MONARPOP  Methods  Techniques  Air sampling

Air sampling

Active samplers, located on three peaks in Austria (Sonnblick), Germany (Zugspitze) and Switzerland (Weissfluhjoch) aspirate the surrounding air and pass it through special filters, where pollutants are trapped. There are low and high volume samplers (regarding the processed air volume) because pollutants have quite different air concentrations and thus need varying air volumes to be sampled.

An array of separate filters (see picture to the right) is used distinguish between pollutant imports from different continental regions. The Austrian Central Institute for Meteorology and Geodynamics (ZAMG) determines the travel route (trajectory) of the incoming air masses. Depending on its origin, the air is loaded onto a corresponding filter. Remote control allows to match filter cartridges and trajectories on a daily base. (The necessary equipment has been developed by the Austrian Umweltbundesamt in co-operation with Dioxin Monitoring Systems, DIGITEL enviro-sense and Kroneis.)

Passive samplers trap pollutants from the ambient air in special substances (e.g., activated carbon) which are chemically similar to the pollutants of interest. A special passive sampler is the SPMD (semipermeable membrane device): a liquid with high affinity to POPs is surrounded by a membrane which lets the pollutants enter but not out again. POPs thus accumulate in the liquid. One can also think of the SPMD as an artificial needle - in contrast to natural conifer needles, frequently used for bioindication. Consequentially, SPMD samples will be compared with pollutant concentrations of Norway spruce needles from the same site.

Deposition samplers at the same sites as active samplers collect wet and dry deposition . Because temperatures at these sites drop to -30 °C and below, a special technical design has to prevent snow and ice from filling up the samplers.