Yazarlar
- Duran, Celal(38)
- Ozdes, Duygu(33)
- Kankal, Murat(13)
- Şan, Murat(12)
- Gundogdu, Ali(11)
- Nacar, Sinan(10)
- Ozeken, Sengul Tugba(7)
- Soylak, Mustafa(7)
- Alemdag, Selcuk(6)
- Bulut, Volkan Numan(6)
- Kıranşan, Murat(6)
- Serencam, Huseyin(6)
- Akar, Bülent(5)
- Baltaci, Cemalettin(5)
- Gücer, Mehmet Ali(5)
- Tufekci, Mehmet(5)
- Akaryali, Enver(4)
- Bozbeyoglu, Pinar(4)
- Camoglu, Aslihan Yilmaz(4)
- Elvan, Hamide(4)
- Imamoglu, Mustafa(4)
- Seker, Serdal(4)
- Akpinar, A.(3)
- Akçay, Fatma(3)
- Alemdağ, Selçuk(3)
- Başoğlu, Aysel(3)
- Günen, Mehmet Akif(3)
- Kaygusuz, K.(3)
- Okkan, Umut(3)
- Senturk, Hasan Basri(3)
- Turfan, Fatma Asya(3)
- Vural, Alaaddin(3)
- Yagmur, Nur(3)
- Yıldız, Mehmet Berkant(3)
- Şibil, Rahim(3)
- Aras, Egemen(2)
- Ayas, Mustafa Sinasi(2)
- Ayas, Selen(2)
- Bahadir, Zekeriyya(2)
- Barinova, Sophia(2)
Yayınlar
- MakaleAçık Erişim20232D and 3D Numerical Simulation of Dam-Break Flooding: A Case Study of the Tuzluca Dam, Turkey
Akgun, Cagri; Nas, Salim Serkan; Uslu, Akin
Unlike river floods, floods caused by dam breaks occur much more abruptly and at higher water velocities. The failure of a dam due to any reason can pose a significant threat to settlements in the downstream area due to the high volume of water in its reservoir. In this case study, 2D and 3D numerical failure simulations of Tuzluca Dam, to be built in the Igdir province of Turkey, was performed using the Flow3D Hydro software. The Shallow Water and Reynolds-Averaged Navier-Stokes (RANS) equations were used to simulate flood propagation. In the numerical models, RNG k-ε was chosen as the turbulence model. In the analyses carried out under different scenarios, it was observed that in both methods (2D and 3D), significant flood depths would occur in two downstream village settlements. Within the scope of the study, the mortality rates in different dam-break scenarios of the Tuzluca Dam were also investigated. It has been observed that the dam failure time and breach geometry have a significant impact on the flood propagation and the loss of life in settlements. Additionally, a dam-break experiment in literature dam-break experiment was numerically solved using the Flow3D Hydro software to validate the numerical model, and a satisfactory harmony was observed between the experimental results and the numerical models. Although the 3D analysis provided a more accurate representation of the experimental results, it took approximately 20 times longer to complete the dam failure simulation in the case study compared to the 2D model. As a result, it has been determined that for comprehensive studies such as those of dam failures, 2D analyses may be more practical, while for smaller-scale scenarios or situations requiring greater precision, 3D modelling is appropriate.
- MakaleYalnız künye2023Application of Magnetic Fe3O4 Alnus glutinosa Sawdust Biochar/SiO2/CTAB as a New Sorbent for Magnetic Solid Phase Extraction of Heavy Metals from Fruit and Waters Samples
Duran, Celal; Ozdes, Duygu
The coating of magnetic Fe3O4 Alnus glutinosa sawdust biochar with SiO2 and further functionalising by cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was described for the first time in the current paper. The magnetic Fe3O4 Alnus glutinosa sawdust biochar/SiO2/CTAB(MAGBC/SiO2/CTAB) was implemented to separate and preconcentrate the Cu2+, Cd2+, and Pb2+ions efficiently in waters and a number of fruit samples by solid-phase extraction (SPE) method. Adsorbent characterisation was realised by fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Fundamental factors affecting the extraction yield of the analyte ions including solution pH, adsorbent amount, sample volume and desorption contact time were fully researched and optimised as 8.0, 0.25 g, 500 mL and 60 min, respectively, and the eluent was specified as 5.0 mL of 0.1 M of HCl solution. The adsorption equilibrium eventuated after 15 min of contact time and it was noticed that the chemisorption mechanism was dominant upon the analyte ions adsorption. The limits of detection (LOD) were calculated as 0.24, 0.62 and 1.55 µg L−1 and the limits of quantitation (LOQ) were determined as 0.81, 2.08, and 5.17 µg L−1 for Cu2+, Cd2+, and Pb2+ ions, respectively. The relative recoveries (RR%) were in the ranges of 93.3–103.4%, 92.5–102.8%, and 91.8–101.9% for Cu2+, Cd2+, and Pb2+ ions, respectively, while the relative standard deviations (RSD%) were obtained lower than 4.0% (n = 10) by applying the method at optimised conditions. The maximum adsorption capacities of MAGBC/SiO2/CTAB were obtained as 123.7, 80.0 and 118.5 mg g−1for Cu2+, Cd2+, and Pb2+ions, respectively. Consequently, the developed new, simple, rapid, sensitive, and economical SPE method based on MAGBC/SiO2/CTAB was successfully implemented to waters and some of the fruit samples to determine the Cu2+, Cd2+, and Pb2+ions simultaneously.
- MakaleYalnız künye2023Characterization of the Adsorption Mechanism of Cadmium(II) and Methylene Blue upon Corncobs Activated Carbon
Gundogdu, Ali; Bozbeyoglu, Pinar; Imamoglu, Mustafa; Baltaci, Cemalettin; Duran, Celal; Bulut, Volkan N.
A promising new activated carbon (AC) was produced from corncobs (CCs) by boric acid-based chemical activation to remove methylene blue (MB) as an organic pollutant and cadmium ions (Cd2+) as an inorganic pollutant from aqueous solutions. After the produced activated carbon (CCs-AC) was characterized, the adsorption mechanism of CCs-AC, which is one of the most interesting topics in the literature, was the primarily focus. The possible adsorption mechanisms of Cd2+ and MB on CCs-AC from aqueous solutions are discussed with respect to pH, thermodynamic values, and regeneration parameters. The results show that the adsorption of Cd2+ on CCs-AC was favorable at pH values higher than 4. In contrast, the adsorption process was almost pH-independent for MB. Variation of pH showed that the adsorption of Cd2+ on CCs-AC primarily occurs by electrostatic interaction. However, MB adsorption may also involve pi-pi dispersion forces and partial hydrogen bonding. The Cd2+ adsorbed on CCs-AC was quantitatively desorbed by HCl, whereas MB was not desorbed quantitatively by any solution. While a temperature increase has a positive effect on the adsorption of both methylene blue and Cd2+, the thermodynamic results show that MB adsorption is primarily chemisorption (Delta H of 24.28 kJ/mole), while Cd2+ adsorption is mostly physisorption (Delta H of 7.20 kJ/mole). Using Langmuir adsorption isotherms, the MB adsorption capacity of CCs-AC, which primarily has a microporous structure, was 0.88 mmol/g, while the Cd2+ adsorption capacity was 1.28 mmol/g.
- MakaleAçık Erişim2022Geochemical investigation of the potability of surface water in Çit River and related creeks in Avliyana Basin (Gümüşhane, NE Türkiye)
Saka, Fatih; Soylak, Mustafa; Bulut, Volkan Numan; Vural, Alaaddin; Gundogdu, Ali
In the study, physico-chemical parameters of Çit Stream and related creeks in Avliyana Basin (Gümüşhane, NE Turkey) were determined. In terms of physical parameters, it is seen that the Büyük Çit Stream has drinking water quality. According to piper diagram, all of the samples except one have fallen into region of class of CaCO3 and MgCO3 waters. The different one is the mixed water class. It has been determined that the metal content that may pose a risk to water is below the permissible limits. It has been seen that there may be only one point of risk for lead. As a result, physico-chemical aspect of water quality of Çit River and related creeks in Avliyana Basin has been seen to be suitable for drinking water standards.
- MakaleAçık Erişim2022Sentinel-2 görüntüleri kullanılarak su yüzey alanlarının belirlenmesinde sınıflandırıcıların performanslarının incelenmesi
Günen, Mehmet Akif
Nehirler, akarsular, göller ve göletler gibi su yapılarının haritalanması, su kaynaklarının gözlenmesi, zaman içerisinde değişiminin belirlenmesi ve yönetilmesi açısından oldukça önemlidir. Su yüzey alanlarının tespit edilmesi birçok faktörden etkilenen karmaşık bir süreçtir. Su ve su olmayan alanların belirlenmesi problemi için çeşitli çok kanallı bantlı uydu görüntüleri ve sınıflandırma tabanlı yaklaşımlar kullanılmaktadır. Bu çalışmada, sınıflandırma algoritmalarının etkinliğinin araştırılmasında indeks tabanlı yöntemlerden daha başarı sonuç üreten parametrik olmayan (Destek Vektör Makinalar, k-En Yakın Komşuluk ve Karar Ağaçları), olasılıksal (Saklı Markov Model) ve derin öğrenme (Oto- Kodlayıcı) tabanlı danışmalı sınıflandırma yöntemleri kullanılmıştır. Çok bantlı ve yüksek mekansal çözünürlüklü uydu görüntüleri yüksek maliyetli olduğundan sınıflandırma için Sentinel-2 uydu görüntüsüne ait sadece kırmızı, yeşil ve mavi bantlar kullanılarak Arıklar ve Denizli Göletlerine ait su yüzey alanları belirlenmiştir. Deneysel sonuçlar doğruluk, özgüllük, kesinlik, duyarlılık, f-skor gibi karışıklık matrisinden elde edilen metrikler ve görüntü kalite belirlemede kullanılan ortalama karesel hata, yapısal benzerlik indeksi, pik sinyal-gürültü oranı ve Kohen’in Kappa metriği gibi istatistiksel araçları kullanılarak karşılaştırılmıştır. Elde edilen nicel ve nitel deneysel sonuçlarda derin öğrenme tabanlı oto-kodlayıcı istatistiksel olarak en başarılı yöntem olurken, zamansal karşılaştırma açısından karar ağaçları yönteminin daha hızlı çalıştığı belirlenmiştir.
- MakaleAçık Erişim2022Atık Sulardan Cd(II) İyonlarının Adsorpsiyonu için Doğal Adsorban Olarak Kızılçam (Pinus Brutia Ten.) Talaşının Performansının Değerlendirilmesi
Duran, Celal; Ozdes, Duygu; Torun, Erdem
Bazı ağır metallerin çok düşük derişimlerde bile vücuda alınımı, kan bileşiminin bozulmasına, merkezi sinir sistemi fonksiyonlarında azalmaya ve akciğer, böbrek ve karaciğer gibi organlarda hasarlara neden olabilir. Bu nedenle ağır metal iyonlarının, alıcı ortama verilmeden önce sulardan ve atık sulardan uzaklaştırılması gerekmektedir. Bu çalışmada, Cd(II) iyonlarının sulardan ve atık sulardan adsorpsiyon tekniğiyle gideriminde etkili ve ucuz bir adsorban olarak kızılçam (Pinus Brutia Ten.) talaşının kullanılabilirliği değerlendirilmiştir. Adsorpsiyon deneylerinde kullanılan kızılçam talaşı fiziksel veya kimyasal herhangi bir ön işleme tabi tutulmadan doğal olarak kullanılmıştır. Kızılçam talaşı, çeşitli yöntemlerle karakterize edildikten sonra adsorpsiyon verimi üzerine başlangıç sulu çözelti pH’ı, denge süresi, adsorban miktarı ve başlangıç Cd(II) derişimi gibi deneysel faktörlerin etkileri incelenmiş ve ayrıca endüstriyel atık sularda Cd(II) iyonlarıyla birlikte bulunabilecek bazı tuzların etkileri araştırılmıştır. Elde edilen sonuçlardan optimum pH 6.0 ve denge süresi 240 dk olarak belirlenmiştir. Mekanizma hakkında fikir edinmek için elde edilen verilere izoterm modelleri (Langmuir ve Freundlich) uygulanmıştır. Kızılçam talaşının maksimum adsorpsiyon kapasitesi Langmuir izoterm modeli kullanılarak 11.88 mg g-1 olarak hesaplanmıştır. Sonuç olarak kızılçam talaşının atık sulardan Cd(II) iyonlarının uzaklaştırılmasında etkili bir adsorban olarak kullanılabileceği ortaya konulmuştur.
- MakaleYalnız künye2022Karaağaç (Ulmus glabra) ve Dut (Morus alba) Talaşı ile Sulu Çözeltilerden Adsorpsiyon Yöntemiyle Rodamin 6G Giderimi
Duran, Celal; Reis, Ceyhun; Ozdes, Duygu
Bu çalışmada, canlı metabolizmasında toksik etki gösteren katyonik yapıda boyarmadde olan Rodamin 6G’nin (R6G) sulardan ve atık sulardan uzaklaştırılmasında doğal karaağaç (Ulmus glabra) (UGT) ve dut (Morus alba) (MAT) talaşlarının ucuz ve etkili adsorbanlar olarak kullanılabilirliği araştırılmıştır. R6G’nin gideriminde adsorban olarak literatürde ilk defa bu çalışmada kullanılan UGT ve MAT çeşitli yöntemlerle karakterize edilmiştir. Adsorpsiyon deneyleri kesikli sistemle yürütülmüş olup, R6G’nin adsorpsiyon verimi üzerine başlangıç sulu çözelti pH’ı, denge süresi ve başlangıç R6G konsantrasyonu gibi deneysel parametrelerin etkileri incelenmiştir. R6G’nin her iki adsorban üzerine adsorpsiyonu için optimum sulu çözelti pH’ının 7.0 ve denge süresinin 180 dakika olduğu görülmüştür. Adsorpsiyon mekanizmasının aydınlatılabilmesi için elde edilen deneysel verilere çeşitli kinetik (yalancı birinci ve ikinci mertebeden kinetik model ile parçacık içi difüzyon modeli) ve izoterm modelleri (Langmuir, Freundlich, Temkin ve Dubinin-Radushkevich) uygulanmıştır. Adsorpsiyon kinetiğinin, ikinci mertebeden kinetik modeli takip ettiği ve deneysel verilerin hem Langmuir hem de Freundlich izoterm modellerine iyi bir uyum gösterdiği tespit edilmiştir. UGT ve MAT’in maksimum adsorpsiyon kapasitesi Langmuir izoterm modeli kullanılarak sırasıyla 50.5 ve 31.8 mg g-1 olarak hesaplanmıştır. Yapılan çalışma sonucunda karaağaç ve dut talaşının boyarmadde gideriminde kullanılacak etkili ve düşük maliyetli alternatifler olabileceği görülmüştür.
- MakaleYalnız künye2022Farklı İklim Değişikliği Senaryoları için Doğu Karadeniz Bölgesindeki Meteorolojik Kuraklıkların Eğilim Analizi
Kankal, Murat; Nacar, Sinan; Okkan, Umut; Şan, Murat
Kuraklık diğer doğal afetlerden farklı olarak gelişimi daha uzun zaman alan ve etkileri daha uzun süre devam eden bir afettir. Meydana gelmesi muhtemel bir kuraklığın önceden belirlenmesi, kuraklığın olumsuz etkilerinin daha etkili bir şekilde azaltılmasını mümkün kılmaktadır. Standartlaştırılmış Yağış İndeksi (SYİ) farklı iklim koşullarına sahip, farklı zaman dilimleri ve bölgeler arasındaki kuraklıkları tanımlamak için en sık kullanılan kuraklık indeksidir. Bu çalışmanın amacı almış olduğu yağış miktarı bakımından Türkiye’nin en önemli hidrolojik havzalarından biri olan Doğu Karadeniz Havzası’nın (DKH) geçmiş ve gelecek dönem kuraklık analizini SYİ parametresi ile gerçekleştirmek ve bu parametrenin eğilimini belirlemektir. Bu kapsamda DKH içinde ve çevresinde yer alan 12 meteoroloji istasyonundan ölçülmüş olan 1981-2010 dönemi aylık toplam yağış verileri kullanılarak SYİ değerleri hesaplanmıştır. Ayrıca CMIP5 arşivinde yer alan GFDL-ESM-2M genel dolaşım modelinin iyimser (RCP4.5) ve kötümser (RCP8.5) senaryolar altındaki bölgesel ölçeğe indirgenmiş olan 2021-2050 dönemi çıktılarına da aynı işlemler uygulanmıştır. Meteorolojik kuraklığın eğilim analizleri için 1 ve 3 aylık SYİ değerleri üzerinde Yenilikçi Eğilim Analizi yöntemi kullanılarak üç farklı grupta ve %95 güven düzeyinde tekdüze olarak eğilim analizi gerçekleştirilmiştir. Gözlem değerlerinde ve RCP senaryolarında istasyonların yaklaşık %25’inde şiddetli yağışlarda ve şiddetli kuraklıklarda artış görülmüştür. Ancak SYİ değerlerinde geçmiş dönem periyodunda Akçaabat istasyonu (azalan eğilim) hariç tekdüze anlamlı artan eğilim görülürken gelecek dönem periyodunda her iki senaryo için azalan yönde eğilim görülmüştür.
- MakaleYalnız künye2022Performance comparison of deep learning and machine learning methods in determining wetland water areas using EuroSAT dataset
Günen, Mehmet Akif
Wetlands are critical to the ecology because they maintain biodiversity and provide home for a variety of species. Researching, mapping, and conservation of wetlands is a challenging and time-consuming process. Because they produce temporal and geographical information, remote sensing and photogrammetric approaches are useful tools for analyzing and managing wetlands. In this study, the water areas of five different wetlands obtained with Sentinel-2 images in Turkey were classified. Although obtaining large amounts of high-dimensional dataset labeled for various land types is costly, it is a significant advantage to use it after model training in a wide range of applications. In this paper, the EuroSAT dataset was used in the validation process. Proposed deep learning–based 1D convolutional neural networks (CNN) and traditional machine learning methods (i.e., support vector machine, linear discriminant analysis, K-nearest neighborhood, canonical correlation forests, and AdaBoost.M1) were compared quantitatively (i.e., accuracy, recall, precision, specificity, F-score, and image quality assessment metrics) and qualitatively. Finally, pairwise comparison was made with chi-square-based McNemar’s test. There is a statistical difference between 1D CNN and machine learning method (except the support vector machine vs linear discriminant analysis in Test 1 area). CNN models outperform machine learning algorithms in terms of non-linear function approximation and the ability to extract and articulate data features. Since 1D CNNs can process data in a highly complex and unique feature space, they are very successful in segmenting strongly related and highly correlated discrete signals. It also has advantages over machine learning methods for water body extraction in that it can be integrated with sophisticated image pre-processing and standardization tools, is less susceptible to low-level random noise, and provides shift in variations and contrast-invariant image local transforms.
- MakaleAçık Erişim2022Insights into brewed tea waste as a green and low-priced adsorbent for solid-phase extraction of Cd(II) ions: isotherm, kinetic, and artificial neural network approach
Ozdes, Duygu; Tilki, Nida; Seker, Serdal; Duran, Celal
In the present research, brewed tea waste (BTW) was utilized as a green, low-priced, and abundant adsorbent for separation/preconcentration of Cd(II) ions through solid-phase extraction method from water and foods for the first time. BTW was applied as a natural adsorbent, without using any chelating agent to bind Cd(II) ions or any chemical reagent for its modification. A three-layer artificial neural network model using backpropagation algorithm was utilized to explicate a prediction model for the extraction performance of Cd(II) ions by selecting the input parameters as solution pH, quantity of BTW, sample volume, eluent concentration and volume, and equilibrium time for desorption. The preconcentration factor, relative standard deviation, and detection limit were attained as 100, 3.03%, and 0.56 µg L−1, respectively. It was decided that the Langmuir isotherm model is acceptable to characterize the retention of Cd(II) ions on BTW. This result pointed out that the active binding sites on the BTW surface are homogeneously distributed. Adsorption capacity of BTW was achieved as 41.5 mg g−1 which is higher than several expensive and difficult-to-prepare adsorbents. Adsorption kinetics was elucidated by pseudo-second order kinetic model. After confirmed the accuracy of the method with spike/recovery studies, it was employed for Cd(II) determination in water (stream and sea water) and food (eggplant, lettuce, parsley, apple, and apricot) samples with high accuracy. The inferences of the study proved that the BTW offers a magnificent application prospect in the extraction of Cd(II) ions.
- MakaleAçık Erişim2022Innovative approaches to the trend assessment of streamflows in the Eastern Black Sea basin, Turkey
Akçay, Fatma; Kankal, Murat; Şan, Murat
The issue of detection of hydrometeorological trends remains relevant because of the importance of climate change in design, operation, and management studies related to water resources. This study examines the effects of changes in climate and land use on monthly flows (1962–2018) in the Eastern Black Sea basin, Turkey, using innovative trend analysis methods. In this context, innovative polygon trend analysis (IPTA) and innovative trend significance test (ITST) were used to detect the trends and compared with Mann-Kendall test. Only stations with homogeneous data that did not experience non-climatic changes are used in the analysis. IPTA and ITST approaches are much more sensitive than Mann-Kendall in detecting trends. Although the innovative methods are mostly compatible with each other (90%), IPTA presents additional information about trend transitions between successive parts of time series. Results indicate significant decreasing trends in summer months, likely due to diminishing precipitation and effective evaporation.
- MakaleAçık Erişim2021The Investigation of the Alternative Fuel Biogas Potential for Model Town
Saribiyik, Oguz Yunus; Kılıç, Rahman
The investigations have been intensively continuing for responding of energy and food demand depending on the world populationincrease and the development of the industrial progression. The energy necessities eliminate by using fossil fuels based sources suchas natural gas, coal and petrol. However, the amount of the fossil fuels is limited and they create the green houses gas problems,therefore, many of the researches have been focusing on new sustainable alternative energy sources, such as wind power, biodiesel,biogas, solar and biomass. The methane which is released by the methanogen bacteria is occupy a places in green gases which arecarbon dioxide and methane. Biogas as an alternative biofuel has higher impact in alternative fuels because of its applicability,sustainability, low production cost, keep the greenhouse gases in balance and produces bio-fertilizer after digestion processes. In thosepurposes, the biogas investment and investigation increases for all over the world however the potential of biomass conversion andthe examination for bio gas production have paid less concern in our country.In this study, the potential biomass and the amount of the biogas depending on the biomass potential have been investigated on one ofthe model town, Şiran in Gümüşhane. According to obtained results, it is seen that the biomass potential and the amount of the biogasproduction are highly enough for model town for natural gas demand and using bio fertilizer which is produced after digestion ofbiomass can be decreased by the utilization of the synthetic inorganic fertilizer, causing for soil pollution.
- MakaleAçık Erişim2021Investigation of Hydrogeochemical Characteristics and Quality of the Water Resources in Şiran (Gümüşhane) District Center, Turkey
Alemdag, Selcuk; Semiz, Ümmühan; Gücer, Mehmet Ali
The study area is located of Şiran District Center in the southwest of Gümüşhane (NE Turkey). In this study, hydrogeochemical characteristics of water resources in district center were examined and metal element contents were determined. In the study area, the basement rocks are represented by Eocene Kelkit formation, which is composed of sandstone, claystone, marl, shale and tuff, and this unit is covered unconformably by the Quaternary aged alluvium. These units form granular porous unconfined aquifers according to the hydrogeological features. The pH, specific conductance (SC) and hardness (Fr°) values of the water resources in the study area varied between 5.41-7.48, 106.9-141.3 µS/cm and 4.72-6.78 (n= 18), respectively. According to the classification of Intra-Continental Water Resources, these data show that the samples are mostly class-I and II, rarely class-III water quality characteristics. The water resources in the study area are generally classified as Ca-Mg-HCO3 type carbonated (Ca+Mg>Na+K), and generally their weak acids are more than strong acids (HCO3>SO4+Cl). In the study area, (Ca+Mg)/(SO4+HCO3) ratios indicated the effect of silicate weathering in the waters, and the Cl/(Cl+HCO3) and (Na+K)/(Na+K+Ca) ratios show that the chemistry of waters is controlled by the chemical weathering of rock-forming minerals, hence, reflect the water-rock interaction. Except for a few, the concentration of dissolved potentially toxic elements in the water samples were distributed within acceptable limits. Consequently, the hydrogeochemical results showed that the water resources in the study area were in the category of good class waters in terms of drinking water
- MakaleAçık Erişim2021Investigation of the removal of sulfamethoxazole drug waste from aqueous solutions under the effect of zinc oxide/montmorillonite nanocomposite by photocatalytic ozonation process
Özyürek, Işıl Nihan; Kıranşan, Murat; Karaca, Semra
In this study, the synergistic effect of photocatalysis and ozonation processes to degrade the sulfamethoxazole (SMX), one antibiotic pharmaceutical compound, has been studied through the influence of main operational variables such as zinc oxide/montmorillonite (ZnO/MMT) dos-age, SMX initial concentration, ozone flow rate, pH and the addition of organic and inorganic scavengers. Synthesized ZnO nanoparticles were immobilized on the montmorillonite surface to prepare ZnO/MMT catalyst as a photocatalyst. The catalyst was characterized by X-ray fluo-rescence, X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscope and N2 adsorption/desorption. The highest SMX degradation efficiency (80.84% for 30 min of reaction time) was obtained for the photocatalytic ozonation process compared to adsorption, single ozonation, catalytic ozonation, and photolysis. ZnO/MMT was more effective photocatalyst according to ZnO, indicating its usability as a promising photocatalyst for the removal of organic contaminants in aqueous solutions. The reduced degradation efficiency with the addition of organic and inorganic scavengers showed the important role of the photo-produced radicals and holes as well as direct ozonation in SMX degradation. A mechanism is also proposed for photocatalytic ozonation degradation by using the gas chromatography-mass spectroscopy (GC-MS) analysis method. Finally, several by-products were identified by GC-MS analysis, which allowed to depict a possible mechanism for the sulfamethoxazole degradation.
- MakaleYalnız künye2021Long and short-term assessment of surface area changes in saline and freshwater lakes via remote sensing
Yagmur, Nur; Bilgilioglu, Burhan Baha; Dervisoglu, Adalet; Musaoglu, Nebiye; Tanik, Aysegul
Advances in remote sensing technology enable monitoring and detection of these vulnerable water bodies that bear numerous functions and ecological services beyond their intended use. As such, valuable data and information may be provided for long and short-term analyses and stored in a database for future projections. This paper initially grouped 18 natural lakes of the Konya Closed Basin of Turkey according to their salinity level. Freshwater, saline and brackish lakes have then undergone temporal analysis for every 5-year intervals via Landsat satellite images. Freshwater lake surfaces have not changed noticeably during the inspection period; however, saline waters have decreased in surface area by 32%. Beysehir Lake constituting 94% of the freshwater category and Tuz Lake representing 97% of the saline group were selected for the short-term analysis that was monthly conducted for years 2017 and 2018 with optical and SAR images to better verify cause and effect relationship.
- MakaleYalnız künye2021Preparation of melon peel biochar/CoFe2O4 as a new adsorbent for the separation and preconcentration of Cu(II), Cd(II), and Pb(II) ions by solid-phase extraction in water and vegetable samples
Ozdes, Duygu; Duran, Celal
The present research describes the successful preparation of melon peel biochar modified with CoFe2O4 (MPBC/CoFe2O4) followed by its usage as a new sorbent to separate, preconcentrate, and determine the toxic heavy metal ions by magnetic solid-phase extraction. The metal ion desorption was performed by 0.1 M HCl solution with a volume of 5.0 mL. Flame atomic absorption spectrometry (FAAS) was utilized for detection of the analyte levels. SEM–EDX, TEM, XRD, and FTIR techniques were carried out to illuminate the structure of MPBC/CoFe2O4. The fundamental variables affecting the adsorption and elution efficiencies of the analyte ions including solution pH, MPBC/CoFe2O4 amount, type and concentration of eluent, adsorption and desorption equilibrium time, and sample volume were optimized. The detection limits were calculated as 0.41, 1.82, and 3.16 µg L−1 for Cu2+, Cd2+, and Pb2+ ions, respectively, with the relative standard deviation of lower than 4.2%. There were no substantial interference effects on the analyte ion recovery due to the presence of foreign ions at high levels. Five minutes of contact time was adequate to attain the adsorption equilibrium. The adsorption capacity of MPBC/CoFe2O4 was obtained as 106.4, 65.4, and 188.7 mg g−1 for Cu2+, Cd2+, and Pb2+ ions, respectively, by utilizing Langmuir isotherm model. The pseudo-second order model is favorable to identify the adsorption kinetics. The method was validated by spike/recovery test, and then, it was successfully implemented to determine the aforementioned analyte levels in sea and stream water, pepper, black cabbage, eggplant, and tomato samples.
- MakaleAçık Erişim2021Satellite-derived shallow wetland bathymetry using different classification algorithms and datasets
Dervisoglu, Adalet; Yagmur, Nur; Bilgilioglu, Burhan Baha
Remote sensing (RS) effectively identifies, analyzes, and monitors wetlands. In addition to these two-dimensional studies, RS is used with several techniques in determining shallow water depths. The primary purpose of this study is to obtain shallow wetland bathymetry utilizing spectral reflections obtained at different water depths by field study and satellite images. Machine learning (ML) algorithms, which are widely used in remote sensing, are used in this study. Four algorithms were selected as random forest (RF), support vector machine (SVM), Neural Networks (NN), and Maximum Likelihood Classification (MLC). Since machine learning algorithms use training samples/datasets, the classification accuracy is directly related to selecting these data. The effect of pixel counts on classification was investigated by using two different training data set also. Duden (Kulu) Lake, which is a shallow wetland, was chosen as the study area. The Iterative Self-Organizing Data Analysis Technique (ISODATA) classification algorithm divided into as many clusters as possible was applied on Sentinel-2 multispectral images. All classes were rede-fined using measured spectral signatures and were created a bathymetric map. This map was used as reference data in creating training sets and the accuracy assessment of ML algorithms. When the water surface areas obtained from algorithms were compared with the bathymetric map and Normalized Difference Water Index, the best result was obtained with RF. According to the accuracy assessment results, it was seen that the number of training data affects the accuracy, and the best results were obtained with SVM and RF algorithms with training data containing more pixels (overall accuracy 93.87% and 92.64, kappa 0.89 and 0.87, respectively).
- MakaleAçık Erişim2021Land subsidence and its relations with sinkhole activity in karapınar region, turkey: A multi-sensor insar time series study
Orhan, Osman; Oliver-Cabrera, Talib; Wdowinski, Shimon; Yalvac, Sefa; Yakar, Murat
The Karapinar basin, located in the Central Anatolian part of Turkey, is subjected to land subsidence and sinkhole activity due to extensive groundwater withdrawal that began in the early 2000s. In this study, we use Interferometric Synthetic Aperture Radar (InSAR), Global Navigation Satellite System (GNSS), and groundwater level data to monitor and better understand the relations between groundwater extraction, land subsidence, and sinkhole formation in the Karapinar basin. The main observations used in the study are InSAR-derived subsidence velocity maps calculated from both Sentinel-1 (2014–2018) and COSMO-SkyMed (2016–2017) SAR data. Our analysis reveals broad areas of subsidence with rates exceeding 70 mm/yr. The InSAR-derived subsidence was compared with GNSS data acquired by a continuously operating GNSS station located in the study area, which show a similar rate of subsidence. The temporal characteristic of both InSAR and GNSS time series indicate a long-term subsidence signal superimposed by seasonal variability, which follows the overall groundwater level changes, with over 80% cross-correlation consistency. Our results also indicate that sinkhole activity is limited to slow subsidence areas, reflecting strong cohesion of near-surface rock layers that resist subsidence but yield to collapse in response to aquifer system deformation induced by groundwater extraction.
- MakaleAçık Erişim2021Analysis of salt lake volume dynamics using sentinel-1 based SBAS measurements: A case study of lake Tuz, Turkey
Bilgilioğlu, Burhan Baha; Erten, Esra; Musaoğlu, Nebiye
As one of the largest hypersaline lakes, Lake Tuz, located in the middle of Turkey, is a key waterbird habitat and is classified as a Special Environmental Protection Area in the country. It is a dynamic lake, highly affected by evaporation due to its wide expanse and shallowness (water depth <40 cm), in addition to being externally exploited by salt companies. Monitoring the dynamics of its changes in volume, which cause ecological problems, is required to protect its saline lake functions. In this context, a spatially homogeneous distributed gauge could be critical for monitoring and rapid response; however, the number of gauge stations and their vicinity is insufficient for the entire lake. The present study focuses on assessing the feasibility of a time-series interferometric technique, namely the small baseline subset (SBAS), for monitoring volume dynamics, based on freely available Sentinel-1 data. A levelling observation was also performed to quantify the accuracy of the SBAS results. Regression analysis between water levels, which is one of the most important volume dynamics, derived by SBAS and levelling in February, April, July and October was 67%, 80%, 84%, and 95% respectively, for correlation in the range of 10–40 cm in water level, and was in line with levelling. Salt lake components such as water, vegetation, moist soil, dry soil, and salt, were also classified with Sentinel-2 multispectral images over time to understand the reliability of the SBAS measurements based on interferometric coherence over different surface types. The findings indicate that the SBAS method with Sentinel-1 is a good alternative for measuring lake volume dynamics, including the monitoring of water level and salt movement, especially for the dry season. Even though the number of coherent, measurable, samples (excluding water) decrease during the wet season, there are always sufficient coherent samples (>0.45) over the lake.
- MakaleAçık Erişim2021Experimental and numerical studies on predicting and improving the full-scale wastewater treatment plant hydrodynamics
Şibil, Rahim; Aras, Egemen; Kankal, Murat
This paper presents the results of both experimental and numerical studies on biological wastewater treatment plant (WWTP), oxidation ditches (OD) hydrodynamics to design and develop the desired flow conditions of the WWTP. Computational fluid dynamics (CFD) models were developed using CFD software, ANSYS Fluent (V13) with the three-dimensional, steady, incompressible flow based on the Reynolds-Averaged Navier-Stokes equations for flow field calculations in the combined ODs. Also, three different turbulence models [standard k–ε (ske), renormalization group k–ε (RNG), and realizable k–ε (real)] were performed for a comparative study. The numerical model was verified based on the experimental data in the relative errors for ske, RNG, and real 13%, 17%, and 18%, respec-tively. According to the parametric studies, the hydrodynamic characteristics of the existing WWTP were investigated. The maximum wastewater velocity occurred at the inlet and outlet, affecting the flow field in ODs. Moreover, the water velocity decreased as it moved away from the inlet and outlet locations at vertical and horizontal. It can also be noted that there was no homogeneous flow field distribution in ODs. Because the current OD model needs improvement hydrodynamically, a new original OD geometry was presented to eliminate the hydraulic weakness of existing WWTP by CFD analysis. The new original geometry provides a more homogeneous flow field in ODs that mean it will also help treatment efficiency and energy saving according to the operating principles of this facility.
