A closed analytical formula for the characteristic spatial range of persistent organic pollutants

In order to use mobility as a criterion for priority setting amongst enviro nmental chemicals the characteristic spatial range of a substance has been introduced. Roughly spoken, the spatial range is the typical distance a che mical can travel before degradation - after release from a point source in an isotropic environment with the same average gee-chemical properties as t he earth. The present contribution starts with a formal definition of spati al ranges in terms of exposure. Then a simple isotropic model of global cir culation is set up in analogy to previous unit-world models, covering globa l long-range transport and (pseudo-)first-order degradation. Afterwards, th e model is solved analytically, and a closed formula for spatial range is o btained. The formula is then evaluated for a selection of representative en vironmental chemicals. The characteristic spatial ranges thus obtained are identical with results obtained by M. Scheringer on the basis of a more det ailed computer model. It is stressed that the present result allows for a c lassification of environmental chemicals with respect to spatial range simp ly by inserting known measurable quantities into a given formula. The whole approach was designed to make the assessment procedure as workable as poss ible. (C) 2000 Elsevier Science B.V. All rights reserved.