Paper focuses on the analysis of geochemical data with values below the limit of detection (LOD). Such values are treated as text and are difficult to use in further calculations of mean, standard deviation and other statistical parameters. To estimate several methods for substitution of values below the LOD with fractions of LOD (zero, LOD/2, LOD/√2, LOD and no data values), a large dataset of generated values with normal and lognormal distributions was tested for different percent of censoring from 1 % to 50 %, plus the censored data of five selected geochemical parameters. Results indicate that the best substitution method is by LOD/√2, as it produces the smallest errors. The greatest errors are found for substitution methods with zero or no data. This is valid both for normally and lognormally distributed data. Median is not affected by most methods for censoring level below 50 %. For real geochemical parameters, the interpretation is more complex. For datasets with low amount of censoring (NO3, O2), the errors are small. For others (Sr, F, Mn) the errors are larger, as several LODs exist for each parameter and the LOD is sometimes larger than the mean value.
COBISS.SI-ID: 954974
The chapter describes the correlations between the hydrogeological, structural and geochemical parameters in Slovenian dolomites. 15 different dolomite types were analyzed, which are visually not distinguishable. However, differences appear when analyzing the hydrogeological parameters (hydraulic conductivity, specific capacity etc.), where more "clean" dolomites have higher transmissivities than the others. This is confirmed by geochemical analysis of ground waters. As a new result, correlations were found between the mentioned parameters and the fractal flow dimension.
COBISS.SI-ID: 880734
Methods of numerical and graphical analyses of hydrogeochemical data, gathered during the postdoc project, were applied to fractured rocks of Ca-HCO3-SO4 and other types, in geothermal system in NE Macedonia, in collaboration with foreign researchers. Geothermal water has a large potential for exploitation (temperatures over 50ºC). In the paper are presented the results of geochemical analyses, which indicate that some groundwater parameters exceed the permissable concentrations according to drinking water regulations, and some of the potential problems during the possible explotation were detected due to precipitation of minerals (this was confirmed in the fiels). Geothermal potential for exploitation remains, with proper treatment of water or by exloitation of water for other uses.
COBISS.SI-ID: 943966