Persistent organic pollutants (POPs)

It has recently been discovered that semi-volatile persistent organic pollutants (POPs), which occur globally as a result of human release, become concentrated in cold regions. The reason is that these compounds condense at low temperature and become trapped in high mountains and polar ice masses. In northern lakes and glaciers, such compounds can accumulate to toxic levels. So far POPs are the only category of pollutants where cold condensation effects are known. For example, semi-volatile organochlorine compound deposition rates have increased 60-100-fold in snowpack over a 2300 m rise in elevation in the Canadian Rockies (Blais et al. 1998).