1. Online screening tool for precipitation stable isotopes records : hybrid distance / density based outlier filtering approach via interactive web applicationIstván Gábor Hatvani, Dániel Erdélyi, Polona Vreča, Sonja Lojen, Klara Žagar, Jan Gačnik, Zoltán Kern, 2026, original scientific article Abstract: The ratio between the heavy and light stable isotopes in precipitation is an effective tool for addressing questions in e.g., hydrology, climatology, biogeochemistry etc., but only if spatiotemporally sufficient data is available from precipitation monitoring networks. However, when data from multiple sources are gathered into large databases these can contain errors severely impacting research outcomes. The most common practices for stable isotopic database filtering apply static thresholds, not accounting for the spatially dynamically changing nature of the variable. We propose a distance-based outlier detection approach in the form of an online tool. The IsoQC App is developed to identify likely-outliers or inconsistent data points by deriving adjustable elevation-corrected average isotope values for nearby stations within an adjustable search radius (0 < R ≤ 500 km). The IsoQC is showcased on the records of the precipitation stable isotope network of Slovenia and its vicinity. It enables an objective and reproducible analysis of spatial and temporal patterns of nearby precipitation stable isotopic records by employing thresholds for dissimilarity between regional averages and individual station records in a dynamic graphical user interface. The interactive nature of the application allows users to explore spatial and temporal variations in precipitation isotope compositions, identify anomalous data points, and empirically assess regional isotope patterns in real time. The developed IsoQC tool is freely available at https://sapps.geochem.hu/isoqc/
Keywords: isotope composition, datasets, spatiotemporal data, web application
Published in DiRROS: 21.04.2026; Views: 57; Downloads: 22
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2. Green synthesis of a magnetite/graphitic carbon nitride 2D nanocomposite for efficient ▫$Hg^{2+}$▫ remediationRaghuraj S. Chouhan, Jan Gačnik, Igor Živković, Sreekanth Vijayakumaran Nair, Nigel Willy Van de Velde, Alenka Vesel, Primož Šket, Sonu Gandhi, Ivan Jerman, Milena Horvat, 2023, original scientific article Abstract: Novel nanoadsorbents demonstrate the potential to efficiently eliminate harmful substances, such as Hg2+, from the environment while preserving ecological balance. However, the search for environmentally-friendly nanomaterials as ideal adsorbents, as well as the development of suitable synthesis protocols, remains a challenge. This study presents an effective thermal-sonication technique for producing unique de novo tris-s-triazine carbon nitride nanosheets decorated with magnetite nanoparticles (M-g-CN). The structural integrity and chemical properties of the M-g-CN nanocomposite were extensively characterized using a battery of analytical instruments, including FTIR, SEM, TEM, XRD, XPS, AFM, Raman, and NMR. The obtained data, along with the analysis results, are discussed in detail. The novel synthesis method yields a high percentage (97.7%) of stable, highly selective, and reusable M-g-CN (40 mg mL−1). The resulting M-g-CN effectively binds Hg2+, with binding efficiencies of 96.0%, 97.5%, 98.2%, and 99.4% for Hg2+ concentrations of 50 pg mL−1 in marine, stream, precipitation, and ultra-pure matrices, respectively. Also, the magnetite-decorated particles can be easily retrieved using an applied magnetic field. This greener and scalable synthesis method does not require harsh chemicals, making it cost-effective, eco-friendly, and non-toxic compared to other technologies such as carbon filters, ion exchange resins, chemical precipitation, membrane filtration, electrochemical methods, and biological remediation. Overall, the synthesized M-g-CN exhibits wide-ranging potential applications, particularly as a green adsorbent in passive samplers or materials for remediation purposes.
Keywords: mercury, elimination, nanoadsorbents, nanocomposites
Published in DiRROS: 05.01.2026; Views: 377; Downloads: 179
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3. Climate change reflected in 40-year isotopic composition trends of precipitation in SloveniaJan Gačnik, Klara Žagar, István Gábor Hatvani, Zoltán Kern, Polona Vreča, 2026, original scientific article Abstract: Long-term monitoring of stable isotopes in precipitation (δ18O, δ2 H), alongside meteorological data, is key to understanding how large-scale hydroclimate variability influences regional and local climate. This study presents one of the longest records in Central and Southeastern Europe: the multi-decadal (1981–2024) dataset of monthly composite precipitation stable isotope records from Ljubljana, Slovenia. The δ18O, δ2 H, and d-excess values are increasing (+0.02 ‰, +0.18 ‰, and +0.05 ‰ per year, respectively), consistent with regional warming. Seasonal patterns were evident, with elevated d-excess values during autumn. The decomposition of the δ18O, δ2 H and d-excess time series using Hilbert-Huang Transform revealed statistically significant annual oscillations in all variables. These oscillations correlated strongly with the annual oscillation of temperature, but a lag of 2–3 months was identified for d-excess. Lower-frequency (multi-year) oscillations of d-excess were also observed. HYSPLIT back-trajectory analysis confirmed a significant contribution of Mediterranean-sourced air masses to autumn precipitation, but did not explain d-excess oscillations. Similar results were observed also for coastal (Portoroˇz, Slovenia) and continental (Vienna, Austria) stations. The findings imply an accelerating, exponential-like isotopic response to warming that has already propagated into the water cycle, providing isotope evidence that precipitation-surface water-groundwater interactions in investigated region changed in last decade.
Keywords: precipitation stable isotopes, trend analysis, Hilbert-Huang transform, ensemble empirical mode decomposition, HYSPLIT
Published in DiRROS: 19.11.2025; Views: 390; Downloads: 201
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