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Water 15(13), 2398 - (2023). doi:10.3390/w15132398, Published by MDPI, Basel

Comprehensive research of several springs of the Holy Mountain has been conducted.

The diversity of processes which take place in hillslope agro-ecosystems makes the estimation of vadose zone hydrology very challenging. This research presents first results related to the measurements of meteorological data, soil water content, granulometric composition and isotopic signature of soil water and precipitation within SUPREHILL project. Vadose zone observatory has been placed on agricultural sloped area in Zagreb, within experimental field Jazbina. For the evaluation of soil water origin and dynamics, precipitation and soil water have been sampled. First four sampling campaigns have been done in two week intervals, while after it was decided to start sampling on a monthly time period. Stable isotopes of hydrogen (Δ2H) and oxygen (Δ18O) from soil water and precipitation have been determined by laser spectroscopy. First results showed different isotopic signature in soil water compared to precipitation which suggests the existence of different infiltration patterns in the experimental site. Isotopic signature corresponds to the variation of water content at different depths. Furthermore, results suggest that preferential flow and infiltration of precipitation can be expected till the maximum depth of 0.8 m which is probably related to the existence of low permeable layer. Future research and long-term monitoring will focus on the quantification of subsurface soil water dynamics and preferential flow, as well as on the non- linear agrochemical transport processes.

Frequent use of agrochemicals results in increased concentration of certain metals in vineyard soils, with the slope of terrain promoting their uneven spatial distribution. Therefore, at the SUPREHILL critical zone observatory (Jazbina experimental station, Zagreb), 27 vineyard soil samples were taken at three soil depths (0-30, 30-60, 60-90 cm) in October of 2020 at the top, middle, and the bottom of the slope, and digested in Aqua regia by microwave technique using MARSXpress system, CEM (HRN ISO 11466:2004). Metal (Fe, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn, and Hg) total concentrations in soil extracts were then measured using ICP-OES (Vista MPX AX, Varian ; HRN ISO 22036:2011). Data processing was done using Statistical Analysis Software (SAS Institute Inc., Version 8.3 Update 1, Cary NC USA, 2019-2020), with the analysis of variance done using One-Way ANOVA, and the significance of differences between the means determined using Tukey's test at P

U radu je prikazan hrvatski pristup za određivanje graničnih vrijednosti tvari i pokazatelja mogućih onečišćenja podzemne vode u vodnom području rijeke Dunav i jadranskom vodnom području. Detaljno su obrazloženi kriteriji za određivanje graničnih vrijednosti, prilagođeni značajkama hidrogeoloških sustava te s njima povezanih ili o njima ovisnih kopnenih i vodenih ekosustava u Republici Hrvatskoj, koji se odnose na referentne standarde kakvoće, odnosno kriterijske vrijednosti, te na pozadinske koncentracije. Analizirane su različite metode procjene pozadinskih koncentracija, koje su korištene u postupku određivanja graničnih vrijednosti u RH, te je razmotrena pouzdanost rezultata dobivenih primjenom različitih metoda na osnovi zajedničkih kriterija. Prikazan je postupak utvrđivanja kriterijskih vrijednosti za važne prijamnike i vidove korištenja podzemne vode, a posebno su analizirani i opisani glavni tipovi graničnih vrijednosti koji se koriste u postupku ocjene kemijskoga stanja ili procjene rizika u pojedinim vodnim područjima. Na primjeru grupiranoga tijela podzemne vode Istočna Slavonija – sliv Drave i Dunava prikazan je postupak određivanja pozadinskih koncentracija i graničnih vrijednosti za odabrane tvari i pokazatelje., The paper presents the Croatian approach to the determination of limit values and indicators of potential groundwater pollution in the Danube River Basin District and Adriatic River Basin District. The criteria for determining limit values are elaborated in detail and adapted to the characteristics of hydrogeological systems and their associated or dependent terrestrial and aquatic ecosystems in the Republic of Croatia, i.e. referent quality standards, such as criteria values and background concentrations. Different methods for assessing background concentrations, which were used in the procedure of limit value determination in the Republic of Croatia, were analysed and the reliability of results obtained by applying different methods based on shared criteria were considered. The procedure of determining the criteria values for important recipients and different groundwater uses were described; the main types of limit values used in the procedures of chemical status assessment and risk assessment in individual river basin districts were analysed and described in particular. The procedure of determining background concentrations and limit values for selected substances and indicators were demonstrated on the example of the groundwater body group Eastern Slavonia – Drava and Danube basin., In der Arbeit wird der kroatische Ansatz zur Bestimmung der Grenzwerte von Materien und des Anzeigens möglicher Verunreinigungen von Grundwasser im Wassergebiet des Flusses Donau und im adriatischen Wassergebiet dargestellt. Die Kriterien zur Bestimmung der Grenzwerte sind genauestens erläutert und den Merkmalen von hydrogeologischen Systemen angepasst, sowie den damit verbundenen oder von ihnen abhängenden Land- und Wasserökosystemen in der Republik Kroatien, die sich auf referierende Qualitätsstandards, beziehungsweise Kriteriumswerte beziehen, ebenso auf Hintergrundkonzentrationen. Analysiert wurden verschiedene Schätzungsmethoden von Hintergrundkonzentrationen, die beim Bestimmungsverfahren der Grenzwerte in der Republik Kroatien benutzt wurden. Außerdem wurde die Verlässlichkeit der Resultate beurteilt, die bei der Anwendung verschiedener Methoden mit gemeinsamen Kriterien erhalten wurden. Dargestellt wurde die Bestimmungsmethode von Kriteriumswerten für wichtige Empfänger und Arten der Nutzung von Grundwasser, besonders analysiert und beschrieben wurden die Typen von Grenzwerten, die beim Verfahren der Beurteilung des chemischen Zustandes oder Schätzung von Risiken in den einzelnen Wassergebieten benutzt werden. Am Beispiel des gruppierten Körpers des Grundwassers Ostslawonien - das Becken von Drau und Donau wurde das Verfahren zur Bestimmung von Hintergrundkonzentrationen und Grenzwerten für ausgesuchte Materien und Indikatoren dargestellt.

In late 2020, the first weighing lysimeters in Croatia were installed at the SUPREHILL vadose zone observatory, at the top and bottom of the hillslope. The use of undisturbed weighable lysimeters is commonly used to measure water and solute fluxes at the profile scale, which can also be representative at the field scale. The lysimeters are monolithically filled, equipped with a pressure-controlled lower boundary in order to mimic field dynamics (upward and downward fluxes), and are weighable so that high-precision calculations of hydraulic fluxes (i.e. rainfall, drainage, evapotranspiration, or dew) are possible. The first glance at the 2021 data shows differences between the top and bottom of the hillslope in observed evapotranspiration, while lesser differences are observed in measured precipitation using the system. As a result of the position on the hillslope, different behavior of the soil-water potential that serves as a reference value for establishing equilibrium between the field and lysimeters is observed. Along with the first data from the observatory, the presented material includes installation methodology, system specifications, and description of the feedback control of the lower hydraulic boundary condition with its main components.

In the soil vadose zone, one of the critical processes is the water flow which is important for the root uptake but could also enhance transport of potentially harmful agricultural substances to surface and groundwater. Thus, we established the first Croatian critical zone observatory SUPREHILL to specify subsurface preferential flow and nonlinear agrochemical transport processes. Among other instruments, wick lysimeters were installed at the 40 cm depth at the top, middle, and bottom of the vineyard hillslope. The water volumes collected in lysimeters were measured every two weeks. For estimation of soil hydraulic properties (SHP) using HYPROP and WP4C techniques, the undisturbed soil cores (250 cm3) were taken from the same positions at 1520 and 3540 cm depth in three repetitions. The first results from one-year research showed the highest amount of water collected in lysimeters at the hilltop and the lowest at the middle part of the hillslope. Estimated SHP showed that the middle position mostly has the highest values of bulk density and the lowest values of porosity which could cause slower vertical water movement. Furthermore, the water volume in lysimeters could be a result of variable slope in the investigated hillslope. For example, the slope on the top is minor compared to the middle and the bottom thus resulting in the slowest lateral subsurface flow and the highest amount of collected water. The middle and the bottom have similar slopes, but below the bottom position, the slope becomes less steep affecting the water movement at that position and reducing lateral subsurface flow causing a higher amount of water compared to the middle part. At the middle position, the subsurface runoff is possibly the main water pathway since the middle part has a steep slope that continues to the bottom of the hillslope. Thus, to precisely determine water movement at vineyard hillslope and therefore the agrochemical transport, later in research we will combine results obtained by sensors set at the field at various depths, undisturbed soil columns experiments, CT-scanning, and numerical simulations.

Granične vrijednosti onečišćujućih tvari koriste se u postupcima ocjene kemijskoga stanja tijela podzemne vode i procjene rizika od nepostizanja okolišnih ciljeva za podzemne vode. U radu je detaljno obrazložena pravna osnova za određivanje graničnih vrijednosti, koja proizlazi iz EU direktiva, te su prikazane smjernice za određivanje graničnih vrijednosti iz relevantnih CIS vodiča, proizašlih iz aktivnosti Zajedničke provedbene strategije Okvirne direktive o vodama (2000/60/EZ). Razmotreni su znanstveni aspekti pristupa za određivanje graničnih vrijednosti, koji se temelje na primjeni okolišnoga kriterija, usmjerenoga prema zaštiti okoliša, i kriterija korištenja, usmjerenoga prema zaštiti pitke vode i drugih legitimnih vidova korištenja vode. Analizirana je mogućnost primjene odgovarajućih numeričkih pokazatelja djelovanja procesa razrjeđenja i procesa razgradnje onečišćujućih tvari te značenje i metode određivanja ambijentalnih pozadinskih koncentracija tvari u podzemnoj vodi. U radu su prikazani i rezultati komparativnih analiza primjene i usporedivosti metodologija za određivanje graničnih vrijednosti u državama članicama EU, provedenih tijekom 2012. i 2015. godine., Pollutant limit values are used in the procedures of chemical status assessment of groundwater bodies and risk assessment of failure to achieve environmental objectives for groundwater. The paper elaborates in detail the legal basis for determining limit values according to EU directives and presents the guidelines for determining limit values from the relevant CIS guidance documents resulting from the Common Implementation Strategy for the Water Framework Directive (2000/60/EC). Scientific aspects of the approach to determining limit values were based on the application of the environmental criterion (environmental protection) and use criterion (protection of drinking water and other legitimate water uses). A possibility to implement suitable numerical indicators of dilution and pollutant breakdown impacts, as well as the importance and methods for determining ambient background concentrations of substances in groundwater were analysed. The paper also presents the results of comparative analyses of the implementation and comparability of methodologies for determining limit values in EU Member States, which was conducted during 2012 and 2015., Grenzwerte verunreinigender Materien benutzt man bei Verfahren zur Beurteilung des chemischen Zustandes von Grundwasserkörpern und beim Beurteilen des Risikos vom Nichterreichen der ökologischen Ziele für Grundwasser. In der Arbeit wurde die rechtliche Grundlage basierend auf EU-Direktiven detailliert erörtert. Außerdem sind die Richtlinien zur Bestimmung von Grenzwerten aus relevanten CIS Broschüren, die aus der Aktivität Gemeinsame Durchführungsstrategien der Rahmendirektive über Wasser (2000/60/EZ) hervorgegangen sind. Erwägt wurden wissenschaftliche Aspekte des Ansatzes zur Bestimmung von Grenzwerten, die auf der Anwendung des Umweltkriteriums (zum Schutz der Umwelt) und des Anwendungskriteriums (zum Schutz von Trinkwasser und anderen legitimen Anwendungen von Wasser) basieren. Die Anwendungsmöglichkeit entsprechender numerischer Indikatoren zum Verdünnungsprozess wurde analysiert, ebenso wie zum Zersetzungsprozess verunreinigender Mittel sowie die Bedeutung und die Methoden zur Bestimmung ambientaler Hintergrundkonzentrationen von Materien im Grundwasser. In der Arbeit wurden auch die Resultate vergleichender Analysen der Anwendung und Vergleichbarkeit von Methodologien zur Bestimmung von Grenzwerten in den Mitgliedstaaten der EU dargestellt, die in den Jahren 2012 und 2015 durchgeführt wurden.

Transboundary groundwater resources are very important sources of water for different uses and represent a significant role in some region, although monitoring and management are an major issue. The Bregana – Obrežje (Slovenia) / Sava – Samobor (Croatia) aquifers were identified by the International Network of Water-Environment Centres for the Balkans (INWEB) inventory as transboundary aquifers. The main goal is to set up a cooperative framework so that institutions from both sides can effectively work together and ensure effective monitoring and management of transboundary aquifers.

Soil critical (vadose) zone is one of the most complex terrestrial systems as it covers root zone, different soil layers, and compaction effects. Soil heterogeneities have an impact on soil water and solute dynamics, which is especially pronounced on sloping arable terrains (e.g., vineyards). Thus, we established the first Croatian critical zone observatory SUPREHILL to specify subsurface preferential flow and nonlinear agrochemical transport processes. By using extensive sensor-based equipment combined with laboratory and numerical methods, we will collect a wide range of data allowing us to accurately estimate heterogeneities on a local scale. Results collected with sensors showed higher volumetric water content values on the hilltop compared to the bottom part. According to results obtained using HYPROP, saturated water content is decreasing through the soil profile with depth. Results obtained using sensors showed lower volumetric water content in the upper horizons compared to the lower ones. The oscillations in water content were largest at the first depth (5 and 15 cm ) due to the faster impact of precipitation and evaporation on the surface horizon. Sensors showed higher water content on the hilltop on 5 and 90 cm depth, but lower on 45 cm compared to the bottom. Higher water content at the last depth at the top can be a result of a sharp increase of clay content (26 % at 60 – 90 cm, and 39 % at 90 – 110 cm) which could lead to increased water retention. On the other hand, according to HYPROP results, the hilltop has higher bulk density, lower porosity and hydraulic conductivity than the bottom part which can result in slower water flow and more steady water content. The differences can initiate preferential flow and nonlinear transport dynamics, which will be further investigated using soil columns, dye tracer experiments, CT-scanning, and numerical simulations.

Copper (Cu) is found in many agrochemicals frequently used in vineyards and its concentration in topsoil may progressively increase. Cu forms rather stable complexes with soil organic matter (OM) thus binding of Cu on OM is an efficient mechanism for the retention of Cu in soil, minimizing its leaching. However, continental vineyards are mostly located at hillslope terrains, so other solute transport pathways could be important for Cu transport in sloped soil. Hypothesis was that because of Cu affinity for particulate organic compounds in soil, surface runoff will have a greater significance for total transported Cu if erosion processes occur and therefore transport of Cu-OM complexes along the hillslope. Another hypothesis was that subsurface Cu transport will be related to the amount of dissolved organic carbon (DOC) in the soil solution, but it is not expected to be highly significant if there is sufficient amount of particulate OM in soil. This study is a part of the SUPREHILL research project with the ongoing experiment located at the Jazbina experimental station (University of Zagreb Faculty of Agriculture, Croatia). The experiment is conducted on a vineyard hill with a pronounced slope (upper hill ~10 % and lower hill ~20 %) and with inter- row grass mulching practice, and it is ongoing since December 2020 (i.e., beginning of measurements after the equipment installation). Three surface and subsurface water collection systems are installed at the bottom of the hill, with water collected and analyzed monthly for basic chemical parameters, including Cu concentration. First results suggest that soil chemical properties define the amount of Cu transported by surface runoff and soil subsurface lateral flow. Soil pH is a major factor affecting Cu transport by subsurface lateral flow, i.e. acidic pH promoted the proportion of Cu2+ in the soil solution, enabling its transport by preferential lateral flow.

The aim to this paper was to estimate trends of hydrometeorological variables in a different time scales in order to see whether it will generate an indication of the impact of climate change in the wider research area. Trends were estimated on a monthly and yearly basis for precipitation, air temperature, evapotranspiration and maximum water available for infiltration at meteorological station Pleso, and for Bregana River water levels at hydrological station Koretići. Both locations are important because they can show patterns that could be characteristic for the wider Zagreb area, and are associated with Zagreb aquifer recharge. Linear regression and t-test were used for trend estimation. Monthly analysis showed ascending trends for air temperature and evapotranspiration, especially in the summer months. Descending trends for Bregana River water levels were observed when minimum and average values were considered, while statistically significant ascending trend for maximum water levels was observed only for February. Yearly trends showed similar patterns. Moreover, it was shown that evaluation of trends only on a yearly basis can sometimes hide important information. All results suggest that more dry periods should be expected, while floods could be more frequent in February. Bigger difference between high and low waters, i.e. extremes, was observed, but the results were not statistically significant. Trends showed that smaller infiltration from precipitation and reduced inflow from Bregana River to Sava River will probably result with the smaller recharge to the Zagreb aquifer, what can potentially be result of a climate change.

U okviru IAEA (engl. International Atomic Energy Agency) TC (engl. Technical Cooperation) projekta An environmental isotope investigation of the groundwater-surface water interactions at the regional well field Kosnica in the area of the city of Zagreb, CRO7001, praćena je koncentracija aktivnosti radioaktivnog izotopa vodika, tricija (3H), te omjeri stabilnih izotopa 2H/1H i 18O/16O u uzorcima s opažačkih postaja u širem području vodocrpilišta Kosnica. Istraživanja ovog vodocrpilišta provode se u svrhu određivanja brzina toka podzemne vode i područja prihranjivanja vodocrpilišta koje će u budućnosti biti jedno od glavnih vodocrpilišta za vodoopskrbu grada Zagreba i Zagrebačke županije. Podaci o izotopnom sastavu površinske savske vode i oborina na području Zagreba se sakupljaju dulji niz godina u svrhu prikupljanja podataka za svjetsku bazu podataka GNIR (engl. Global Network of Isotopes in Rivers), odnosno za svjetsku bazu podataka GNIP (engl. Global Network of Isotopes in Precipitation) [1-3]. Obje baze održavane su od strane IAEA, a podaci sakupljeni u bazama služe kao ulazni podaci kod hidrogeoloških i drugih istraživanja. Ovdje prikazani rezultati odnose se na razdoblje jednogodišnjeg uzorkovanja tijekom provođenja spomenutog IAEA TC projekta. Istraživanje izotopnog sastava voda na širem području vodocrpilišta Kosnica pokazala su da izotopni sastav δ2H, δ18O podzemnih voda (piezometri) odgovara izotopnom sastavu površinske vode (Save) što potvrđuje prihranjivanje vodocrpilišta vodom iz Save. Izotopni sastav oborina ovisi o temperaturi te su vrijednosti raspoređene unutar širokog raspona od maksimalnih ljetnih vrijednosti do minimalnih zimskih.

U okviru IAEA (engl. International Atomic Energy Agency) TC (engl. Technical Cooperation) projekta An environmental isotope investigation of the groundwater-surface water interactions at the regional well field Kosnica in the area of the city of Zagreb, CRO7001, praćena je koncentracija aktivnosti radioaktivnog izotopa vodika, tricija (3H), te omjeri stabilnih izotopa 2H/1H i 18O/16O u uzorcima s opažačkih postaja u širem području vodocrpilišta Kosnica. Istraživanja ovog vodocrpilišta provode se u svrhu određivanja brzina toka podzemne vode i područja prihranjivanja vodocrpilišta koje će u budućnosti biti jedno od glavnih vodocrpilišta za vodoopskrbu grada Zagreba i Zagrebačke županije. Podaci o izotopnom sastavu površinske savske vode i oborina na području Zagreba se sakupljaju dulji niz godina u svrhu prikupljanja podataka za svjetsku bazu podataka GNIR (engl. Global Network of Isotopes in Rivers), odnosno za svjetsku bazu podataka GNIP (engl. Global Network of Isotopes in Precipitation) [1-3]. Obje baze održavane su od strane IAEA, a podaci sakupljeni u bazama služe kao ulazni podaci kod hidrogeoloških i drugih istraživanja. Ovdje prikazani rezultati odnose se na razdoblje jednogodišnjeg uzorkovanja tijekom provođenja spomenutog IAEA TC projekta. Istraživanje izotopnog sastava voda na širem području vodocrpilišta Kosnica pokazala su da izotopni sastav δ2H, δ18O podzemnih voda (piezometri) odgovara izotopnom sastavu površinske vode (Save) što potvrđuje prihranjivanje vodocrpilišta vodom iz Save. Izotopni sastav oborina ovisi o temperaturi te su vrijednosti raspoređene unutar širokog raspona od maksimalnih ljetnih vrijednosti do minimalnih zimskih. This paper presents results of isotopic investigation (tritium activity, A3H, stable isotope composition δ2H and δ18O) of water samples from Zagreb aquifer – Kosnica well field, the future main well field of the Zagreb County. Research was conducted within the IAEA TC project An environmental isotope investigation of the groundwater-surface water interactions at the regional well field Kosnica in the area of the city of Zagreb, CRO7001. Results obtained from 10 piezometers (ground water) and surface water (Sava, Domovinski most) showed that stable isotope values are within very narrow range both for δ2H and δ18O: -64.3 ‰ – (-57.0) ‰ and 9.6 ‰ – (-8.7) ‰, respectively and fit within the LMWL: y = 7.7x + 3.7 (Local Meteoric Water Line) obtained from precipitation collected within one-year period from Meteorological Station Grič – Zagreb. A3H of precipitation showed natural values between 4,5 and 10, 4 TU. The maximum A3H of 168,6 TU observed in the Sava River due to discharge of cooling water from Nuclear Power Plant Krško (30 km upstream) was reflected in piezometer nearest to the Sava River (Mp-5) with 2-month delay and smaller intensity (A3H = 32.3 TU), indicating A 3H as excellent tracer for the Zagreb aquifer studies.

The Sava River is the longest river in Croatia and the main source of water for the Zagreb aquifer system. The fluctuations of the Sava River water levels cause fluctuations in the groundwater levels of the Zagreb aquifer, especially in the vicinity of the Sava River. Due to constant decrease of groundwater levels and possible groundwater quantity issues, especially in dry periods, construction of a new regional well field Kosnica is in progress. Kosnica well field is considered as a main well field supplier for Zagreb and determination of recharge areas is of prime concern, as such areas have to be protected in order to preserve good groundwater quality and quantity. Groundwater often consists of a mixture of recharge from surface water (lakes or rivers) and local precipitation. It is important to know the proportions of the recharge components in order to increase the sustainable supply of drinking water through bank infiltration, and to prevent drinking water pollution by infiltration of water from a contaminated surface water source. Different recharge components can be identified through the stable isotope composition of groundwater (2H and 18O) because of different isotope composition of end components and evaporation in surface water bodies. Tritium has also been used as a good tracer. In the case of the Sava River there is additional source of anthropogenic tritium from Krško Nuclear Power Plant (30 km upstream from Zagreb) which can be used as a tracer. Samples for determination of isotopic composition, 3H activity and 2H and 18O, were collected during 2016 in the Sava River, precipitation (monthly samples from Zagreb–Grič, meteorological station included in GNIP–Global Network of Isotopes in Precipitation) and groundwater at 10 monitoring wells close to the Sava River. 3H activity was measured by liquid scintillation counter (Quantulus 1220) and samples were electrolytically enriched before measurement. 2H and 18O were determined by Liquid water isotope analyser, Los Gatos. Significant increase of 3H activity in the Sava River was observed in October 2016, (178 ± 21) TU, and in groundwater of the observation well nearest to Sava River with damped response (maximum 35 TU) and with delay of 2.5 months related to the Sava River. This increase was explained by release of tritiated water from the Krško Nuclear Power Plant. Stable isotope analyses showed similar range of δ2H and δ18O values for the Sava River and groundwater samples with higher variations in surface water. Differences in monthly variations of δ18O values between particular monitoring wells, together with 3H values, indicated different infiltration times of surface water of the Sava River to different observation wells in the vicinity of Kosnica well field. Research and purchase of stable isotope analyser was financed by IAEA TC Project, CRO 7001.

The Zagreb aquifer presents the main source of potable water for the City of Zagreb and part of Zagreb County, and is protected by Croatian state government. In the last decades issues regarding groundwater quantity and quality have been observed. Groundwater levels are declining in average 1-2 m per decade, generally due to lowering of the Sava River bed and excessive pumping. Currently, groundwater for water supply is pumped from six different well fields. There is new regional well field Kosnica on- going project, with aim to avoid groundwater quantity issues in future, especially in dry periods. Isotopic research at Kosnica site has been performed in 2016. Samples from the Sava River, Zagreb precipitation and groundwater from 10 observation wells were taken on monthly basis. The Sava River has been identified as a main boundary condition of the Zagreb aquifer. The influence of this boundary, on groundwater levels in the Kosnica area, has been investigated. Kosnica well field is located approximately 800 m from the Sava River what suggested, as well as all the results of previous research, that the Sava River will be the main source of recharge for the new well field. Previous researches recognised three main zones of identical groundwater table changes in time. Recession curve models also revealed areas near the river with higher impact of the Sava River on groundwater levels. Water stable isotopes (2H and 18O) were determined by liquid water isotope analyser, Los Gatos Research. Data was prepared, processed and interpreted in LIMS (laboratory information management system). 3H activity was measured by liquid scintillation counter (Quantulus 1220) and samples were electrolytically enriched before measurement. The results of environmental isotopes measurements in groundwater near Kosnica well field in the Zagreb area indicate strong connection between the Sava River and nearby observation wells. Accordingly, mixing of water from the Sava River and groundwater is occurring in the near vicinity of the Sava River and it weakens further away. Furthermore, local precipitation has a small contribution to groundwater recharge and attention needs to be directed to the Sava River. Determined groundwater velocity in combination with existing Croatian legislation point to the distinction of two different protection zones between the Sava River and the Kosnica well field. The results of this study allow better understanding of the relationship between surface water and groundwater and consequently more precise definition of the sanitary protection zones of the Kosnica well field.

U usporedbi s ostalim biomaterijalima, autologna kost je jedini materijal koji posjeduje osteoinduktivna, osteokonduktivna i osteogena svojstva, stoga se smatra zlatnim standardom.Unatoč tome, posjeduje i neke nedostatke: dva kirurška polja (donorsko mjesto i mjesto koštanoga defekta), visoki morbiditet, ograničena količina autologne kosti koje se može sakupiti intraoralno i produženo vrijeme trajanja zahvata. Uporabom alogenih koštanih blokova možemo smanjiti vrijeme trajanja zahvata i morbiditet. Također, na raspolaganju nam je neograničena količina biomaterijala pa smo u mogućnosti regenerirati i opsežne defekte alveolarne kosti. U prikazu slučaja pacijentice s potpuno bezubom maksilom i izrazitim koštanim horizontalnim defektom, korišteni su alogeni koštani blokovi kako bi omogućili ugradnju implantata i izradu fiksno protetskog rada.