J) Environmental chemistry

1. Novel radioactive tracers for the purpose of atmospheric studies

Within the master topic student will investigate usability of novel radioactive tracers for the purpose of using in atmospheric studies. Particle reactive radionuclides, such as Pb-210 and Po-210 will be investigated in different atmospheric samples, as well as cosmogenic radionuclide Be-7. Following sampling, student will develop methodological framework for analysis and statistical interpretation of data to be able to predict different atmospheric processes relevant for studying transport and fate of atmospheric pollutants.

Mentor: dr. Marko Štrok (marko.strok@ijs.si), dr. Janja Vaupotič (janja.vaupotic@ijs.si)

2. Application of historical datasets from radionuclide monitoring for study of environmental processes

The main purpose of radionuclide monitoring is to asses impact of radionuclides on human health. However, such data could be also used for other purposes as for instance for study of biogeochemical processes in the environment. Of main interest are radionuclides such as H-3, Sr-90 and Cs-137, which were released to the environment either due to past nuclear bomb tests, nuclear accidents and some of them, such as H-3, are regularly released during routine operation of nuclear facilities. As such, they represent possible interesting tracers of biogeochemical processes in the environment. Within master topic student will collect available datasets about environmental monitoring of radionuclides, evaluate them and use statistical methods to find their usability for tracing of different biogeochemical processes.

Mentor: dr. Marko Štrok (marko.strok@ijs.si)

3. Development of method for radiometric dating with C-14

Radiometric dating with C-14 is valuable tool for different environmental, geological and paleontological purposes. Student will develop and validate methodology for sample preparation and measurements of C-14 with liquid scintillation counter for different samples. After that, it will apply it to the samples with the aim of estimation of age of the sample.

Mentor: dr. Marko Štrok (marko.strok@ijs.si)

4.  Characterization of 50 Slovenian springs with the help of tritium, geochemical parameters and novel isotopic tracers

Student will perform field sampling of water and rocks from different Slovenian springs and will perform their geochemical characterization by using tritium, different geochemical parameters, stable isotopes and novel isotopic tracers such as U. This will be followed by statistical data treatment and interpretation.

Mentors: dr. Marko Štrok (marko.strok@ijs.si), dr. Tjaša Kanduč (tjasa.kanduc@ijs.si), Leja Rovan (leja.rovan@ijs.si)

5. Alternative approaches for mass bias corrections for multicollector inductively coupled plasma mass spectrometry

Mass bias corrections are of paramount importance for ensuring high quality of results for isotope ratio measurements with multicollector inductively coupled plasma mass spectrometer. Student will investigate different mass bias correction models on different isotopic systems and try to establish improved procedures for assessment of mass bias.

Mentors: dr. Marko Štrok (marko.strok@ijs.si), dr. Tea Zuliani (tea.zuliani@ijs.si)

6. Distribution and isotope fractionation of molybdenum and uranium during precipitation of authigenic carbonate in rivers

 The thesis is a part of the project dealing with the potential use of non-traditional isotopes as identifiers of authigenic carbonate, which is one of the largest continental carbon sinks. U and Mo are redox sensitive elements, which are distributed between the solid and liquid phase during the precipitation of carbonate in different ways, depending upon the redox conditions of the environment. While their distribution and isotopic fractionation is relatively well established for marine carbonates, little is known on the same process in continental freshwater settings. The aim of the thesis is to determine the distribution and isotopic fractionation of uranium and molybdenum between water and authigenic precipitate in the process of the formation of tufa barriers in karst rivers. The work will encompass the extraction and analysis of concentration and isotopic composition of uranium (234U/238U, δ238U) and molybdenum (δ98Mo) in water, in carbonate and non-carbonate fraction of tufa using advanced mass spectrometric methods (multicollector ICP-MS). Two topics are available – distribution and isotopic fractionation of Mo and distribution and isotopic fractionation of U.

Mentors: dr. Marko Štrok (marko.strok@ijs.si), dr. Tea Zuliani (tea.zuliani@ijs.si)

7. Leaching and isotopic fractination of molybdenum and uranium during infiltation of precipitation in karst aquifers

The formation of authigenic carbonate incrustations and cements in karst aqifers represents one of the major continental sinks of CO2. Trace elements and their distribution between different environmental compartments can be relevant tracers of dissolution and precipitation of carbonates. The aim of the thesis is to explore the processes o leaching of molybdenum and uranium from soil and carbonate rocks along the pathway of precipitation from through soil and bedrock to the karst spring using laboratory experiment, and to compare the obtained results with field measurements. The laboratory work will encompass the analysis of natural water, soil, bedrock and eluates obtained in leaching experiments using advanced mass spectrometry methods (multicollector ICP-MS. Two topics are available – leaching and isotopic fractionation of Mo and leaching and isotopic fractionation of U.

Mentors: dr. Marko Štrok (marko.strok@ijs.si), dr. Tea Zuliani (tea.zuliani@ijs.si)

8. Distribution and isotopic fractionation of molybdenum and uranium in stream sediments accorss the redox boundary

The isotopic composition of trace elements in the environment has been recently used as a natural tracer of their origin, which is of particular interest in the appointment and distribution of sources of metal contaminants in the environment. However, the isotopic composition of metals in nature depends not only upon their source, but also in their speciation which governs their solubility, mobility and distribution between different  phases and environmental compartments, and is often depending upon the physico-chemical conditions in the environment, such as pH and redox potential. The aim of the thesis is to determine the distribution and isotopic composition of two redox sensitive trace elements - uranium and molybdenum in the river water and in the sediment column across the redox boundary.  The laboratory work will  comprise the extraction and determination of concentration and isotopic composition of Mo and U from water and sediment samples. Two topics are available – distribution and isotopic fractionation of Mo and distribution and isotopic fractionation of U.

Mentors: dr. Marko Štrok (marko.strok@ijs.si), dr. Tea Zuliani (tea.zuliani@ijs.si)

9. Distribution and isotopic fraction of magnesium and strontium in river sediments accross the redox boundary

Magnesium and strontium occur in aquatic environment dissolved as cations, while during precipitation of carbonate they often substitute Ca2+ ions in the crystal lattice of calcite or aragonite. Although authigenic calcite represents  a common cement in aquatic sediments and acts one of the major continental CO2 sinks, its magnitude still hasn't been quantified appropriately. The usual identifier of authigenic calcite in carbonaceous sediments in the isotopic composition of carbon, however, in precipitates formed in anoxic sediments rich in organic matter the isotopic fractionation of carbon occurs in different processes which fractionate the C isotopes simultaneously in different directions.  Therefore, the isotopic composition of Mg and Sr will be tested as potential identifiers of authigenic carbonate in an organic rich lacustrine sediment, where the redox conditions are changing in the sediment column from oxic to strongly anoxic (methanogenic). The laboratory work will comprise the extraction and analysis of concentration of Sr and Mg and their isotopic composition in the pore water and the mineral phase of the sediment core form a lentic flow section of a tufa precipitating karstic stream. 

Mentor: dr. Sonja Lojen (sonja.lojen@ijs.si)

10. Distribution and isotope fractionation of magnesium and strontium during abiotic and biomimetic precipitatio of CaCO3 in laboratory experiments

The isotope composition of light elements (C and O) in carbonate has been used for decades as a tracer of temperature and environmental conditions at the locus of the carbonate precipitation in natural environments. The isotope composition of metals in water and in carbonate has recently been used for appointment of sources of respective metals, while the relation between metal isotope fractionation and environmental conditions during carbonite precipitation have not yet been properly investigated. The aim of the thesis will be to explore the partitioning and isotope fractionation of Mg and Sr during precipitation of calcium carbonate in karst-identical conditions during abiotic precipitation from supersaturated solutions via degassing of excess CO2, and and during biomimetic calcite precipitation via splitting of dissolved urea to produce the CO2 used for the calcite precipitation. Mother solutions with variable Ca:Mg:Sr ratios will be used. The obtained results will be useful for better interpretation of natural climate and palaeoenvironmental archives (e.g. speleothems, spring and fluvial carbonates). The analytical methods used for characterisation fo samples will be scanning electron microscopy with microanalysis, isotope ratio mass spectrometry and multicollector ICP mass spectrometry for metal isotope analysis.

Menthor: dr. Sonja Lojen (sonja.lojen@ijs.si)

11. Comparison of natural isotope tracers in laminated stream carbonates

Laminated tufa is often used as natural paleoenvironemntal archive since the distribution of elements and isotopic composition of carbon and oxygen in carbonate reflect the climate and environmental conditions at the locus of their precipitation and in the wider catchment area. The advanced analytical methods for the isotope analysis of alien cations in CaCO3 (e.g. Mg, Sr) enable the aquisition of new data which can support the paleotemperature and paleoenvironmental interpretation based on multi-proxy analysis, which can reduce the uncertainties of traditional geochemical and O isotope thermometers and provide better insight into paleohydrological conditions. With the analysis of recent laminar tufa from a known location (National Park Krka), we will explore the potential of d26Mg, 87Sr/86Sr and d88Sr in carbonate as new paleoenvironmental proxies. Electron microscopy with microanalysis, isotope ratio mass spectrometry and the multicollector ICP-MS will be use to obtain the necessary data.

Mentor: dr. Sonja Lojen (sonja.lojen@ijs.si)

12. The sources and transport of CO2 in the air

The topic is related to the project J1-1716 and the cycling of carbon (C) in the environment. The research would include measurements of black carbon, PM10 particles and stable C isotopes at selected locations in Ljubljana. This would help to identify the sources and transport of CO2 and particulate matter in urban environments, where traffic and individual combustion plants contribute significantly to CO2 formation. The work will include the measurements, data processing and collection of ancillary data from the available ARSO stations.

Mentors: dr. Nives Ogrinc (nives.ogrinc@ijs.si), dr. Janja Vaupotič (janja.vaupotic@ijs.si), dr. Bor Krajnc (bor.kranjc@ijs.si)

13. Determination of the geographical origin of wood based on the isotopic composition of strontium

The 87Sr/86Sr ratios varies with rock type and is further transferred to soil waters where it becomes bioavailable, that is available to be absorbed by plant roots and subsequently deposited in the cellulose during tree ring growth. Thus, by measuring 87Sr/86Sr ratio in a given sample of wood is possible to identify the geochemical signal of water and soil at the site of tree growth.

For the master thesis, the 87Sr/86Sr ratios will be determined in soil, water and wood samples in order to test this geochemical-based tool for wood provenancing.

Mentor: dr. Tea Zuliani (tea.zuliani@ijs.si)

14. Bioaccumulation and trophic transfer of potentially toxic elements

The level of element accumulation in fish is governed by abiotic factors such as nature and intensity of pollution, water pH, alkalinity and temperature, and biotic factors, such as size, age, feeding habits, and reproductive cycle. Since different fish species accumulate and eliminate toxic elements in different ways, it is important to analyse various fish species. In order to distinguish recent from long-term exposure, fish of varying age (size) and from different trophic levels should be also analysed.

Cr, Cu, Fe, Se, Zn, Co and Mn in trace amounts are biologically essential for normal growth and functioning of fish, but at high concentrations they may cause adverse effects. As, Cd, Pb, Ni, and Hg are all nonessential elements and are highly toxic even at low levels. Some elements, such as Hg, can potentially accumulate and magnify along the food chain. Regular human consumption of such fish may lead to serious adverse health effects. For the master thesis, in the fish sampled in 2016 in the lower stretch of the Sava River (Serbia) potentially toxic elements as well as isotope composition of light elements (C and N) will be determined. The main goal is to investigate the trophic relationships in foodwebs and any potential biomagnification of contaminants. 

Mentor: dr. Tea Zuliani (tea.zuliani@ijs.si)

15. Monitoring of selected contaminants of emerging concerns in a municipal wastewater treatment plant 

AIM OF THE WORK: Development of an analytical method for the determination of twelve bisphenols (BP) in activated sludge, determination of bisphenols at a wastewater treatment plant (WWTP), e.g. in activated sludge, influent and effluent and the development of a model for bisphenol cycling in during wastewater treatment.

BACKGROUND: The topic is included within modern trends in wastewater treatment, where wastewater treatment plants (WWTPs) are not only treating wastewater, but carry out a comprehensive approach to waste and energy recovery. The aim is to create raw material, and extract energy and nutrients from treated wastewater and excess sludge, for example, as a source of water for irrigation and fertiliser in agriculture. One of the main concerns remains when using products of WWT is the presence of contaminants of emerging concern (CEC) such as chemicals from personal care products, pharmaceuticals, and industrial chemicals, which pose a risk, if they reach the environment or enter the food chain. It is essential to be aware of the cycling of the contaminants of emerging concerns from their production to their discharge into wastewater, WWT efficiency, and CEC levels entering the environment. In this work, we will address 12 BPs with potential endocrine disrupting properties.


Step 1) A review of the literature dedicated to the determination of BPs in wastewater and activated sludge from the municipal WWTPs.

Step 2) Development of an analytical method for the determination of 12 BPs in activated sludge from the municipal WWTP, including sampling, extraction, purification, separation, and quantification of BPs with GC-MS

Step 3) Sampling and determination of BPs in WWTP influent, effluent and activated sludge

Step 4) Understanding processes involved and building for the simulation of BPs concentrations in the municipal WWTP

Step 5) Development of a mathematical model and fitting of the simulation model to the measurement results.

OUTCOMES: The project will deliver an analytical method for the determination of 12 BPs in municipal WW matrices (WW and activated sludge) including evaluated BP concentrations in influent, effluent and activated sludge under normal operating conditions, and established models for the simulation and prediction of BPs at various stages of WW treatment.

Mentor: dr. Ester Heath (ester.heath@ijs.si)

16. Development of an analytical method for determination of selected estrogens in whole surface waters

AIM OF THE STUDY: To Develop an analytical method for the quantification of selected estrogens (17-beta-estradiol (17βE2), 17-alpha-ethinylestradiol (17αEE2), estrone (E1), 17-alpha estradiol (17αE2) and estriol (E3)) in whole sample surface waters achieving limits of detection set by the EU’s Water Framework Directive.

BACKGROUND:Trace levels of natural and synthetic hormones are known to disrupt the hormonal system (EDC, Endocrine Disrupting Compounds). For this reason, the EU Water Framework Directive (WFD), sets exceptionally low detection limits for the determination of 17-beta-estradiol, estrone and 17-alpha-ethinylestradiol in surface waters. This research will additionally include 17-alpha-estradiol and estriol in surface waters, which will enable comparative measurements with European laboratories.

WORKFLOW: As part of the master’s thesis, we will develop and validate a chromatographic-mass spectrometric method for the determination of selected hormones in surface waters. The study aims to achieve the low limits of detection/quantification as stipulated in the Water Framework Directive (sub ng/L). For sample preparation, liquid-liquid extraction and solid-phase extraction will be tested. The whole water sample and the dissolved fraction (the aqueous phase after filtration) will be extracted to evaluate the proportion of compounds adsorbed on SPM (Suspended Particulate Matter). The developed and validated analytical method will be evaluated in an interlaboratory comparative analysis.

OUTCOMES: A validated analytical method for the determination of five estrogens in aqueous samples at limits of detection determined by the WFD.

Mentor: dr. Ester Heath (ester.heath@ijs.si)

17. Screening of river water and sediments for the potential presence of inorganic nanoparticles

Anthropogenic nanoparticles (NPs), that are used in different applications or are non-intentionally produced during industrial processes, can be released into the surface waters. In addition, natural NPs with similar composition and size to anthropogenic NPs may be present in the environment as well. To assess the risk of anthropogenic NPs, the information on their concentration, size distribution and fate in different environmental compartments is required.

The aim of the thesis is to follow the potential presence of different inorganic NPs (containing Ag, Ce, Cu, Fe, Si, Ti, Zn, etc.) in river water and sediment samples. NPs, which presence in the samples is confirmed, will be further quantified and characterized by using single particle ICP-MS method. The laboratory work will include optimization of sample preparation procedures for extracting NPs from water and sediment samples and optimization of the single particle ICP-MS method for sensitive and accurate detection of inorganic NPs. In addition, an attempt will be made to distinguish anthropogenic NPs from naturally occurring counterparts based on the determined particle size distribution. The obtained results will improve the knowledge on the potential presence of different inorganic NPs in the river environment and will help to understand their behaviour and fate.

Mentor: dr. Janja Vidmar (janja.vidmar@ijs.si)