Studia Quaternaria

In recent years, the impacts of natural disasters on rural areas, urban settings, farmlands, transportation systems, and constructed infrastructures have received considerable focus. This study began with recognizing natural hazards by evaluating available data and conducting field research. Following that, a risk layer was created by superimposing environmental elements that affect the likelihood of risks, including geological features and landform types, which were analyzed through geomorphon techniques. The research also measured the probability of risk occurrence across various categories of independent variables. Results indicate that geological and topographical elements are vital in influencing the types of natural hazards within the Arangeh catchment. In particular, rock formations such as conglomerate, green tuff, sand, shale, and young alluvium found in young terraces exhibit the highest potential for hazards. The likelihood and variety of hazards amplify when these lithological units are located on elevated and steep landscapes. Additionally, the presence of faults significantly influences hazards associated with mass movements, including rock falls. The widest range of hazards within the Arangeh catchment can be found in slope, hollow, and valley landforms. To prevent an increase in risks, it is essential to avoid expanding settlements in these areas designated for garden purposes.

The Kremenets Mountains are among the characteristic areas of the Podolian Upland (Ukraine), which remains insufficiently studied. The study area was characterised using the main methods of automatic classification of landforms, namely the geomorphon method and the topographic position index (TPI). The obtained results were correlated with the geological maps of a bedrock and superficial Quaternary sediments, scale 1:200,000, to identify relief types within the Kremenets Mountains. The main types of relief of the Kremenets Mountains were categorised, and their regionalisation was carried out according to the reference landforms. Structural and denudational, denudational and fluvial types of relief were identified. Gravitational, karst, biogenic and technogenic landforms were also specified, including a field research. Morphometric maps of the study territory were constructed, and its main indicators were characterised according to equal-sized (1×1 km) squares, namely slope gradient, vertical and horizontal relief dissection. Analysis of these maps allowed us to identify regions with high, mean and minimum values of indices, which formed the foundations for separation of the geomorphological subregions within the Kremenets Mountains, namely Kremenets steeply sloping highly dissected subdistrict, Zalistsi moderately sloping meanly dissected subdistrict, and Kutianka gently sloping slightly dissected subdistrict.

Morocco, like many countries in arid zones, is faced with desertification, particularly in the south and southeast. Shifting dune sand is a key indicator of this phenomenon. The study of aeolian dynamics in the Merzouga-Tafilalet region aims to understand desertification processes, from rock erosion to sediment transport and deposition. A mineralogical and granulometric analysis of dune sand was carried out to determine their composition and origin. The study was based on petrographic examination and identification of the transport mechanisms involved. The sandy deposits are predominantly composed of quartz, with the presence of oxides, heavy minerals, feldspars, micas and calcite. These elements originate from the crystalline formations of the Anti-Atlas and are transported by aeolian and hydrological processes. Analysis of the quartz grains reveals different morphologies, reflecting the history of their transport and deposition. Aeolian dynamics have led to the formation of distinct granulometric fractions, each corresponding to a specific aeolian period. The mixing of these fractions results from the alternation of strong and weak wind regimes, as well as stabilization phases linked to wind degeneration. This study provides a better understanding of the evolution of dune sand in the face of environmental change.

This study aims to investigate the effects of acidic phosphate solution (PS) from phosphogypsum collected from the Tunisian Chemical Group in Gabes, with a pH of 2.6, on the physico-chemical and mechanical properties of Tunisian clay soils, Aleg (AG) and El Haria (EH). Here, the feasibility of employing these soils as natural impermeable barriers for phosphogypsum (PG) disposal sites has been explored. Mineralogical and chemical compositions of raw and modified clays were identified using XRD and XRF. The contact effect of phosphoric aqueous waste in comparison to tap water on raw clays, was revealed by a clear disappearance of the carbonate peak. The drained shear strength of Aleg soil decreased to 48 kPa. Conversely, the cohesion of El Haria soil increased with phosphate solution. Triaxial test results showed c’ and φ’ decreased to 44 kPa and 21° for AG and increased to 155 kPa and 27° for EH. AG and EH clays showed an important support capacity that reached 38 m and 57 m, respectively.

The ostracod fossils are extremely important for the reconstruction of the prehistoric environment. This is also the case for lake environments (pH, carbonate content, isotope geochemistry, water depth, temperature, vegetation cover). In a lake of hydrothermal origin, such as Lake Peţea in the north-western part of Romania, it is of particular importance, as the lake has now dried up and a significant part of the endemic fauna has disappeared. The conclusions drawn from the Ostracoda remains, together with other taxa, could be of great help to local conservation efforts to restore the lake to its former state. Based on our results the following taxa were identified in the Early Holocene deposits of the lake: Candona weltneri var. obtusa, Pseudocandona rostrata, Cypridopsis vidua.