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Journal of the Croatian Geological Survey and the Croatian Geological Society heterogeneous hydraulic properties manifested by rapid groundwater flows concentrated in conduits and disolutionally widened fractures, usually sparsely distributed, while the storage of groundwater is mainly related to surrounding fractured rock matrix and surficial epikarst (or subcutaneous) zone (GOLDS-CHEIDER et al., 2007). Because of its complexity, karst aquifer research necessitates an interdisciplinary approach (DREYBRODT, 1988; COVING-TON et al., 2011). In addition to conventional methods, the use of environmental stable isotope tracers supplemented by statistical analysis, contributes to a better understanding of karst hydrogeology (CRISS et al., 2007; PALMER, 2010; GRIMMEISEN et al., 2017). Stable isotopes of water (2 H and 18 O) are analysed for several reasons, e.g. to explore recharge processes and reservoir mixing (LONG & PUTNAM, 2004; MALOSZEWSKI et al., 2002), to explore vadose water mixing, residence times and storage in non-conduit parts of karst systems (PALMER, 2010; MO-ERMAN et al., 2014; DÓŠA et al., 2011), to estimate mean recharge area elevations (BARBIERI et al., 2005; CHARIDEH & RAHMAN, 2007), etc. Detailed knowledge of the various processes within a karst hydrological system is crucial for the sustainable management of water resources, their allocation, and protection against pollution (MANCE et al., 2018 a, b). The black-box approach is often used

During the last years, the report of the occurrence of waterborne disease symptoms related to non-enteric pathogens has increased, without any record of higher levels of indicator bacteria (Escherichia coli and intestinal enterococci). Therefore, the use of current indicators is not always adequate when assessing the overall potential health risk and the inclusion of additional parameters needs to be examined. This paper reports on the incidence and levels of Staphylococcus aureus at 258 locations in Primorje-Gorski Kotar County (Croatia) recorded by official bathing water quality monitoring, as well as supplemental monitoring carried out at the two most frequented beaches in the City of Rijeka. The number of bathers was found to be the main factor affecting S. aureus levels (r = 0.321, p < 0.05). The share of S. aureus positive samples from the official monitoring was significantly lower, when compared to the share of samples from supplemental monitoring (2.2% and 36.3%, respectively; p < 0.01). Besides the number of bathers, one of the main reasons is likely the higher sampling frequency. No correlation was found between S. aureus levels and the indicator bacteria. The results indicate that the determination of S. aureus and increased sampling frequency is recommended for overcrowded beaches.

Stock and flow pollution differentiation is the basis for efficient pollution-abatement mechanism designs. The focus of our research has been marine pollution from land-based sources. Stable isotope analysis of groundwater is an acknowledged method for karst aquifer characterisation. We have tested whether stable isotopes of water, when used as a proxy for groundwater dynamics in the karst, could also be used as an indicator of marine pollution differentiation in terms of flow and stock pollution. The focus has been on two close coastal locations characterized by differences in terms of open and closed sea as well as anthropogenic pressure. A static Estimated General Least Squares (EGLS) statistical model described the closed bay location suggesting stock pollution. For a good description of the open sea location, we have had to resort to dynamic Generalised Method of Moments (GMM) statistical modelling, indicating flow pollution. Stable isotopes of groundwater together with appropriate statistical tools have proved to be a useful tool of marine pollution differentiation into stock or flow.

Objective A few studies focused on determinants of apical periodontitis other than technical or biological factors. This research aimed to investigate to what extent socio‐economic and health status can predict apical periodontitis in adult patients. Subjects and Methods The cross‐sectional study included 599 adult patients. Medical history, health habits and socio‐economic status of each participant were recorded using a self‐administered structured questionnaire. For caries detection, the World Health Organization diagnostic thresholds were used, and oral hygiene level was estimated using plaque index. Periapical index system was used to analyse the periapical status of all teeth. Dental, socio‐economic and health‐related variables were tested against dependent variable (periapical disease ratio) in a multiple linear regression analysis. Results Dental independent variables explained 71.7% of the observed variation in periapical disease ratio (R2 = 0.717; p < 0.001). Periapical disease ratio increased with the increase in number of carious teeth, plaque index and number of root‐filled teeth, but also with decrease in number of coronal fillings (all p < 0.001). Socio‐economic and health‐related variables accounted for lower portion of variability, 15.5% and 12.9%, respectively (both p < 0.001). Conclusions Dental variables are more important predictors of periapical status than socio‐economic and health‐related variables.

The article presents findings of a two-year systematic study of stable isotope content in two karst groundwater resources in Primorsko-goranska county (Croatia): the Martinšćica wells (MWs) and the Dobrica spring (DBC). The temporal and spatial variation of hydrogen and oxygen isotopes is commonly studied in conjunction with hydrogeological conditions such as groundwater dynamics and discharge conditions. However, since this information was incomplete, we were forced to work with limited data and rely on analyses of stable isotope monitoring results. The obtained results show that winter precipitation is the most common recharge source for the systems, and the average residence time of water in the subsurface is less than a year. Furthermore, the MWs system is a typical dual-porosity system with dominant base flow. The results of the nonparametric regression analysis show that the possibility of seawater intrusion into the spring affecting DBC isotope content cannot be ruled out. We believe that the results presented in the paper demonstrate that when combined with statistical analyses, environmental stable isotopes are a powerful tool for gaining insights in karst hydrogeology.