Projects / Programmes
Groundwater age determination in deep aquifers of Slovenia
| Code |
Science |
Field |
Subfield |
| 1.06.07 |
Natural sciences and mathematics |
Geology |
Natural resources (mineral and energy raw materials, water) |
| Code |
Science |
Field |
| P470 |
Natural sciences and mathematics |
Hydrogeology, geographical and geological engineering |
| Code |
Science |
Field |
| 1.05 |
Natural Sciences |
Earth and related Environmental sciences |
groundwater, deep aquifers, groundwatera age, groundwater retention time, hydrochemistry, environmental isotopes, tritium, carbon-14
Researchers (19)
Organisations (2)
Abstract
The project Groundwater age determination in deep aquifers of Slovenia aims to improve the knowledge of Slovenian deep aquifers. A more detailed systematic determination of deep confined aquifers in Slovenia will be elaborated with regard to groundwater age, its recharge dynamics and chemical properties. The present chemical status of deep aquifers represents the zero situation for further monitoring of possible changes due to groundwater exploitation.
Also elaboration and testing of criteria and methodology for the determination of deep confined aquifers will be done. Hydrochemical and isotopic indicators (markers), typical of deep aquifer structures in Slovenia will be defined. We will also attempt to identify the indicators of anthropogenic influences upon deep aquifers.
The most important deep aquifers from the entire Slovenian territory will be included into the project. Two sampling campaigns will be performed in selected deep aquifers with the intention to determine the chemical and isotope composition of water in the aquifer. During the initial analytical phase tritium activity will be determined, on the basis of which very old groundwater will be distinguished from the more recent, approximately up to 100-year old groundwater. In waters where no tritium will be detected, we will attempt to determine groundwater age by using carbon isotope C-14. We will also study the possibility of using isotope argon-39 in studying groundwater dynamics in Slovenian deep aquifers. Besides radioactive isotopes also the isotope composition of stable isotopes, primarily of oxygen-18, deuterium and carbon-13 will be determined in groundwater samples.
The second part of the project will be dedicated to more detailed research of those deep aquifers where increased concentrations of individual anthropogenic pollutants have already been detected. At the moment three deep aquifers in Slovenia have a quite critical pollution situation which already has a pronounced effect on the possibility of water supply from these aquifers. The project has an applicative use, and is because of its topical issues cofinanced by three water supply companies which exploit also deep aquifer water for distribution to the cities Ptuj, Domžale, and Grad.
In the research group reseachers from the Geological Survey of Slovenia will perform hydrogeological and hydrochemical investigations of deep aquifers, and researchers from the Jožef Stefan Institute will carry out analyses and development of new methods for measuring the concentrations of radioactive isotopes in groundwater.
Significance for science
New data about groundwater age in deep aquifers enable a better understanding of groundwater circulation dynamics also in this type of aquifers, which have so far been quite neglected from the point of view of research. Beside specific natural conditions which in many cases have influence on the chemistry of groundwater, it has been found out that these structures can still contain ecological burdens from the past due to the very slow groundwater circulation. Such past burdens are for example increased atrazine and desethylatrazine concentrations.
Significance for the country
The project Groundwater age determination in deep aquifers of Slovenia offered numerous solutions for the improvement of drinking water supply in Slovenia. A more detailed view of the situation in this respect shows that the exploitation of deep aquifers for water supply is in several cases impeded due to the bad chemical status of groundwater. The research within the project has shown that the bad status may result either from the natural hydrogeological and geochemical conditions in the system, or from the anthropogenic pollution. Anthropogenic pollution can be due to the old ecological burdens which are stored in deeper layers, which can at the same time also present the water bearing structures of groundwater. Research shows that desethylatrazine, a decomposition product of the herbicide atrazine, is often such old ecological burden. In previous decades the use of this herbicide was very widespread, mostly to treat weeds in cornfields. When it was found out how persistent its decomposition products are, atrazine was banned also in Slovenia. At present, atrazine and desethylatrazine cause the biggest problems in public drinking water supply in the Dravsko polje and Ljubljansko barje aquifers. In Dravsko polje, atrazin is still present in the shallow Holocene aquifer. Although its concentrations in groundwater are still considerably above the maximum allowed values, a constant decreasing trend of its concentrations can be observed. A quite different situation with regard to atrazine as an old ecological burden is present in the Ljubljansko barje aquifer, where the public drinking water supply of the southern part of Ljubljana from the Brest pumping station is difficult due to excessive atrazine concentrations. In this area desethylatrazine is captured in the sandy-clay layers of the Ig alluvial fan aquifer. The analyses of tritium content in groundwater showed the presence of the so called »bomb« tritium resulting from the period of intensive surface nuclear experiments. On this basis, groundwater age was estimated to between 10 and 50 years, which corresponds to the period of intensive use of atrazine in this area. On the basis of obtained results we expect that desethylatrazine concentrations in pumped water will decrease rather slowly. Therefore we suggested a modification in the pumping scheme so that the main part of the pumping is transfered more towards the southern part of the pumping facility. Atrazine is still present also in the deeper aquifer of the Kamniško-Bistriško polje, where it is captured in dolomite layers. At present the lower aquifer is still not exploited for water supply, but preparations for its exploitation are already under way. In the deeper aquifer of the Kamniško-Bistriško polje ''bomb'' tritium was detected, so groundwater age was determined between 10 and 50 years. On the basis of obtained results it was estimated that the exploitation of groundwater in the deeper aquifer would result in the decrease of desethylatrazine concentrations to levels below the maximum allowed limit. With regard to these results the continuation of investment for the exploitation of water from the deeper aquifer is reasonable. The Skorba pumping station, which supplies the city of Ptuj and its surroundings with drinking water, exploits the deep Pliocene and the shallow Holocene aquifer of Dravsko polje. During recent years a considerably fast increase in nitrate concentrations has been observed also in the lower aquifer. These concentrations were low at the beginning of exploitation of the deeper aquifer. During the course of the project it has been found out that tritium concentrations in water from the deep aquifer started to grow, which indicates that younger, more polluted water from the upper aquifer flows into the lower aquifer. Because the recharge of the lower aquifer is limited, measures for the improvement of groundwater chemical status of the upper aquifer were proposed as the only solution.
Most important scientific results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
2012,
2013,
final report,
complete report on dLib.si
