This study investigated the influence of different cooling regimes on the microstructure and consequent reactivity of belite-sulfoaluminate clinkers. The cement clinkers were synthesized by incorporating secondary raw materials, such as titanogypsum and bottom ash, to the natural raw materials. Clinker phases were determined by Rietveld quantitative phase analysis, while the distribution morphology and the incorporation of substitute ions in the phases were characterized by scanning electron microscopy using energy-dispersive X-ray spectroscopy (SEM/EDS). Clinker reactivity was studied using isothermal calorimetry and was additionally investigated through compressive strength, which was determined for the cement prepared from the synthesized clinkers. X-ray diffraction analysis showed that, as well as the three main phases (belite, calcium sulfoaluminate, and ferrite), the clinkers contained additional minor phases (mayenite, gehlenite, arkanite, periclase, and perovskite), the ratios of which varied according to the cooling regime utilized. Microscopic observations indicated that the cooling regime also influenced the crystal size and morphology of the main phases, which consequently affected clinker reactivity. Furthermore, a smaller amount of substitute elements was incorporated in the main phases when cooling was slowed. Results showed that, in comparison to clinkers cooled at slower rates, air quenched clinkers reacted faster and exhibited a higher compressive strength at 7 days.

The isotope and elemental composition of tap water reflects its multiple distinct inputs and provides a link between infrastructure and the environment over a range of scales. For example, on a local scale, they can be helpful in understanding the geological, hydrogeological, and hydrological conditions and monitor the proper functioning of the water supply system (WSS). However, despite this, studies examining the urban water system remain limited. This study sought to address this knowledge gap by performing a 24 h multiparameter analysis of tap water extracted from a region where the mixing of groundwater between two recharge areas occurs. This work included measurements of temperature and electrical conductivity, as well as pH, δ2H, δ18O, d, δ13CDIC, and 87Sr/86Sr ratios and major and trace elements at hourly intervals over a 24 h period. Although the data show only slight variations in the measured parameters, four groups were distinguishable using visual grouping, and multivariate analysis (Spearman correlation coefficient analysis, hierarchical cluster analysis, and principal components analysis). Finally, changes in the mixing ratios of the two sources were estimated using a linear mixing model. The results confirm that the relative contribution from each source varied considerably over 24 h.

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 and carbon stable isotope ratios. Information about the methods used and results obtained are summarised, and the knowledge gaps identified. Overall, we identified 102 records published between 1976 and 2019. Among them, 41 reported stable isotope data of groundwater, surface water and precipitation and were further analysed. Isotope investigations of the Ljubljansko barje began in 1976, while groundwater and surface water investigations of the Ljubljansko polje and along the Sava River began as late as 1997. Isotope investigations of carbon started even later in 2003 in the Ljubljansko polje and in 2010 in the Ljubljansko barje. These investigations were performed predominantly in the frame of short-term groundwater research projects at five main wellfields and sites along the Sava River. Almost no large-scale, long-term stable isotope studies have been conducted. The exceptions include groundwater monitoring by the Union Brewery in Ljubljana (2003- 2014) and precipitation in Ljubljana since 1981. Since 2011, more detailed surveys of the Ljubljansko barje were performed, and in 2018, the first extensive investigation started at wellfields and objects that form part of the domestic water supply system. Given the number of available studies, we felt that publishing all the numerical data and appropriate metadata would allow for a better understanding of the short and long-term dynamics of water circulation in the urban environment. In the future, systematic long-term approaches, including the appropriate use of isotopic techniques, are needed.

<p>River water represents the spatial and temporal integrator of the isotopic composition of precipitation in a catchment area. Stable isotope measurements of oxygen and hydrogen (<em>δ</em><sup>18</sup>O and <em>δ</em><sup>2</sup>H) in stream waters and precipitation are widely applied to investigate hydrological pathways and transit times. In this study, we apply the stable isotope approach to improve knowledge on the hydrological characteristics of the River Sava, Slovenia, by performing monthly sampling of river water at two locations: Brod and Šentjakob and precipitation at one location (Ljubljana–Reactor), between 2020 and 2021. Gathered data was used for preliminary estimations of water transit times in streamflow. Moreover, different methods were used to determine the Local Meteoric Water Line and comparison with precipitation data for the period 1981–2021 to estimate temporal changes and transit times of the River Sava at selected locations.</p><p>The climatic characteristics of the investigated area are also reflected in <em>δ</em><sup>18</sup>O and <em>δ</em><sup>2</sup>H of precipitation that has been monitored since 1981. The <em>δ</em><sup>18</sup>O and <em>δ</em><sup>2</sup>H values of precipitation reveal strong seasonal variations, while the tracer output signal in the River Sava is dampened. Site-specific long-term (1981–2021) covariation of <em>δ</em><sup>18</sup>O and <em>δ</em><sup>2</sup>H is also in good agreement with Global Meteoric Water Line (GMWL), while short-period lines (2020–2021) differ in slope and intercept but lie close to the line GMWL. A longer time series is more suitable for the determination of the LMWL, as the error is much higher for shorter two-year periods. </p><p>The exponential flow model produced mean stream water transit times of 4.2 and 3.1 years at Sava Brod and Sava Šentjakob, respectively, whereas estimated transit times were longer compared to the results of previous investigations. Although the identified results are hydrologically plausible, the limitation of this and previous studies are presented as uncertainties resulting from a short sampling period and low sampling frequencies.</p>