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A.R.D. Stebbing . R.I. Willows
8.3.1
Definitions
The original definition of assimilative capacity was applied to freshwater pollution and
meant the ability of an ecosystem to cope with certain levels of waste discharges, without suffering any significant deleterious biological effects (Cairns 1977). This was broadened later to mean "the amount of material that could be contained within a body of
seawater without producing an unacceptable biological impact" (Goldberg 1981). It was
then redefined by the GESAMP (Group of Experts on the Scientific Aspects of Marine
Environmental Protection) and given a wider meaning as "a property of the environment, defmed as its ability to accommodate a particular activity, or rate of activity,
without unacceptable impact" (Pravdic 1985). (GESAMP renamed "assimilative capacity', as "environmental capacity", but this change has not been taken up byenvironmental economists and social scientists, so the original term will be retained here.)
The history and semantics of the concept are considered in more detail by Stebbing
(1992 ).
We emphasize two points: First, Cairn's definition referred to an ability to "cope"
with discharges, while Goldberg's refers to the amount of material that could be "contained", but Pravdic's wording provides more insight describing assimilative capacity
as accommodating a "rate of activity". This is an important distinction, as we will show
in Section 8.3.2. Second, throughout the evolution of the concept, the aim has been to
permit the use of the assimilative capacity of receiving waters to accept wastes without causing harmful biological effects.
The GESAMP considered the concept in some depth and agreed that it was based
on three premises, which give greater meaning to their definition:
1. A certain level of some contaminants may not produce any undesirable effect on
the marine environment and its various uses.
2. Each environment has a finite capacity to accommodate some wastes without unacceptable consequences.
3. Such capacity can be quantified, apportioned to a certain activity, and utilized.
GESAMP changed the emphasis of the definition to "levels of contaminants", rather
than their "biological effects", and much hangs on the use of the word 'undesirable'.
We consider this to have been a retrograde shift of emphasis, since it is as though the
presence of chemical contaminants in the marine environment, rather than their deleterious effect, that is of more importance.
The related concept of "pollution" has been defined by GESAMP and their definition generalized by Holdgate (1979) is as follows:
"The introduction by man into the environment of substances or energy liable to cause hazards to
human health, harm to living resources and ecological systems, damage to structures or amenity, or
interfere with legitimate uses of the environment:' (Authors emphasis)
The concepts of "pollution" and "assimilative capacity" are dearly related terms,
although the way in which they have been defined does not link them explicitly
(Pravdic 1985). The underlying intent of both "assimilative capacity" and "pollution" is
the prevention of deleterious effects on biological systems. Pollution or "harm to liv-
A.R.D. Stebbing . R.I. Willows
8.3.1
Definitions
The original definition of assimilative capacity was applied to freshwater pollution and
meant the ability of an ecosystem to cope with certain levels of waste discharges, without suffering any significant deleterious biological effects (Cairns 1977). This was broadened later to mean "the amount of material that could be contained within a body of
seawater without producing an unacceptable biological impact" (Goldberg 1981). It was
then redefined by the GESAMP (Group of Experts on the Scientific Aspects of Marine
Environmental Protection) and given a wider meaning as "a property of the environment, defmed as its ability to accommodate a particular activity, or rate of activity,
without unacceptable impact" (Pravdic 1985). (GESAMP renamed "assimilative capacity', as "environmental capacity", but this change has not been taken up byenvironmental economists and social scientists, so the original term will be retained here.)
The history and semantics of the concept are considered in more detail by Stebbing
(1992 ).
We emphasize two points: First, Cairn's definition referred to an ability to "cope"
with discharges, while Goldberg's refers to the amount of material that could be "contained", but Pravdic's wording provides more insight describing assimilative capacity
as accommodating a "rate of activity". This is an important distinction, as we will show
in Section 8.3.2. Second, throughout the evolution of the concept, the aim has been to
permit the use of the assimilative capacity of receiving waters to accept wastes without causing harmful biological effects.
The GESAMP considered the concept in some depth and agreed that it was based
on three premises, which give greater meaning to their definition:
1. A certain level of some contaminants may not produce any undesirable effect on
the marine environment and its various uses.
2. Each environment has a finite capacity to accommodate some wastes without unacceptable consequences.
3. Such capacity can be quantified, apportioned to a certain activity, and utilized.
GESAMP changed the emphasis of the definition to "levels of contaminants", rather
than their "biological effects", and much hangs on the use of the word 'undesirable'.
We consider this to have been a retrograde shift of emphasis, since it is as though the
presence of chemical contaminants in the marine environment, rather than their deleterious effect, that is of more importance.
The related concept of "pollution" has been defined by GESAMP and their definition generalized by Holdgate (1979) is as follows:
"The introduction by man into the environment of substances or energy liable to cause hazards to
human health, harm to living resources and ecological systems, damage to structures or amenity, or
interfere with legitimate uses of the environment:' (Authors emphasis)
The concepts of "pollution" and "assimilative capacity" are dearly related terms,
although the way in which they have been defined does not link them explicitly
(Pravdic 1985). The underlying intent of both "assimilative capacity" and "pollution" is
the prevention of deleterious effects on biological systems. Pollution or "harm to liv-