A pollutant can be any chemical (e.g., organic or inorganic compounds, radionuclide, organo-phosphorus compound, or trace gas) or geochemical (e.g., dust, sediment, substance, biological organism or product, or physical property (e.g., noise, heat) that is released intentionally or inadvertently by man into the environment with actual or potential adverse, harmful or unpleasant and inconvenient effects.
Such undesirable effects may be direct (i.e., affecting man) or indirect, being mediated via his resource organisms or climatic change. Defined simply, a water pollutant can mean anything put into water which was not there in its natural state. Any substance can be a pollutant if too much of it is present; how much is too much depends on the water use involved.
Certain indicator organisms can often be used to monitor or detect pollution. The presence of certain species may indicate the probability of some form of pollution; other species may be used to show some detectable response to pollutants and there can be certain organisms that accumulate a pollutant in large and measurable quantities, in a quantified response to exposure (see UNESCO, 1974).
Image Source: cdn.yourarticlelibrary.com
ADVERTISEMENTS:
A MAB Project (No. 14) was instituted to study environmental pollution with the objectives:-
(a) to understand the structure and functioning of ecosystems by studying a range of sites exposed to varying degrees of pollutant-load, and
(b) to identify chemical and biological observations and measurements that could be used to monitor and assess current environmental states with a view to forecasting future consequences of pollution.
ADVERTISEMENTS:
It is intended to tackle this problem by:-
(a) identification of critical environmental variables and key Species through a series of pollutant gradients,
(b) determining the correlations between pollutants and their effects in the field, and
(c) quantitative and qualitative studies of transformation and cycling of pollutants within ecosystems.
ADVERTISEMENTS:
The Project also hopes to identify and concentrate its work on certain priority pollutants, e.g., those characterized by their severity of actual or potential effects on man’s health and well-being, and on climate or on terrestrial or aquatic ecosystems, and those which are of a persistent nature being resistant to decay and degradation in the environment and accumulation in food-webs.
Recently, the list of priority pollutants (i.e., those substances which are actually or potentially carcinogenic, teratogenic or mutagenic) has been greatly expanded to include 129 priority pollutants (see Anthony and Preimhurst, 1981). This list includes 13 metals, 114 organics, cyanide, and asbestos. All these 129 substances show one or more of the properties of a priority pollutant.
The effects of toxic pollutants on receiving water have also received much recent attention. The chief problems caused by these pollutants are the restriction of domestic and industrial usage of surface water and toxicity to aquatic biota. Those toxic pollutants which accumulate in food-webs are particularly important in this context.