Persistent organic pollutant#Long-range transport

The atmospheric long-range transport (English: long-range atmospheric transport or long-range transport distance ), the airborne transport of pollutants over a long distance (typically several hundred or thousand km).

The atmosphere is one of the main transport medium for contaminants. Both transformation products as well as the actual pollutant can put down in distant source regions ( deposited ) are. In terms of the above-mentioned definition, however, is only the wide distribution of the actual pollutant to take atmospheric long-range transport by the term. The only prerequisite is that the pollutant stable ( inert) to environmental factors, i.e., during transportation is not subject to chemical transformation. Most pollutants that are stable according to belong to the group of persistent organic pollutants (POPs) [ of Engl. Persistent organic pollutants ].

Background

The theory of long-range transport of pollutants in the atmosphere has been developed in order to explain the presence of pollutants far from their areas of application can.

One of the world most polluted with POPs of these are the Inuit, who have fallen victim to this effect, although they themselves do not emit POPs.

The concentrations of pollutants such as DDT, lindane and other pesticides are sometimes in areas where it hardly be applied, higher than in tropical countries, where they are used for pest control. Some areas may, depending on the season, both as sinks as well as sources of persistent organic pollutants ( POP) function. Since this process is similar to the chemical process of distillation ( only evaporate then condense ), the process of the long range transport will be referred to as global or distillation grasshopper effect.

Mechanism

The theory of global distillation ( also locusts effect or grasshopper effect called ) states that pollutants, depending on their physico-chemical properties (eg solubility, vapor pressure, etc.) can be varied widely transported in the atmosphere before they are dry and wet deposition return to the earth. Here, a pollutant repeatedly deposited and ( included in the air) by vaporization / evaporation again remobilized be before it is finally disposed of ( grasshopper effect). The final deposition of the long-range atmospheric transport underlying pollutant takes place especially in the polar regions, since a re- evaporation / volatilization is unlikely due to the low temperatures.