Macmillan Dictionary of the Environment

382 Pages·1994·25.919 MB·English

by  Michael Allaby (auth.)

MACMILLAN
DICTIONARY
OF
THE
ENVIRONMENT
MACMILLAN
DICTIONARY
OF
THE
ENVIRONMENT
FOURTH EDITION
MICHAEL ALLABY
M
© Michael Allaby, 1977, 1983, 1988, 1994
All rights reserved. No reproduction, copy or
transmission of this publication may be made without
written permission.
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Any person who does any unauthorised act in relation to
this publication may be liable to criminal prosecution and
civil claims for damages.
First edition published 1977, paperback 1979.
Second edition published 1983, paperback 1985.
Third edition published 1988, paperback 1988.
Reprinted 1991.
Fourth edition first published 1994 by
THE MACMILLAN PRESS LTD
London and Basingstoke
Associated companies in Auckland, Delhi, Dublin,
Gaborone, Hamburg, Harare, Hong Kong, Johannesburg,
Kuala Lumpur, Lagos, Manzini, Melbourne, Mexico City,
Nairobi, New York, Singapore, Tokyo.
A catalogue record for this book is available from The
British Library.
ISBN 978-0-333-61655-0 ISBN 978-1-349-13495-3 (eBook)
DOI 10.1007/978-1-349-13495-3
Preface to the Fourth Edition
During the six years that have passed since the publication of the third edition of the
Dictionary of the Environment the study of environmental sciences has established itself
firmly in the curricula of most schools, although not always under that formal name. Envir
onmental sciences also feature in many courses in further and higher education undertaken
by students whose careers will require them to understand the environmental effects of
human activities and the laws and regulations intended to control those effects. If, as some
believe, there was once a time when people carelessly regarded their surroundings as no
more than a source of materials and repository for their wastes, that time is long past.
Today, planners, builders, manufacturers, providers of services, and you and I as house
holders are required to take account of the environmental consequences of our actions.
This, of course, is as it should be.
As comment on environmental matters has advanced from pious exhortation to practical
application, the language employed has grown more technical. The intensification of scient
ific research has generated new expressions, many of which occur in newspapers and broad
casts, along with a proliferation of organizations, regulations, and acronyms. In this revision
of the Dictionary I have added most of the scientific terms and organizations that have
emerged since the last edition. Scientific terms have been identified partly from scientific
journals and textbooks on environmental sciences. The newly added organizations and
acronyms include those associated with the 1992 United Nations Conference on Environ
ment and Development (UNCED), which was variously nicknamed the 'Earth Summit' and
'Rio Summit' (after the city in which it was held).
Preparation of a dictionary begins with a definition of its scope. When the first edition of
this Dictionary was planned, the 'environment' was assumed to comprise the rocks and
land-forms of the Earth's surface, the oceans and atmosphere, living organisms, industrial
and technological processes, organizations, and concepts derived from economics. Within
this vast framework, a small team of contributors and advisers attempted to select a neces
sarily limited number of the most relevant terms. This produced a general structure that
has survived through subsequent revisions, including this one.
Retention of the essential structure implies no lack of rigour in making revisions, and this
revision has been very thorough. I have added many new entries, removed some earlier
ones, and altered a large number, sometimes substantially, to clarify them or bring them
up to date. Some of the taxonomic terms, for example, have been modified to take account
of recent changes in classification. Every entry has been studied carefully and where I saw
room for improvement I made it. I have added those environmental disasters which occurred
since the last edition, both as entries in their own right and in summary form in the table
of 'environmental disasters', which I introduced in the Third Edition and have retained.
As with the last edition, for this revision I have not approached those who contributed
entries to the earlier editions. The revisions are my own and I must bear responsibility for
any errors I may have introduced. Nevertheless, many of the definitions included here are
essentially those contributed and verified by Ailsa Allaby, Dr G. Browning, Dr M.D.
Hooper, John Macadam, Margaret Palmer, Professor F. Roberts, Professor R.S. Scorer,
and Professor E.K. Walton, to whom I remain deeply grateful.
Michael Allaby
Wadebridge, Cornwall
January 1994
A
A. See AMPERE. dates are usually quoted with a plus or minus
error.
a. See ATIO-.
absolute humidity (humidity mixing rate). The
aa. (1) In many parts of Europe, a small river, amount of water present in a unit mass of air,
the word (derived originally from the Latin usually expressed as grams of water per kilo
aqua, 'water') often forming part or all of the gram of air.
name. (2) In volcanology, a Hawaiian term
describing a basaltic (see BASALT) LAVA with a absorbate. See ABSORPTION.
rough, blocky surface, often covered with
clinker, and formed by rivers of lava that may absorbent. See ABSORPTION.
overflow. Compare PAHOEHOE.
absorbing duct. The tube used in a ventilator
aba~a. Manila hemp (Musa textilis), grown to attenuate sound waves while offering low
mainly in the Philippines and the toughest of resistance to a continuous flow of air.
all natural fibres. It is used to make ropes and
is resistant to salt water. absorption. (1) A process in which one material
(the absorbent) takes up and retains another
abaxial. The surface of a leaf that faces away (the absorbate) to form an homogeneous solu
from the stem (i.e. the DORSAL surface). Com tion. (2) The process by which substances
pare ADAXIAL. become attached to a solid surface by physical
forces (see ADSORPTION), e.g. absorption of
abiocoen. All the non-living components of the sulphur dioxide (S02) by stone, vegetation,
environment. particulate AEROSOLS, etc. (3) The transfer of
energy from radiation passing through the
atmosphere to a substance such as aerosols, or
abioseston. The non-living matter floating in
to a gaseous atmospheric component (e.g. of
water. See SESTON. Compare BIOSESTON.
ULTRAVIOLET (UV) radiation by OZONE (03)
or of infra-red radiation by CARBON DIOXIDE
abiotic. Non-biological. Compare BIOTIC.
(C02) or water vapour). Absorption also
occurs in the ocean. The absorption of gases by
ablation. The removal of a surface layer. The plants depends on the state of the vegetation,
term is applied especially to the melting and HUMIDITY, temperature, and various physical
evaporation of the surface of ice, and to the laws. The absorption of light by water may be
removal of loose surface material by the wind expressed as the path length in which the
(DEFLATION). intensity is reduced by the factor e
(approximately 2.73) or by the reduction of
abscisic acid. See ABSCISIN. intensity per unit of path length.
abscisin (abscisic acid, dormin). An AUXIN absorption coefficient (acoustics). If a surface
which induces leaf-fall and dormancy in seeds is exposed to a field of sound, the ratio of the
and buds, probably by inhibiting the synthesis sound energy absorbed by the surface to the
of nucleic acid (see DNA, RNA) and PROTEIN. total sound energy that strikes it. An absorp
tion coefficient of 1 would mean that all of the
absolute age. The age of a ROCK, MINERAL, or sound energy was absorbed. See ANECHOIC.
FOSSIL in years, determined as a RADIOMETRIC
AGE or by counting VARVES. Radiometric absorption tower. A structure, most commonly
dating involves experimental errors, so such found in chemical factories, in which a liquid
2 absorptive capacity
is made to absorb a gas (e.g. in the production Acacia albida. A leguminous (see
of SULPHURIC ACID from sulphur dioxide/ LEGUMINOSAE) tree, native to semi-arid Medi
trioxide and water). terranean regions, that bears its leaves during
the dry season and is leafless throughout the
absorptive capacity (assimilative capacity). A rainy season. The leaves and pods (whose
measure of the amount of waste that can be nutritional value is not reduced by drying) are
deposited in a particular environment without palatable to livestock and the seeds (containing
causing adverse ecological or aesthetic change. up top 27% crude PROTEIN) also to humans,
See BEST PRACTICABLE ENVIRONMENTAL usually mixed with meal.
OPTION.
acanthite (Ag2S). A major ORE MINERAL of
abstractive use. Of water, a use which removes silver found in HYDROTHERMAL deposits, char
it so that it is lost temporarily as a resource acteristically with lead, zinc, and copper min
(e.g. in a COOLING TOWER). Compare NON erals, which also contain silver by atomic sub
ABSTRACTIVE USE. stitution. Acanthite also occurs in SUPERGENE
deposits. Nearly all the silver produced is a by
abyssal. Very deep. Applied to the sea bed at product from mining for lead, zinc, and
water depths greater than about 2000 m copper. Apart from its uses in photography,
(compare BATHYAL). The term may also be most industrial applications of silver utilize its
applied to the zone in lakes below the depth of high reflectivity and conductivity, as well as its
effective (i.e. for PHOTOSYNTHESIS) penetra resistance to organic corrodants. Compare
tion of light. See also ABYSSOPELAGIC. ARGENTITE.
abyssal gap. A gap in a SILL, RIDGE, or rise Acanthocephala (spiny-headed worms). A
that separates two ABYSSAL PLAINS and phylum of about 600 species of parasitic (see
through which the sea floor slopes from one PARASITISM) worms, with affinities to the
plain to the other. NEMATODA, whose common name refers to the
spiny proboscis by means of which they attach
abyssal hill. A relatively small topographic fea themselves to their hosts. The larvae live in
ture of the deep ocean floor, ranging up to 1000 insects or CRUSTACEA, the adults in the gut of
m high and a few kilometres wide. vertebrates, including mammals, and they can
cause serious illness and sometimes death (e.g.
Echynorhynchus proteus, the adult of which
abyssal plain. A large, relatively flat area of the
lives in ducks and the larva in freshwater
deep sea floor lying seaward of the CONTIN·
shrimps).
ENTAL SLOPE and rise, where gradients become
less than 1:1000.
Acanthodii. An extinct group of small fishes,
abyssobenthos. An ocean floor at great depths. originating in the SILURIAN PERIOD, that were
the first vertebrates known to possess jaws.
See BENTHOS.
Their fins were supported by long spines.
abyssopelagic. Applied to PELAGIC organisms
living at water depths greater than about 3000 acaricide. A chemical (e.g. DERRIS and some
m. Compare BATHYPELAGIC, EPIPELAGIC, ORGANOPHOSPHORUS, DINITRO, and ORGAN·
MESOPELAGIC. OCHLORINE compounds) used to kill ticks and
mites (ACARINA).
Acacia (wattles). A genus of leguminous (see
LEGUMINOSAE) trees of the tropics and sub Acarida. See ACARINA.
tropics, especially Australasia, which may form
the dominant vegetation in arid areas. Dyes, Acarina (Acarida; mites and ticks). An order
perfumes, timber, and many other commercial of small ARACHNIDA with rounded bodies.
products are derived from acacias and Mites are very abundant in the soil, feeding on
increased exploitation of some (e.g. A. ALBIDA) plant material and invertebrate animals. Some
might be of great value to people living in arid parasitic mites (e.g. 'red spider') damage crops
regions. and can be serious pests. Others cause diseases
acetic acid 3
in animals (e.g. mange). Ticks are blood point may be reached at which the accident
suckers, some being VECfORS of diseases (e.g. becomes inevitable and secondary prevention
Rocky Mountain spotted fever in humans, is needed to minimize its effects. Tertiary pre
relapsing fever in humans and fowls, and loup vention, involving measures implemented after
ing-ill in cattle and sheep). the accident, is directed towards the recovery
of injured persons and repair of environmental
acceleration. Rate of change of velocity with damage.
time. According to Newton's laws, acceleration
x mass = force = rate of change of momentum. accident scenario. A simulation of an imagined
Momentum is a vector, and motion in a curved disaster (g. the catastrophic failure of a nuclear
path therefore requires the application of a reactor, a major fire releasing toxic fumes,
force. In the atmosphere or ocean, vertical etc.) to test the response of emergency services
motion always requires horizontal accelera and to help estimate the extent of damage and
tion, which results from BUOYANCY forces. injury. Such scenarios may be planned at any
organizational level, but those involving major
access agreement. As defined by the COUNTRY incidents with international implications com
SIDE COMMISSION, in British planning, an monly involve extensive international collab
agreement allowing the public access to pri oration and the sharing of resulting data.
vately-owned land, being OPEN COUNTRY suit
able for open-air recreation. acclimatization. The process of adapting to ABI
OTIC environmental conditions, by phenotypic
access order. As defined by the COUNTRYSIDE (see PHENOTYPE) rather than genetic variation.
COMMISSION, in British planning, an order
allowing the public access to privately-owned accretion. The attachment of airborne material
land, being OPEN COUNTRY where an ACCESS to fixed, falling, or flying objects. Ice accretion
AGREEMENT is impracticable or does not occurs on wires, hailstones, or aircraft wings
adequately secure public access to the land for when the air contains supercooled (see
open-air recreation. SUPERCOOLING) cloud droplets, DRIZZLE, or
rain, and is particularly dangerous on the rig
accessory species. A species which occurs in ging of ships in polar regions or on TV masts
one-fourth to one-half of a STAND. Compare on hills in winter. Pollution accretion is exem
ACCIDENTAL SPECIES. plified by smoke deposition on window frames,
ventilation intakes, etc., where the airflow is
accessory mineral. A MINERAL occurring in swift and curved.
small amounts in a ROCK and disregarded in
the classification of that rock (which is based Acer (maples). A genus of trees and shrubs
on ESSENTIAL MINERALS). Accessory minerals (family Aceraceae) found in temperate
can yield evidence about the origin of the rock regions. They yield charcoal and timber, and
(e.g. the presence of metamorphic (see A. saccharum is the source of maple sugar.
METAMORPHISM) minerals in a SANDSTONE sug
gests a provenance, at least in part, from a acetaldehyde (ethanal, CHCHO). A direct
3
metamorphic belt). oxidation product of ETHANOL (ethyl alcohol),
made industrially from ethene ( ~H4), which
accidental species. A species which occurs in can be further oxidized to ACETIC ACID. It is
less than one-fourth of a STAND. Compare an important raw material for certain organic
ACCESSORY SPECIES. compounds, has medical uses, and, being very
volatile, is used as solid pellets to fuel cooking
accident profile. A description of an accident stoves. It has the flavour of apple, and is used
which includes the preceding and succeeding as a food ADDITIVE.
events as well as the accident itself. During the
first phase, often extending over several years, acetic acid (ethanoic acid, CH .COOH). The
3
primary prevention may identify and correct acid in vinegar, and an important industrial raw
events that may contribute to an eventual acci material, obtained by FERMENTATION from
dent. In the absence of primary prevention a alcohols.
4 acetone
acetone (propanone, CH3COCH3). An import acid droplets. Minute liquid particles emitted
ant laboratory and industrial solvent, and raw by certain industrial processes, which act as
material for making PLASTICS. It is miscible CONDENSATION NUCLEI. See ACID RAIN, SUL
with water. PHURIC ACID.
acetylcholine (Ach). A substance released in acidic (acid). Applied to IGNEOUS rocks con
minute amounts at many nerve endings when taining more than a certain percentage
impulses arrive, so transmitting the impulses to (commonly set at 65%) of SILICA (Si02) in their
other nerve cells or effectors (e.g. muscles). Its chemical composition. Most of the silica is in
effects disappear rapidly after secretion the form of SILICATE MINERALS (e.g.
because it is destroyed by the ENZYME FELDSPARS, MICAS, and AMPHIBOLES), but the
cholinesterase. excess silica manifests itself in the presence of
10% or more free QUARTZ. GRANITE, RHYOL
ITE, and OBSIDIAN are all acidic rocks. In PET
acetylene (ethyne, ~H2). A colourless, poison
ous, HYDROCARBON gas, which can be pre ROLOGY, acidic is contrasted with INTERME
DIATE, BASIC, and ULTRABASIC, but not with
pared by the action of water on calcium
dicarbide, though other methods are also used ALKALINE.
industrially. It is used for welding, the synthesis
of ACETIC ACID, and as a starting material for acidophile. See CALCIFUGE.
many chemicals, e.g. PVC (POLYVINYL
CHLORIDE). acid rain. Generally, PRECIPITATION in any
form, or dry deposition, with a pH lower than
would be expected from natural causes (most
Ach. See ACETYLCHOLINE.
rain is slightly acid, with a pH of about 5).
Unusually acid rain was first reported in 1852,
achene. A dry, one-seeded fruit which does not downwind from Manchester, England, but it
split open (e.g. the fruit of the buttercup). Dis emerged as a serious problem in the early 1970s
persal may be aided by wings (e.g. sycamore), first in Scandinavia, where poorly BUFFERED
plumes (e.g. old man's beard), or hooks (e.g. lakes were affected, and later in central
wood avens). Europe, where forests were damaged. The
term 'rain' is somewhat misleading, since mist
achira (Queensland arrowroot). The starchy and dry deposition are more injurious to
root of Canna adulis, first domesticated in Peru vegetation than rain. The cause of acid rain is
before 2200 BC and still cultivated for human uncertain, but in some areas it is probably due
consumption. The tops are sometimes fed to to NITROGEN OXIDES, mainly from vehicle
cattle. exhausts, leading to photochemical reactions
yielding OZONE, in other areas to SULPHUR
achondrite. A stony METEORITE, without chon DIOXIDE, mainly from coal-fired power genera
tion. Natural causes (e.g. prolonged dry
drules. Compare CHONDRITE.
weather, or disease) may produce symptoms
similar to those of acid-rain damage, and high
acicular. Needle-shaped, applied especially to
emissions of dimethyl sulphide from marine
elongated crystals.
phytoplankton may also contribute sulphur,
especially in southern Scandinavia.
aciculilignosa. Needle-leaf forest and bush
comprising evergreen, coniferous vegetation. acid refractory. Materials composed mainly of
SILICA and designed to resist acid slags that are
acid. (1) (geol.) See ACIDIC. (2) (chem.) See used to line furnaces. See BESSEMER PROCESS.
pH.
acid smut. See ACID SOOT.
acid dipping. The immersion of a metal object
into a tank of suitable acid or acids to remove acid soot (acid smut). Particles of carbon held
scale and clean the surface. The process often together by water which is made acidic through
produces hazardous fumes and acid mists. combination with SULPHUR TRIOXIDE. The
actinide 5
carbon particles (soot) are emitted during com ment programmes, increasing poverty, and
bustion and are roughly 1-3 mm in diameter. consequent social and political unrest.
Where oil-burning installations have metal
chimneys, acid soot can acquire iron sulphate Acrania (Cephalochordata). A small subphy
which makes brown stains on materials and lum of the CHORDATA comprising the living
damages paintwork. Acid soot emissions can lancelets (Amphioxus) and the extinct Jaymoy
be reduced by using low-sulphur fuels, by redu tius which lived in the SILURIAN. Lancelets are
cing the airflow to minimize sulphur trioxide small, fish-like, ciliary feeders with poorly
formation, by making flues airtight, by insulat developed heads, no brain, bone or cartilage,
ing chimneys, by raising the temperature, etc. and nephridia (see NEPHRIDIUM) as excretory
organs. They may be similar to the ancestors
acoustic. Applied to properties or character of fish.
istics connected with sound (e.g. the acoustic
qualities of an auditorium). It is not used to Acraniata. See INVERTEBRATA.
refer to people, where the term is 'acoustical'
(e.g. acoustical engineer). acre-foot. The volume of any substance (but
usually water) that will cover one acre of a level
acoustical. See ACOUSTIC. surface to a depth of one foot (i.e. 43 560 cubic
feet, in SI units equal to 1232.75 m3).
acoustic reflex. The mechanism by which the
mammalian EAR protects itself against sounds Acrididae (short-horned grasshoppers). A
that are too loud, by adjusting the connecting family of grasshoppers (ORTHOPTERA) which
muscles that regulate the relative positions of have antennae shorter than their bodies. Some
the ossicles. (e.g. the locust, Locusta migratoria), although
commonly solitary, under certain conditions
develop a gregarious and migratory form which
acquired character. A variation in an organism
causes incalculable harm to crops.
which appears as a response to environmental
influence. See LAMARCK.
acrodont. Having teeth fused to the bones, a
condition found, e.g., in most bony fishes.
acquired immune deficiency syndrome. (AIDS)
A condition in humans in which the immune Compare PLEURODONT, THECODONT.
system suffers a progressive failure, leaving the
victim susceptible to opportunistic infections. acrosome. The projection on the head of a
It is caused by the human immunodeficiency sperm containing ENZYMES which play a part
virus (HIV), a slow-acting RETROVIRUS which in the fusion of egg and sperm.
invades and kills T4 helper cells. These are
integral to the immune system. AIDS is acrylic resins. A group of synthetic resins,
believed to have occurred first in the late 1950s obtained by the polymerization (see POLYMER)
and was identified as a distinct medical condi of MONOMERS derived from acrylic (propenoic)
tion in the early 1980s. It is believed to have acid (CH2.CHCOOH). They are transparent,
originated in Africa, probably by several resistant to light, weak acids, alkalis, and alco
mutations of a virus transmitted from green hols, but are attacked by oxidizing acids,
monkeys to humans in an area where green ORGANOCHLORINES, KETONES, and ESTERS.
monkeys are eaten, and within a few years fur They are used widely. Acrilan and perspex are
ther mutations produced a number of distinct acrylic resins.
viral strains. Estimates of the number of
infected persons who will develop the full actinide (actinoid). The elements ranging in the
range of symptoms varies widely, but in the periodic table from actinium (Z = 89) to
absence of an effective anti-viral drug the great lawrencium (Z = 103), and including: actinium
majority of those who develop symptoms will (Z = 89); thorium (Z = 90); proactinium (Z =
die. Some epidemiologists fear that by the end 91); uranium (Z = 92); neptunium (Z = 93);
of the century the death toll in Africa will plutonium (Z = 94); americium (Z = 95);
number tens of millions, in which case there is curium (Z = 96); berkelium (Z = 97); califor
reason to fear severe disruption of develop- nium (Z = 98); einsteinium (Z = 99); fermium