Identification of surface water infiltration in a shallow unconfined aquifer using artificial sweeteners as waste water markers

Andrea Bichler1, Christian Muellegger1, Thilo Hofmann1
1 Department für Umweltgeowissenschaften, Universität Wien

O 6.10 in Grundwasser-, Boden- und Oberflächenwasser-Interaktionen

30.05.2014, 15:00-15:20, H19, NW II

In shallow or unconfined aquifers infiltration of contaminated river water might be a major threat to ground water quality. Thus, the identification of hydrological pathways in coupled surface- and groundwater systems is of paramount importance to ensure water quality.

Tracers have the potential to elucidate both, sources and flow patterns, and are widely applied in hydrological flow studies. Besides conventional tracers (Cl-, SO42-, stable water isotopes δ18O, δ2H, etc.) only recently another class of tracers are emerging: trace contaminants as waste water markers. Compounds, such as artificial sweeteners, might enter the aquatic environment via discharge of waste water treatment plants and are ubiquitously found in sewage water receiving waters.

The hereby presented field study aims at the identification of infiltration areas and the quantitative assessment of river bank filtrate using conventional tracers and artificial sweeteners (e.g. acesulfame ACE) as waste water markers. The investigated aquifer is located in a mesoscale alpine head water catchment and used for drinking water production. It is hypothesized that a large proportion of the groundwater flux originates from bank filtrate of a nearby losing stream.

Water sampling campaigns in March and July 2012 confirmed the occurrence of artificial sweeteners at the investigated site. Water samples are classified with respect to their hydrochemical and isotopic composition using hierarchical clustering, identifying two predominant types of water in the aquifer: (1) groundwater influenced by bank filtrate and (2) groundwater originating from recharge. The mixing proportions of river water and spring water, representing bank filtrate and groundwater recharge, respectively, are determined by end member mixing analysis. The presence of ACE in more than 80% of the observation wells indicate considerable influence of sewage water loaded surface water throughout the aquifer, thus underlining the results obtained by cluster and mixing analysis. Moreover, it is shown that the combination of physicochemical parameters and artificial sweeteners allow for a clear delineation of infiltration areas in the investigated aquifer system.

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Letzte Änderung 18.10.2013