Using moss as a biomonitor is an established technique for monitoring atmospheric deposition of trace elements, including lead (Pb), a metal that is toxic for most organisms. Lead enters the environment during production and combustion processes and during the use of leaded gasoline. There are four stable isotopes of Pb, and the isotopic composition can be used to determine sources and pathways of atmospheric Pb pollution. In this study we determined Pb concentrations and isotope ratios in moss (Hypnum cupressiforme and Pleurozium schreberi) collected from 1990 to 2015 in Switzerland and from 2006 to 2015 in Slovenia. We used microwave sample digestion and inductively coupled plasma mass spectrometry (ICP-MS) for Pb concentrations and multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) for Pb isotope ratio determination. The aim was to assess the change in atmospheric Pb deposition over time and the differences between and within the two countries. Additionally, we assessed the current Pb isotope ratios for both countries and evaluated the change over time in Switzerland. The Pb concentration in moss decreased significantly over time in both countries. In 2015, at the end of the study period, concentrations were significantly higher in Slovenia compared to in Switzerland. Higher Pb concentrations in Slovenia may be related to the prolonged use of leaded gasoline or to the larger influence of industrial sources. Within Switzerland Pb concentrations...
COBISS.SI-ID: 5153702
Energy efficiency is among the main reasons for the increasing popularity of electric vehicles. Even though they are significantly more efficient in comparison to internal combustion powered vehicles, their efficiency varies. In the literature a significant gap between real world energy consumption and declared figures is noted. The paper includes a review of real-world energy consumption studies and measurements and identifies variables that affect it, such as vehicle drivetrain configuration, battery management systems, traffic and environmental conditions. A simplified EV energy consumption model based on the VSP (Vehicle-Specific Power) is presented and evaluated on standard driving cycles, where it provided improvement over existing models due to the use of a charging power limiting function that better describes energy flow during braking energy regeneration. The model was also evaluated under diverse traffic conditions on trajectories obtained from traffic microsimulation using the SUMO (Simulation of Urban Mobility) model. A case study example demonstrating the impact of traffic light control on energy consumption was analysed as energy consumption is affected in a different way in comparison to internal combustion powered vehicles. This was illustrated by carrying out simulation with and without braking energy regeneration.
COBISS.SI-ID: 2892899
The current governing economic policies and models are favoring maximizing overall solar panel power production in an effort to mitigate climate change. Those were adequate for relative low share of solar power within entire energy mix. As the share of photovoltaic energy production rises, those principles directly cause high mid-day summer productions peaks and even negative prices for the electricity, when solar power is in abundance. This prompts for different approach for calculating solar technical and economic potential, which can offer valuable data for planning future energy sources. This paper uses a simplified model to evaluate prevailing self-sustainable rooftop solar electricity production for typical households and micro-grids in combination with battery storage (Solar Plus). The used model is nevertheless covering most important features of solar power production: the weather pattern, load curves and roof orientation and can be used either for single home-owners or small businesses. Typical applications and main benefits of the assessment are discussed and critically reviewed. The used model is suitable for use on single households or house clusters in scattered populated area and was developed based on extensive empirical knowledge.
COBISS.SI-ID: 32165159
The deployment of geothermal energy systems can significantly contribute to climate change mitigation and play a part in the transition to a low carbon society. This study proposes a framework for identifying the shallow geothermal energy potential of new individual and district heating (DH) systems. The model accounts for thermal interference between neighbouring wells and borehole heat exchangers, where the main criteria for analysis are ground temperature, thermal conductivity, heat flow, and heat capacity. The paper presents a cost-effective area method for the identification of potential new DH areas, while considering the cost competitiveness of the heat supplied. Economic potential is determined based on the cost-effectiveness of the competing technologies, separately for urban and rural areas. The results show that although 54% of technical DH potential in Slovenia remains untapped, the future of shallow geothermal energy systems lies predominantly in individual systems, which have proven to be the most cost efficient solution on locations with favourable geological or hydro-geological conditions. Where possible, shallow geothermal energy can contribute from 2% to 25% of energy for heat production in analysed existing fossil fuel based DH systems, thus making shallow geothermal energy suitable for supplying base load power in an economical manner.
COBISS.SI-ID: 32491559
This study quantifies the behaviour of uranium isotope ratios (235U/238U and 234U/238U) with different aqueous sample preparation and separation techniques using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) measurements and optimization of the MC-ICP-MS measurement protocol to obtain high precision and accuracy for uranium isotope ratios. The obtained results were compared with reference values, and they show that different sample preparation and separation methods influence the uranium isotopic composition and consequently the final results of unknown samples. The analytical procedure with the highest achievable precision and accuracy for uranium isotopes was the combination of coprecipitation with Ca3(PO4)2 and extraction chromatography with precleaned UTEVA resins. The combination of coprecipitation with Fe(OH)3 and ion exchange chromatography (DOWEX resins) provided the lowest achievable accuracy for uranium isotopes. The results reveal the extent of uranium biases during different physicochemical processing of samples in the range of -254 to 2.60‰ for 235U/238U and -299 to 8.90‰ for 234U/238U. A combination of sample preparation and measurement protocol optimization is of importance for various applications requiring extensive sample pre-treatment procedures where the 233U/236U double spike method for correcting for mass bias during sample preparation and separation steps is not feasible and to establish a methodology which enables the accurate determination of uranium isotope ratios in low-level concentration samples.
COBISS.SI-ID: 32543271