ON THE OCCURRENCE OF A VOLCANIC ASH LAYER IN THE XYLOKASTRO AREA, NORTH PELOPONNESUS, GREECE: MINERALOGY AND GEOCHEMISTRY

This paper reports, for the first time, the occurrence of an ash layer intercalated within the Plio-Pleistocene lacustrine deposits near Xylokastro area, North Peloponnesus, Greece. Petrographic and geochemical characteristics of the ash layer are the basis of this study. An attempt was made to correlate the present findings to the reported data from other ash deposits. The composition of the ash bed showed a dacitic to rhyolitic calc alkaline suit. The geochemistry of the volcanic ash indicates high crustal contamination of the lava and points to an origin from the northwest part of the Aegean volcanic arc

HowkGPT: Investigating the Detection of ChatGPT-generated University Student Homework through Context-Aware Perplexity Analysis

As the use of Large Language Models (LLMs) in text generation tasks proliferates, concerns arise over their potential to compromise academic integrity. The education sector currently tussles with distinguishing student-authored homework assignments from AI-generated ones. This paper addresses the challenge by introducing HowkGPT, designed to identify homework assignments generated by AI. HowkGPT is built upon a dataset of academic assignments and accompanying metadata [17] and employs a pretrained LLM to compute perplexity scores for student-authored and ChatGPT-generated responses. These scores then assist in establishing a threshold for discerning the origin of a submitted assignment. Given the specificity and contextual nature of academic work, HowkGPT further refines its analysis by defining category-specific thresholds derived from the metadata, enhancing the precision of the detection. This study emphasizes the critical need for effective strategies to uphold academic integrity amidst the growing influence of LLMs and provides an approach to ensuring fair and accurate grading in educational institutions

Synthetic zeolites from lignite fly ash and biomass ash for agricultural applications

The production of zeolites is one of the potential applications of fly ash production to obtain high value industrial products with environmental technology utilization. The synthesis of zeolite products from fly ash is analogous to the formation of natural zeolites from volcanic deposits or other high-Si-Al rocks,rich in amorphous phases, by the interaction of hot alkaline water on the glass fraction of the rocks. That zeolite development process may take thousands of years in order to form natural zeolites. In the laboratory, the process can be speeded up (to days or hours) for both volcanic and fly ash. Previous studies have demonstrated the utilization of lignite fly ash Na bearing synthetic zeolitic materials for the removal of heavy metals from wastewater, for mine-water treatment and as soil amendments in acid mining soils. Since K is considered as a nutritient in agriculture KOH was selected as an activation solution, in order to develop a K-rich synthetic zeolite suitable for utilization in agriculture. In the current study we are evaluating the results of the hydrothermal activation of lignite fly ash and biomass asses from Greece, by KOH in order to produce synthetic zeolites, for agricultural applications

Geological modelling for investigating CO2 emissions in Florina Basin, Greece

Published version also available at http://dx.doi.org/10.1515/geo-2015-0039This paper presents an investigation of naturally occurring CO2 emissions from the Florina natural analogue site in Greece. The main objective was to interpret previously collected depth sounding data, convert them into surfaces, and use them as input to develop, for the rst time, 3D geological models of the Florina basin. By also locating the extent of the aquifer, the location of the CO2 source, the location of other natural CO2 accumulations, and the points where CO2 reaches the surface, we were able to assess the potential for CO2 leakage. Geological models provided an estimate of the lithological composition of the Florina Basin and allowed us to determine possible directions of groundwater ow and pathways of CO2 ow throughout the basin. Important modelling parameters included the spatial positions of boundaries, faults, and major stratigraphic units (which were subdivided into layers of cells). We used various functions in Petrel software to rst construct a structural model describing the main rock boundaries. We then de ned a 3D mesh honouring the structural model, and nally we populated each cell in the mesh with geologic properties, such as rock type and relative permeability. According to the models, the thickest deposits are located around Mesochorion village where we estimate that around 1000 m of sediments were deposited above the basement. Initiation of CO2 ow at Florina Basin could have taken place between 6.5 Ma and 1.8 Ma ago. The NESW oriented faults, which acted as uid ow pathways, are still functioning today, allowing for localised leakage at the surface. CO2 leakage may be spatially variable and episodic in rate. The episodicity can be linked to the timing of Almopia volcanic activity in the area

Hazard identification of the Mediterranean Temporary Mountain Pond ecosystems in Central Greece: Α Geo-environmental approach

Mediterranean Temporary Ponds (MTPs) are shallow water bodies which are characterized from a short wet period and their small size. MTPs of Europe have are under an effective protection status, as a result of their identification as a priority habitat (Annex I code 3170*) in the EU Directive 92/43/EEC (Habitats' Directive). These ponds are very delicate ecosystems regarding their hydrological and geochemical characteristics. Due to their small size, they are open to random destruction or other unpredictable dangers. Although small in size, MTPs are complex ecosystems where topography, soil, water and hydrological conditions and microorganisms are closely connected. The conservation and restoration of such ecosystems is very difficult because of their unique characteristics. The most common threats for MTPs include destruction of the hosting area through human and animal pressures, hydrological disturbance, fire and generally changes in ecological conditions resulting in an increase of competitive plants, nutrition influx, toxic contaminants and wastes, sedimentary deposit filling, exotic-invasive fauna and flora and negative effects from domesticated or hunted fauna. The study was carried out in the MTPs area of the National Forest Park of Mt. Oiti (GR2440004) and Mt. Kallidromo (GR2440006). Overall, the survey has included seven small and independent MTPs of high altitude in the areas of Mt. Oiti (Louka, Livadies, Greveno and Alikaina) and Mt. Kallidromo (Nevropolis, Mourouzos and Souvala). This study aims to present a dataset of the geo-environmental parameters in order to assess the potential hazards for these priority habitats. Furthermore, it is also worth mentioning that MTPs are unevenly studied, regarding their geological, hydrological, hydrochemical, geochemical and mineralogical characteristics and this work provides a first report on an integrated evaluation of these parameters regarding the qualitative and quantitative risk identification of the MTPs in Central Greece

Assessment of the impact of CO 2 storage in sandstone formations by experimental studies and geochemical modeling: the case of the Mesohellenic Trough, NW Greece

Representative sandstone samples from Mesohellenic Trough (NW Greece) were selected to investigate the geochemical reactions that occur when they come in contact with CO2 under representative in-situ conditions (T = 70 °C, P = 150 bar, 6 months reaction in batch experiments). Those sandstones consisted of predominant calcite and quartz, with lesser amounts of feldspars, chlorite, ankerite, dolomite, kaolinite, montmorillonite and muscovite. After reaction with CO2, the brine became acidic and was enriched in cations as a result of mineral dissolution. Minor mineralogical changes were observed that involved: a) the dissolution of carbonate minerals and b) the incongruent dissolution of chlorite to form clays and silica. The results related to these, have been linked with geochemical modelling using the PHREEQC code. Simulation results for a 10 ka time period predicted that chlorite was expected to dissolve completely within 100 years, leading to boehmite growth and increasing the mass of dolomite. Feldspars were expected to react at a later stage in the reaction sequence. Sensitivity tests were run to access the effect of various adjustable parameters on the outcome results. The geochemical experiments and modelling lend support to the view that Pentalofos and Tsotyli sandstone formations of the Mesohellenic Trough are suitable for the long-term storage of CO2 produced in the neighbouring lignite-fired power plants, at least in terms of mineralogy and geochemistry