137
Chapter 7
Toxic Pollution
7.1 TOXIC POLLUTANTS, BIOACCUMULATION
AND BIOMAGNIFICATION
Many toxic pollutants can be characterised as “general” because they act
on various parts of the environment (air, water, ground, biomass in food
chains). Their potential hazard for organisms depends at each moment in
time on their concentration and toxicity. A number of general pollutants
that move by means of foods within the trophic chains appear in increasing concentrations from the lowest to the highest trophic levels. This phenomenon is known as biomagnification and can occur when pollutants are
persistent, that is, when they do not break down or break down only with
difficulty (e.g. metals, radioactive elements, stable organic compounds) and
are not quickly eliminated by organisms. Biomagnification is due to a combination of the low rate at which the pollutants are eliminated or broken
down and low energy efficiency all along the food chain (Chapter 4). The
concentration of a persistent pollutant on one trophic level may appear on
the next level increased by a factor even of the order of 10.
Biomagnification lends another, very serious aspect to some problems
of pollution. A pollutant’s toxic effect depends on its concentration in the
bodies of organisms; therefore even a low concentration of a toxic pollutant
in the environment can have a serious toxic effect on an organism if great
biomagnification occurs. As a result, the persistence (stability) of a pollutant greatly affects its environmental hazard potential (Table 7.1).
Another important phenomenon that increases the toxic impact of pollutants on organisms is bioaccumulation, which does not occur along a food
chain but in an organism’s tissues; for example the increased concentration
of a toxic pollutant in the fat, the liver, the brain or other organs able to
store certain substances.
As a rule, toxic pollution is anthropogenic, because it results directly
or indirectly from production activities. However, there are cases where
toxic effects are due to natural “pollution.” Many organisms produce toxic
substances for defence, and many other organisms are susceptible to them.
DOI: 10.1201/b14609-7
Chapter 7
Toxic Pollution
7.1 TOXIC POLLUTANTS, BIOACCUMULATION
AND BIOMAGNIFICATION
Many toxic pollutants can be characterised as “general” because they act
on various parts of the environment (air, water, ground, biomass in food
chains). Their potential hazard for organisms depends at each moment in
time on their concentration and toxicity. A number of general pollutants
that move by means of foods within the trophic chains appear in increasing concentrations from the lowest to the highest trophic levels. This phenomenon is known as biomagnification and can occur when pollutants are
persistent, that is, when they do not break down or break down only with
difficulty (e.g. metals, radioactive elements, stable organic compounds) and
are not quickly eliminated by organisms. Biomagnification is due to a combination of the low rate at which the pollutants are eliminated or broken
down and low energy efficiency all along the food chain (Chapter 4). The
concentration of a persistent pollutant on one trophic level may appear on
the next level increased by a factor even of the order of 10.
Biomagnification lends another, very serious aspect to some problems
of pollution. A pollutant’s toxic effect depends on its concentration in the
bodies of organisms; therefore even a low concentration of a toxic pollutant
in the environment can have a serious toxic effect on an organism if great
biomagnification occurs. As a result, the persistence (stability) of a pollutant greatly affects its environmental hazard potential (Table 7.1).
Another important phenomenon that increases the toxic impact of pollutants on organisms is bioaccumulation, which does not occur along a food
chain but in an organism’s tissues; for example the increased concentration
of a toxic pollutant in the fat, the liver, the brain or other organs able to
store certain substances.
As a rule, toxic pollution is anthropogenic, because it results directly
or indirectly from production activities. However, there are cases where
toxic effects are due to natural “pollution.” Many organisms produce toxic
substances for defence, and many other organisms are susceptible to them.
DOI: 10.1201/b14609-7