Among the emerging contaminants today, pharmaceuticals are some of the most demanding chemical compounds when it comes to understanding their transport within aquifers. The transport of ...pharmaceuticals in an unsaturated zone is influenced by many factors, including compound sorption and degradation, which is essential in assessing contaminant migration in soil and groundwater. Coarse-gravel aquifers are particularly important for drinking water sources and industrial water supply. Globally, little data on the transport characteristics of coarse-gravel unsaturated zones is available. However, such data is crucial to understanding the transport of pollutants and to implementing the appropriate management strategies to protect the aquifers. In this article, we present tracer experiments employed to determine pharmaceutical transport parameters in the coarse-gravel unsaturated zone. The tracer experiment was performed as a multi-tracer exercise, where deuterated water was infiltrated as a conservative tracer to define the characteristics of the unsaturated zone, together with pharmaceuticals (propyphenazone, caffeine and carbamazepine) as reactive tracers. Based on the breakthrough curves measured at various depths, inverse modelling in combination with analytical and numerical methods (HYDRUS-1D) was performed. Hydraulic parameters for the unsaturated zone were estimated. Linear sorption coefficients (Kd) and degradation half-lives (t1/2) were evaluated for each pharmaceutical. In the unsaturated zone of the coarse-gravel aquifer caffeine has the lowest sorption capacity (mean Kd = 0.027 Lkg-1), while the sorption coefficient of propyphenazone is higher (Kd = 0.07 Lkg-1). Results for the degradation constant of the first order and t1/2 indicate that caffeine has the fastest decay rate (highest t1/2 = 69.3 days), followed by propyphenazone (highest t1/2 = 92.4 days). The parameters for carbamazepine could not be determined using an advection dispersion equation.
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•The hydraulic parameters of coarse gravel unsaturated zone can be determined using a tracer experiment.•Sorption and degradation of studied pharmaceutical is governed by different transport mechanisms.•Caffeine has a low sorption capacity (Kd = 0.027 Lkg-1) and high degradation half-life (t1/2 = 69.3 days).•Propyphenazone shows higher sorption (Kd = 0.07 Lkg-1) and lower degradation (t1/2 = 92.4 days).•In our experiment the transport of carbamazepine cannot be determined using an advection dispersion model.
Northern hemisphere elementary circulation mechanisms, defined with the Dzerdzeevski classification and published on a daily basis from 1899-2012, are analysed with statistical methods as continuous ...categorical time series. Classification consists of 41 elementary circulation mechanisms (ECM), which are assigned to calendar days. Empirical marginal probabilities of each ECM were determined. Seasonality and the periodicity effect were investigated with moving dispersion filters and randomisation procedure on the ECM categories as well as with the time analyses of the ECM mode. The time series were determined as being non-stationary with strong time-dependent trends. During the investigated period, periodicity interchanges with periods when no seasonality is present. In the time series structure, the strongest division is visible at the milestone of 1986, showing that the atmospheric circulation pattern reflected in the ECM has significantly changed. This change is result of the change in the frequency of ECM categories; before 1986, the appearance of ECM was more diverse, and afterwards fewer ECMs appear. The statistical approach applied to the categorical climatic time series opens up new potential insight into climate variability and change studies that have to be performed in the future.
To achieve sustainable and efficient use of shallow geothermal resources, it is important to understand the heat transfer in the subsurface of the planned geothermal system. In the City Municipality ...of Murska Sobota, NE Slovenia, the use of geothermal open-loop systems has increased in recent years. Their high spatial density raises the question of possible mutual interference between the systems. By compiling geological, hydrogeological, and thermal data, obtained from the monitoring network, fieldwork, and knowledge of regional hydrogeological conditions, we have developed a transient groundwater flow and heat transfer model to evaluate the impact of the open-loop systems on the subsurface and surrounding systems. The transient simulation showed that the thermal state in the observed area is restored over the summer, when the systems are not in operation. Also, the systems do not have significant mutual interference that would affect their efficiency. However, as interest in installing new systems in the area increases, simulations of the thermal plumes of new geothermal systems are needed to ensure sustainable and efficient use of shallow geothermal energy in the future.
Droughts are natural phenomena affecting the environment and human activities. There are various drought definitions and quantitative indices; among them is the Standardised Precipitation Index ...(SPI). In the drought investigations, historical events are poorly characterised and little data are available. To decipher past drought appearances in the southeastern Alps with a focus on Slovenia, precipitation data from HISTALP data repository were taken to identify extreme drought events (SPI ≤ -2.00) from the second half of the 19th century to the present day. Several long-term extreme drought crises were identified in the region (between the years 1888 and 1896; after World War I, during and after World War II). After 1968, drought patterns detected with SPI changed: shorter, extreme droughts with different time patterns appeared. SPI indices of different time spans showed correlated structures in space and between each other, indicating structured relations.
Urban areas can significantly alter the quality status of aquifers if appropriate strategies to prevent and detect groundwater contamination are not implemented in time. The prevention of groundwater ...contamination should be a priority due to its potential long-term impact on the environment and the high cost of remediation. For effective and sustainable groundwater management, it is crucial to proactively monitor a wide range of compounds to prevent their spread, progression and increasing concentrations. This study is one of the few to analyse the trends of various urban groundwater contaminants (nitrate, sulphate, hexavalent chromium, pesticides, PCE and TCE) from a groundwater management perspective. Characteristic trends are assessed using linear regression and the Mann–Kendall method, while significant changes in trends are determined using the Darken and Pettitt tests. The time span of the analysed trends covers the transition period before and after the implementation of the Water Framework Directive (2000/60/EC) and the Groundwater Directive (2000/60/EC). This study confirms the effectiveness of enforcement measures to protect groundwater quality, as evidenced by several statistically significant decreasing trends. On the other hand, this study emphasises the importance of intervention-targeted sampling campaigns and the reporting of raw analytical values according to the ISO 11843 series of standards. This approach is essential to detect upward trends in emerging contaminants at an early stage and prevent them from reaching levels that could negatively impact the economy or even jeopardise the safety of drinking water supplies.
The Alps represent an area where many deep groundwater circulations occur as thermal springs. In the Bled case study, the thermal water temperature, at it is discharged to the surface, is between ...19–23 °C. In order to determine the extent (e.g., geometry) and the origin of the pronounced deep circulation system in the Bled area, chemical and isotopic measurements of waters from different hydrogeological systems were performed (e.g., surface water, thermal water, fresh groundwater). Hydrogeochemical methods were used to tie together the above-mentioned parameters. The results have shown that thermal outflow in Bled is determined by the presence of a deep-water circulation system, where the dissolution of carbonates minerals is the main hydrogeochemical process affecting chemical components of natural water flow. The correlation of the major ions suggests that the recharge area is represented by both limestone and dolomite rocks. Moreover, the results of δ18O and δ2H of all samples indicate that the recharge is mainly meteoric precipitation. The recharge altitude was estimated for two sampled fresh groundwater springs. The isotopic compositions of those two springs suggest the range from δ18O = −8.68‰, δ2H = −57.4‰ at an elevation of 629 m to δ18O = −9.30‰, δ2H = −60.1‰ at an elevation of 1216 m. The isotopic analysis has confirmed that the thermal water recharges from altitudes of 1282–1620 m a.s.l.
In order to investigate stream water, spring waters and water from a borehole facies, weathering processes, residence times and average recharge altitudes in the Radovna River valley were analysed ...for their concentrations of dissolved Ca
2+
, Mg
2+
, K
+
, Na
+
, HCO
3
−
, Cl
−
, NO
3
−
, SO
4
2−
and for the isotope compositions of hydrogen, oxygen and dissolved inorganic carbon (DIC). All water samples show a Ca
2+
–HCO
3
−
water facies with low contents of K
+
, Na
+
, Cl
−
, NO
3
−
and SO
4
2−
. Water–rock interaction and carbonate weathering are the significant contributors to water geochemistry. Analysis of the water chemistry indicates that waters drain a monolithological terrain and non-anthropogenically influenced watershed. The
δ
2
H and
δ
18
O values are seasonally dependent on the snowmelt, precipitation and evaporation. The average recharge altitudes for all sampling locations are between 1120 and 2130 m. The average residence time for the stream water is 2.4 years and for karst springs 1.2 years. The
δ
13
C
DIC
values in all samples are influenced by dissolution of carbonates, degradation of organic matter and by equilibrium with atmospheric CO
2
. All geochemical and isotope analyses show changes in stream water in the downstream direction and are highly dependent on the inflow of karstic spring. Based on hydrogeological mapping, geochemical and stable isotope results, a conceptual hydrogeological model of the Radovna system, in which karstic and alluvial aquifers are in contact, was determined.
•Monitoring of stable isotopes in precipitation.•Precipitation events related to atmosphere circulation patterns.•Isotopic composition of precipitation dependent on elementary circulation mechanism – ...ECM of atmosphere.•ECM-isotopic model for estimating statistical distribution of isotope composition in precipitation.
Precipitation generating processes depend on atmospheric circulation patterns and consequently it is expected that its water stable isotopic composition of hydrogen and oxygen is related to them. Precipitation generated at similar atmospheric circulation patterns should have similar empirical distribution of δ2H and δ18O values. Mathematical model based on the linear combination of δ2H and δ18O values and on precipitation amount weighted average related to elementary air circulation mechanisms – ECM is proposed. The model enables estimation of average δ2H and δ18O values and their standard deviation for the precipitation generated at distinctive atmospheric circulation patterns. Approach in which atmospheric circulation patterns were classified as ECM based on the Dzerdzeevskii classification was applied. Application of the model is illustrated on the long term precipitation record from Ljubljana GNIP station Slovenia. Estimated values of the parameters for empirical distributions of δ2H and δ18O of each ECM subtype have shown that calculated estimates are reasonable. Further applications of the proposed model enable new insight into the understanding of isotopes spatial and temporal distribution in precipitation important also for better understanding of climate proxies.
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