Çevre Bilimleri Enstitüsü

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16S rDNA analysis of microbial communities in a highly polluted region of the Marmara Sea
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2007., 2007.) Türker, Gökhan.; İnce, Bahar Kasapgil.
The Marmara Sea is a small (size 70 x 250 km) intercontinental basin connecting Black Sea and Mediterranean Sea. The population of Marmara region reaches to 25 million and therefore there is large number of domestic and industrial wastewater discharges to the Marmara Sea from different points. Also large quantities of Central Asian oil and gas are transported to the west through the Marmara Sea. Combining effect of pollution sources create a chronic pollution at the Marmara Sea and formed several anoxic sediments in highly polluted sites. One of the areas is Küçükçekmece region. The region is populated by both residential and industrial sites and takes domestic and industrial effluent of more than 3 million people. Industrial sites mainly composed of metal industry, textile and leather industry, medicine industry, paper industry, chemical industry, rubber and plastic industry. Also in 1999 due to tanker accident at Küçükçekmece beach, the region was polluted with more than 3000 tones of petroleum. Sediment is a carbon and nutrient pool for aquatic environments. The presence of hydrocarbon compounds creates a suitable environment for the growth of anaerobic bacteria. Anaerobic biodegradation processes are slower than aerobic biodegradation. However, anaerobic processes can be a significant factor in removal of organic contaminants owing to the abundance of anaerobic electron acceptors relative to dissolved xygen; therefore promising a stable and long term removal of contaminants. It has been estimated that less than 1% of the total microbial population in the land environment and even less in the marine environment have been successfully isolated in pure culture. Marmara Sea has great importance not only because of geological position but also its composition of microbial life which still remains in darkness. The microbial diversity in this unique ecosystem has not been studied using culture-independent molecular techniques yet. Microbial community analyses together with chemical analyses of the sediments will undoubtly form a base to develop bioremediation strategies to overcome chronic pollution at the Küçükçekmece coast. Main aim of this study is to find a suitable microbial community in anoxic sediments taken from Marmara Sea for a bioremediation strategy depending on anaerobic biodegradation. The microbial diversity and community structure were analyzed by Denaturing Gradient Gel Electrophoresis (DGGE) and 16S rDNA Clone Library method. The results were evaluated with sediment quality parameters along the sampling point. Established results will be used with other information from the literature to analyze the suitability of any of the community in the anoxic sediments from the Küçükçekmeçe coast for bioremediation purposes. Suitable communities will be marked and used as a cornerstone for a bioremediation strategy based on anaerobic biodegradation. DGGE results indicate presence of 34 different bands for bacterial community and 15 different bands for archaeal community with each band representing a different organism. Clone library results are parallel to results of DGGE. In bacterial clone library there are 23 different clones and 26 different clones for September 05 and December 06 respectively. In archaeal 16S rDNA clone library, 19 different clones and 20 different clones were found in September 05 and December 06 respectively. The result of sequencing of bacterial dominant clones indicate presence of Trichococcus pasteurii, Clostridium glycolicum in September 05 and Elbe River snow isolate Iso26, Xanthomonas sp. CC-FH5, and Gallicola barnesae in December 06. Archaeal dominant clones are Methanoplanus petrolearius, Methanoplanus limicola, Methanogenium organophilum in September 05 and Methanogenium frigidum and Methanosaeta sp. in December 06. Results of clone library generation show that syntrophic relations are running in both times. In September 05, fermentation and hydrogenotrophic methanogenesis dominated pathway. In December 06, anaerobic respiration and fermentation coupled with acetoclastic and hydrogenotrophic methanogenesis dominated the pathway.
16S rDNA analysis of microbial communities in anoxic marine sediments of the Marmara Sea
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2007., 2007.) Sezgin, Aslı.; İnce, Bahar Kasapgil.
The sediments of the Marmara Sea are of importance since they are believed to have been a rather sensitive recorder of climatic, biological and chemical changes and water-mass movements in the region. In this study, overall microbial community of coastal sediments from the Marmara Sea was characterized by cloning and sequencing of 16S rRNA genes. Denaturing Gradient Gel Electrophoresis was used to investigate the seasonal distribution of the microbial communities in coastal sediments from Tuzla and Moda. The sequencing of clone libraries revealed a higher microbial diversity in anoxic sediment samples of Tuzla than that of derived from Moda. and served to understand the potential dominant metabolic processes prevailing under anoxic conditions. Methylotrophic methanogenesis and denitrification were found as the potential dominant metabolic processes in Tuzla sediments, whereas hydrogenotrophic methanogenesis and fermentation appeared to be the potential dominant metabolic processes in Moda sediments. DGGE data revealed a more significant seasonal change in microbial community structure of Tuzla sediments.|Keywords: Marmara Sea, Anoxic Marine Sediments, 16S rDNA, Microbial Diversity, Clone Library
A dynamic simulation approach to soil salinity and sodicity in Konya plain of Turkey
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2021., 2021.) Tunca, Mehmet Can.; Saysel, Ali Kerem.
Soil salinity and sodicity are twin problems potentially affecting soil fertility, farmers’ livelihoods and food security. Management and control of these problems, particularly on irrigated farmlands require knowledge and expertise crafted through appropriate models and experiments. The accumulation of salts on the soil profiles may occur through natural processes as well as by human actions, that are mostly related to poor agricultural and irrigation practices. Accumulation of salt in soil water impedes crop evapotranspiration, sodicity threatens the soil structure and degrades its hydraulic qualities. These problems are more pervasive in arid and semi-arid regions. Therefore, irrigation and agricultural practices are crucial in controlling these problems to avoid their undesired consequences. In this research, a dynamic simulation model is built to represent salinization and sodification in soil layers so as to test the long-term impact of alternative irrigation practices with respect to water quality, quantity and schedule, on soil fertility and farm yields. The model is developed based on the system dynamics methodology. Model parameter values are selected as representative of the field conditions of Konya Plain in Turkey, which is a semi-arid region partially experiencing soil salinization problems. This study is completed as a part of the TÜBİTAK-funded research project entitled, “Soil Salinity and Sodicity Management by Sustainable Irrigation Practices in Konya Plain”. Based on the scenario analyses performed in the research, irrigation water quality, irrigation method as well as crop rotations found to be important factors on soil salinization and sodification process in soil.
A dynamic simulation model of carbon circulation and methane feedbacks in anthropogenic climate change
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2010., 2010.) Akpınar, Yeşim Atağ.; Saysel, Ali Kerem.
The human induced climate change is the most serious and difficult environmental issue to manage that has emerged in the recent decades. The complexity of this problem lies in the fact that if the increase in atmospheric greenhouse gas concentrations continue in an uncontrolled manner, its potential damage can be very severe but the costs associated with the mitigation activities are very high. Although the severity of the problem and the need for urgent action are unquestionable today, people usually prefer "wait and see" policies instead of prompt action. One reason of this tendency is inherent difficulties of understanding the dynamics of anthropogenic climate change and anticipating the possible future results of today's actions. Climate change is a good example of a dynamic systems problem. It embodies several delays, feedbacks, nonlinearities and uncertainties in its dynamically complex structure. Therefore, the need for and the usefulness of descriptive and simpler models that explain these dynamic complexities are undisputed. The aim of this study is to construct such a dynamic simulation model. The method used is system dynamics, which is a powerful approach to model and analyze complex dynamic systems to create hypotheses on structure and to predict future behavior. The model integrates several components of the climate system. It includes the carbon cycle, radiative forcing of CO2, CH4, N2O and induced temperature change as well as the temperature feedback affecting terrestrial carbon absorption rates. It also proposes a representation of the permafrost melting and methane feedback process. The model aims at enabling the user to test the effects of these feedbacks, the emission scenarios and parameter uncertainty on greenhouse gas concentrations and average surface temperature change. The simulation length is 240 years from 1860 to 2100. Model structure is validated with indirect structure tests. Historical emissions and temperature change data are used to calibrate the model behavior. Model reference behavior is based on IS92a emission scenario of IPCC. The model can be transformed to an interactive learning environment and be used as a tool to improve the public understanding about dynamics of climate change and to increase awareness. It is also possible to develop it and to transform to a web application that enables the users to test different policy options and observe the results.
A genetic investigation on the evolution and taxonomy of the genus nannospalax in Turkey
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2014., 2014.) Karaman, Kübra.; Bilgin, Raşit.
Currently there is no consensus over the details of evolutionary history and taxonomical classification of the genus Nannospalax in Turkey. This includes the geographical distribution of the different cytotypes, their relationships to one another, and the number of recognized species. In this thesis, in order to try to answer some of these questions, a 896 bp segment of the mitochondrial D-loop region of 120 samples belonging to N. xanthodon, N. leucodon and N. Ehrenbergi were amplified by the PCR method and sequenced. The relationships between species and between chromosomal forms of these species were investigated through various phylogenetic analyses. The results showed that N. leucodon and N. ehrenbergi were distinct species living in Thrace and Southeast Anatolia, repectively. Moreover, the idea that only N. xanthodon was distributed in the rest of Anatolia was not supported. Nine cytotpes were seen to cluster into three main groups, suggesting the presence of three different species in Turkey. N. labaumei includes 2n= 52S, 56W, 58 and 60 cytotpes, N. xanthodon contains 2n=36, 38, 40, and 52N cytotypes (western populations) and N. nehringi has 2n=50E, 54C and 56S cytotypes.
A life cycle perspective for hydrometallurgical and biohydrometallurgical metal recovery from weee
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2019., 2019.) Karal, Engin.; Copty, Nadim.
Rare earth elements (REEs) are being employed in an increasing number of critical or widely popular consumer/ industrial products leading to increase in their demand particularly in the last few decades. Since almost all of REEs are produced in China, the European Commission and US energy department have identified REEs as critical elements and have directed special efforts to obtain sustainable resources of REE. End of life consumer electrical products contain significant amounts of metals and plastics. Thus the aim of this study is focused on recycling metals from waste electric and electronic equipment (WEEE). WEEE contains high amounts of base metals, precious metals and REEs. The concentration of metals in waste streams is higher than that of natural ores. Current recycling methods consume high amounts of energy and chemicals. Economically feasible industrial facilities (waste incineration) perform poorly for environment. In this study life cycle assessment (LCA) of two metal recovery systems were examined: biohydrometallurgical recovery of copper and hydrometallurgical recovery of neodymium from WEEE. Biohydrometallurgical methods are identified as environmentally friendly and low cost operation methods. An ex-ante scaled-up life cycle assessment (LCA) model was created for copper metal recovery. Results show that recovering only copper metal from WEEE is neither economically feasible nor environmentally friendly. The feasibility and environmental performance of neodymium metal recycling experiment model was investigated with a LCA scenario of neodymium iron boron magnet production model. It was found that neodymium metal recycling economically and environmentally performed better than virgin magnet production.
A multiresidue analytical method for the determination of organic contaminants in agricultural soil
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2018., 2018.) Sefiloğlu, Feride Öykü.; Balcıoğlu, Işıl.
Agricultural pollution is one of the biggest environmental concerns regarding the contamination of both soil and water resources. Owing to the mobility of pollutants in soil-water system, contamination of soil can be considered as a risk factor for the human health as well as aquatic ecosystem. Therefore, monitoring of soil contamination has a prime importance not only for the evaluation of the risk for the environment but also for the development of treatment and remediation methods for contaminated sites. Hence, development of a multiresidue analytical method was targeted for a wide range of chemicals selected from 39 frequently used pesticides in rice cultivation and 28 industrial pollutants detected in water samples collected from Ergene River in 2017-2018. Simultaneous extraction of the target analytes from soil samples and their quantification were performed with acetate buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) method and liquid chromatography coupled with tandem mass spectroscopy (LC-MS/MS), respectively. The developed method gave satisfactory recoveries within 70-120% for 78% of the target compounds. The method was applied to 22 soil samples collected from mainly paddy fields located in southwestern Thrace region adjacent to Ergene River in order to determine the agricultural pollution caused by the pesticide application and irrigational activities. The residues of the selected pesticides were found in all soil samples within the concentration range of 0.04-406 µg/kg, whereas the industrial pollutants were dominantly detected in soil samples taken from paddy fields as 0.05-807 µg/kg.
A numerical model for the Marmara sea
(Thesis (M.S.)- Bogazici University. Institute of Environmental Sciences, 1987., 1987.) Albek, Erdem Ahmet.; İnel, Yüksel.
In this study, a numerical model has been developed to predict currents and water levels prevailing in the Marmara Sea. The model is a depth averaged two-layer transient model to adequately simulate stratified flow conditions in the sea. The nonlinear partial differential equations of the model have been solved by using an explicit finite difference scheme and employing a local integral method to reduce truncation and round-off errors and to improve accuracy. Special emphasis has been laid on the prediction of currents and water levels under strong winds.
A QSAR study on the mutagenic activity of azo dyes and aromatic amine derivatives
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2019., 2019.) Küçükali, Müge.; Saçan, Melek Türker.
In the present study, the mutagenic activity of diverse structure of azo dyes and aromatic amine derivatives on TA98 Salmonella typhimurium bacterial strain with S9 activation was used to generate a quantitative structure – activity relationship (QSAR) model. The descriptors required for the model development were obtained by SPARTAN (v.10), DRAGON (v.7.0) software packages. The selection of descriptors was carried out by the tools implemented in QSARINS (v.2.2.3) software. Many division trials were performed on the dataset as training and test sets which comprise the 80% and 20% of the whole set, respectively. 6 descriptors (CIC2, Chi_D/Dt, L/Bw, TDB09p, Mor28s and piPC08) constitute the final model. The applicability domain (AD) of the generated QSAR model was defined by both the ranges of response and descriptors. The predictive ability of the final model was tested using an external dataset consisting of currently used 33 anionic water soluble textile dyes (eight anthraquinone and 25 azo dyes) with no experimental mutagenicity data. The proposed QSAR model had 70% structural coverage for the external set chemicals. The mutagenic activities of 22 current textile dyes belonging anthraquinone and azo dyes fell within the applicability domain of the proposed QSAR model which means that they were well predicted by the model. The order of 6 anthraquinone dyes which are mainly used for cotton, fiber dyeing and leather shading with the most mutagenic activity is: Acid Blue 62>Acid Blue 40>Acid Blue 45>Acid Blue 80>Acid Blue 230>Acid Blue 344. The least mutagenic azo dye is Direct Orange 34 which is mainly used for cotton, silk, wool and their blended fabric dyeing and printing, also can be used for leather and paper shading.
A simple method for small scale wastewater treatment plants for the thickening of sludges: mesh filter and foam filter
(Thesis (Ph.D.)-Bogazici University. Environmental Sciences, 2008., 2008.) Gökyay, Orhan.; Erdinçler, Ayşen.
The ultimate disposal of wastewater sludge (biosolids) continues to be one of the most difficult and expensive problems in the field of wastewater engineering. Wastewater treatment plants generate different sludges, like primary settled sludge, waste activated sludge, chemical sludge and anaerobic sludge, according to their operating systems. These excess sludges have to be managed by reducing their volume and stabilizing them before their ultimate disposal. Generally used volume reduction methods are thickening and dewatering that are usually coupled with conditioning. Sludge thickening and dewatering require either a big capital investment or a big surface area. Moreover, most of the mechanical dewatering technologies use polymers to condition the sludge before dewatering. These polymers have high cost rendering the mechanical dewatering uneconomical. Small-scale wastewater treatment facilities play an important role in the aquatic environment in many countries. Although sludge treatment is essential for overall wastewater treatment, it is difficult and non-economical for small-scale treatment plants to use mechanical equipments. Considering these points, there is therefore a need for alternative technologies for high performance and easy to operate small-scale wastewater treatment facilities. In this study, mesh filter and foam filter are used as a liquid-solid separator instead of the conventional equipments like gravity sludge thickener, dissolved air flotation or centrifuge. By this way, it is possible to reduce the water content of the sludge as mechanical devices and make thickening process economical.
A social-ecological systems analysis of water supply governance on Samothraki, Greece
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2021., 2021.) Beaucamp, Anna.; Saysel, Ali Kerem.
The island of Samothraki in the North Aegean Sea features astonishing water resources of pris tine quality and high quantity. Contrary to what the condition of the water resources would suggest, the residents of Samothraki suffer from water shortages and incidents of contamination, as well as unsteady water provision to economic activities. Meanwhile, the natural water resource system starts showing signs of degradation. The situation is associated with inappropriate municipal water man agement within the frame of a collective action problem. The local municipality’s inability to provide sufficient network coverage and quality control is facing resource-intense and hard-to-control surface water abstractions by individuals for agricultural purposes. Without a coherent understanding of the structures, dynamics and interdependencies underlying management decisions, the situation is likely to continue and cause social conflict as well as ecological harm . Through the application of the Social-Ecological Systems Framework (McGinnis and Ostrom 2014), I first map out a wide range of variables connected to water management and analyse them according to their their relevance and interdependence. The results show that water mismanagement on the island is a much more complex issue than suggested until now, with strong symbiotic links between current informal and official, collective, individual and municipal institutions. I thus argue that the water supply on Samothraki is best understood as a complex social-ecological system. In a second step I draw on insights from adaptive and decentralized governance approaches to eval uate the potentials of sustainable resource management inherent in current practices on Samothraki. I find that informal networks currently contribute most to the social-ecological system’s sustainability and resilience, and embody the incubators of new approaches of sustainable governance.
A study of shipping industry and assessment of environmental impacts in Turkey
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 1998., 1998.) Tuzcu, M. Fikret.; Kocasoy, Günay.
In recent years, the importance of the environmental concerns at shipping and the related standards/safety measures have become subject to clear understanding and acceptance of each country at international platforms. The aim of this study was to evaluatelinvestigate the reflections of the international standardization developments at Turkey and the ways for reaching the very strict and internationally requested standards at her shipping industry at once. For this purpose; general evaluation of the prospective Turkish Shipping Industry, its development during the recent years, its current performance in the terms of conforming with the international standards and ways for reaching these standards with a better conformance have been investigated. The necessary steps that Turkey should immediately take during this period have been evaluated by specifically studying the problems of the Turkish Ports that can be defined as evident indicators of the economic power of a country. The results were expressed by analyzing the economic, commercial and technological means of overcoming the sub standardization at Turkish ShippingIPorts. Moreover, 'Pipe-Line' alternative has been suggested instead of 'Straits' alternative with social cost/benefit analysis of marine pollution and other environmental effects that have been studied by evaluating the effects of tanker accidents on environment and human nature.
Absorbance spectroscopy based evaluation of humic acid under non-oxidative and oxidative conditions
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2011., 2011.) Paçal, Müge.; Bekbölet, Miray.
The aim of this study was to examine the mathematical relationships between humic acid concentration and UV-vis spectroscopic parameters under oxidative and non-oxidative conditions. Humic acid concentration was represented by dissolved organic carbon contents (DOC). UV-vis spectroscopic parameters were presented by absorbance measurements at wavelength λ = 436 nm as Color436, λ= 365 nm as UV365, λ=280 nm as UV280, and λ= 254 nm as UV254. Humic acids were selected as representing terrestrial humic acids (FHA, AHA and RHA) and aquatic humic acid (NHA). As a lot of different humic molecules in very diverse physical associations are mixed together in natural environments, it is difficult to determine their exact concentrations (units of ppm, mg L-1 or mol L-1) and allocate them to a certain class of organic molecules. Since direct determination of humic acid concentraton is not possible to the unspecified chemical structure,various methods have been developed to express the humic acid contents of the aqueous humic solutions. Due to the fact that humic acid does not have a well identified structure, the researchers applied some methods to represent the humic acid concentration as a function of DOC concentration and/or UV-vis parameters (UV254, UV280, UV365 and Color436).This study includes evaluation of the experimental work performed on the UV-vis parameters in relation to the humic acid “prepared” concentration and DOC contents. The mathematical relationships between i. DOC concentration and HA “prepared” concentration, ii. DOC concentration and UV-vis parameters (UV254, UV280, UV365 and Color436) and iii. HA “prepared” concentration and UV-vis parameters (UV254, UV280, UV365 and Color436) were investigated for NHA, FHA, AHA and RHA under the non-oxidative conditions. DOC concentrations, corresponding to HA concentration (NHA, FHA, AHA, and RHA), were correlated with UV-vis parameters (UV254, UV280, UV365 and Color436) under the non-treatment condition and HA concentrations (NHA, FHA, AHA, and RHA) were correlated with UV-vis parameters (UV254, UV280, UV365 and Color436) with high regression coefficient under the non-treatment condition. Furthermore, the overall humic acids (NHA, FHA, AHA, and RHA) and also DOC concentrations of the overall humic acids were correlated with UV-vis parameters. The same steps were done under the oxidative treatment conditions where photocatalytic treatment was applied. In general, photocatalytic oxidation can be considered as an example of innovative technologies collectively known as ‘‘Advanced Oxidation Processes’’ that rely on the generation of very reactive oxygen radicals. Those reactive species are subsequently used to degrade non selectively organic compounds. The known concentrations of NHA and AHA was treated by photocatalytic treatment. The removal of DOC concentration of NHA and AHA were determined by using TOC analyzer and the removal of UV-vis parameter (UV254, UV280, UV365 and Color436) was determined by using UV-vis spectrophotometer after the photocatalytic treatment.The mathematical relationships between DOC concentration of NHA and AHA, and UV-vis parameters (UV254, UV280, UV365 and Color436) were investigated after the photocatalytic treatment. DOC concentrations of NHA (in the presence of 0.25 mg mL-1 TiO2) and AHA (in the presence of 0.10, 0.25 and 1.00 mg mL-1 TiO2) were correlated with UV-vis parameters under the treatment condition (the photocatalytic treatment). Some researchers represented the removal of HA as a function of UV-vis parameter under the photocatalytic treatment. Moreover, DOC ‘DOCcalc’ was calculated as a function of UV254, UV280, UV365 and Color436 parameter of the removed HA concentration, by using the non-treatment Equations of NHA and AHA. The mathematical relationship between DOCobs and DOCcalc was evaluated..
Activated carbon production from pretreated and fermented agricultural residues
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2016., 2016.) Yıldırım, Hacer.; Cılız, Nilgün.
All forms of lignocellulosic biomass consist of three major chemical components: cellulose, hemicellulose and lignin. The remaining lignin from bioethanol production can be utilized as a feedstock for green chemicals. The purpose of this study was to produce activated carbon from pretreated and fermented agricultural residues and to investigate the influence of different process conditions such as feedstock type, impregnation ratio, and carbonization temperature on the pore structure of the products. This is the first study that investigated the production of activated carbon as a high value-added product from lignin-rich residues generated from bioethanol processes. The first step in the experimental path of the study was the recovery of lignin-rich biomass samples. Four samples were prepared from ethanol production wastes; the first one was from the pretreatment of corn stover, the second one was from pretreatment of wheat straw, the third one was from fermentation of corn stover, and the fourth one was from fermentation of wheat straw. The second step was the chemical characterization of feedstocks. In the third step, feedstocks were impregnated with 30%, 40% and 50% (w/w) H3PO4 and then carbonized with a rate of 20ºC/min to carbonization temperatures of 400ºC, 500ºC, 600ºC and 700ºC. The N2 adsorption/desorption capacities of products were compared according to their specific surface area and pore volume by applying the Brunauer-Emmett-Teller (BET) equation. The results demonstrated that the best way to produce activated carbon from lignin-rich residue was using pretreated wheat-based lignin, which was impregnated with 40% H3PO4 concentration and carbonized at 700ºC. In addition, both pretreated corn and fermented wheat-based products, which were impregnated with 50% H3PO4 and carbonized at 500ºC, had quite well developed specific surface area. Interestingly, mesoporous structures dominate in H3PO4-impregnated lignocellulosic material-based activated carbon. Therefore, these carbons are ideal for the adsorption of large molecules and decolorization.
Aerobic biodegradation of dominant micropollutants in the Ergene river by river microcosms and pure cultures of bacteria
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2019., 2019.) Karakaya, Emre.; Tezel, Ulaş.
The Ergene River is the most polluted surface water in Turkey. A great number of micropollutants, which have potential toxic and endocrine-disruptive effects and play a role in antibiotic resistance, are identified in the Ergene River. Once discharged into the environment, micropollutants are exposed to various natural attenuation processes such as dilution, sorption onto solids and sediments, photolysis, hydrolysis, and biodegradation. However, biodegradation is considered the most important process for the removal of most micropollutants. In this study, aerobic biodegradation of forty-three micropollutants belonging to different chemical groups such as industrial chemicals i.e. plasticizers, UV blockers, surfactants etc., antibiotics, pesticides and personal care products i.e. fragrances, pharmaceuticals etc. were investigated in river water samples taken in August 2017, November 2017, February 2018, and May 2018. Analysis of the micropollutants was performed using ultra-high-performance liquid chromatography and tandem mass spectrometry (UHPLC-MSn). At the end of the study, most compounds such as acetaminophen, celestolide, piperonyl butoxide, oxybenzone, and 3-chloraniline were degraded via river microcosms at different rates whereas diuron, N-Ethyl-p-toluenesulfonamide, benzo[a]pyrene, benzanthrone, terbutryn, prochloraz, and omethoate were not removed in any samples. Aerobic biodegradability of hexa(methoxymethyl)melamine, the most abundant target micropollutant in the river was also investigated using different bacterial strains previously isolated at BIOMIG Lab. A strain named Pseudomonas sp. BIOMIG1 transformed almost all hexa(methoxymethyl)melamine into melamine in 45 days. With this study, aerobic biodegradability of various micropollutants in the Ergene River and the biotransformation of hexa(methoxymethyl)melamine have been first revealed.
Aggregation on natural colloidal particles under solar irradiation
(Thesis (M.S.) - Bogazici University. Institute of Environmental Sciences, 2021., 2021.) Sağlık, Didem.; Bekbölet, Miray.
Aggregation/agglomeration of nanoparticles affects their fate and transport in natural waters. Although nanoparticles behave as colloidal matter expressing aggregation/agglomeration properties under natural water conditions, the role of aggregation/agglomeration during photocatalysis has not been demonstrated clearly so far. The main objective of this study could be described as assessment of the colloidal behavior of the binary system i.e., NOM representative organics and nanoparticles representative of photocatalyst specimens described by following basic experimental procedures prior to, during and under post photo-treatment conditions. To fulfill this aim, dynamic light scattering, sedimentation and turbidity experiments were performed. Aggregation and/or agglomeration of TiO2 nanoparticles were assessed by using the above indicated physico-chemical parameters in relation to water matrix effects as well as photocatalytic removal efficiencies. Aggregation and/or agglomeration behavior of both matrix components provided information on expected reactivity under irradiation during photocatalysis. Overall evaluation of the systems provided information both during photocatalysis as well as light induced reactions under environmental conditions. Therefore, a broader insight was deduced on the fate of nanoparticles through photocatalysis.
Agricultural decision-making in Turkey from climate change perspective :|a new road map for the period of 2021-2050
(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2020., 2020.) An, Nazan.; Yenigün, Orhan.; Kurnaz, M. Levent.
The expectation that it can affect basic life resources and particularly food security on a global, regional, and local scale with its impact on the ecosystem has made climate change one of the most urgent issues on the global agenda. Extreme weather events due to climate change may degrade food quality, affect access to food and raise food prices, markedly affecting agricultural productivity. Many countries have already been faced the global impacts of climate change, therefore studies on the effects that may occur on ecosystems are of great importance. As one of the regions that may be most affected by climate change, the Mediterranean Basin is at risk in terms of agricultural production due to temperature increases and precipitation regime changes, and what’s more the increase in the frequency and severity of extreme weather events due to climate change. As a country located in the Mediterranean Basin, Turkey may also suffer from climate change. This situation poses a risk in terms of crop production value and export income, particularly for products with high commercial value grown in Turkey. Therefore, the study has focused two crops of the country i.e., hazelnut and grape with the high commercial value. In the first stage, the climate data for different phenological periods and different variables for each crop was obtained from the regional climate model, RegCM4.4 with the MPI-ESM-MR global climate model under the RCP8.5 pessimistic scenario for the baseline of 1991-2012 and the future period of 2021-2050. In the second stage, the change in hazelnut yield was analyzed by statistical approach, panel data method, and the change in grape yield was analyzed using the crop growth simulation model, STICS. At the last stage, how the climate conditions of hazelnut (88 locations) and grapes (96 locations) will change in the future has been examined by using membership function. However, considering the crop production values of these two crops and export revenue contribution to the national economy, the possibility of new locations where these crops may grow in the future has been analyzed in 923 locations throughout Turkey. Accordingly, at this stage of the thesis, climate suitability index was calculated for hazelnut and grape, and climatic suitability conditions were determined according to 5 classification ranges. In brief, it has been observed that climate change may have a negative impact on both hazelnut and grape yields in the future and it is predicted that there may be significant reductions in climatic suitability conditions in the locations where these two crops grow.
An assessment of soil erosion using rusle model :|a case study from the Marmara region
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2019., 2019.) Ezer, Alkor.; Güven, Başak.; Kurnaz, M. Levent.
Soil is a vital resource for life. Soil erosion is one of the most serious natural problem caused by degrading land, agricultural and other human induced activities. The aim of this study is to predict the soil loss in the Marmara Region as a result of climate change. To achieve this, the Revised Universal Soil Loss Equation (RUSLE) is used and soil loss maps of the region are produced by the the help of remote sensing and geographic information systems techniques. While soil loss maps are produced between the years 1989 and 2017, future projections of soil erosion are also investigated for the period between years 2020 and 2049. For climate projections two scenarios of the Regional Climate Model are used: RCP 4.5 and RCP 8.5. The results showed that, when compared to the historical data, soil erosion risk in the future will increase in the Marmara Region. The soil loss results for the time interval 2020-2049 of the scenario RCP 8.5 is 61% higher than the results of the scenario RCP 4.5. Also, the results based on the historical data of the Regional Climate Model showed that the soil loss ranged from 0 to 24.298 Mg. ha-1. year-1 during the time interval 1989 -2017 in the Marmara Region, and the average soil loss is estimated as 12.2 Mg. ha-1. year-1.
An environmental strategy for medium scaled synthetic leather manufacturing facility
(Thesis (M.S.)-Bogazici University. Institute of Environmental Sciences, 2013., 2013.) Can, Duygu.; Erdinçler, Ayşen.
Environmental friendly production through industries has become one of the most favorable necessities in recent years due to gradually increasing environmental concerns. It is a fact that the old manufacturing facilities, which are the initial step of environmental pollution, are lack of environmental technologies. By taking this into consideration, in this study, the effects of a medium scale synthetic leather facility on the environment were evaluated before and after the application of the proposed strategy to show the improvements in water consumption, waste generation, energy consumption, and the emissions. The results of the study showed that the implementations of the proposed strategy minimized the effects of the focused synthetic leather facility on the environment. In the facility, the dye preparation unit was separated from the process line to prevent of extra water consumption and indoor pollution. In line with energy audits the water leakage points were determined and the facility’s conventional taps were replaced with the photocell basin taps to reduce the water consumption for the domestic usage. All of these improvements in the water consumption systems led to a 38,5 % reduction of in the water consumption rates. In order to minimize energy consumption, energy audits were started by the facility. The audits determined energy consumption and energy loss points and captured a picture of the operations which caused waste in energy. The major energy consuming equipment and their energy efficiencies were identified. Lightning systems were supported by multiple glazing windows and mercury containing fluorescent lighting replaced with energy saving LED lighting, or high-pressure sodium or ceramic metal bulb lighting. All of these energy audits and the improvements enabled a reduction from 812.574kwh/year to 569.963kwh/year and led to a 30% reduction in the energy consumption rates. The synthetic leather facility had no waste management plan and all types of wastes were collected together. In order to separate collection of the hazardous wastes and non-hazardous wastes, waste management plan and a separate collection were put into practice at the facility. Through the waste management policy; the waste was collected based on its type. The reuse of waste in production cycles as secondary raw material was started. Waste was disposed of by licensed companies, and waste management training for employees were also given in the synthetic leather facility. Both the generation of the waste itself as well as effects of the disposed waste on the environment were minimised. While the synthetic leather facility’s emission measurement results did not exceed the limit values, the odour level was high throughout the facility. The VOC emissions were creating this pervasive odour. Furthermore, indoor air emissions were at the harmful level according to occupational health and safety. The synthetic leather facility did not have a ventilation system or effective emission collection system. The door and window systems were the only source of ventilation. The facility’s emissions were not under control. For controlling the system emissions and reducing the low – value VOCs; waste gas collection and combustion systems, and the new ventilation systems were installed. Since these improvements, the synthetic leather facility does not have any reduction in the waste gas, but indeed, it started to prevent high level of indoor air pollution. Another result is that the facility has had huge odour reduction efficiency approximately 78%. When the by-pass stack flue gas and combustion system analysis results are compared, there is an emission reduction efficiency of around 98%. After the all emission systems’ improvements, waste gas emissions and their effect on environment have been brought under control.
An fmri based method for characterizing superficial layer contamination in fnirs signals
(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2014., 2014.) Erdoğan, Sinem Burcu.; Akın, Ata.
Functional near infrared spectroscopy (fNIRS) is a method for monitoring cerebral hemodynamics with a wide range of clinical applications. fNIRS signals are contaminated with systemic physiological interferences from both the brain and superficial tissues, resulting in a poor estimation of the task related neuronal activation. In this study, we introduce an extended superficial signal regression (ESSR) method for cancelling physiology-based systemic interference in fNIRS signals. We apply and validate our method on the optically weighted BOLD signals, which are obtained by projecting the fMRI image onto optical measurement space by use of the optical forward problem. The performance of ESSR method in removing physiological artifacts is compared to i) a global signal regression (GSR) method and ii) a superficial signal regression (SSR) method. The retrieved signals from each method are compared with the neural signals that represent the "ground truth" brain activation cleaned from cerebral systemic fluctuations. We report significant improvements in the recovery of task induced neural activation with the ESSR method when compared to the other two methods with higher spatial localization, lower inter-trial variability, and higher contrast-to-noise (CNR) improvement. Our findings suggest that, during a cognitive task i) superficial scalp contribution to fNIRS signals varies significantly among different regions on the forehead and ii) using an average scalp measurement together with a local measure of superficial hemodynamics better accounts for the total systemic interference. We conclude that maximizing the overlap between the optical pathlength of superficial and deeper penetration measurements is of crucial importance for accurate recovery of the evoked hemodynamic response in fNIRS recordings.|Keywords : Hemodynamic response, systemic interference, functional near infrared spectroscopy, magnetic resonance imaging, physiological artifact removal.

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