Road sediments from gully pots of the drainage system and stream sediments from natural streams in the urban area of Idrija town, the central part of the second largest and strongly contaminated Hg mining district in the world, were investigated for the first time. Total Hg concentrations in road sediments (n=16) are lower than in stream sediments (n=14). They ranged from 16 to 110 mg/kg (Md=29 mg/kg) for (0.125 mm particles and from 7 to 125 mg/kg (Md=35 mg/kg) for (0.04 mm particles, while Hg concentrations in stream sediments ranged from 10 to 610 mg/kg (Md=95 mg/kg) for (0.125 particles and from 10 to 440 mg/kg (Md=105 mg/kg) for (0.04 mm particles. High total Hg concentrations in stream sediments were easily correlated to identified mercury sources (rocks containing mercury ore, areas of former ore roasting sites, ore residue dumps) because they are located in the drainage areas of the streams from which the sediments were collected. In case of road sediments it was not possible to distinguish, which of the identified mercury sources prevails on a single location, because transport pathways of mercury contaminated material are dominated by subaerial processes and are as such hard to trace. Solid phases of mercury were determined by thermo-desorption technique and are similar for both types of sediments. Results show the occurrence of three different forms: elemental mercury (Md= 3%), mercury bound to matrix components (Md= 44%) and cinnabar (Md= 48%). Approximately 50% of samples consist of non-cinnabar fractions. This is important, since they are potentially bio-available. An interesting new discovery according to previous research of environmental media from Idrija area by solid-phase-Hg- thermo-desorption technique is, that elemental mercury was determined in almost all investigated sediments (n=29) in minor amounts.
COBISS.SI-ID: 2207573
A detailed soil geochemical survey has been performed in the abandoned polymetallic (Hg, Pb, Ag, Zn, Ba) mining and smelting region of Litija, central Slovenia. In an area of 30 km2 the soil was systematically sampled using a 500 x 500 m grid (120 sampling sites). Two soil horizons (0-5 cm and 15-30 cm) were sampled in order to distinguish between geogenic and anthropogenic metal sources. Data treatment included multivariate statistical approaches (multivariate cluster and R-mode factor analysis), which allowed the identification of two geogenic and two anthropogenic geochemical associations. The main geogenic group of element includes Ce, Cr, Fe, Hf, Nb, La, Th, Ti, Ta, U, V, W and Zr; high contents of these elements are associated with the sand fraction of the Würm terraces. The second geogenic group includes Al, Ba, K, Li, Rb, and Sc; high concentrations of these elements are related to the alluvial sediments of the Sava tributaries. The third geochemical group is partly geogenic and anthropogenic, linking typical elements (Ca, Mg, Sr) of alluvial sediments of the river Sava and some metals (Cd, Co, Cu, Ni, Mn and Zn); the source of these metals is most probably the ferrous metallurgy in the upper part of the Sava valley. The fourth and also the most important anthropogenic geochemical association (As, Mo, Hg, Pb, Sb and Sn) is typical for the areas affected by past mining and smelting activities.
COBISS.SI-ID: 2228309
The already exploited geothermal resources in the Mura-Zala basin are planned to be further developed. In this study thermal water abstraction and its impact on both the fissured basement aquifers and the intergranular Neogene siliciclastic aquifers were investigated. Total abstraction of thermal water in north-east Slovenia summed to 3.1 million m3 in 2011, with very limited artificial recharge supplied through a single reinjection well. This exploitation has resulted in depletion of the aquifers, with decline in aquifer pressure, piezometric groundwater levels and discharge rates, as well as chemistry variation, being evident in many wells. A research monitoring network has been established in 2009 and has been taking hourly measurements in eight wells. These wells are up to 2 km deep and tap aquifers in the Upper Miocene sandy Mura Formation. Daily, seasonal and annual trends were interpreted, and the measured overall regionally declining static groundwater levels are alarming, reaching 0.53 m per year. Despite the changes in conditions in the aquifers, no change of production temperature has so far been perceived.
COBISS.SI-ID: 2244693
A 3-year geochemical study of groundwater has been undertaken in the main aquifer types in Slovenia. Sampling locations include springs, groundwater observation objects (boreholes, piezometers and wells), and surface waters. The chemical composition of Ca2+, Mg2+ content and their molar ratios in groundwater were studied in detail in 175 water samples. The objective of this study was to evaluate groundwater Ca2+ and Mg2+ content in various lithological rock types in studied aquifers. Based on the Ca2+/Mg2+ molar ratio in groundwater it was possible to estimate the prevailing carbonate rock in the recharge area, and by calculating the saturation indexes of calcite and dolomite to determine the chemical equilibrium status between carbonate minerals and groundwater. Groundwater mostly belongs to Ca2+-HCO3- and Ca2+-Mg2+-HCO3- water type. Most Slovenian groundwaters in carbonate recharge areas are supersaturated with respect to calcite and dolomite (SI mostly up to 1) which is to be expected because a large part of the Slovenian territory is covered by carbonate rocks. The Ca2+/Mg2+ molar ratios in sampled groundwater suggest the groundwater is in contact with either dolomites, limestones or both. The amount of Ca2+ and Mg2+ in groundwater differs between lithological units in recharge areas due to the content and solubility of the prevailing minerals. Ca2+ in groundwater is derived mostly from calcium-rich minerals like calcite and gypsum in carbonate rocks. The source of groundwater Mg2+ is in magnesium-rich minerals such as dolomites, amphiboles and clay minerals. In Slovenia medium hard groundwater prevails with medium high levels of dissolved groundwater Ca2+ and Mg2+ in the form of carbonates which is a consequence of natural weathering of sedimentary rock in the study area.
COBISS.SI-ID: 2284117
Mercury (Hg) solubility and reactivity in soils at two extremely contaminated ancient small scale cinnabar roasting sites in the surroundings of the Hg mining area of Idrija (Slovenia) were determined in order to assess the mobility of Hg in the aqueous phase and to evaluate the extent of leaching of Hg into Idrijca River and further downstream. Water leaching experiments were performed on soil and SOM (soil organic matter) samples from historical roasting sites Pšenk and Frbejžene trate. The determined concentrations of leachable mercury in soil samples from the studied areas range from 16 to exceptionally high value of ~18,200 μg/kg, representing 0.0002 to 1.12 % of total Hg in these samples, while in SOM samples leachable mercury concentrations range between 13.3 and 6,000 μg/kg, which corresponds to 0.0017–0.074 % of total Hg determined in SOM. The soluble mercury content in investigated soil profiles ranges from 183 to 18,400 μg/kg (0.038–1.71 % of total Hg). The values from both roasting sites are very low in comparison with the total mercury content. In all cases the soluble mercury in soil solution is ( 2 % with respect to the total concentration of this metal. On average, more than 90 % of soluble Hg occurs in a non-reactive complex bound form, suggesting the preferentially binding of Hg to humic matter. Soluble mercury in studied soil profiles generally increases with depth. The obtained results show that Hg is effectively transported to deeper soil layers, mainly as soluble organic complexes. It is estimated that there is still about 10 kg of soluble Hg stored in soils of the investigated roasting sites, which is continuously leached to surface waters and deeper into the soil. Because of the predominantly karstic area, considerable amounts of mercury can be transported to aquifers thus posing potential environmental risk.
COBISS.SI-ID: 2258261