Definitions of Pollution
In the UK the Royal Commission on Environmental Pollution has defined pollution as:-
	"The introduction by man into the environment of substances or energy liable to cause hazard to human health, harm to living resources and ecological systems, damage to structures or amenity, or interference with the legitimate uses of the Environment"
Pollution is caused by substances known as "pollutants". In the USA the Environmental Protection Agency defines a pollutant as:- "Any substance introduced into the environment that adversely affects the usefulness of a resource"
Whilst internationally the United Nations Convention on the Law of the Sea (UNCLOS) defines pollution of the marine environment as:-
	"The introduction by man, directly or indirectly, of substances or energy into the marine environment which results or is likely to result in such deleterious effects as harm to living resources, hazards to human health, hindrance to marine activities including fishing,impairment of quality for use of sea water, and reduction of amenities"
These statements identify the essential element of pollution namely that it is manmade and that damage is inflicted on the environment. Although this might seem obvious, the task of identifying pollutants is not necessarily a simple one. Manmade substances are generally produced by processing naturally occurring materials, they may actually be designed to mimic natural systems and it can therefore be very difficult to tell whether a particular emission is "anthropogenic" (manmade) or naturally occurring in the local environment. The task of quantifying the level of pollutant and the related damage can also be very difficult. Some individual pollutants may be present in concentrations that would not be expected to cause damage.However, if a number of these are present together, their combined effect might still lead to environmental damage, i.e. their effects are additive. Some pollutants become more damaging in the presence of other elements. So although analysis might indicate that the pollutant concentration is within "safe" levels, the presence of other elements will increase the "polluting power" of the original contaminant and inflict environmental damage. This is known as a synergistic effect and can have serious implications for environmental chemists. Locations where the "synergistic effect" is taking place may suffer extensive long-term damage since analysis will not indicate damage is expected at these particular concentration levels. The pollutant will therefore continue to cause harm, and until it is clear that something is wrong no action will be taken, unfortunately by this point the damage may be irreparable. In addition to this there are materials that do not appear to cause damage in the short term but their build up in the environment can cause long-term effects and be very damaging. The activity of pollutants can also be affected by environmental factors such as weather conditions. A flash flood for example can often lead to elevated levels of pollution, and therefore damage, as the sediments in rivers become agitated and release pollutants in higher concentrations than normal. Similarly oil spills may cause more damage if the local tidal conditions and landscape tend to trap the oil rather than aiding dispersal. It is fairly clear to see that in the real environment identification of a pollutant can be an extremely difficult and confusing task as each of the various individual factors take effect.
Task 2: Investigate the list below, which of these do you consider to be "polluting" if any and why? a) The spillage of 35,000 tons of oil by the tanker the Exxon Valdez in Alaska b) High concentrations of lead in Cornwall soils c) The accidental dumping of 100 cubic meters of milk from a dairy tanker into a small Scottish stream d) The smoke from 1 cigarette e) The discharge of industrial wool cleaning detergents into the river Aire f) The spraying of fertilizer on farm land