Rozliseni vod Hranickeho krasu na zaklade archivnich analyz

This study aims at evaluating and interpreting the results of archival analysis of water from broader area of Hranice Karst (Czech Republic) and provide first hydrogeochemical characterization of the hydrogeological system of Hranice Karst in the period 20 years ago.
The territory of Hranice Karst is located about 40 km east of Olomouc. Bounded by the municipalities of Hranice, Teplice nad Bečvou and Černotín, Zbrašov Aragonite Caves (ZAC) form the largest cave system in the region. Hranice Abyss (HRA) is another unique formation. The territory is located at an important line of contact between the Bohemian Massif and the Western Carpathians. The opening of the deep structures was dependent on the presence of the contact of two geological units and is accompanied by fluids rising from the Earth’s mantle. Carbon dioxide migrates to the surface and dissolves into infiltrated water or creates gas accumulation in caves. Analysing stable carbon isotopes in CO₂ and isotopic ratios of ³He and ⁴He indicates that the gas is of juvenile (mantle) origin.
A series of analysis work was completed in 1997-1998; focusing on water in Hranice Karst, it aimed at assessing microbial contamination of Zbrašov Aragonite Caves (ZAC) by seepage from the sewerage system. Water samples were collected each time at nine sampling points of five different sites (Hranice Abyss, Zbrašov Aragonite Caves, a cave found in the Na Kučách quarry, Opatovice borehole and the Bečva River); a total of 109 samples were available (Tab. 1, Fig. 1).
Based on the evaluation of the proportion of major anions and cations using the Geochemist's Workbench 8.0 application, five types of water were determined. In the case of mineral water, simple groundwater and water from the Bečva River, it involved the Ca-HCO₃ type. In the case of seepage water sampled in Zbrašov Aragonite Caves it was Ca-HCO₃; two cases at a site called Opona were detected to be Ca-SO₄. The average and median values of the composition and their standard deviations are shown in Table 1.
The contents of major cations and anions were graphically displayed using a Piper diagram (Figs 2 and 3). The Piper diagram shows a clear relationship of mineral waters from all the five sampling points of two sites; more specifically, it involves the water of Hranice Abyss and that of Zbrašov Aragonite Caves - lakes in the caves named Jeskyně smrti, Bezejmenná jeskyně, Béčko and Alfa. A little variance was also demonstrated of chemical composition over time at individual sites. Groundwater from the JVLNK - Hluboká site shows a high similarity to surface water in the River Bečva. The seepage water of sites ZAC - Křtitelnice , Opona and Turecký hřbitov, with a distinct difference of seepage water from Opona, have a greater variability in chemical composition over time. Surface water of the Bečva River is a separate set; the little-mineralised water from the borehole of Opatovice is separate phenomenon.
Piper diagrams confirmed the types of water identified by means of the Geochemist’s Workbench 8.0 application.
Statistical analysis of principal components (PCA) split the evaluated analytes into three factors which overall represent 93.4 % of the variance of the data set. In terms of data variance, a factor is mostly (74.45 %) involved that corresponds to the content of bicarbonates, sodium, calcium and magnesium while sulphates form the analyte exhibiting the smallest variance.