPC licensing in Ireland from 2004 onwards in an enhanced form based on Best Available Techniques (BAT).
Invertebrates - Animals which do not possess a backbone.
Karst - An area of limestone or other highly soluble rock, in which the landforms are of dominantly solutional origin, and in which the drainage is usually underground in solutionally enlarged fissures and conduits.
Karstification - The processes of solution and infiltration by water, mainly chemical but also mechanical, whereby the surface features and subterranean drainage network of a karstland are developed to form a karst topography, including such surface features as dolines, karren, and mogotes and such subsurface features as caves and shafts.
Kyoto Protocol - The 1997 protocol to the Convention on Climate Change under which industrialised countries will reduce their combined greenhouse gas emissions by at least 5 percent compared to 1990 levels by the period 2008-2012.
Leachate - The seepage of liquid through a waste disposal site or spoil heap.
Leaching - The removal of the soluble constituents of a rock, soil or ore (that which is leached being known as the leachate) by the action of percolating waters.
Limit Value - A level fixed on the basis of scientific knowledge, with the aim of avoiding preventing or reducing harmful effects on human health and/or the environment as a whole, to be attained within a given period and not to be exceeded once attained.
Machair - Coastal grassland formed when sand is blown inland over extensive areas.
Macroinvertebrates - Larger invertebrates, e.g. worms, snails and insects.
Macrophytes - Large plants which in water include rooted and floating species.
Maërl - Calcareous red algae.
Margin of Tolerance - The percentage of a limit value by which this value may be exceeded.
Megalithic Tomb - Prehistoric tomb using a large stone.
Mesotrophic - Applied to water bodies which are moderately nourished, moderately productive.
Monoculture - In forestry terms, even-aged, single-species forest crops.
Monofilament Gill Netting - A static net suspended vertically used to capture fish which entangle themselves in the net, usually by the forward part of the body near the gills.
Montreal Protocol - The Montreal Protocol and subsequent amendments set out a programme for the phasing out of the compounds with the greatest ozone-depleting potential, as well as some of their replacements, many of which are also greenhouse gases, by mid to late 1990s. This included such substances as methyl bromide and hydrochlorofluorocarbons (HCFC).
Moor - A tract of open, uncultivated upland, typically covered with heather.
Municipal Waste - Defined in the Waste Management Act 1996 as household waste as well as commercial or other waste which, because of its nature and composition, is similar to household waste.
Mutagen - An agent that changes the hereditary genetic material that is a part of every living cell. Such a mutation is probably an early step in the sequence of events that ultimately leads to the development of cancer.
Nitrate (NO3) - A salt of nitric acid (HNO3).
Nitrogen Oxides (NOX) - A gas which usually includes the two pollutants nitric oxide (NO) and nitrogen dioxide (NO2,) produced by high temperature combustion and some natural processes.
Nutrient - Element or chemical essential for growth, e.g. phosphorus, nitrogen, silica, oxygen and carbon.
Oligotrophic - Applied to water bodies which are poorly nourished, unproductive.
Oocysts - The infective phase in the life cycle of parasites such as Cryptosporidium. Mature oocysts are resistant to normal forms of water treatment such as chlorination and thus pose particular dangers in public water supplies.
Organotins - Compounds containing at least one bond between tin and carbon. One of these compounds, Tributyltin, has been used since the 1970s as an antifoulant on ships and marine structures, but there has been increasing concern about its impact on non-target species due to its toxicity and hormone-disrupting effects.
Ozone (O3) - A secondary pollutant in which the molecule of oxygen consists of three atoms rather than two.
Ozone Precursor - A substance which contributes to the formation of ground-level (tropospheric) ozone.
Pathogen - Biologically hazardous organisms such as viruses, bacteria or parasites that may give rise to illness in humans or animals.
Peatbog - Peatland with water table at or near the surface; includes both upland and lowland bogs and a variety of vegetation cover from heath dominated to moor-sedge dominated.
Pelagic Fish - Fish such as herring, mackerel and blue whiting that spend most of their time swimming in the water column as opposed to resting on the seabed. Usually refers to the adult stage of the species.
Pesticide - A general term for any chemical agent which is used in order to kill unwanted plants (‘weeds’), animal pests, or disease causing fungi.
pH - The measure of the acidity or alkalinity of a substance.
Phosphate (PO4) - The commonly occurring form of phosphorus taken up by plants in the aquatic environment and essential for their growth.
Photosynthesis - The process by which all green plants manufacture sugars from water and carbon dioxide (CO2).
Phytobenthos - Microscopic plants, including diatoms, living on surface layer of bed of streams, rivers, lakes, estuaries or seas.
Phytoplankton - Microscopic small plants which float or swim weakly in fresh or salt water bodies.
Plankton - Organisms suspended in water by currents, the presence of air sacks or by their own swimming movements Phytoplankton refers to microscopic plants, and zooplankton refers to microscopic animals.
PM10 - Particulate Matter measuring less than 10 microns in diameter.
PM2.5 - Particulate Matter measuring less than 2.5 microns in diameter.
Point Source Pollution - Pollution that arises from a well defined point typically the end of a discharge pipe but may include farmyard sources.
Polycyclic or Polynuclear Aromatic Hydrocarbons (PAHs) - Complex organic molecules found in soot, tar, vehicle exhausts and combustion products of fuels.
Population Information Threshold - The concentration of a pollutant used to inform the public that levels are increasing and beyond which there is a risk to human health from brief exposure for particularly sensitive sections of the population.
Precipitation - The manner by which water and other matter in the atmosphere reach the earth’s surface. Wet precipitation includes rainfall, snow, hail, mist and fog. Dry precipitation describes the deposition of gases, aerosols and particles not dissolved in atmospheric borne water.
Radiative Forcing/Radiative Balance - Radiative forcing is the general term for a change in the net radiant atmospheric energy, expressed in Watts per square metre (Wm-2), due to an internal atmospheric change or external changes, e.g. internally due to a change in the concentration of carbon dioxide or externally due a change in the output of the Sun. Such changes are said to change the Radiative balance.
Raised Bog - An area of ombrogenous (i.e. originating as a result of wet climates) acid peatland with a convex profile.
Reforestation - Replanting of forests on lands that have recently been harvested. - Renewable Resource - A resource that can be exploited without depletion because it is constantly replenished, e.g. solar radiation and wind.
Riparian Vegetation - Vegetation growing close to a watercourse, lake, wetland, or spring that is generally critical for wildlife cover, fish food organisms, stream nutrients and large organic debris, and for streambank stability.
Salt Marsh - An area of coastal grassland that is regularly flooded by seawater.
Selective Catalytic Reduction - An emissions abatement technology for nitrogen oxides that involves the injection of ammonia (NH3) into the flue gas that passes through a catalyst bed in which the ammonia and nitrogen oxides react to form harmless nitrogen and water vapour.
Sewage - Liquid wastes from communities, conveyed in sewers. Sewage may be a mixture of domestic sewage effluents from residential areas and industrial liquid waste.
Sewage Sludge - Semi-solid and solid waste matter removed from sewage at sewage treatment plants.
Sewerage - A network of pipes and associated equipment for the collection and transportation of sewage.
Sludge - The suspended matter in industrial effluent or sewage remaining after partial drying.
Slurry - The animal waste generated in animal housing units that have slatted floors and in which there is no use made of bedding material.
Stream Morphology - The form and pattern of streambeds and stream channels.
Sulphate (SO4) - A constituent of rain and acid aerosols produced by oxidation of SO2, in the atmosphere.
Sulphur Dioxide (SO2) - A colourless gas produced mainly by oxidising the sulphur in fossil fuels through combustion.
Sustainable Development - Defined by the Bruntland Commission (1987) as ‘development that meets the needs of the present without compromising the ability of the future generations to meet their own needs’.
Sustainable Tourism - Sustainable tourism development should meet the needs of present tourists and host regions while protecting and enhancing opportunity for the future. It is envisaged as leading to management of all resources in such a way that economic, social and aesthetic needs can be fulfilled while maintaining cultural integrity, essential ecological processes, biological diversity and life support systems. Sustainable tourism products are products, which are operated in harmony with the local environment, community and cultures, so that these become the permanent beneficiaries not the victims of tourism development.
Tangle Netting - A static net placed on the bottom of the sea, aimed at trapping fish and shellfish that entangle themselves in the net.
Topography - The study of the physical features of a geographical area.
Total Allowable Catch (TAC) - The TAC is the total fish catch allowed to be taken from a resource in a specified period (usually a year), as defined in the management plan. The TAC may be allocated to the stakeholders in the form of quotas as specific quantities or proportions.
Toxic Equivalent (TEQ) - Toxic equivalent is a system of toxicity weighting factors, adopted by the WHO, which allows concentrations of the less toxic compounds to be expressed as an overall equivalent concentration of the most toxic dioxin, 2,3,7,8-TCDD.
Trophic Status - The extent of enrichment of a waterbody as assessed by the nutrient concentrations, amount of planktonic algae and macrophytes, water transparency and oxygen levels. The trophic categories oligotrophic, mesotrophic, eutrophic and hypertrophic are used to describe waters varying from un-enriched to highly enriched.
Turlough - A temporary water body on carboniferous limestone.
Ulcerative Dermal Necrosis Disease - A disease that primarily affects salmonids returning from the sea to freshwater with ulcers near the head. The cause is probably viral but the ulcers are typically infected by bacteria and fungi.
Volatile Organic Compounds (VOCs) - Organic compounds which evaporate readily and contribute to air pollution mainly through the production of secondary pollutants such as ozone.
Waste Arisings - A measure of the amount of waste generated by a specified sector or activity.
Wetland - An area covered permanently, occasionally, or periodically by fresh or salt water (e.g. flooded pasture land, marshland, inland lakes, rivers and their estuaries); also includes bogs.