Water absorption process effect on strength of Ayazini tuff,such as the uniaxial compressive strength (UCS), flexural strength and freeze and thaw effect

Tuffs have been used as a construction material possibly since ancient times. In Afyonkarahisar, Turkey, there are numerous buildings constructed by tuff. Tuff has been a local construction material, during the Roman, Seljuk and Ottoman periods. Even though tuffs have relatively low durability and low strength values compared to marble, etc., they have survived with no major deterioration failures on many historical buildings. It has also been preferred because of its high porous texture, lightweight and easy shaping and process properties in the building sector. Naturally, it would be easily affected by water and humidity because of its porous structure. However, having this kind of structure leads to poor durability properties due to keeping water in it. The main objective of this study was to evaluate the physical and mechanical properties of the tuff quarried from the region and possible water effect, which may lead to degradation of its strength and durability of the material, thereby shortening the life span of the building structure used. Samples, which were tested after exposing to water and the freeze and thaw effects, were measured at a certain time. In this study, uniaxial compressive strength and flexural strength tests were conducted on test samples. The test results indicate that water may deteriorate the tuff’s strength properties and durability of the materials in due time.     

Ecological quality status of coastal benthic ecosystems in the Sea of Marmara

The macrofauna in the north Marmara Sea were identified and evaluated with univariate measures and biotic indices (BENTIX, AMBI). As expected, the diversity and species' variety decreased as the sediments became muddier and as the stress increased. The AMBI index failed to detect the spatial differentiation of the EcoQ between the sites whereas, the BENTIX index succeeded (in 70% of the cases) in producing an ecologically relevant classification reflecting the environmental pressures. Results suggested that risks of reduced species' richness and diversity from organic loading and other associated stressors in sediments should be relatively low at TOC concentrations < about 6 mg/g, high at concentrations>about 22 mg/g, and intermediate at concentrations in-between. It is suggested that these TOC critical points may be used as a general screening-level indicator for assessing the EcoQ in association with reduced biodiversity over coastal areas receiving organic wastes and other pollutants from human activities. It is further suggested that both assignment of species to ecological groups and classification scales for biotic indices (AMBI, BENTIX) for sites in the Mediterranean Sea should be readjusted so as to be closer related to environmental variables.     

Earthquake imprints on a lacustrine deltaic system: The Kürk Delta along the East Anatolian Fault (Turkey)

Deltas contain sedimentary records that are not only indicative of water‐level changes, but also particularly sensitive to earthquake shaking typically resulting in soft‐sediment‐deformation structures. The Kürk lacustrine delta lies at the south‐western extremity of Lake Hazar in eastern Turkey and is adjacent to the seismogenic East Anatolian Fault, which has generated earthquakes of magnitude 7. This study re‐evaluates water‐level changes and earthquake shaking that have affected the Kürk Delta, combining geophysical data (seismic‐reflection profiles and side‐scan sonar), remote sensing images, historical data, onland outcrops and offshore coring. The history of water‐level changes provides a temporal framework for the depositional record. In addition to the common soft‐sediment deformation documented previously, onland outcrops reveal a record of deformation (fracturing, tilt and clastic dykes) linked to large earthquake‐induced liquefactions and lateral spreading. The recurrent liquefaction structures can be used to obtain a palaeoseismological record. Five event horizons were identified that could be linked to historical earthquakes occurring in the last 1000 years along the East Anatolian Fault. Sedimentary cores sampling the most recent subaqueous sedimentation revealed the occurrence of another type of earthquake indicator. Based on radionuclide dating (¹³⁷Cs and ²¹⁰Pb), two major sedimentary events were attributed to the ad 1874 to 1875 East Anatolian Fault earthquake sequence. Their sedimentological characteristics were determined by X‐ray imagery, X‐ray diffraction, loss‐on‐ignition, grain‐size distribution and geophysical measurements. The events are interpreted to be hyperpycnal deposits linked to post‐seismic sediment reworking of earthquake‐triggered landslides.     

Investigating water quality and arsenic contamination in drinking water resources in the Tavşanlı District (Kütahya,Western Turkey)

Arsenic is a natural component of the earth’s crust, and it is transported into surface water and groundwater through the dissolution of rocks, minerals and ores. In addition, arsenic leaching processes contaminate water sources and this geogenic arsenic contamination causes significant water quality problems in many parts of the world. In this study, water quality, arsenic contamination and human health risks of drinking water resources in the Tav?anl? District were determined and the origins were discussed. For this purpose, geological and hydrogeological properties were investigated. In situ measurements and chemical analyses were carried out on water samples taken from drinking water sources such as wells, springs and surface waters for hydrogeochemical studies. According to the obtained results, water resources are Ca–Mg–HCO₃, Mg–HCO₃ and Na–HCO₃ type. Total As (As_T) concentration of the water samples sometimes exceeds the permissible limit given by the TSI-266 (Standards for drinking waters, Turkish Standards Institution, Ankara, 2005) and WHO (Guidelines for drinking-water quality, World Health Organization, Geneva, 2008) for drinking water. H₃AsO ₃ ⁰ and HAsO₄ ^2? are dominant arsenic species in groundwater and surface water, respectively. Typically high total arsenic concentrations can be found in regions characterized by magmatic rocks. In addition, As concentrations in surface waters were found to be higher than in groundwater in the region, due to the anthropogenic influence of mining activities in the region.     

Assessment of variations in water quality using statistical techniques: a case study of Işıklı Lake, Çivril/Denizli,Turkey

A study of the hydrochemical evaluation of waters in the I??kl? Lake and surrounding area was carried out with the objective of identifying the geochemical processes and their relation with water quality in the region. The multivariate statistical techniques were used in the hydrochemical evaluation of waters. Statistical analysis of water quality parameters was made to seeing the interrelationship between different variables in order to explain the water quality and pollution status of study area. For this purpose, water samples were taken from lake, river, stream, and springs which are represented by investigated area and water qualities were evaluated. Generally, Ca²⁺, Mg²⁺, and Cl^?, HCO₃ ^? ions are dominant within surface water and water sources. Arsenic concentration increase is determined in I??kl? spring and Kufi stream water samples. Also, aluminum concentration is high level in the Kufi stream water samples. This increase was related to igneous rocks as geogenic origin. Also, geogenic contamination was identified in R-mode factor and cluster analyses. There is high correlation between electrical conductivity and major ions of waters.