Biogeographical distribution and diversity of bacterial and archaeal communities within highly polluted anoxic marine sediments from the marmara sea

Physicochemical and microbiological characterization of anoxic sediments taken from seven highly polluted sites of the Marmara Sea was carried out. The 16S rRNA based microbial community structure analyses were performed using domain-specific PCR followed by denaturant gradient gel electrophoresis (DGGE) and sequencing of characteristic bands. The results showed that the microbial communities in these sediments were diverse and evenly distributed. Relating the prokaryotic and geochemical variables through statistical tools revealed that the microbial diversity in the sediments significantly related to depth, and S, Mn and Fe content of the sediments. Fermentative bacteria, denitrifying bacteria and hydrogenotrophic methanogens were dominant whereas sulfate reducing bacteria were absent in the DGGE patterns. This unusual microbial community structure implied that the newly discovered anaerobic methane oxidation coupled to denitrification process may occur in these subseafloor environments.     

Determination of Dips and Depths of Near Surface Layers by Radon Transform

The refracted arrivals on seismic shot records have long been recognized as an efficient tool for the computation of detailed near-surface information. In this paper, a new concept of refraction static, which is based on the Radon transform and avoids the tedious process of picking first arrival times, is proposed. This method is particularly suitable when a rough near-surface problem necessitates the utilization of numerous shallow refraction data for the one reflector case. Quasi-linearity of refractors and a constant velocity medium are assumed within the shooting range. Synthetic and real cases have been tested to evaluate the performance of the method. The result is revealed to be satisfactory. Comparison of the synthetic model with the results obtained through the Radon transform reveals a very good accuracy for the proposed method.     

Potential impact of land use change on land productivity dynamics with focus on land degradation in a sub-humid terrestrial ecosystem

The aim of this study was to generate a land productivity dynamics (LPD) map of a degraded catchment located in sub-humid terrestrial ecosystem via a land degradation assessment using three indicators, namely land use and land cover, land productivity, and soil organic carbon density. The study was carried out in two adjacent microcatchments located in Gediz River Basin and conducted between 2001 and 2015. For this purpose, Landsat satellite images were used to determine changing of land use and land cover and vegetation density. In addition, 319 soil samples were collected from surface and subsurface soil depths to detect soil organic carbon density of the study area in May 2015. According to the study results, in more than 23% of the catchments’ area of approx. 3896 ha, land productivity is observed to decline while about 24% shows early signs of decline level. Some of these areas used under agricultural cropping, overgrazed pasture, and artificial areas showed evidence of soil erosion problem. Only very small area of the catchment shows stable and increasing land productivity dynamics trend during the 14-year period.     

Building a semantic based public transportation geoportal compliant with the INSPIRE transport network data theme

Interoperability is becoming essential for the today’s geographic information systems. Geographic information is usually available as datasets stored in databases and accessible via GIS. However, these information sources are increasingly heterogeneous and show differences in data formats, database schema and object concepts. To satisfy the increased demand for the use and sharing of geographic data in common applications, considering the heterogeneity and the methods to support interoperability are required by the GIS community. The implementation of Spatial Data Infrastructure (SDI) such as the European INSPIRE (Infrastructure for Spatial Information in the European Community) enables accessibility and the sharing of geographic data and interoperability among the systems. In addition to this, traditional GIS systems perform spatial queries using a keyword-based method. However, this approach remains incapable of fully expressing the users' needs due to a lack of geographic concepts (semantics) in the dataset. Different terms may refer to similar concepts, while the same terms may refer to different concepts. This causes semantic heterogeneity in the dataset. In this context, the most promising approach is the implementation of geospatial semantics by means of ontology in the geospatial dataset to overcome this kind of ambiguity. The aim of this research is to investigate the implementation of INSPIRE as a SDI standard and the use of Semantic Technology to empower the traditional GIS approach. In this regard, a public transportation geoportal has been developed for the experimental investigation which uses a revised sample transportation data complaint with the INSPIRE Transport Network Data Theme and a developed Transportation Ontology Domain, including concepts, relationships and individuals to provide a semantic spatial search.     

Assessment of scaling properties of groundwater with elevated sulfate concentration: a case study from Ergene Basin, Turkey

In this study, the Langelier saturation index and the Ryznar stability index of the groundwater of the east of Ergene Basin were evaluated to assess the corrosivity or scale-forming tendencies. Corrosion is one of the most complicated and costly problems facing drinking water utilities. Corrosion can affect public health, public acceptance of a water supply, and the cost of providing safe drinking water. For this purpose, total of 17 representative groundwater samples were collected. Except for well nos. 1, 2, and 3 with corrosive characteristics, all the groundwater samples were stable or had a slight tendency for dissolving of scale. Results showed that the amount of precipitation and irrigation caused seasonal variation in corrosive characteristics. Increased ionic concentration of SO₄ ^?2 contributes to the corrosivity of groundwater.     

The geochronology and origin of mantle sources for late cenozoic intraplate volcanism in the frontal part of the Arabian plate in the Karacadağ neovolcanic area of Turkey. Part 2. The results of geochemical and isotope (Sr-Nd-Pb) studies

A geochemical and isotope-geochemical (Sr-Nd-Pb) study has been carried out for the Karacada? neovolcanic area, which is situated within the frontal part of the Arabian plate. The obtained data and the results of petrological modeling show that the petrogenesis of parental magmas in the Karacada? neovolcanic area involved two compositionally different mantle sources; one consisted of garnet-bearing peridotites of the asthenosphere mantle and the other was spinel-bearing peridotites of the enriched subcontinental lithosphere mantle. During early stages in the evolution of the magmatic system, deep-seated asthenospheric magmas were ascending to the surface while intensively interacting with the melts that had been generated at upper mantle depths. The interaction gradually diminished, so that the later effusive rocks mostly have compositions that are similar to those of the primitive asthenospheric magmas. It is shown that a significant (up to 17–18 wt % of the mantle melt) assimilation of crustal material could take place only during the initial phases of the magmatism. Periodic replenishment of the magma chambers by primitive magmas, which resulted in an observable high degree of homogeneity in the composition of young effusive rocks, was also of importance in the petrogenesis of lavas during the evolution of volcanic activity.     

Geochemistry of the limestone of Mortas Formation and related terra rossa,Seydisehir, Konya,Turkey

The purpose of this study was to determine and evaluate the geochemical characteristics of the limestone of the Upper Cretaceous Mortas Formation and related terra rossa in a 50 km² area which is located 20 km south of the city of Seydisehir, Central Anatolia, by using data obtained from the ICP-MS analysis of randomly collected 42 samples of limestone and 18 samples of the terra rossa.The limestone of the Mortas Formation is composed of fossilliferous, gray-cream colored, medium to thick bedded, partially dolomitic carbonate rocks, and generally has dismicrite, intrapelmicrite composition. It includes the largest bauxite reservior in Turkey and has many occurences of terra rossa formation on it. According to mean distance, the Ba, Be, Hg, Mo, Nb, Sb and Th concentrations in the limestones overlying and underlying the bauxite deposits are different, but the main oxides, REE and other trace elements are same. In factor analysis, the first component reflects relative enrichment of clay against to CaO contents of the limestone, the second component corresponds to the degree of dolomitization. The PAAS-normalized REEs pattern for the Mortas Formation limestone samples illustrate similar main features as seawater.The terra rossa soils in the study area are considered to be highly weathered and weakly mature soil with respect to their generally low Al₂O₃ (21%), but high CaO (2%) contents, and their alteration indices. The element ratios in the terra rossa and limestone show that in the process of the transformation from limestone to terra rossa, Ba, Si, Ti, Al and Fe were enriched together by staying in-situ. Except Ce, all lanthanides show similar behavior, but the HREE, which were richer in limestone, were consumed fast relative to the LREE during soil formation. The association and the enrichment of Co, Cu, Cr, Ni and Pb as well as Ba, Zr, Ga, Nb and Rb in soil relative to the limestone are interpreted as being resulted from eolian transportation. Ca, Au, Hg, Sr, Se, Sb, Mo, Ag, U, Cd and Na were found to be the most mobile elements during pedogenic transformation. According to main oxide composition ratios of the limestone and terra rossa, the soils were described as representing a well washed soil completing the leaching and accumulation phase, but not totally completing the silicate weathering phase. In the processes of soil formation, 97.76% of the limestone was washed away; only 2.24% of limestone was deposited as soil. Therefore, 61 times mass reduction was realized.     

Zircon Lu-Hf isotope systematics and U–Pb geochronology,whole-rock Sr-Nd isotopes and geochemistry of the early Jurassic Gokcedere pluton,Sakarya Zone-NE Turkey: a magmatic response to roll-back of the Paleo-Tethyan oceanic lithosphere

The early Mesozoic was a critical era for the geodynamic evolution of the Sakarya Zone as transition from accretion to collision events in the region. However, its complex evolutionary history is still debated. To address this issue, we present new in situ zircon U–Pb ages and Lu-Hf isotope data, whole-rock Sr-Nd isotopes, and mineral chemistry and geochemistry data of plutonic rocks to better understand the magmatic processes. The Gokcedere pluton is mainly composed of gabbro and gabbroic diorite. LA-ICP-MS zircon U–Pb dating reveals that the pluton was emplaced in the early Jurassic (177 Ma). These gabbros and gabbroic diorites are characterized by relatively low SiO₂ content of 47.09 to 57.15 wt% and high Mg# values varying from 46 to 75. The samples belong to the calc-alkaline series and exhibit a metaluminous I-type character. Moreover, they are slightly enriched in large ion lithophile elements (Rb, Ba, Th and K) and light rare earth elements and depleted in high field strength elements (Nb and Ti). Gabbroic rocks of the pluton have a depleted Sr-Nd isotopic composition, including low initial ⁸⁷Sr/⁸⁶Sr ranging from 0.705124 to 0.705599, relatively high ε _Nd (t) values varying from 0.1 to 3.5 and single-stage Nd model ages (T _DM1 = 0.65–0.95 Ga). In situ zircon analyses show that the rocks have variable and positive ε _Hf (t) values (4.6 to 13.5) and single-stage Hf model ages (T _DM1?=?0.30 to 0.65 Ga). Both the geochemical signature and Sr-Nd-Hf isotopic composition of the gabbroic rocks reveal that the magma of the studied rocks was formed by the partial melting of a depleted mantle wedge metasomatized by slab-derived fluids. The influence of slab fluids is mirrored by their trace-element characteristics. Trace-element modeling suggests that the primary magma was generated by a low and variable degree of partial melting (~5–15%) of a depleted and young lithospheric mantle wedge consisting of phlogopite- and spinel-bearing lherzolite. Heat to melt the mantle material was supplied by the ascendance of a hot asthenosphere triggered by the roll-back of the Paleo-Tethyan oceanic lithosphere. The rising melts were accompanied by fractional crystallization and encountered no or minor crustal contamination en route to the surface. Taking into account these geochemical data and integrating them with regional geological evidence, we propose a slab roll-back model; this model suggests that the Gokcedere gabbroic pluton originated in a back-arc extensional environment associated with the southward subduction of the Paleo-Tethyan oceanic lithosphere during the early Jurassic period. Such an extensional event led to the opening of the northern branch of the Neotethys as a back-arc basin. Consequently, we conclude that the gabbroic pluton was related to intensive extensional tectonic events, which peaked during the early Jurassic in response to the roll-back of Paleo-Tethyan oceanic slab in the final stage of oceanic closure.     

Modeling of seawater intrusion in a coastal aquifer of Karaburun Peninsula,western Turkey

Seawater intrusion is a major problem to freshwater resources especially in coastal areas where fresh groundwater is surrounded and could be easily influenced by seawater. This study presents the development of a conceptual and numerical model for the coastal aquifer of Karareis region (Karaburun Peninsula) in the western part of Turkey. The study also presents the interpretation and the analysis of the time series data of groundwater levels recorded by data loggers. The SEAWAT model is used in this study to solve the density-dependent flow field and seawater intrusion in the coastal aquifer that is under excessive pumping particularly during summer months. The model was calibrated using the average values of a 1-year dataset and further verified by the average values of another year. Five potential scenarios were analyzed to understand the effects of pumping and climate change on groundwater levels and the extent of seawater intrusion in the next 10 years. The result of the analysis demonstrated high levels of electrical conductivity and chloride along the coastal part of the study area. As a result of the numerical model, seawater intrusion is simulated to move about 420 m toward the land in the next 10 years under “increased pumping” scenario, while a slight change in water level and TDS concentrations was observed in “climate change” scenario. Results also revealed that a reduction in the pumping rate from Karareis wells will be necessary to protect fresh groundwater from contamination by seawater.