The issues of bioaccumulation, persistence, and mobility, as discussed previously, are closely related to the concern over long-range transport (LRT) of an environmental pollutant. The importance of this concern is at the international level, as evident from the workshop held recently addressing the LRT of air toxics into and out of the Great Lakes basin (Ann Arbor Statement, 2003).

Another indication of this importance is the editorial comments by Matthies and Scheringer (2001) concerning the occurrence of pesticides and other industrial chemicals in the Arctic, which is a rather remote region of the earth. As they put it, "These substances have never been emitted in such regions and, thus, must have been transported over long distances from moderate or even tropical climatic zones."

Contrary to classic belief, the mode of LRT is no longer restricted to atmospheric. There are data (AMAP, 1997) showing that nuclear wastes and certain persistent organic pollutants (POPs) can be transported in ocean currents over long distances, such as from reprocessing plants in Europe to the Arctic Ocean. In addition, as already discussed in Part II in relation to bioaccumulation, at least one study (Ewald et al. 1998) suggested that POPs like PCBs can be transported over a long distance by animal migration, such as by pacific salmon.

Interestingly enough, with the aid of storms or cyclone activities, even soil dust emitted from the Chinese and Mongolian arid regions could be transported over the North Pacific Ocean, all the way to North America (Takemura et al., 2002).