Application of Inductively Coupled Plasma Spectrometric Techniques and Multivariate Statistical Analysis in the Hydrogeochemical Profiling of Caves—Case Study Cloșani, Romania

Abstract

The aim of the study was to develop the hydrogeochemical profiling of caves based on the elemental composition of water and silty soil samples and a multivariate statistical analysis. Major and trace elements, including rare earths, were determined in the water and soil samples. The general characteristics of water, anions content, inorganic and organic carbon fractions and nitrogen species (NO3− and NH4+) were also considered. The ANOVA—principal component analysis (PCA) and two-way joining analysis were applied on samples collected from Cloșani Cave, Romania. The ANOVA-PCA revealed that the hydrogeochemical characteristics of Ca2+-HCO3− water facies were described by five factors, the strongest being associated with water-carbonate rock interactions and the occurrence of Ca, Mg and HCO3− (43.4%). Although organic carbon fractions have a lower influence (20.1%) than inorganic ones on water characteristics, they are involved in the chemical processes of nitrogen and of the elements involved in redox processes (Fe, Mn, Cr and Sn). The seasonal variability of water characteristics, especially during the spring, was observed. The variability of silty soil samples was described by four principal components, the strongest influence being attributed to rare earth elements (52.2%). The ANOVA-PCA provided deeper information compared to Gibbs and Piper diagrams and the correlation analysis.

Health Risk Assessment in Southern Carpathians Small Rural Communities Using Karst Springs as a Drinking Water Source

“…The main sources of Ca in the spring waters are the dissolution of carbonate minerals (calcite, dolomite, aragonite, vaterite), gypsum, and silicates (anorthite, pyroxene), while HCO 3 − originate from the dissolution of calcite and dolomite [ 4 ]. Barium, Sr, and Ni may also originate from the dissolution of carbonate rocks [ 11 ]. The dissolution of silicate minerals is enhanced in the presence of Ba in water and further leads to the release of associated trace elements [ 35 ].…”

“…The limit of detection (LOD) was calculated as the ratio between 3 times the standard deviation resulting from 10 measurements of the reagent blank and the slope of the calibration curve ( Table 2 ) [ 10 , 11 ].…”

Sr Isotope, Major, and Trace Element Signatures in Karst Groundwaters

“…In the lab blanks, as well as in most of the field blanks, the concentrations of the elements were below the limit of detection (LOD), or were negligible compared to the concentrations that were measured in the samples. The LOD (Table 2) was calculated as three times the ratio between the standard deviation of the signal of 10 reagent blank measurements and the slope of the calibration curve [36]. The expanded uncertainty (U) was calculated by multiplying the combined standard uncertainty with the coverage factor (k = 2) for a level of confidence of 95%.…”