Technical note: GUARD – an automated fluid sampler preventing sample alteration by contamination, evaporation and gas exchange, suitable for remote areas and harsh conditions

摘要

Automated water sampling devices adapted to field operation have proven highly usefulfor environmental research as well as in the public and private sectors,where natural or artificial waters need to be tested regularly for compliancewith environmental and health regulations. Such autosamplers are alreadyavailable on the market in slightly differing versions, but none of thesedevices are capable of sealing the collected samples to prevent samplealteration by contamination, evaporation or gas exchange. In many samplingcases, however, this feature is essential, for instance for studying thehydrological cycle based on isotopes in rainwater, or for monitoring waterscontaminated with toxic gases or other volatile compounds detrimental tobiota and human health. Therefore, we have developed a new mobileautosampler, which injects water samples directly into airtight vials, thuspreventing any sample alteration. Further advantages include low productioncosts, compact dimensions and low weight allowing for easy transport, a widerange of selectable sampling intervals as well as a low power consumption,which make it suitable for long-term applications even in remote areas andharsh (outdoor) conditions due to its heavy-duty water-proof casing. In thispaper, we demonstrate (1) the sampler's mechanical functioning, (2) thelong-term stability of the collected samples with regard to evaporation andgas exchange and (3) the potential of our device in a wide variety ofapplications drawing on laboratory and field experiments in different karstcaves, which represent one of the most challenging sampling environments.