Analysis of PCB levels in snow from the Aconcagua Mountain (Southern Andes) using the stir bar sorptive extraction

This paper presents a first result of an investigation of the presence of anthropogenic pollutants named polychlorinated biphenyls (PCBs, sum of 25 congeners) in snow samples in the Aconcagua Mountains in the Andean Range, along an altitudinal gradient. Samples were taken during an expedition in 2003 and analysed by using a specific technique of thermodesorption and GC-MS adapted to small amount of sample. Mountain ecosystems could be efficient natural trap of persistent organic pollutants (POPs) transported by the atmosphere, and it is shown in this note that PCBs are also present in snow samples but at low concentrations, levels ranged from 0.02 to 0.190 ng/L. The detected congeners were those more persistent (PCB 138, PCB180) and compared to other mountain and cold areas around the world, detected levels are in the low range indicating that pollution levels are lower in the southern hemisphere. This results points out the need of investigating with some more detail the role of mountains in the trapping of POPs and the associated risks including the climate change.