Waste management in Europe has improved in recent years, reducing the amount of waste disposed at landfills. However, there are still many landfills in the countries. It is well known that landfills ...that do not have measures in place to control leachate entering groundwater can contaminate groundwater long after the landfill is closed. Collecting monitoring results from all landfills allows permitting and management agencies to improve action plans. This relies on a synoptic risk assessment that allows prioritization and milestones to be set for required actions. The developed method of synoptic risk assessment is based on a conceptual model of the landfill and the results of chemical groundwater monitoring tested at 69 landfills in Slovenia. The study confirms that most landfills have a direct or indirect impact on groundwater quality. All landfills were classified into three priority classes on the basis of the synoptic risk assessment. The results show that a total of 24 landfills have a clearly pronounced impact on groundwater. A total of 31 landfills have a less pronounced impact due to the favorable natural attenuation capacity of the soil or the technically appropriate design of the landfill itself. A total of 14 landfills have a less pronounced or negligible impact on groundwater.
The paper presents the use of passive sampling in combination with factor analysis to assess the presence of anthropogenic organic pollutants, and to determine the type of pollution and seasonal ...variability of contamination. This combined method enables the assessment of groundwater quality and the evaluation of pollution sources, and serves as the basis for recommended measures to improve the quality of groundwater. The method has been tested on the Vrbanski plateau aquifer near Maribor, Slovenia. Groundwater pollution was monitored at 15 observation points, and at one in the Drava River. Two sampling campaigns covered a period of roughly one year (May 2010–September 2010 and September 2010–March 2011). The data set of 54 samples with 12 variables (pollutants) was based on unbalanced nested hierarchical sampling design, and is expressed as intensity on an ordinal scale from 1 to 5. Nonparametric Kruskal-Wallis test for testing statistical significance of pollutants at various levels of sampling design, and factor analysis based on polychoric correlation, were used in this study. Results of the factor analysis show that groundwater contains organic pollutants from three different types of sources. Factor analysis split the group of pesticides into two factor-groups: Factor 1, representing pesticides which are indicators of agricultural activities, and Factor 2, including atrazine and desethyl-atrazine, which indicate old burdens or their illegal use. Pharmaceuticals and compounds of personal care products are loaded on Factor 3, which shows groundwater pollution from urban activities, while Factor 4 represents volatile aliphatic halogenated hydrocarbons, which are indicators of industrial contamination. Factor scores also revealed considerable differences between the two sampling campaigns at individual sampling points. The results show that the influence of pollution from various anthropogenic activities depends on the meteorological conditions in each sampling campaign. The passive sampling technique combined with multivariate statistical analysis has proved to be a useful approach to assessing groundwater quality, with a substantially cheaper and more effective monitoring design than the more commonly used monitoring methods.
•Organic pollutants in groundwater were studied using passive sampling and factor analysis on ordinal data.•Results of factor analysis were confirmed by results of hierarchical cluster analysis.•Groundwater contains organic compounds from agriculture, urban activities and industry.•The summer period is the main season for organic compounds of agricultural and industrial origin.•Winter is the main season for urban pollution.
Ljubljansko polje and Ljubljansko Barje aquifers are the main groundwater resources for the needs of Ljubljana, the capital of Slovenia. Carbonate chemistry and isotope analysis of the groundwater ...were performed to acquire new hydrogeological data, which should serve as a base for improvement of hydrogeological conceptual models of both aquifers. A total of 138 groundwater samples were collected at 69 sampling locations from both aquifers. Major carbonate ions and the stable isotope of oxygen were used to identify differences in the recharging areas of aquifers. Four groups of groundwater were identified: (1) Ljubljansko polje aquifer, with higher Ca2+ values, as limestone predominates in its recharge area, (2) northern part of Ljubljansko Barje aquifer, with prevailing dolomite in its recharge area, (3) central part of Ljubljansko Barje aquifer, which lies below surface cover of impermeable clay and is poor in carbonate, and (4) Brest and Iški vršaj aquifer in the southern part of Ljubljansko Barje with higher Mg2+ in groundwater and dolomite prevailing in its recharge area. The radioactive isotope tritium was also used to estimate the age of groundwater. Sampled groundwater is recent with tritium activity between 4 and 8 TU and residence time of up to 10 years.
The Water Framework Directive (WFD) requires EU member states to assess the chemical status of groundwater bodies, a status defined according to threshold values for harmful elements and based on/the ...natural background level (NBL). The NBL is defined as the expected value of the concentration of elements naturally present in the environment. The aim of this study is to propose a methodology that will be broadly applicable to a wide range of conditions at the regional and national scale. Using a statistical approach, the methodology seeks to determine NBLs for SO4, As, Cd, Cr, Cu, Ni, Zn, and F based on the lithology of aquifers from which groundwater monitoring data were collected. The methodology was applied in six EU countries to demonstrate validity for a wide range of European regions. An average concentration was calculated for each parameter and chosen water point and linked to a lithology. Based on the dataset created, significant differences between lithologies and pressure categories (urban, agricultural, industrial, and mining) were tested using a nonparametric test. For each parameter, 90th percentiles were calculated to provide an estimation of the maximum natural concentrations possible for each lithology.
Groundwater is the most important source of drinking water in the world. Therefore, information on the quality and quantity is important, as is new information related to the characteristics of the ...aquifer and the recharge area. In the present study we focused on the isotope composition of oxygen (δ18O) in groundwater, which is a natural tracer and provides a better understanding of the water cycle, in terms of origin, dynamics and interaction. The groundwater δ18O at 83 locations over the entire Slovenian territory was studied. Each location was sampled twice during the period 2009–2011. Geostatistical tools (such us ordinary kriging, simple and multiple linear regressions, and artificial neural networks were used and compared to select the best tool. Measured values of δ18O in the groundwater were used as the dependent variable, while the spatial characteristics of the territory (elevation, distance from the sea and average annual precipitation) were used as independent variables. Based on validation data sets, the artificial neural network model proved to be the most suitable method for predicting δ18O in the groundwater, since it produced the smallest deviations from the real/measured values in groundwater.
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•Isotopic composition of oxygen (δ18O) in groundwater in shallow aquifers was investigated.•83 groundwater sampling points during dry and wet periods (2009–2011)•Different prediction models were used for prediction of δ18O spatial distribution.•Model parameters: distance from sea, elevation, and amount of precipitation•Best groundwater δ18O prediction model is artificial neural network.
This paper presents the stable isotope data of oxygen (δ ¹⁸O) and hydrogen (δ ²H) in groundwater from 83 sampling locations in Slovenia and their interpretation. The isotopic composition of water was ...monitored over 3 years (2009–2011), and each location was sampled twice. New findings on the isotopic composition of sampled groundwater are presented, and the data are also compared to past studies regarding the isotopic composition of precipitation, surface water, and groundwater in Slovenia. This study comprises: (1) the general characteristics of the isotopic composition of oxygen and hydrogen in groundwater in Slovenia, (2) the spatial distribution of oxygen isotope composition (δ ¹⁸O) and d-excess in groundwater, (3) the groundwater isotope altitude effect, (4) the correlation between groundwater d-excess and the recharge area altitude of the sampling location, (5) the relation between hydrogen and oxygen isotopes in groundwater in comparison to the global precipitation isotope data, (6) the groundwater isotope effect of distance from the sea, and (7) the estimated relation between the mean temperature of recharge area and δ ¹⁸O in groundwater.
Nitrate leaching into groundwater is a serious issue in many parts of the world. Usually agricultural use of fertilizers is blamed to be the main source of pollution, but other human activities, like ...leaky or inexistent sewage systems can also be important in this regard. The aim of this study is to assess nitrate transport from soil to ground and surface waters with nuclear techniques. Two study sites were chosen-both featuring agricultural production in vulnerable areas of alluvial plains. Shallow groundwater below the surface is the main source of drinking water in both areas. Stable isotope techniques provide an innovative and unique methodology to trace and monitor the movement of nitrates (organic and inorganic) from the soil to ground and surface waters and to determine possible sources.
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