Passive sampling as a tool for determination of micro-organic compounds in groundwater resources

Micro-organic (MO) compounds have been recognized as an important factor in environmental pollution. Developments in a range of analytical techniques are expanding the number of MOs that can be detected in groundwater. They may not be new contaminants, but recently detected using improved sampling and analytical methods. Monitoring programmes for groundwater are largely based on the collection of grab (spot) samples. One of the methods to determine the presence of organic compounds in groundwater v can also be passive sampling. Contrary to grab sampling, passive sampling is less sensitive to accidental extreme variations of the organic compounds concentrations in groundwater and it also allows determination of a large range of contaminants at once. A passive sampler can cover a long sampling period, integrating the pollutant concentration over time. This paper presents the application of the passive sampling technique for monitoring organic pollutants within the four major alluvial aquifers in Slovenia used for water supply. Passive samples were analyzed by gas chromatography mass spectrometry (GC-MS). For the interpretation of chromatograms, the AMDIS deconvolution was used. The deconvolution was covered by the GC-MS library with retention times for 921 organic contaminants from Agilent USA, as well as by the NIST 2008 library of mass spectra. Most frequently detected MO substances were classified in different pollutant groups with respect to their origin (urban source, agriculture or industry). Based on the results, a comparison of the presence of MOs in the present aquifers was made. Passive sampling with active carbon fibres was proved to be an appropriate method for monitoring micro-organic pollutants in groundwater.