abiotic: non-living or physical and chemical influences, such as temperature and pH

abstraction: the removal or drawing of a resource (e.g. water)

acidification: reduction in pH, usually of soil

acid sulfate soils: a mix of low-lying coastal clays and sands that contain sulfur-bearing compounds at concentrations above 0.05% in clays and 0.01% in sands

adaptation: a particular part of the anatomy, a physiological process, or a behaviour pattern that improves an organism's chances to survive and reproduce

aerodynamic: pertaining to forces acting upon any solid or liquid body moving relative to a gas (especially air)

agrochemicals: chemicals used in agriculture to destroy insects, fungi, bacteria, pests, weeds, and to regulate plant growth (e.g. fertilisers)

airshed: an area delineated by topographical or meteorological characteristics within which emitted pollutants interact

air toxics: gaseous, aerosol or particulate contaminants present in the ambient air in trace amounts with characteristics (toxicity, persistence) which make them a hazard to human health, plant and animal life

alluvium: clay, silt, sand, gravel or similar material deposited by running water especially during recent geological time

ambient: the background or surrounding parameters occurring in the environment

amenity: intangible environmental and social benefits such as peace and beauty

anaerobic: without atmospheric oxygen

anthelmintic chemicals: chemicals used to control internal parasites in livestock

anthropogenic: produced or caused by human activity

anti-microbial agent: a chemical compound that either destroys or inhibits the growth of microscopic and sub-microscopic organisms

aquaculture: cultivation of aquatic organisms including fish, molluscs and plants in fresh or salt water

aquifer: porous sediments and rocks which hold and yield ground water

attenuation: the reduction in level of a quantity or over an interval of a variable

bacteria: single-celled organism

bagasse: the crushed, juiceless remains of processed sugar cane

ballast water: water carried in tanks to maintain stability when a ship is lightly loaded; normally discharged to the sea when the ship is loaded with cargo

basalt: dark-coloured rocks of volcanic origin

baseflow: the continual flow of ground water into surface waters

benthic: bottom-dwelling; usually refers to organisms living on the substrate at the bottom of a water body

benthos: the assemblage of organisms living on the substrate on the bottom of a water body

benzene: a colourless, liquid, flammable, aromatic hydrocarbon that boils at 80.1oC and freezes at 5.4-5.5oC; used to manufacture styrene and phenol; can be a component of fuels such as petrol, or may result from incomplete combustion of fuels

bilateral: having two sides; affecting reciprocally two sides or two parties

bioaccumulation: the process by which chemicals are taken up by organisms from the environment leading to a concentration of the substance in their tissues

bioavailability: a chemical substance in a form that is readily taken up by plants

biodiversity: the variety of all life forms

biogenic: essential to the maintenance of life; produced by actions of living organisms

biological communities: see 'ecological community'

biological control: use of organisms (predators, herbivores, parasites and disease-producing organisms) to control pests and weeds

biological indicators: assessment of living organisms used to measure ecosystem health

bioluminescence: the emission of light without heat by living organisms; occurs in glow-worms and fireflies, bacteria and fungi, and in many deep-sea and freshwater fish; in animals it may serve as a means of protection or species recognition or it may provide mating sig

biomass: the total living matter in a specific area

biosolids: organic products from the treatment of sewage; also known as sewage sludge

biota: collectively, the plants, microorganisms and animals of a region

biotechnology: the use of biological processes, as through the exploitation of living organisms or biological systems, as a component in the development or manufacture of a product or in the technological solution to a problem

bloom: an unusually dense and visible growth of organisms (algae or phytoplankton) in water, resulting from proliferation caused by increased nutrients (e.g. phosphorus), possibly toxic and generally resulting in reduced oxygen in the water

blue-green algae: members of the cyanobacteria (or Cyanophyta), characterised by blue-green pigmentation and a lack of cellular organisation

buffer: an area of land separating two conflicting activities or land uses

bycatch: species taken incidentally in a fishery along with the target species; often discarded

carbon sequestration: the process of removal of carbon dioxide from the atmosphere and its storage, particularly in soils and plant biomass; forms a significant part of global strategies for combating the threat of climate change

carcinogenic: any agent that incites development of a cancer or any other sort of malignancy

cardiovascular: those structures, including the heart and blood vessels, which provide channels for the flow of blood

carrying capacity: the maximum biomass which an area can maintain indefinitely (e.g. the maximum stocking rate which an area of grazing land can support throughout the greatest period of stress each year), or the maximum amount of harvesting of wild populations that an eco

catalytic technology: a device installed in the exhaust system of motor vehicles containing a substance which acts as a catalyst by triggering a chemical reaction and converting the major pollutants to water, carbon dioxide and nitrogen

catchment: the drainage basin of a water body that captures all precipitation that falls on it

chondrichthyan: a class of vertebrates comprising the cartilaginous, jawed fishes characterised by the absence of true bone

co-generation: the production of two forms of useful power, typically electricity and heat, from a single fuel source in a single process

cold water pollution: see 'thermal pollution'

coliform bacteria: a group of bacteria originating from animal (including human) intestines and used as an indicator of the sanitary quality of water

colluvial: arising from sediments deposited from hillslope weathering and erosion

combustion: the burning of gas, liquid or solid in which the fuel is oxidised, evolving heat and often light

community (ecological): aggregation of organisms characterised by a distinctive combination of two or more ecologically related species

concentration: in solutions, the mass, volume, or number of moles of solute present in proportion to the amount of solvent or total solution

conductivity: see 'electrical conductivity'

consumer price index (CPI): an index of consumer prices in the marketplace

consumption: the act or action of consuming or destroying; the use of economic goods in the satisfaction of wants or in the process of production resulting in immediate destruction, gradual wear and deterioration, no change aside from natural decay, or transformation

contaminant: an undesirable or harmful impurity

continental shelf: relatively shallow seabed from the shore to the edge of the continental slope (which slopes to the deep ocean floor)

covenant: pledge in formal agreement; to lay down as a condition before signing

cyanobacteria: see 'blue-green algae'

degradation: any decline in the quality of natural resources, commonly caused by human activities

demersal: found at or near the bottom of the sea or lake

demographics: relating to the dynamic balance of a population, especially with regard to density and capacity for expansion or decline

deregulation: the opening of industry to competition

diatom: marine or freshwater unicellular algae with cell walls composed of pectin impregnated with silica; found in huge numbers in plankton and important in the food chains of seas and rivers

diffuse-source pollution: also known as non-source pollution; usually refers to multiple small sources of pollution spread over a wide area (e.g. catchment run-off of sediments from land use)

dinoflagellate: member of the algal division Dinophyta, which is a group of single-celled algae, with cells surrounded by a rigid, sculptured wall and transported by two flagella; major part of marine and freshwater plankton

dioxins: chemical compounds largely formed as waste products or byproducts in the manufacture of other chemicals; some are hazardous to humans at relatively low levels

discharge: (rivers) volume of water transported per unit time; (pollution) something that is released or unloaded

disturbance (ecological): any discrete event in time which disrupts ecosystem structure and resource availability

diversion: volume of water diverted from a stream or aquifer on a sustained basis to supply water for rural, urban and industrial usage; includes diversions undertaken by a water authority, private company or a group of individuals authorised to act as a water supp

drainage division: the primary subdivision of groups of catchments

dryland salinity: soil salinity levels high enough to affect plant growth; occurs as a result of natural soil-forming process or in disturbed landscapes through clearing or other activities that interfere with the water and salinity balance and lead to shallow watertables

dysfunction: impaired or abnormal functioning (as of an organ of the body)

ecological capacity: the ability of ecosystems to sustain life despite anthropogenic pressures

ecological community: an aggregation of organisms characterised by a distinctive combination of two or more ecologically related species

ecological footprint: a measure of the impact of direct and indirect consumption of resources and production of wastes

ecological sustainability: the capacity of ecosystems to maintain their essential processes and functions and to retain their biological diversity without impoverishment

ecologically sustainable development (ESD): using, conserving and enhancing the community's resources so that ecological processes, on which life depends, are maintained, and the total quality of life, now and in the future, can be increased

ecosystem: a functional system which includes communities of living organisms and their associated physical, non-living environment, which interact to form an ecological unit, such as a tidal rockpool, wetland or forest

ecosystem processes: the numerous interactions between different components (both living and non-living) of an ecosystem that support the biological elements of the system; these processes include the storage and recycling of nutrients and minerals, disturbance, competition,

ecosystem services: any function provided by an ecosystem, such as the provision of clean air and water, the maintenance of soil fertility and the removal of wastes, that benefits humankind

ecotourism: nature-based tourism which involves education and interpretation of the natural environment and is managed to be ecologically sustainable

ecotoxicological: the degree of toxic impact on the biota

effluent: the water discharged after use in the treatment of sewage

El Niño – Southern Oscillation (ENSO): a natural oscillation in the state of the ocean–atmosphere system that leads to substantial changes in atmospheric circulation throughout the Asia–Pacific region

electrical conductivity (EC): an indirect measure of charged particles in water which is used to estimate salinity

emissions: gaseous or liquid discharge, or noise given out by a source

emissions trading: emissions trading schemes provide for market-based allocation of discharge opportunities; the environmental regulator first determines total acceptable emissions and then divides this total into tradeable units (often called credits or permits); these un

endangered species: species or ecological communities likely to become extinct unless action is taken to remove the factors that threaten their survival

endemic: originating in a given area and confined only to that area

endocrine system: the chemical coordinating system in animals (the endocrine glands) that produce hormones

enhanced greenhouse effect: the 'greenhouse effect' is the natural warming of the earth's atmosphere as a consequence of the concentration of certain gases in the atmosphere which retard the escape of heat radiation; the 'enhanced greenhouse effect' refers to the expected increase

environmental flows: minimum flows of water (by volume and season) necessary to maintain all aquatic biota and ecosystem processes

enzymes: any group of catalytic proteins that are produced by living cells and that mediate and promote the chemical processes of life without themselves being altered or destroyed

ephemeral: organisms that have a short life span or a watercourse that does not flow all the time

erosion: the loosening and transportation of soil, chiefly by wind and running water

eutrophication: the over-enrichment of a body of water with nutrients, primarily nitrogen and phosphorus, resulting in excessive growth of organisms and depletion of the oxygen concentration

evapotranspiration: the combined loss of water by evaporation from a free water surface (e.g. the surface of a wetland) and water evaporating from the leaves of plants (transpiration)

evolutionary processes: the processes of biological and organic change in organisms by which offspring come to differ from their ancestors and through which new species are formed

exceedence: occasion on which results are greater than a limit, goal or standard

exchangeable sodium percentage (ESP): the relative proportion of sodium to calcium and magnesium that is held on the clay surfaces within the soil

exotic: a plant or animal that has been introduced to a region in which it does not naturally occur

externalities: external unpriced side-effects of economic activity; may be beneficial or harmful (e.g. pollution costs)

fallowing: the ploughing or tilling of land without sowing it for a season

fauna: the entire animal life of a region

feedstock: the raw material furnished to a machine or process

ferrous: denotes compounds of iron

flocculation: to cause to aggregate into small lumps or loose clusters, or into a flocculent mass or deposit

floodplain: relatively smooth valley floors subject to inundation by the overflow of adjacent rivers

flora: the entire plant life of a region

fluvial: to flow, produced by river action

food web: a network describing the feeding interactions of the species in an area

fossil fuel: any hydrocarbon deposit that may be used for fuel such as petroleum, coal and natural gas

fragmentation: the division of continuous habitat by vegetation clearance for human land-use activities, isolating the remnants and the species within them and limiting genetic flow

freshes: water flows resulting from localised rainfall that remain within the river banks

fumigant: to expose to smoke or fumes, as in disinfecting

fungi: neither plants nor animals, fungi are characterised by long filaments, contain spores and are devoid of chlorophyll

gastrointestinal system: the portion of the digestion system including the stomach, intestine and all accessory organs

gene mutation: genetic material which may undergo qualitative or quantitative alteration or rearrangement

genetic diversity: the diversity of genes present in a given population or species

geomorphology: the study of the earth's form, especially the surface and physical features, and the relationship of these to the geological structures beneath

global stewardship: cooperation between nations on a global basis to manage common environmental problems

global warming: the expected rise in global temperatures caused by an increase in the concentration of greenhouse gases mostly emitted as a result of human activity

gradient: the rate of ascent or descent (steepness of slope) of any topographic feature, such as streams or hillsides

Great Artesian Basin: an enormous store of underground water underlying much of the drier regions of eastern Australia

greater metropolitan region (GMR): the combination of the statistical division of Sydney and the statistical subdivisions of Newcastle and Wollongong, as defined by the Australian Bureau of Statistics

greenfield developments: new housing developments

greenhouse effect: natural warming of the earth and other associated effects as a consequence of the concentration of certain gases in the atmosphere which prevent the escape of solar radiation; see also 'enhanced greenhouse effect'

greenhouse gases/emissions: atmospheric gases which enhance the natural greenhouse effect, including carbon dioxide, methane, chlorofluorocarbons, nitrous oxide, ozone and water vapour; see 'enhanced greenhouse effect' for the impact of these gases on the atmosphere and global clim

gross domestic product (GDP): the total market value of all final goods and services produced for money in a nation within a given period of time, after deducting the cost of goods and services used in the process of production, but before depreciation

gross state product (GSP): the total market value of all final goods and services produced for money in a state (such as NSW) within a given period of time, after deducting the cost of goods and services used in the process of production, but before depreciation

ground water: all subsurface water, especially the part that is in the zone of saturation

groundwater management areas (GMAs): zones within groundwater provinces that are either independent or mutually dependent aquifer systems; the zones are geographically independent and are locations where management may be needed to control groundwater extraction

growth promotant: any factor, genetic or extrinsic, which affects growth

habitat: a geographic area that can provide the key resources to sustain a population

hazardous waste: any harmful solid, liquid or gaseous waste product which is inherently dangerous to handle or dispose of

hazard reduction burning: the deliberate burning of the understorey by controlled fire kept at cooler temperatures, usually in winter to reduce ground fuel; part of forest management to reduce the incidence of summer wild fires thereby preventing damage to life and property

heavy metals: a group of metals with high atomic weights which are generally toxic to plant and animal life; some are always toxic (e.g. lead, mercury, cadmium) and others are toxic at high concentrations (e.g. zinc, copper)

herbicide: any chemical agent that destroys or inhibits plant growth

herbivore: an animal that consumes plants

high-volume sampler (HVS): provides 24-hour samples of particle levels on a 1-day-in-6 cycle

household: a social unit comprised of those living together in the same dwelling place

hydrocarbons: one of a very large group of chemical compounds composed only of carbon and hydrogen

hydrologic cycle: the cycle through which water passes, through water bodies, living organisms, on and in the land, and through the atmosphere; see Water Backgrounder 1.1 for a full description

hydrology: the science that treats the occurrence, circulation, distribution and properties of water and its reaction with the environment

impoundment: a pond, lake, tank, basin or other space, either natural or created in whole or part by the building of engineering structures, which is used for storage, regulation and control of water

indicator: a measurable item or unit used to monitor and report changes

Industrial Revolution (historic): a widespread change in industrial methods towards production by machine and away from manual labour, which began in England in the late 18th and early 19th Centuries

infiltration: the passage of water through the soil surface and into the soil matrix

infrared radiation: electromagnetic radiation with wavelengths in the range from 0.75 or 0.8 micrometres (the long wavelength limit of visible red light) to 1000 micrometres (the shortest microwaves)

infrastructure: the system of essential services, utilities and public and community facilities necessary to enable human communities to function

inorganic: matter other than plant or animal, and not containing a combination of carbon, hydrogen and oxygen

intergenerational equity: the principle that the present generation should pass on to future generations an environment which is not impoverished and degraded, and which will not reduce the quality of life for future generations

intertidal: between the levels of low and high tide; the intertidal zone is often called the littoral zone

invertebrate: an animal without a backbone composed of vertebrae, such as insects, worms, snails, mussels, prawns and cuttlefish

irrigation salinity: caused by poor irrigation practices where more water is applied than can be used by the crop and by clearing of deep-rooted vegetation such as trees; results in rising watertables bringing high concentrations of salt within the root zones of plants, kill

kelp beds: large stands of seaweed

kinetic: the motion of material bodies and the forces and energy associated with it

lakebed cropping: agricultural crop production within a lake system

land capability: a classification system for rural land, developed by the NSW Department of Land and Water Conservation, which delineates the ability of the land to remain stable under particular land uses

land degradation: the decline in condition or quality of the land as a consequence of misuse or overuse, involving changes to soil, flora, fauna, water quality and quantity, visual quality and production levels by humans

landfill: solid or liquid material disposed of by burial in the ground

land salinity: the concentration of salts in soil

land suitability: a classification system for rural land, developed by NSW Agriculture, which delineates the ability of the land to support agricultural production, based on socioeconomic and productivity factors as well as land capability

La-Niña – Southern Oscillation: the extensive cooling of the central and eastern Pacific Ocean in Australia (particularly eastern Australia); La Niña events are associated with increased probability of wetter conditions

leachate: liquid containing dissolved solids which has percolated through soil or rock

lichen: a group of organisms consisting of fungi and algae growing together symbiotically

littoral: of or pertaining to a shore, especially a seashore; littoral zone

littoral rainforest: rainforest found next to the sea and influenced by the sea, especially adapted to salt and wind

load-based licensing: a pollution control system where licence fees are linked to emission levels

macroinvertebrate: larger invertebrate, with a body length that usually exceeds 1 mm

macrophyte: a plant visible to the naked eye, especially in an aquatic habitat

mangrove: a plant (belonging to any of a wide range of species, mainly trees and shrubs) or a community of such plants that grow in sediment regularly inundated by sea water

mariculture: the cultivation of marine organisms, plant and animal, for the purposes of human consumption

metalloid: a non-metallic element, such as carbon or nitrogen, which can combine with a metal to form an alloy

methane: a colourless, odourless and tasteless gas, lighter than air, which reacts violently with chlorine and bromine in sunlight

metropolitan air quality study (MAQS) region: an area from 20 kilometres north of Newcastle to 15 km south of Wollongong (201 km north-south by 150 km east-west); bounded by AMG Eastings 261-421 and Northings 6174-6375

microbalance: a small, light type of analytical balance that can weigh loads up to 0.1 gram to the nearest microgram

microorganism: a microscopic organism, including bacteria, protozoans, yeast, viruses and algae

monoculture: the cultivation of a single species, usually a single crop on land

mutagenic: an agent that raises the frequency of mutation above the spontaneous rate

naturalised: introduced species which have become established

non-renewable resources: natural resources that are in fixed supply, but whose lifespan can be extended through more efficient or reduced use, reuse or recycling (e.g. minerals, oil, coal)

non-target organisms: organisms that are not the intended target of control programs, but may be incidentally affected by these programs

non-vascular plant: see 'vascular plant'

nursery (ecological): a relatively sheltered area of habitat suitable for the early growth and development of juvenile fish

nutrient cycle: the pattern of transfer of nutrients among the components of a food web and other non-living components of an ecosystem

organic (agriculture): agriculture which excludes the use of synthetic chemicals for fertiliser and pest control

organic (chemical): chemical compounds based on carbon

organochlorine: chlorines derived from an organic source

organophosphate: phosphates derived from an organic source

overland flow: downslope, surface movement of run-off other than in defined channels

oxidising agent: compound that gives up oxygen easily, removes hydrogen from another compound, or attracts negative electrons; also known as 'oxidant'

ozone: a gas made of three oxygen atoms; occurs naturally in the stratosphere where it is provides protection for the earth from solar ultraviolet radiation; ozone in the troposphere is due to anthropogenic emissions and is a major component of photochemical sm

ozone-depleting substances (ODSs): substances, such as chlorofluorocarbons and halons, which destroy ozone in the stratospheric ozone layer and allow increased ultraviolet radiation to reach the earth

ozone layer: a layer of the stratosphere (12-50 kilometres above the earth) where oxygen molecules are split by ultraviolet radiation to produce ozone and which absorbs harmful solar ultraviolet radiation

parasite: an organism that lives on or in another organism of different species from which it derives nutrients and shelter

parna: areas blanketed with a layer of wind-blown salt-pelletised clays

particulates: fine solid particles which remain individually dispersed in gases and stack emissions

pastoralism: the practice of grazing livestock

pathogen: a disease-causing organism

pelagic: associated with the surface or middle depths of a body of water

percolation: gravity flow of ground water through the pore spaces in rock or soil

perennial: a plant that lives for an indefinite period, dying back seasonally and producing new growth each year

pesticides: any substance used to harm or kill pest organisms

petajoules: unit of measurement for energy flow

petrochemicals: chemicals made from feedstocks derived from petroleum or natural gas

pH: a measure of the degree of acidity or alkalinity; expressed on a logarithmic scale of 1 to 14

photochemical reaction: a chemical reaction which takes place in sunlight

photochemical smog: forms in the lower atmosphere through the action of sunlight on the pollutants, oxides of nitrogen and hydrocarbons

photosynthesis: the biochemical process in plants and certain other organisms by which energy from the sun, captured by chlorophyll, powers the production of organic matter from carbon dioxide and water, releasing oxygen

photovoltaic: the production of an electrical force through sunlight falling on the junction of two dissimilar materials, such as a metal and a semi-conductor

phytoplankton: suspended, drifting aquatic plants (mainly algae and cyanobacteria); usually microscopic

phytotoxicity: poisonous to plants

plankton: suspended, very small aquatic plants or animals

plantation forestry: a large group of trees under managed cultivation

plume: an elongated open and mobile column or band (as of smoke, blowing sand or snow, or of cloud)

point-source pollution: source of pollution that can be pinpointed, such as a drain or chimney stack (compare with 'diffuse-source pollution')

pore-water: water filling the spaces between sediment particles

potable: fit for human consumption

potentially acid sulfate soils: soils generally found less than 5 metres above sea level; can produce sulfuric acid when drained, which can move through the soil affecting ground water and surface waters, with impacts on urban areas, farming productivity and fish

precautionary principle: when there are threats of serious of irreversible damage, scientific uncertainty should not be used to postpone cost-effective measures to prevent environmental degradation

precipitators: a substance separating, from a liquid as solid particles due to a chemical or physical change

predation: the killing and eating of an individual of one species by an individual of another species

pre-Holocene: occurring prior to the Holocene geologic period

prescribed burning: see 'hazard reduction burning'

primary pollutants: pollutants which are emitted directly into the atmosphere (e.g. lead)

productivity (biological): the rate of accumulation of organic material in an ecosystem

propellants: a combustible substance that produces heat and supplies ejection particles as in a rocket engine

protozoa: unicellular or acellular, usually microscopic, organisms regarded either as simple animals or members of the Protista (a kingdom into which all organisms of simple biological organisation can be classified)

putrescible: liable to foul decay, decomposition, especially by anaerobic bacteria

pyritic: soil composed of a common mineral consisting of iron disulfide, with a pale brass-yellow colour and brilliant metallic lustre

radiation: the emission and propagation of waves transmitting energy through space or through some medium; when unqualified, usually refers to electromagnetic radiation

Ramsar: commonly used name to describe the Convention onWetlands of International Importance Especially as Waterfowl Habitat, which was signed in Ramsar, Iran, in 1971

rangelands: areas of native grasslands, shrublands and woodlands that cover a large proportion of the arid and semi-arid regions where regular cropping is not practised and the predominant agricultural use, if any, is grazing of sheep and cattle on native vegetation

rare species: species which are uncommon but which are not currently considered endangered or vulnerable; may be represented by a large population in a small area or small populations thinly distributed over a large area

reactivity: the relative capacity of an atom, molecule or radical to combine chemically with another atom, molecule or radical

recharge: the process whereby surface water from rain, irrigation or streams infiltrates into ground water; the amount of water added to or absorbed into a groundwater system; or groundwater that feeds surface waters (also known as 'baseflow')

recharge area: an area where water is absorbed to be added to a water body, such as ground water or a lake

reclamation: the recovery of land or other natural resource that has been abandoned because of water or some other cause, e.g. drainage of saltmarshes

refugia: areas which have escaped the great changes undergone by a region as a whole, providing conditions in which relic communities of plants and animals can survive

regional environmental plan (REP): a plan relating to a region which is preceded by an environmental study, providing a framework to ensure that the best use of land resources is achieved; it must be consistent with any relevant state environmental planning policies (SEPPs)

regolith: unconsolidated residual or transported material that overlies or covers the solid rock in place

regulated discharge: water discharged after use where that discharge does not match the natural flow regime of the receiving water body; practically all waters extracted and subsequently discharged are considered regulated

regulated river: those rivers proclaimed under the Water Act 1910 as having their flows controlled by the major Government rural dams; 'regulation' means that the flows along the length of the river are controlled or regulated by releases made from major dams to meet the

remediation: to clean up a contaminated area to the level required for the intended use, often according to regulations

remnant (ecologic): a small fragmented portion of the former dominant vegetation which once covered the area before being cleared for human land use

renewable resource: natural resource that is naturally replenished, but whose continued supply depends, in many cases, on proper management (e.g. trees, fresh water, fish)

respiratory: the processes by which tissues and organisms exchange gases with their environment

reticulation: supply and disposal of water transported by pipes

retrofitting: a modification of equipment to include changes made in later production models

riffle: shallow water flowing rapidly over stones and gravel

riparian vegetation: vegetation situated on or belonging to a river or a stream bank

riparian zone: any land which adjoins, directly influences, or is influenced by a body of water

run-off: the portion of precipitation (rain, hail, snow) which flows across the land surface and does not soak into the ground; can be a major agent of water erosion

salinisation: the accumulation of salts in the soil to an extent which causes degradation of soils and vegetation

salinity: occurs as a result of natural soil-forming processes or in disturbed landscapes through clearing or other activities that interfere with the water and salinity balance and lead to shallow watertables

scheduled waste: wastes for which there are no environmentally acceptable disposal facilities currently available in Australia

secondary pollutants: pollutants formed by chemical reaction in the atmosphere (e.g. photochemical smog results from the mixing of oxides of nitrogen and volatile organic compounds in the presence of sunlight)

sedimentation: deposition of material of varying size, both mineral and organic, away from its site of origin by the action of water, wind, gravity or ice

selective logging (forestry): the removal of any part of the existing growing stock at any harvest, repeated at relatively short intervals so that there is regular regeneration of new seedlings in the stand

sewage: waste matter discharged to a sewerage system

sewerage: works for collecting, treating and disposing sewage

siltation: deposition of sediments from water in channels or harbours

sink: processes or places that remove or absorb materials from a system

snag: a fallen log or debris in a waterway that provides important habitat for some species

socioeconomic: relating to or involving a combination of social and economic factors

sodic soils: soils with a high proportion of sodium that cause poor physical conditions; about 30% of Australian soils

soil buffering capability: the ability of the soil to resist pH changes

solvent: that part of a solution that is present in the largest amount, or the compound that is normally liquid in the pure state (as for solutions of solids or gases in liquids)

Southern Oscillation Index (SOI): a climatic index based on the difference in surface air pressure between Tahiti and Darwin

species: a group of organisms which are biologically capable of breeding and producing fertile offspring

species diversity: a measure of the number of individuals and their relative abundance in an area

spray drift: the transport in the air of droplets of chemical away from the application area when chemicals (such as pesticides, herbicides) are applied by spraying

state environmental planning policy (SEPP): policy prepared under the Environmental Planning and Assessment Act 1979; includes polices for urban bushland, coastal wetlands, littoral rainforest, hazardous development and cattle feedlots

stormwater: the run-off from rainfall events

stratification (water): the arrangement of a body of water into two or more horizontal layers of differing characteristics

stratosphere: the layer of the atmosphere approximately 12-50 kilometres above the earth

stubble: a stump of a cultivated plant (such as wheat, corn, clover, beans or grasses) left in the ground after cutting or harvest

subtidal: below low-water level

suspended solids: any solid substance present in water in an undissolved state, usually contributing directly to turbidity

sustainability: environmentally sound economic growth balanced over a period of time

Sydney statistical division (SSD): includes the area bounded by Gosford and Wyong, Hawkesbury and Blue Mountains, Campbelltown, Wollondilly and the Sutherland Local Government Areas (LGAs)

tailwater: irrigation drainage water that escapes the farm following irrigation tapered element oscillating microbalance (TEOM)

tapered element oscillating microbalance (TEOM): an instrument that samples the air continuously and collects the particles on a filter attached to an oscillating microbalance

taxa: a group of organisms similar in characteristics such as biology, biochemistry, genetic composition and evolutionary history

taxonomy: the classification, identification and description of organisms into groups based on similarities of biology, biochemistry, genetic composition and evolutionary history

temperature inversion: a layer in the atmosphere in which temperature increases with altitude; the principal characteristic of an inversion layer is its marked static stability, so that very little turbulent exchange can occur within it

Thematic Mapper: a scanner on-board the LANDSAT 4 and 5 satellites that records seven bands of digital data in the visible and infrared areas of the electromagnetic spectrum

thermal pollution: the discharge of heated effluents into bodies of water at temperatures and in quantities that may be detrimental to the local or downstream environment

thermocline: the steep vertical temperature gradient between two of the layers in a stratified lake

threatened species: species facing threatening processes such as extensive destruction of habitat, which may jeopardise the survival, abundance or evolutionary development of the species

total catchment management (TCM): the coordinated and sustainable use and management of land, water, vegetation and other natural resources on a catchment basis to balance resource use and conservation

toxicity: effect of any substance which harms living organisms; described as acute (lethal) or chronic (sublethal)

toxicology: the study of poisons, including their nature, effects, detection and methods of treatment

toxins: any of various poisoning substances that are specific products of the metabolic activities of living organisms

transitway: dedicated portion of a road or highway for transport vehicles

transpiration: the loss of water by evaporation from the leaves of plants

troposphere: lowest atmospheric layer; approximately 18 kilometres high at the equator and six kilometres at the poles; layer in which the earth's weather occurs

tubestock: the growing of plant material in tubes

turbidity: a measure of the amount of suspended solids (usually fine clay or silt particles) in water and thus the degree of scattering or absorption of light in the water

ultraviolet (UV): shortwave radiation invisible to the human eye which is higher in energy than visible light; too much exposure can cause human skin cancer; the UV spectrum has three bands

unflued: an appliance without a connection to the outside air for its exhaust gases

unregulated river: refers to non-regulated rivers in the State, including those where the flows are not controlled by dams or weirs; on these rivers, volumes are not currently specified on irrigation licences, although conditions on the timing of pumping often are

upwelling: divergence of water currents or the movement of surface water away from land leading to a 'welling-up' of deeper water that commonly is richer in nutrients than surface waters

urban consolidation: policies/programs intended to increase the density of dwellings and population in urban areas to make more efficient use of the existing infrastructure, to limit urban spread into surrounding rural areas

urban salinity: the presence of saline soils in urban areas

vascular plant: a grouping of plants that includes ferns, the gymnosperms (e.g. pines) and flowering plants

volatile: easily able to be vaporised at a relatively low temperature

vulnerable species: species that may soon become endangered if causal factors (habitat destruction, over-exploitation, and other environmental disturbances) continue

waste hierarchy: the levels of waste management including avoidance, reuse, recycle and reprocess, and disposal

waste stream: designated sectors of waste including municipal, commercial and industrial, and construction and demolition, as recognised in the national solid waste classification scheme

waste water: water that carries waste from homes, businesses and industries; a mixture of water and dissolved or suspended solids

water column: general term to describe the water overlying the bed of a water body

water cycle: the natural cycle of supply and application of water in the environment

watertable: the interface between ground water and the soil substrate or air

watershed: the drainage area of a stream

wetlands: land areas situated along fresh and saltwater courses that are inundated with shallow fresh, brackish or saline water on a temporary or permanent basis, that is usually slow-moving or stationary

wilderness: an area which, together with its plant and animal communities, is in a state that has not been substantially modified by humans or is capable of being restored to such a state; is of sufficient size to make its maintenance in such a state feasible; and i

zooplankton: microscopic animals which move passively in aquatic ecosystems