WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 19Citation - Scopus: 18An Appraisal of the Local-Scale Spatio-Temporal Variations of Drought Based on the Integrated Grace/Grace-fo Observations and Fine-Resolution Fldas Model(Wiley, 2023) Khorrami, Behnam; Ali, Shoaib; Gündüz, OrhanThe gravity recovery and climate experiment (GRACE) observations have so far been utilized to detect and trace the variations of hydrological extremes worldwide. However, applying the coarse resolution GRACE estimates for local-scale analysis remains a big challenge. In this study, a new version of the fine resolution (1 km) Famine early warning systems network Land Data Assimilation System (FLDAS) model data was integrated into a machine learning model along with the GRACE data to evaluate the subbasin-scale variations of water storage, and drought. With a correlation of 0.99 and a root mean square error (RMSE) of 3.93mm of its results, the downscaling model turned out to be very successful in modelling the finer resolution variations of TWSA. The water storage deficit (WSD) and Water Storage Deficit Index (WSDI) were used to determine the episodes and severity of drought events. Accordingly, two severe droughts (January 2008 to March 2009 and September 2019 to December 2020) were discerned in the Kizilirmak Basin (KB) located in Central Turkiye. The characterization of droughts was evaluated based on WSDI, scPDSI, and model-based drought indices of the soil moisture storage percentile (SMSP) and groundwater storage percentile (GWSP). The results indicated discrepancies in the drought classes based on different indices. However, the WSDI turned out to be more correlated with GWSP, suggesting its high ability to monitor groundwater droughts as well.Article Citation - WoS: 31Citation - Scopus: 34Model-Coupled Grace-Based Analysis of Hydrological Dynamics of Drying Lake Urmia and Its Basin(Wiley, 2023) Khorrami, Behnam; Ali, Shoaib; Şahin, Onur Güngör; Gündüz, OrhanLake Urmia basin (LUB), in northwestern Iran, is under the influence of extreme degradation due to a number of natural and anthropogenic factors. The existence of the Lake is critical for the microclimate of the region as well as the quality of human life and wildlife, which necessitates an up-to-date and holistic analysis of its hydrological dynamics. In this premise, satellite-based terrestrial water storage (TWS) received from the Gravity Recovery and Climate Experiment (GRACE) mission was coupled with hydrometeorological modelling and assessment tools to analyse the hydrological status of the lake and its basin. As a new gap-filling approach, the Seasonal-Trend decomposition using Locally estimated scatterplot smoothing (LOESS) (STL) decomposition technique was proposed in this study to reconstruct the missing TWS data. Integrating satellite precipitation data with the Catchment Land Surface Model (CLSM) and WaterGAP model outputs, the hydrological status of the lake was investigated. The STL-based TWS turned out to concord well with the simulated TWS from the CLSM indicating the acceptable performance of the proposed technique. The findings revealed that the LUB had undergone an alarming hydrological situation from 2003 to 2021 with a total loss of 10 and 7.56km3 from its TWS and groundwater storage (GWS), respectively. The water level time series also indicated that the water level of the lake had diminished with an annual rate of -70 +/- 21cm/year corresponding to a total water level depletion of about 13.35 +/- 3.9m during the 2003-2021 period. The GRACE-derived TWS and GWS also agreed well with the CLSM simulations. Assessment of the extreme events of the LUB suggested that the basin suffered from a severe dry event in 2008 resulting in the depletion of its water storage and water level. It was also found that from 2003 onward, a critical hydrological setting had dominated the LUB with a negative hydrological balance of -0.96km3.Article Citation - WoS: 2Citation - Scopus: 2A Deterministic and Stochastic Assessment for Exposure and Risk of Arsenic Via Ingestion of Edible Crops(Springer Verlag, 2019) Can Terzi, Begüm; Gündüz, Orhan; Sofuoğlu, Sait CemilNatural arsenic contamination is a critical problem for various places around the world. Simav Plain (Kutahya, Turkey) is one such area that was shown to have natural arsenic contamination in its waters and soils. Arsenic exposure through ingestion of edible crops cultivated in Simav Plain and associated health risks were assessed in this study. To achieve this objective, arsenic levels in 18 crop species were estimated based on measured soil arsenic concentrations. Individual and aggregate non-carcinogenic and carcinogenic risks associated with ingestion of arsenic-contaminated crops were then assessed with scenario-based deterministic point estimates and stochastic population estimates. Monte Carlo simulation was used for the estimation of population health risks. Accordingly, wheat was found as the highest-ranked crop specie for the both types of health risks, followed by tomato and potato, which are three of the most consumed crops in the region. The risk levels estimated in this study were relatively high, indicating consumption of crops grown in the plain may be posing significant health risks even at lower-bound estimates. Consuming wheat, tomato, potato, and their products from uncontaminated sources was found to reduce the aggregate risks up to 88% implicating the importance of proposing suitable management measures for similar risk-prone areas.Conference Object Citation - WoS: 2Citation - Scopus: 2Arsenic in Groundwater in Western Anatolia, Turkey: a Review(University of Silesia Press, 2010) Gündüz, Orhan; Baba, Alper; Elpit, HandanOccurrence of arsenic (As) in groundwater has been a major problem worldwide for the last hundred years. Considering its toxic effects on human health, the presence of elevated levels of arsenic in groundwater resources used in drinking water supply has been an active research field throughout the world (Van Halem et al., 2009). In this regard, case studies from Bangla-desh, India, Nepal, El Salvador, Ecuador, Honduras, Mexico, Chile, China, Canada, Argentina, Peru, Taiwan, United States, Bolivia and Turkey have been documented with regards to the detection of natural levels in groundwater, the occurrence and distribution mechanisms, the human health effects and the in-situ and ex-situ treatment techniques (Jean et al., 2010). In many of these locations, arsenic is naturally found in the subsurface strata within volcanic and sedimentary formations as well as in areas of geothermal systems related to tectonic activity. Western Anatolia in Turkey is one such area of complex geology with active tectonics and high geothermal potential. This natural setting serves as a suitable environment for the presence of high levels of arsenic in subsurface waters. Based on these fundamentals, this study presents a general overview of arsenic presence in western Anatolia.Conference Object Occurrence of Arsenic and Related Microbial Signature of Hydrothermal Systems in Western Turkey(Taylor & Francis, 2012) Chen, Chienyen; Maity, Jyoti Prakash; Bundschuh, Jochen; Bhattacharya, Prosun; Baba, Alper; Gündüz, OrhanThe naturally occurring aqueous Arsenic (As) and other toxic elements are found around the world. The present study concentrates on arsenic concentrations, speciation and related microbial diversity in a hydrothermal system in Western Turkey. The surface temperatures of hot springs reach up to 90°C and deep well (reservoir) temperatures vary in the range of 40 to 230°C. The elements such as As, B, Br, Ba, Cr, Fe, Mn, V and Zn are found in high concentration in hydrothermal waters. Hydrogeochemically, Seferihisar hot spring exhibited a Na-Cl water type. On the other hand, Karahayit, Pamukkale, Emirfaki, Alaşehir and Sart exhibit a Ca-HCO 3 water type and Çitgöl exhibited a Na-HCO 3-SO 4 water type. The arsenic (As) concentrations in geothermal waters of Western Anatolia have been detected to range from 0.03 mg/L to 1.5 mg/L, including Buharkent (İnalti) (1.50 ± 0.005 mg/L), Kizildere (1.13 ± 0.005 mg/L), Eynal (0.71 ± 0.005 mg/L) and Sarayköy (0.06 ± 0.004 mg/L). Arsenic (III) is the dominant species in geothermal water of Western Anatolia. The 16S rRNA gene sequences of bacterial diversity show that the thermophilic, sulfur/thiosulfate-oxidizing bacterium (Thiobacter subterraneus) is present in Kula geothermal water and mesophilic sulfur- and thiosulfate-oxidizing Sulfurovum lithotrophicum bacterium occurs in Sarayköy geothermal spring. Also, Bacillus fumarioli, (a thermophilic, aerobic endospore forming bacterium growing on (NH 4) 2 SO 4, MgSO 4 and MnSO 4 at 50-55°C), Schlegelella thermodepolymerans and Methylocaldum szegediense are rich in geothermal water.Article Citation - WoS: 18Citation - Scopus: 22The Health Risk Associated With Chronic Diseases in Villages With High Arsenic Levels in Drinking Water Supplies(Springer Verlag, 2017) Gündüz, Orhan; Bakar, Coşkun; Şimşek, Celalettin; Baba, Alper; Elçi, Alper; Gürleyük, Hakan; Mutlu, Merdiye; Çakır, AyşeThis study is intended to compare and assess the distribution and possible causes of current chronic diseases in villages with high arsenic levels in drinking water supplies. It is a cross-sectional epidemiological research that analyzes the frequency and underlying risk factors of chronic diseases in villages with varying levels of arsenic exposure through drinking water. Sample space of study included 1003 individuals, 614 of whom were from villages with high arsenic levels in drinking water and remaining 389 were from two control villages with below-limit arsenic levels in drinking water. While nutritional habits and living environments of two groups were similar, cigarette smoking and alcohol use were higher in villages with low arsenic levels. Mini mental state examination test results in 60+ age group were lower in villages with high arsenic levels. Although no statistically significant differences were detected in chronic disease occurrence between the groups, the number of cases was higher in villages with higher percentage of cigarette smoking and alcohol use. Moreover, cases of lung, colon, and stomach cancers were higher in villages with high arsenic levels in drinking water supplies.Article Citation - WoS: 20Citation - Scopus: 22Modeling of Seawater Intrusion in a Coastal Aquifer of Karaburun Peninsula, Western Turkey(Springer Verlag, 2017) Mansour, Ahmed Y. S.; Baba, Alper; Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Murathan, Alim; Sözbilir, HasanSeawater 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.Article Citation - WoS: 17Citation - Scopus: 28Effect of Geogenic Factors on Water Quality and Its Relation To Human Health Around Mount Ida, Turkey(MDPI Multidisciplinary Digital Publishing Institute, 2017) Baba, Alper; Gündüz, OrhanWater-rock interactions strongly influence water quality. Waters originating from highly altered zones affect human health. Mount Ida region in western Anatolia is an example for such geogenic interactions and additional anthropogenic impacts. A water quality monitoring study was held and a total of 189 samples were collected from 63 monitoring stations to characterize the quality of water resources and its relation with human health. The results indicated that waters originating from altered volcanic rocks that are mainly used for drinking purposes have low pH, high conductivity and elevated trace element levels. In addition, a number of acidic mining lakes were formed in the open pits of abandoned mine sites in the study area and pyrite oxidation in altered volcanic rocks resulted in extremely acidic, high mineral content and toxic waters that demonstrate an eminent threat for the environmental health in the area. Overall, the water quality constituents in Mount Ida region had a spatially variable pattern and were locally found to exceed the national and international standards, mainly due to geogenic alteration zones and anthropogenic intervention.Article Citation - WoS: 27Citation - Scopus: 31Statistical Analysis of Causes of Death (2005-2010) in Villages of Simav Plain, Turkey, With High Arsenic Levels in Drinking Water Supplie(Taylor and Francis Ltd., 2015) Gündüz, Orhan; Bakar, Coşkun; Şimşek, Celalettin; Baba, Alper; Elçi, Alper; Gürleyük, Hakan; Mutlu, Merdiye; Çakır, AyşeThe purpose of this research was to compare the causes of death in 5 villages situated in Simav Plain, Turkey, during 2005-2010 where different arsenic levels were detected in drinking water supplies. Since groundwater in Simav Plain had arsenic concentrations that ranged between 7.1 and 833.9 ppb, a two-phase research was formulated. In the first phase, public health surveys were conducted with 1,003 villagers to determine the distribution of diseases. In the second phase, verbal autopsy surveys and official death records were used to investigate the causes of death. In total, 402 death cases were found in the study area where cardiovascular system diseases (44%) and cancers (15.2%) were major causes. Cancers of lung (44.3%), prostate (9.8%), colon (9.8%), and stomach (8.2%) were comparably higher in villages with high arsenic levels in drinking water supplies. Furthermore, the majority of cases of liver, bladder, and stomach cancers were observed in villages with high arsenic levels. © 2015 Taylor and Francis Group, LLC.Article Citation - WoS: 2Citation - Scopus: 2Sample Collection Into Sterile Vacuum Tubes To Preserve Arsenic Speciation in Natural Water Samples(American Society of Civil Engineers (ASCE), 2013) Gündüz, Orhan; Gürleyük, Hakan; Çakır, Ayşe; Elçi, Alper; Baba, Alper; Şimşek, CelalettinThe accurate speciation analysis of arsenic is a serious concern for water quality monitoring programs. Because the preservation of sample integrity until analysis is one of the most important aspects of speciation, this study aims to compare the performance of four different sample preservation methods under diverse conditions of sample quality. Natural samples with different characteristics were collected into the following containers to study their effectiveness: (1) standard high-density polyethylene bottle with no preservative; (2) empty, sterile Vacuette tube with no preservative; (3) sterile tripotassium ethylenediaminetetraacetic acid (K3EDTA) Vacuette tube with K3EDTA additive; and (4) empty, sterile Vacuette tube with added hydrochloric acid (HCl). Known concentrations of arsenite [As(III)] were also added to each container to monitor the oxidation of As(III) to arsenate [As(V)]. The results revealed recovery ratios exceeding 95% in all containers with sterile vacuum conditions. In particular, the K3EDTA Vacuette tube yielded a recovery very close to 100% of the spiked As(III), which is known to rapidly oxidize to As(V). Overall, collecting the sample into a container under sterile vacuum conditions and using a universally accepted preserving agent such as EDTA or HCl significantly improved the preservation of the original species distribution in the water matrix studied, compared to sampling without the use of preservation methods. After validation by future research, these sterile vacuum tubes can possibly be utilized for collecting and storing samples for the routine speciation analysis of other elements such as selenium, chromium, and antimony.