Sonja Lojen

• PhD in Geology
• Scientific counselor at Jožef Stefan Institute

The Slovenian climate has undergone significant fluctuations, and an understanding of the past climate is necessary to improve models and recognise long-term patterns. The cryosphere environment, such as ice core samples, provides valuable palaeoclimate data. Palynology and dendroclimatology are also effective ways to study long-term changes in veg...

The application of biostimulants based on hydrolysed animal protein to leaves (foliar) or nutrient solution was studied on hydroponically grown Genovese 'Marian' basil grown under salinity conditions. The effect on N yield and N fertilizer utilization was tested with the stable isotope 15 N, which indicated the part of the plant that accumulated th...

Background Climate change is increasingly impacting agriculture all over the world, with extended periods of drought, flooding, hail, winds and temperature extremes. To negate the effects of climate change, researchers are trying to find new agricultural production techniques, to save resources without losing yield quality and quantity. A study on...

The utility of the Mg/Ca elemental ratio of calcite ((Mg/Ca)calcite) as a temperature indicator in continental carbonate deposits is a matter of debate due to the different results obtained by diverse authors. In this study, we aimed to test the reliability of the (Mg/Ca)calcite in fluvial carbonates. We selected the recent tufa stromatolite record...

The Jama v Dovčku cave on the eastern edge of the Dinaric Karst region in Slovenia provides suitable conditions for the study of Holocene paleoclimatic events by dating stalagmites. However, in order to determine the context of stalagmite growth, a thorough speleogenetic reconstruction of the cave was undertaken. The cave entrance opens on the Gorj...

The accuracy and uncertainty of paleoclimate interpretations of geochemical and isotopic proxies from stalagmites depend critically on how accurately isotopic signals are transmitted through the vadose zone of the aquifer and how the elemental composition of the groundwater feeding the stalagmite changes as it passes through the aquifer. Results o...

Greenhouse production of chilies requires constant irrigation and fertilization. Due to climate change, water availability is decreasing, and thus new techniques are being developed, one of which is deficit irrigation, also applied in controlled conditions, such as greenhouse production This allows us to improve yield quality with minimal or no red...

From 1992-1994, trace metal concentrations of bog water, Sphagnum mosses and peat cores of the bog „Georgenfelder Hochmoor“ at Zinnwald-Georgenfeld in the Eastern Ore Mountains (Germany) were investigated. A sampling campaign in September 2019 allows the comparison of the older measurements with today’s trace metal concentrations. No changes were f...

The concentration and isotopic composition of uranium (δ²³⁸U, ²³⁴U/²³⁸U activity ratio) in combination with traditional isotopes (δ¹⁸O, δ¹³C) were examined as potential tracers of authigenic carbonate formation in a karst aquifer. The U concentration and ²³⁴U/²³⁸U activity ratios in the tufa-precipitating sections of two connected karst rivers (Krk...

A detailed knowledge of the stable isotope signature of precipitation is the basis of investigations in a variety of scientific fields and applications. To obtain robust and reliable results, the representativity of the currently operating (at least, as of 2018) precipitation stable isotope monitoring stations across Slovenia (n = 8) and Hungary (n...

Water isotope investigations are a powerful tool in water resources research as well as in understanding the impact that humans have on the water cycle. This paper reviews past hydrological investigations of the Ljubljansko polje and Ljubljansko barje aquifers that supply drinking water to the City of Ljubljana, with an emphasis on hydrogen, oxygen...

Abstract The controls that affect the structure and timing of terminations are still poorly understood. We studied a tufa deposit from the Iberian Peninsula that covers Termination II (T-II) and whose chronology was synchronized to speleothem records. We used the same chronology to synchronize ocean sediments from the North Atlantic to correlate ma...

The karst aquifer of the Ljubljanica River catchment, which has numerous springs and sinks, presents an interesting environment for studying hydrogeological processes. This study aims to explore the behavior of U isotopes and to evaluate their use as tracers of hydrogeochemical processes as an alternative to classical geochemical tracers (i.e., phy...

Lake sediments are key archives for paleoenvironmental investigation as they provide continuous records of the depositional history of the lake and its watershed. Lake Futalaufquen (42.8°S) is an oligotrophic waterbody located in Los Alerces National Park in the Andes of northern Patagonia, South America. A sedimentary sequence covering 1600 years...

The Mareza karst aquifer is the most important drinking water resource for the water supply system of the City of Podgorica, the capital of Montenegro. This study presents the first assessment for the determination of the Mareza catchment area. Water chemistry and stable isotopic composition (δ¹⁸O and δ²H) of monthly precipitation samples (as input...

Termoelektrarna Plomin (TEP) se nahaja na vzhodni obali Istre (Hrvaška) in je bila dolgo glavni onesnaževalec zraka v Istri. V obdobju 1970-2000 je TEP uporabljala domači črni premog iz Raše, za katerega je značilna visoka naravna radioaktivnost in izredno visoka vsebnost žvepla (do 14,0 ut. %) in sodi med premoge s super visoko vsebnostjo organske...

Karst systems can be generally characterised by their high hydrological heterogeneities related mainly to highly variable permeabilities, which can significantly change over small spatial scales. This makes tracing and quantification of water flow pathways an extremely demanding task. In this study we present an analysis of hydrological characteris...

Deep caves on the Nullarbor Plain in southern Australia are characterised by a long dominant passage reshaped by collapses and consequently lacking original solutional features on the ceilings and walls. Their formation is not yet fully understood; solution during wetter periods in the Oligocene and/or Pliocene, mixing corrosion, crystal wedging an...

Large deep caves with little relation to surface topography are distinctive karst features on the Nullarbor Plain of Australia. The presence of gypsum deposits and chemoautotrophic bacteria within the caves have been suggested as evidence for cave formation and (or) enlargement via sulfuric acid speleogenesis. To test this hypothesis, the stable su...

The Kornati National Park (Croatia) is considered an environment with minimal anthropogenic input. The purpose of this study was to determine the isotopic characteristics of the sediment and muscle tissues of the banded dye-murex Hexaplex trunculus. We selected locations in the park according to their estimated risk of anthropogenic pollution (larg...

The impressive deep caves of the Nullarbor Plain mainly consist of one long passage with a simple form - flat roofs, smoothly arched walls and dome-like ends prone to collapse. It has been suggested that their formation is due to solution that occurred during pluvial periods in the Oligocene and/or Pliocene, although several other processes have be...

The application of stable and radioactive isotopes of the water molecule in various research activities is steadily increasing worldwide. Precipitation isotope mapping has revolutionized during last decades and isoscapes were calculated based on data from Global Network of Isotopes in Precipitation (GNIP) database and different regional databases....

The traceability of food products in terms of their geographical origins is getting more and more public attention. To be certain of the origin of organically grown potato (Solanum tuberosum L.), samples were subjected to stable isotope analysis of the major bioelements (δ¹³C, δ¹⁵N, δ¹⁸O, δ³⁴S) and to element profiling (Na, Mg, P, S, Cl, K, Ca, Mn,...

The stable isotope composition of precipitation records processes taking place within the hydrological cycle. Potentially, moisture sources are important controls on the stable isotope composition of precipitation, but studies focused on this topic are still scarce. We studied the moisture sources contributing to precipitation at Postojna (Slovenia...

Paleoclimate reconstructions based on speleothems require a robust interpretation of their proxies. Detailed transfer functions of external signals to the speleothem can be obtained using models supported by monitoring data. However, the transferred signal may not be stationary due to complexity of karst processes. Therefore, robust interpretations...

Combination of stable isotopes measurements and more frequently used measurements such as rainfall or discharge data observations can be used to investigate hydrological characteristics of the nonhomogeneous catchments. For example, with stable isotopes flow paths of rainfall water to the river network can be determined and mean residence times can...

In the present research, the applicability of stable isotope (δ13C, δ15N, δ34S, δ18O) and multi-element (P, S, Cl, K, Ca, Zn, Br, Rb, Sr) data for determining the geographical origin of garlic (Allium sativum L.) at the scale of Slovenia was examined. Slovenia is a rather small country (20273 km2) with significant geological and biological diversit...

In recent years, the geographical authentication of different agro-products, including vegetables, has gained an increasing amount of attention. This study investigated different approaches, both independently and in combination, to assign the country of origin to commercial tomato samples from Slovenia, Italy, Spain and Morocco. To create a model...

The presence of potentially toxic elements (PTE) was determined in different tissues of five selected marine organisms. The As, Cd, Cu, Mn, Mo, Ni, Pb and Zn concentrations were measured in the seagrass Cymodocea nodosa , the green alga Cladophora echinus , the red alga Gelidiella lubrica , the marine topshell Phorcus turbinatus and the littoral cr...

Management of deep geothermal resources in Slovenia is very complex because of the depth of the geothermal aquifers. In this study we have developed a conceptual model for the management of deep geothermal aquifers in Northeastern Slovenia, which has turned out to be much more complex. Evolution of the problems that occurred when developing a conce...

This study reports for the first time thesulphur isotopes and S forms measured in soil polluted with sulphur derived from the thermoelectric power plant Plomin (TPPP). The TPPP is located on the eastern coast of the Istrian peninsula (North Adriatic, Croatia), and is considered as the prime air polluter in Istria (Božičević Vrhovčak et al., 2005)....

By using stable oxygen and hydrogen isotopes in hydrological studies one can obtain answers to questions that are difficult to answer with standard hydrological measurements. For example, with stable isotopes we can determine where the water goes when it rains and identify the flow paths of rainfall to the streams. This paper shows theoretical back...

Recently, increased public attention has been paid to the geographical authentication of food, including vegetables, which are considered to be one of the major health-promoting components in a balanced diet. The purpose of the present study was to investigate the suitability of the use of isotopic compositions of light elements (δ¹³C, δ¹⁵N, δ¹⁸O,...

Since all of the questions in hydrology cannot be answered with hydrological measurements, hydrologists have been applying stable isotopes analyses for several decades in their research. For example, with stable isotopes flow paths of rainfall to the streams can be identified and mean residence time can be estimated. Only with traditional measureme...

The importance of collecting data on the water isotope composition of precipitation in the frame of the Global Network of Isotopes in Precipitation (GNIP) has been steadily increasing since it was initiated by the IAEA and the WMO in 1958, particularly in the last decade (Terzer et al., 2013). GNIP provides an important database for water resources...

Padavine so pomemben del hidrološkega kroga, saj predstavljajo ključni vir vode na kopnem. Poznavanje njihove izotopske sestave v posameznih porečjih pa nam omogoča sledenje izvora površinskih in podzemnih vod ter določitev dinamskih značilnosti znotraj posameznih vodnih teles. V Sloveniji potekajo raziskave izotopske sestave padavin že več kot 40...

This paper investigates recent sedimentation processes and geochemistry of sedimentary organic matter (SOM) and trace elements in a unique semi-enclosed lacustrine sedimentation system in a transitional land-sea environment of the Neretva River delta. The results have shown that the influence of the Neretva River on the lake sedimentation processes...

Tufa sediments are freshwater carbonates that precipitate in karst regions after degassing of CO2 from groundwater in contact with the atmosphere. When laminated, these carbonates can provide high-resolution records for the study of climate, hydrological and environmental conditions at the time of their precipitation. The formation of these carbona...

Tufa samples from 16 consecutive barrages along a 13 km section of a groundwater-fed Krka River (Slovenia) were analysed for their petrographical, mineralogical, elemental and stable carbon (δ13C) and oxygen (δ18O) isotope composition, to establish their relation to current climatic and hydrological conditions. Waters constantly oversaturated with...

This chapter represents the mineralogical, geochemical and isotopic characteristics of recent lacustrine sediments, shells of the Anodonta cygnea and fish species (Rutilus rutilus dojranensis) from the Lake Dojran (FY Republic of Macedonia, southern part of the Serbo-Macedonian Massif (SMM)) which provide indirect evidence regarding biomineralizati...

This research focuses on the mechanisms that transfer the variations in surface atmospheric temperature into caves to evaluate whether they record the warming trend of recent decades. As a study case, we use the data from a hall in Postojna Cave (Slovenia), which was monitored from 2009 to 2013. The low-frequency thermal variability of this cave ch...

In order to estimate the quality of Makirina bay, samples of surficial peloids (0-5 cm), water and biota (seagrass, green algae, gastropoda and shore crab) were collected to analyse quantitatively for the presence of several potentially toxic elements (PTE), including As, Cd, Cu, Mo, Ni, Pb and Zn.

Several characteristics of Makirina bay peloid were determined.

This research focuses on determination of the mineralogical composition, geochemical characteristics and evaluation of pollution status of the Makirina Bay sediments. Calculated enrichment factor (EF) values show no enrichment (< 1) for Cd, Ni, and Zn, minor enrichment (< 3) for As, Cu, and Pb, and minor to moderate enrichment for Mo. The results o...

The oxygen and carbon isotope compositions of carbonate samples from the carbonatite-like dyke of the Madenska River complex at the Kriva Lakavica section, samples of calcite skarns from the Damjan Fe-ore deposit and the Sasa Pb-Zn ore deposit, and samples of marbles from the Pohorje Mountains were analyzed to provide critical evidence in favor of...

Makirina Bay peloid mud was analysed in the interest of determining its physico-chemical and geochemical characteristics in order to assess the suitability of peloid mud use for cosmetic and/or therapeutic purposes as material for mud wraps or baths. The properties of Makirina Bay peloid mud were compared with various raw geological materials (Dead...

Recent marine sediments from Makirina bay are according to their organoleptic properties, treated as peloid or healing mud, already frequently used by local people and tourists as pomades. The application of peloids in balneotherapy is mainly intended for therapeutic treatment generally related to muscle-bone skin pathologies and purposes of wellne...

V članku obravnavamo uporabnost lehnjaka iz reke Krke (Hrvaška) kot paleotemperaturnega arhiva na os-novi izotopske sestave kisika (δ 18 O) in razmerja Mg/Ca. Analizirali smo masivni lehnjak z glavnih pregrad in ga primerjali z laminirano skorjo iz hidroelektrarne Jaruga. Masivni vzorci zaradi velike količine litičnega karbonata (dolomita in kalcit...

Common bottlenose dolphin (CBD) and bottom trawlers exploit the same ecological niche. The estimated CBD population along the Israeli coastline consumes roughly 1280 t of prey annually, similar to the mean annual trawl-fishery yield of 1300 t. In the ultra-oligotrophic Levantine Basin, the potential for competition for limited resources therefore e...

Nitrogen and carbon stable isotope analysis of particulate organic matter (POM) was used to assess the impact of anthropogenically derived organic matter in coastal parts of the Istra Peninsula (Northern Adriatic). The investigation was conducted in areas potentially impacted and enriched with different amounts of organic matter. Elevated d15N valu...

The article deals with chemical and isotopic properties of Borovnica alluvial fan groundwater. Increased concentrations of ammonium and iron were detected in well VB-3 of the Borovnica alluvial fan pumping station. On the basis of analyses it was found out that increased concentrations of both elements are linked to the hydrogeological conditions i...

The research focuses on determination of geochemical characteristics and distribution of Rareearth elements (REEs) in Makirina Bay sediments. The overall REEs concentrations in Makirina Bay sediments samplesdetected during study ranged from 123.94 ppm to 188.74 ppm. REEs content showed a gradual increase towardsthe depth of sediments. The average U...

In support of aquaculture development and sustainable fisheries, survival, condition index, and stable isotope composition of the commercially important bivalve species Arca noae were investigated on individuals suspended in the water column at 2 distances from fish cages and those collected from natural populations. Significant differences were re...

Samples of Hypnum cupressiforme were collected at two types of site in forest areas: within the forest stand and within forest openings, and analyzed for N and S concentrations and δ(15)N. Mosses sampled within forest openings reflect the atmospheric N deposition; however, no influence of throughfall N deposition on the N in the moss that was sampl...

The feeding ecology of four bivalve species co-occurring in the Mali Ston Bay, the most important bivalve aquaculture area of the Eastern Adriatic, were investigated by analysing the stable isotope composition and lipid content in two tissue types. Analyses included two cultured species: Mytilus galloprovincialis and Ostrea edulis, and two naturall...

This paper examines how the mixing of freshwater and seawater, and related mixing of freshwater and marine particulate organic matter (POM) in the permanently stratified estuary of the River Krka, Croatia, are reflected in the stable isotope fingerprints of soft tissues and tubes of the serpulid Ficopomatus enigmaticus. The carbon stable isotope co...

Coastal environments are often exposed to different anthropogenic contaminants that can cause evident differences in coastal ecosystems. For this reason the use of various organisms as an indicator offers an important ecological study. In this survey the limpet Patella caerulea was examined as a potential anthropogenic bioindicator in coastal marin...

In support of aquaculture development and sustainable fisheries, survival, condition index, and stable isotope composition of the commercially important bivalve species Arca noae were investigated on individuals suspended in the water column at 2 distances from fish cages and those collected from natural populations. Significant differences were re...

Identification of six-month intervals in carbonate deposits formed on tablets installed in several fluvial subenvironments of the Monasterio de Piedra Natural Park, from 1999 to 2009, allowed six-monthly stable-isotope analysis of such records. Slight differences in δ13C and δ18O exist between stromatolites (fast-flowing water areas) and moss-beari...

Postojna Cave (Slovenia) is one of the most famous karst caves in South Eastern Europe. Drip water is one of the factors that determines cave interior. During 2010 and 2011 monitoring of drip water in Postojna Cave was performed at 9 locations within the Cave. Drip rate was measured and the isotopic composition (delta 18O) of drip water was determi...

The hydrogeochemical and carbon isotope characteristics of the Krka River, Slovenia, were investigated to estimate the carbon transfer from the land ecosystem in the watershed. During the 3-year sampling period (2008–2010), temperature, pH, electrical conductivity, major ion content, dissolved inorganic carbon (DIC) and dissolved organic carbon con...

Stable isotope composition of soft tissues and carbonate tubes of the serpulids F. enigmaticus and M. cavatica were used to estimate their food sources. Comparison of isotope fingerprints of adjacent estuarine and anchialine cave serpulids showed that they consume predominantly particulate organic matter of terrestrial origin.

Multivariate statistical analyses were applied on the measured physico-chemical (Cd, Pb, Cu, Zn, Mg, Ca, O2, alkalinity, temperature, pH, SAS, DOC and DIC) and isotopic parameters (δ13C and δ18O) to estimate and distinguish anthropogenic from natural influences to the water system of the Krka River. Analyses were conducted on the data collected dur...

Secondary carbonate precipitates (dripstones) formed on concrete surfaces in four different environments--Mediterranean and continental open-space and indoor environments (inside a building and in a karstic cave)--were studied. The fabric of dripstones depends upon water supply, pH of mother solution and carbonate-resulting precipitation rate. Very...

The effect of different fertilisation (broadcast solid NPK application and fertigation with water-soluble fertiliser) and irrigation practices (sprinkler and drip irrigation) on yield, the nitrate content in cabbage (Brassica oleracea var. capitata L.) and the cabbage N uptake was detected, in order to assess the potential risk for N losses, by cul...

The Levantine Basin (LB) is still considered a void as regards its cetacean fauna: species population abundance and distribution patterns are unknown, and even the list of species and their regional status have so far not been finalized. In an effort to fill the knowledge gap, we present original data collected in the LB over the years 1993-2009. T...

Krka is a typical karstic river, which receives a considerable amount of water through diffuse subsurface recharge. The hydrological situation is explained only for the upper part of the Krka watershed, whereas the situation in the middle and lower parts of the stream is yet to be properly described. Sedimentary processes of alternating barrage and...

Stable nitrogen isotope ratios of particulate matter POM, zooplankton and selected biota such as Mytilus galloprovincialiswere used to assess the impact of anthropogenically derived organic matter from untreated domestic sewage, municipal and industrial effluents on the coastal ecosystem of Kosirina Bay (Murter Island). The differences in δ15N valu...

The aim of this study was to obtain preliminary data on δ(15)N values in organically and conventionally grown vegetables available on the Slovenian market to determine whether there are any characteristic differences in δ(15)N values, which could be used as a marker to differentiate between organically and conventionally grown vegetables, namely ve...

The chemical status of the shallow alluvial Savinja Valley groundwater body in Slovenia is poor, mainly due to the high concentration of nitrate in groundwater. This case study is therefore oriented in the assessment of groundwater vulnerability to nitrate pollution, as a base for the measure-planning processes. The article describes the use of iso...

In the search for new technologies that would ensure optimum yield and environmental sustainability, various irrigation, nitrogen and cropping system management strategies for the production of vegetables with a shorter growing period were assessed at a benchmark site in Slovenia for the years 2006 and 2007. In the studied years four irrigation and...

The nitrogen isotopic fingerprint (δ(15)N) is reported to be a promising indicator for differentiating between organically and conventionally grown vegetables. However, the effect on plant δ(15)N of split nitrogen fertilisation, which could enable farmers to cover up the use of synthetic fertiliser, is not well studied. In this study the use of δ(1...

Stable isotope analyses of carbonates and organic matter from the Permo-Triassic boundary section in the Karavanke Mountains, Slovenia, indicate a further example of the “light carbon” event across the boundary. In this section the changes in carbon isotope values were a direct result of the culmination of the marine regression and associated event...