Ph.D. Theses

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Valance molecular connectivity model in the prediction of compartmental distribution of selected aromatic pollutants
(Thesis (Ph.D.)- Bogazici University. Institute of Environmental Sciences, 1987., 1987.) Menemenli, G. Feryal.; İnel, Yüksel.
The main purpose of this work is to develop a mathematical model based on the Valance Molecular Connectivity theory which is initiated as an extension of graph theory having its roots especially in structure-activity studies concerning drug-design and toxicity prediction in pharmaceutical chemistry, to evaluate the compartmental distribution of various aromatic pollutants in the environment. During the last decade concerns have been expressed as to the "best way" to assess the potential hazards posed by exposure to chemical substances. In response to these concerns, the chemical group of OECD initiated a hazard assessment project to examine the available methods for hazard assessment of chemicals. The main purpose being to determine how information on theultimate fate and effects of a chemical can be derived from the set of premarket data, the group accepted four models for the estimation of exposure potentials of chemicals within environmental compartments of major concern. Ail of the four models accepted by OECD chemical group was based on the concept of fugacity and essentially needed the following data e molecular weight e water solubility e vapor pressure e soil sorption constant e octanol-water partition coefficient However, the availability and precission of the set of data proposed, especially for chemicals which have rather large and complicated structures was a drawback of these models. Hence, a reasonable model to evaluate this distribution quantitatively without needing such hard-to-gather data would have been a remarkable advance in prediction of environmental hazards that are going to be caused by unknown chemicals irrespective of size and conformation. In this work a new mathematical model (VMCI) based only on the topological characteristics of molecules is deveioped in order to evaluate the distribution of chemicals within various compartments of the environment such as air, soil, water, biota, suspended solids and sediment. The Valance Molecular Connectivity Index, which is the basis of this new model is known to correlate significantly with a number of structure dependent physicochemical properties, and by this wock lt has now been shown to have a high degree of correlation also with water solubilities, vapor pressures and partition coefficients hence wlth the partitioning properties of molecules. As a result, by comparing the two completely different methods of evaluation (VMCI and Level I Fugacity Models) this work proved that it is possible to predict the compartmental distribution of any aromatic compound quantitatively within a high accuracy just by considering the molecular geometry. The superiority of this model compared to fugacity dependent models accepted by OECD lies in the fact that it does not require the physical data such as solubility, vapor pressure or partition coefficient. Relevantly another superiority comes out to be the ability to stay as accurate when even very complicated molecules are investigated while for fugacity dependent models accuracy diminishes due the difficulties in obtaining the experimental data.
Environmental distribution of polychlorinated biphenyls by topology based characteristic root index
(Thesis (Ph.D.)- Bogazici University. Institute of Environmental Sciences, 1990., 1990.) Saçan, Melek Türker.; İnel, Yüksel.
Relationships between a newly developed index -which is based on topological characteristics ofthe molecules and called the Characteristic Root (CR) index- and the environmentally relevant physicochemical properties of the Polychlorinated Biphenyls, namely, aqueous solubility, vapour pressure, Henry's Law Corastants, and octanol-water partition coefficient are discussed. Correlations performed on the congeners clearly demonstrate that the CR index model accurately predicts the physicochelnicaiproperties of PCBs. Highcorrelationcoefficient (r = 0.998) was calculated for the linear one-parameter correlation between the CR index and molecular total surface area. So, the CR index was used in the prediction of pro2erties dependent on tetal surface area. The quality and reliability of the correlations are show to be high enough for environmental applications. Reported experimental physicochemical data of PCBs are tabulated, Recomended values are given for 58 of the 209 congeners, With the available data, it is possible to estimate what percentage of the chemical will be located in the soil, bottom sediments, water and air. The predicted and experimental physicochemical properties of PCBs were used to predict the environmental compartmentalization of these compounds in an evaluative environment using the fugacity approach.
Waste biomass in Turkey and solar drying as a new alternative for its utilization as feed
(Thesis (Ph.D.) - Bogazici University. Institute Environmental Sciences, 1993., 1993.) Tosun, Ayşe.; Saygın, Ömer.
Sources of waste biomass in Turkey were classified in this study. The amounts belonging to the items of the classification were estimated. The current use of these wastes were discussed and it was suggested that the best way to recycle nutritious wastes was using them as feed. Since some of these wastes are high in moisture, it is essential to protect them against bacterial spoilage by drying. Drying, on the other hand, is an energy intensive process. The economical feasibility as well as the ecological benefit of drying wastes by burning fuels is questionable. An economical solution at least for countries with abundant solar insolation would be the use of solar energy for drying. Various methods of solar drying of food wastes were examined. Open air as well as forced air drying gave bacteriologically inadequate products. Therefore, solar boiler dryers, working at 105°C, were constructed. To prevent the observed temperatures higher than 105°C at the later stages, drying was conducted in two stages. While sterilization and removal of most of the water were achieved by boiling in the solar boiler dryer at the first day, open air drying at the second day allowed to obtain a light brown colored product with trace amounts of bacteria and mold. The energy efficiency for vaporization was 85%. Heat losses of the whole dryer due to reflection, convection, and radiation were calculated to be 13%, 7%, and 20%, respectively. Suitability of the material obtained, as animal feed, was tested on broiler chickens. The results indicated that soybean meal protein in broiler diets, can be replaced by the protein of this product up to 40% without any reduction of the weight gain of the birds.|Keywords: Biomass, Food Wastes, Recycling, Solar Drying of Wastes, Feed from Wastes
Dynamic simulation model for long term comprehensive environmental analysis of GAP
(Thesis (Ph.D.)- Bogazici University. Institute of Environmental Sciences, 1999., 1999.) Saysel, Ali Kerem.; Yenigün, Orhan.; Barlas, Yaman.
Integrated development projects based on water resources development, aiming hydropower production and agricultural modernization have many potential impacts on social and natural environments. Southeastern Anatolian Project (GAP), located in Southeast Turkey, comprising 10% of Turkish lands, targeting irrigation schemes on 1.7 million hectare fertile lowlands and 7400 MW hydropower production on Euphrates and Tigris would have many social and environmental consequences. In this study, potential environmental problems suggested by GAP, questions related with utilization of water resources, land degradation, agricultural pollution and land use are analyzed in systems perspective, focusing on the integrity of environmental, social and economic issues. With this aim, GAP S 1M, a dynamic simulation model is developed to trace long term trajectories of selected parameters, representing the relevant aspects of GAP's social, economic and natural environment. Based on a "systemic" problem definition, GAPSIM simulates the development rate of irrigation schemes, hydropower production with respect to changing irrigation releases, water availability on farmlands, crop selection and production, salinization, erosion, pesticide and fertilizer consumption, rangeland and forest quality, urbanization and population dynamics in GAP during 1990-2030 period, which comprises water facilities construction process. GAPSIM is validated, first "structurally", according to the validation tests suggested by the literature and then, model "behavior" is calibrated with respect to data available for the period 1990-1998. GAPSIM provides a dynamic simulation platform where several scenarios and policy analyses concerning GAP environment can be executed in order to arrive at an improved understanding of GAP as a socio-environmental system. Scenario and policy runs on GAPSIM reveal that, increased intensity of the most evapotranspirant crop cotton on GAP fields may cause significant water scarcity, which hinders the development rate of irrigation into new acres and inhibits crop yields by decreased water delivery to individual farms.
Elucidation of the photocatalytic removal pathways of humic substances: progress towards mechanistic explanations
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2005., 2005.) Uyguner, Ceyda Senem.; Bekbölet, Miray.
The objective of this research was to characterize the spectroscopic properties ofhumic and fulvic acids of different origins as model compounds to represent the naturalorganic matter in aquatic systems. The photocatalytic oxidation of model humic and fulvic acids was carried out using TiO2 Degussa P-25 as the photocatalyst. The degradationkinetics was assessed based on pseudo first order and Langmuir Hinshelwood (L-H)kinetic models. The related data for aquatic and terrestrial humic substances werecomparatively presented in terms of UV-vis parameters such as Color436, Color400, UV365, UV300, UV280, UV254 and total organic carbon (TOC) removal. Furthermore, the molecularand structural characteristics of the humic acid molecule relative to changes duringphotocatalytic oxidation were monitored by spectroscopic techniques.On the basis of their diverse chemical and physical properties such as molecular weight, molecular size, elemental composition and source of origin, substantial differenceswere observed in photocatalytic removal efficiencies of humic and fulvic acids. For all ofthe humic substances, higher removal rates were achieved in terms of UV254 valuescompared to that of Color436. Moreover, humic acids exhibited higher pseudo first order removal rates with respect to that for fulvic acid. The declining trend of the specified UVvisparameters, the related changes in the fluorescence spectra (initial increase of thefluorescence intensities, formation of new fluorophores, shift of the spectra to lowerwavelength region and decline of intensity after long photocatalytic irradiation times), decrease of TOC content during degradation, the spectral changes in FTIR and NMRindicated the oxidative degradation of humic substances.Considering the complexity and polydispersity of the humic macromolecules, theywere fractionated into well defined subcomponents of known molecular sizes usingultrafiltration through membranes in the range of 100-1 kDa. The effect of photocatalyticoxidation on the molecular size fractions of humic substances were also evaluated on acomparative basis by UV-vis and fluorescence spectroscopy. As confirmed by the spectroscopic evaluation of the molecular size distributiondata, photocatalytic degradation of humic acid leads to the formation of lower molecularsize (small fractions) and higher UV-absorbing compounds. For fractions less than 10 kDa,UV254 absorbing moieties in treated humic acid samples become higher than that of rawhumic substances designating the generation of new species during photocatalysis.Based on the comparison between the synchronous scan fluorescence spectra ofthe molecular size fractions of raw and oxidized humic substances, it could be concludedthat oxidative cleavage of the molecule leads to a blue shift of the spectra which isindicative to the formation of new fluorophores in each size fraction. It is assumed thatoxidative degradation of the macromolecule occurs through an unselective pathway, by thereaction of .OH radicals with the various moieties within each fraction.
Evaluation of natural organic matter-metal oxide adsorption isotherms under influential structural concepts
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2006., 2006.) Süphandağ, Şerif Altan.; Bekbölet, Miray.
The adsorption of molecules onto a surface is a necessary prerequisite to any surface mediated chemical process. Therefore, the mechanism of binding of humic acids to TiO2 surface has to be addressed in order to improve the understanding of photocatalytic degradation. From the fundamental point of view, natural organic matter (NOM) for water scientists can be perceived as very complex entities both in terms of chemistry and comprehension. Especially the fulvic (FA) and humic acids (HA), the soluble portions of NOM, are often considered as oligomeric and polymeric materials. In literature, there are ongoing discussions regarding the high molecular mass is due to aggregation of small units, as in micelles, or due to covalently bound units, as in polymers. The essence of this thesis is to evaluate the adsorption under the light of these two debatable approaches and bring reasonable interpretations of the observed isotherm patterns through the use of proposed structures. In this dissertation the isotherms of humic acid (HA) on titanium dioxide are analyzed at acidic, neutral, and basic pH. Combined effects of pH and increasing ionic strength were evaluated in order to asses the effect of changing solution matrix on the molecular structure of humic acid.|Keywords: humic acid, titanium dioxide, adsorption, natural organic matter, metal oxides
Biogeneration of activated carbon in the treatment of phenolic compounds
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2006., 2006.) Aktaş, Özgür.; Çeçen, Ferhan.
This study aimed to clarify the effect of adsorbability, desorbability, biodegradability and activated carbon type on the extent of bioregeneration in the treatment of phenolic compounds in activated sludge systems combined with activated carbon. Bioregenerabilities of activated carbons preloaded with phenol, 2-chlorophenol and 2-nitrophenol were studied. For this purpose, four different activated carbon types; thermally activated and chemically activated powdered carbons (PAC), and their granular countertypes (GAC) with similar physical characteristics were used. Thermally activated carbons were better adsorbers for phenolic compounds than chemically activated ones. However, apparently higher adsorption irreversibility was calculated in the case of thermally activated carbons. The results suggested that, rather than the physical form, carbon activation type and chemical surface characteristics played a more important role on adsorbability of phenolic compounds and its reversibility. Also, adsorption and its reversibility were highly dependent on the type of the target compound. Bioregeneration of chemically activated carbons was also higher than thermally activated ones. This showed that bioregeneration was controlled by the reversibility of adsorption. The results suggested that carbon activation type was of crucial importance for bioregeneration. PAC and GAC countertypes showed comparable bioregeneration efficiencies indicating that carbon size was not an effective factor. Oxidative polymerization of phenol and 2-chlorophenol was a plausible explanation for lesser bioregeneration of thermally activated carbons. However, bioregeneration efficiencies of thermally activated carbons were much higher than their total desorbabilities. This indicated the presence of exoenzymatic bioregeneration. Bi-solute experiments showed that competition for adsorption sites greatly determined the extent of adsorption reversibility and bioregeneration. Cometabolic biodegradation of 2-chlorophenol and 2-nitrophenol in the presence of phenol resulted in efficient bioregenerability of activated carbons, when they were loaded with non-growth substances together with a growth substrate.
Evaluation advanced oxidation technologies and nanoscale particles for water and groundwater remediation
(Thesis (Ph.D)-Bogazici University. Institute of Environmental Sciences, 2008., 2008.) Aksoy, Dila.; İnce, Nilsun.; Copty, Nadim.
Advanced Oxidation Processes (AOP) that are based on the in-situ generation of hydroxyl radicals in solution are extremely powerful tools for the destruction of recalcitrant compounds in water and groundwater. Recent research has shown that subsurface injection of nanoparticles may also be a viable technology for the in-situ remediation of contaminated groundwater resources. The purpose of this study was to assess the degradability of typical groundwater contaminants, namely phenol and 2-chlorophenol by advanced oxidation processes, nanoparticles and combinations thereof. Advanced oxidation processes investigated were ozonation, UV irradiation, sonolysis, and sono-Fenton process. In the second part of the research, flow-through reactors were used to test the mobility of the selected nanoparticle solutions in porous media under different flow configurations. Continuous flow experiments mainly focused on the assessment of the mobility of nanoparticle solutions in porous media under different flow configurations. Comparison of the nanoparticle breakthrough curves to that of the conservative tracers showed that the transport of nanoparticles is influenced by their concentration, which strongly controls the particle size and hence, their mobility. Overall, this study has demonstrated that phenolic compounds in contaminated water and groundwaters may be effectively destroyed by use of optimized hybrid processes involving Advanced Oxidation Processes and nanoparticles.|Keywords: advanced oxidation, ultrasound, nanoparticle, groundwater remediation, phenolic compounds
Mesoscale modeling of aerosol levels in Istanbul using a high resolution MM5/CMAQ air quality modeling system
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2009., 2009.) İm, Ulaş.; Yenigün, Orhan.
İstanbul is the largest and most populated city of Turkey and one of the biggest megacities in the world that frequently experiences high air pollution levels. Statistical approaches have been widely used to study these episodes. However, air quality modeling has not been much used to understand the nature and the meteorological and chemical backgrounds of these episodes. This study aims to evaluate the aerosol levels in İstanbul by establishing a mesoscale air quality modeling system using the PSU/NCAR MM5 meteorological model and CMAQ chemistry and transport model on a high temporal and spatial resolution. A high resolution emission inventory is developed for the modeling purposes for the first time for the city of İstanbul. The inventory covers most of the important anthropogenic source sectors including energy, residential and industrial combustion, traffic and shipping on 2 km horizontal resolution and hourly temporal resolution. The results shows that on-road traffic emissions are the main source for most of the pollutants such as CO, PM and NOx, industrial combustion is responsible for a high portion of SO2 emissions and solvent use and traffic are the main contributors for NMVOC emissions. However large uncertainties may be introduced due to the activity data, emission factors and temporal profiles used in the study. The modeling study is conducted for a 5-day period from January 13 to January 17, 2008. The period included a 5-day winter episode of PM10, with 24-hour averaged concentrations reaching at least twice as high as the EU legislation of 50 μgm-3. The results from the MM5 simulation are compared with observations from Kandilli and Finokalia (Crete) meteorological stations. Statistical measures show that the model captured the surface temperature and wind profiles successfully. On the other hand, better agreement can be achieved by optimization studies that focus on the physics option used for the parameterizations.|Keywords: İstanbul, Aerosol, Mesoscale meteorological modeling, Emission modeling, Chemistry and transport modeling.
An integrated land use-hydrological model for the Bartın spring watershed
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2009., 2009.) Öztürk, Melih.; Copty, Nadim.; Saysel, Ali Kerem.
The Bartın spring watershed located in northwestern Turkey supplies the water needs of the Bartın, Amasra and nkumu city centers. Although the water is presently adequate for the spring, autumn and winter seasons, the city centers suffer water scarcity in summer seasons. It is widely recognized that land use changes have a significant impact on the water budget of a watershed. The purpose of this study is to model the land use and hydrological processes within the Bartın spring watershed and simulate the water yield under different future land use scenarios. For this purpose, a coupled land use-hydrodynamics model was developed. The land use dynamic simulation model was built using STELLA dynamic simulation platform while the MIKE SHE computer program was used to simulate the hydrodynamics of the watershed. The link between the two models is through the Leaf Area Index (LAI) and Root Depth (RD) parameters which are generated in the land use model and supplied to the hydrodynamics model. The dynamic land use model represents several forest stand groups and land use categories with their respective acreages and their conversions. The model was structurally validated and analyzed through a series of sensitivity tests. It was calibrated with respect to the historical geographical data and the calibration results are quite satisfactory. The calibration target for the hydrodynamics model was the river discharge at the downstream end of the watershed, while the calibration parameters were the saturated hydraulic conductivity of the deeper soil, the threshold melting temperature values and the RD value. The optimal simulation produced correlation coefficients, R=0.72 and R2=0.52 with a mean error of 0.01 m3/s. Sensitivity analyses of the hydrodynamics model indicate that it is quite sensitive to the land use type; complete agricultural cover would yield 25- 33% higher discharge compared to a completely forested watershed. The hydrodynamics model is also sensitive to the LAI up to a value of 3 and becomes insensitive for higher values. The model however, is not strongly sensitive to hydraulic conductivity of the saturated zone.
Removal of antibiotics from animal waste by chemical oxidation processes
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2009., 2009.) Uslu, Havva Merih Ötker.; Balcıoğlu, Işıl.
Concern about antibiotic contamination in the environment is growing worldwide because it promotes development of antibiotic resistance in bacterial communities. The study mainly focused on the complete elimination of antibiotics in animal wastes within short time periods to protect their spread on agricultural fields through fertilization. Ozone, Fenton’s reagent, and persulfate oxidants were applied to cow manure contaminated with oxytetracycline and sulfamethazine directly or after the pretreatment with magnesium salt which was applied to desorp oxytetracycline from the manure prior to oxidation. Almost the complete removal of antibacterials in manure was attained by all oxidation processes with the preceding magnesium salt pretreatment. Among the investigated oxidation processes, heat activated persulfate oxidation was the only process which was able to remove antibiotics completely from the manure under the applied experimental conditions. Pretreatment with magnesium salt was not essential for the efficient removal of oxytetracycline by subsequent Fenton and persulfate oxidation processes as it was for ozonation process. The use of bedding materials did not significantly affect the efficiencies of magnesium salt desorption and oxidation processes. Ozone and persulfate oxidation were effective in the removal of antibiotics from animal feeding wastewater with the production of almost non-toxic and biodegradable by-products.|Keywords: Advanced oxidation, antibiotics, animal waste, manure.
Importance of integration of public participation into environmental management
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2009., 2009.) Celep, Ayşe Beyza.; İnce, Nilsun.; Üstün, Beyza
Technical approaches such as wastewater treatment technologies and other pollution prevention methods have generally been considered as the means of improving the environmental conditions in a basin. However, generation and prevention of environmental pollution in a water basin is principally based on socio-economic structures and environmental awareness of the basin population. This study was conducted to integrate a social approach based on basin population and environmental awareness with the classical environmental management approach. The region of study Küçükçekmece, is a precious natural system with the Küçükçekmece Lagoon, its basin and a variety of endemic species. In addition, it is a cosmopolitan social system which is a representative of Turkey’s population suffering heavy pollution due to mismanagement. The method of study was such that preliminary face-to-face interviews and open ended questionnaire were followed by development and evaluation of closed ended questionnaire. Analysis of results showed that the basin generally consisted of people who have low level of education and income. According to these people, environment is mostly defined as ‘people’ such as friends and neighbors. The perception of environmental pollution and problems by five senses was found to be an important factor for the identification of these problems. Within environmental qualifications, ‘environmental attitude’ was the main indicator in the level of environmental awareness of local community in Küçükçekmece. It is followed by ‘system knowledge’ and ‘indigenous knowledge’. Primary school graduation and middle age are the socio-economic characteristics of the people who have the highest score in system knowledge, indigenous knowledge and environmental attitude queations.
Investigation of troposphric aeosols by multiwavelength Mie-Raman lidar
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2010., 2010.) Hüseyinoğlu, Mehmet Fatih.; Bekbölet, Miray.; Allahverdi, Kerim.
Atmospheric aerosols affect the Earth’s radiation balance by absorbing or scattering the fluxes of solar or terrestrial radiation. This change leads to radiative forcing of the atmosphere. Scattering of the solar radiation by aerosols tends to cool the atmosphere and this is called the "aerosol direct effect". Aerosols modify the cloud properties effecting rainfall patterns and this is called the "aerosol indirect effect". Thus, aerosols cause global cooling. Aerosols also have negative effect on public health; inhaling aerosols results with chemicals entering the human body and deposited into lungs causing lung cancer, asthma, premature death and cardiovascular problems. Lidar is the acronym of "light detection and ranging", with a laser transmitter and a telescope receiver supplied with electronic and optical instruments. Aerosol optical and physical parameters and important atmospheric data about the clouds and water vapor can be calculated by analyzing aerosol extinction and backscattering coefficients which can be obtained by the remote sensing technology of lidars. For the purpose of investigating the aerosols, a Multiwavelength Mie-Raman lidar has been designed, developed and operated between 2009 and 2010. By this lidar, extinction and backscattering at multiple wavelengths were measured and converted to microphysical properties of aerosols by mathematical methods. The retrieved data contains size distribution, effective radius, volume, surface area and number density, complex refractive index, volume and particle polarization, water vapor mixing ratio. The ash plums from the Iceland volcanic eruption were detected and characterized.
Impacts of land use change on soil respiration and elemental carbon in the forests of Karasu district
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2010., 2010.) Oral, Hasan Volkan.; Onay, Turgut T.; Yenigün, Orhan.
In recent years, expansion of agricultural activities in the Karasu region which is located in northwest Turkey has led to significant deforestation. As a result, deforestation in this region is one of the most critical in Turkey. The purpose of this study is to evaluate the impact of land use change on soil respiration, soil elemental carbon in the Karasu District. The study also assess the potential seasonal changes on these three key parameters. To achieve this purpose, field trips were carried out over four seasons in 2008-2009. In total 900 soil samples from forested and deforested lands were collected. Geographical Information Systems (GIS) Remote Sensing Technologies (RST) were employed in conjunction with in situ measurements, laboratory experiments and statistical analyses. Soil respiration was measured in situ while soil samples were collected for the laboratory determination of soil elemental carbon (C) and nitrogen (N), C:N ratio, microbial respiration, soil organic matter (SOM), electrical conductivity, gravimetric moisture content, pH and soil textural structure. Analysis of the collected data indicated that the differences in mean soil respiration and elemental carbon due to land use and seasonal variations were statistically significant. The average annual soil respiration and elemental carbon in forested lands was about 27% and 34% higher than that from deforested lands. The statistical analyses also showed that the clay content exhibited high correlations with soil respiration and, particularly, with elemental carbon. Geostatistical analysis was conducted to calculate the spatial average values of soil respiration, surface elemental carbon. The data analyses and interpretation methods developed in this study can serve as an example for future studies in other geographical regions involving the evaluation of soil carbon content and emissions.
Destruction of antimicrobial contaminants in water and waste sludge with chemical oxidation processes
(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2013., 2013.) Öncü, Nalan Bilgin.; Balcıoğlu, Işıl.
Destruction of antimicrobial contamination in both water and sewage sludge was investigated in the thesis. In the first part of the study, the effectiveness of three oxidation processes –chlorination, ozonation, and heterogeneous photocatalysis– on the destruction of a resistance carrier bacterial plasmid DNA isolated from E. Coli were compared and the relative superiority of ozonation or heterogeneous photocatalysis over conventional chlorination was demonstrated. Although the nano-fiber-TiO2 that was prepared in the study did not provide better plasmid DNA destruction compared to commercial TiO2-P25, the material is promising for facilitated catalyst separation from the treated water. In the second part of the study, simultaneous degradation of two model antibiotics, ciprofloxacin (CIP) and oxytetracycline (OTC) in secondary sewage sludge, was investigated by the application of (i) ozonation, (ii) hydrogen peroxide oxidation assisted with microwave irradiation (MW/H2O2), iii) persulfate oxidation assisted with microwave irradiation (MW/S2O8 2-), and (iv) persulfate oxidation activated with ferrous iron and conventional heating (Fe2+/heat/S2O8 2-). While under appropriate conditions all of the processes provided >95% antibiotic degradation along with sludge solubilization, they offer different benefits for waste sludge treatment. Ozonation was found to be more effective to treat the sludge with low content of total solid (TS=2.5 g/L), while the desorption of the antibiotics was required to achieve high rate of degradation at high solid content (10 g/L) of the sludge. On the other hand, owing to the desorption ability of MW in the MW/H2O2 and MW/S2O8 2- processes, and owing to the complexation of the antibiotics with iron in the Fe2+/heat/S2O8 2- process, concurrent antibiotic desorption and degradation was achieved in sludge with high TS (10 g/L). MW/S2O8 2- provided exceptional metal solubilization, considerably enhanced sludge filterability within the shortest treatment time. Along with considerable metal solubilization, the Fe2+/heat/S2O8 2- process resulted in phosphorus precipitation, which can potentially increase the fertilizer value of the sludge.
Designing a system based environmental instruction program and evaluating its effects on seventh grade students
(Thesis (Ph.D.)-Bogazici University. Institute of Environmental Sciences, 2013., 2013.) Doğança, Zerrin.; Saysel, Ali Kerem.
The present research aimed to test the effects of an environmental instructional design with systems approach on seventh grade students. The main focus was to examine whether systems approach is a more effective way to teach environmental issues that are dynamic and complex. The research was a quasi-experimental study that enabled to compare performances on general systems thinking skills, competence in dynamic environmental problem solving, and success in standard science achievement tests of subjects from different groups. The sample of the study included 42 seventh grade students (12-14 year old). The same pre, post, and delayed tests were applied to both groups. The control group was taught according to the standard unit plan suggested by the Ministry of Education, while the experimental group was taught the same content with activities including, feedback loops, stock and flow diagrams, behavior over time graphs, and computer modeling. It was found that after one month of systems based environmental instruction, the experimental group performed better on systems thinking skills and dynamic environmental scenarios (DES) tests at .05 significance level. Besides, the effects of the system based intervention were more enduring on performance on DES test for the experimental group, when delayed tests were taken into account. No significance difference was found on science achievement level between the two groups. In addition to quantitative results, interviews resulted in higher levels of feedback thinking skills of the selected respondents from the experimental group.
Investigating the role of the Turkish straits system as a phylogeographical break in the mediterranean - black sea transition
(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2013., 2013.) Kalkan, Evrim.; Bilgin, İbrahim Raşit.; Bekbölet, Miray.
Understanding the allopatric isolation and evolutionary processes in the marine realm can be difficult due to high dispersal potential of pelagic larvae. In addition, the role of barriers in shaping gene flow patterns between the populations of marine species can be less pronounced than their terrestrial counterparts. Straits are such potential barriers to gene flow in the marine environment, resulting in the isolation of populations on either side. The Turkish Straits System, comprising two straits (the Dardanelles and the Bosphorus Strait) and the Sea of Marmara forms the only connection between the Black Sea and the Mediterranean, and is a unique ecosystem with a well-defined two-layered stratification and current regime. The role of Turkish Straits System on gene flow, as a barrier and/or corridor has been proposed, but not extensively tested using genetics. Here, using three regions of mitochondrial DNA (CO1, COIII and 16S) and five microsatellite markers I tried to understand the effect of the system on gene flow in populations of the Mediterranean Mussel, Mytilus galloprovincialis (Lamarck, 1819), the common European prawn, Palaemon elegans Rathke, 1837 and the marbled crab, Pachygrapsus marmoratus (Fabricius, 1787). With this study, individuals belonging to three species were collected from 42 sampling sites, encompassing the Black Sea, the Turkish Straits System and the Mediterranean Sea. The results of the mtDNA analyses of Mytilus galloprovincialis showed that the Black Sea populations were isolated and differentiated from those in the Aegean during the last ice age and subsequently were able to colonize the Sea of Marmara and Aegean twice, with larval transport via the surface currents of the Turkish Straits System. However, individuals from the Aegean population were not able to migrate into the Turkish Straits System and the Black Sea in the reverse direction due to the lower-layer currents of the system. Microsatellite analyses did not support the mtDNA differentiation observed among the Black Sea and the Aegean mussel populations, suggesting that they did not correspond to different species. Two different haplogroups were detected in Palaemon elegans as a result of the mtDNA analyses, though with a lower degree of differentiation than previously recorded in the literature. The results of CO1 analysis for Pachygrapsus marmoratus also indicated a weak restriction of gene flow from the Mediterranean to the Black Sea. For all three species, the Turkish Straits System played semi-permeable barrier role to gene flow and dispersal. This semi-permeable characteristic of the Turkish Straits System, simultaneously acting as a barrier and corridor to gene flow is relatively uncommon, and has been documented in the Turkish Straits System for the first time, using genetics methods.
Assessment and modelling of the toxicity of phenols: a comparative study with marine and freshwater algae
(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2013., 2013.) Ertürk, Murat Doğa.; Saçan, Melek Türker.
Algae sustain biodiversity in aquatic ecosystems by producing oxygen and recycling nutrients. In contrast to their key role in the environment, toxicity data of many organic pollutants, such as phenols, on algae, especially for marine algae, are severely limited. On the other hand, the data requirement in algal toxicity is almost impossible to be supplied through exhaustive laboratory testing considering the huge number of chemicals to be assessed. Therefore, the use of alternative methods to laboratory testing, such as the quantitative structure-activity/toxicity relationships (QSARs/QSTRs), can help reduce the data gap in algal ecotoxicity. In this study, novel toxicity data of phenols on marine alga Dunaliella tertiolecta and freshwater alga Chlorella vulgaris were generated and subjected to QSAR analysis. The phenols selected for toxicological assessment are known to elicit toxicity through different modes of toxic action including polar narcosis, respiratory uncoupling and reactive mechanisms; as such, the data set was regarded as a miniature model of industrial chemical space and provided a realistic basis upon which to explore the development of algal QSTRs. Multiple linear regression and counter propagation artificial neural network techniques were used to build internally and externally validated QSTR models. Most of the QSTRs highlighted the importance of hydrophobicity and electrophilicity related parameters among numerous descriptors. Hydrophobicity was found to underpin the toxicity of phenols to algae. On the other hand, pyrogallol, hydroquinones and catechols, which are potentially capable of being oxidized to reactive species, displayed algal toxicity in excess of that predicted by hydrophobicity. The toxicity of these reactive phenols was better described by electrophilicity parameters. The external validation of the models was also verified using a data set obtained from literature comprising the toxicity of phenols and anilines to another freshwater alga, Pseudokirchneriella subcapitata. Consequently, the developed QSTRs were shown to be applicable to data from another algal test system and at least for another class of organic compounds. Apart from the QSTRs, investigation of inter-algal and inter-species toxicity correlations between algae and other aquatic organisms such as bacteria, protozoa, daphnia and fish revealed that the response of aquatic organisms to phenols differentiated above the level of polar narcosis. As a result, for a heterogeneous set of compounds acting through different modes of toxic action, the models developed in this study can be used to predict the toxicity of untested compounds provided that the new chemicals are within the applicability domain of the respective model.
Determination of effects of selected veterinary antibiotics on biogas production in anaerobic digestion systems and analysis of resistance gene promotion
(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2013., 2013.) Türker, Gökhan.; İnce, Bahar Kasapgil.
Animal husbandry developed into a gigantic business sector to meet demands of modern society. Manure produced in animal husbandry is a suitable substrate for anaerobic digestion since it brings solution to the problem of manure accumulation. Although anaerobic digestion is an old and well known process; it is still far from understood completely. Microbial communities and its importance have been revealed recently. A better understanding of operational and microbiological parameters should be reached to modify and reshape anaerobic digestion systems according to demands. In recent years, antibiotic build up has been detected in receiving environments due to common use in treating both men and animals. Due to their persistence, they begin to accumulate in environment. Antibiotics may create a selective pressure on microbial communities. Microorganisms can become resistant to antibiotics when antibiotics are in non-therapeutic concentrations. This study presents results of investigation of many laboratory scale anaerobic digesters operated with cattle manure of OTC vaccinated animal. Excretion pattern of oxytetracycline after treatment was observed and excreted amount of antibiotic was calculated. Anaerobic digestion of cattle manure was monitored and performances were recorded in presence of antibiotic and changing operational parameters. Manure amendment to soil was performed to monitor fate and effect of oxytetracycline and digester microbial communities on soil microbial communities Within the scope of the dissertation, it was found that OTC inhibits digester performance significantly. Effect of OTC was higher on bacterial population rather than archaea. OTC excreted from animal body as at least 18% of initial amount within solid manure. This amount will further increase because of repetitive injections and liquid manure addition. These manures were used as feedstock in anaerobic digesters operated under common operational parameters for farm type anaerobic digesters. 50% inhibition in biogas production was observed. Temperature was most influential parameter of digester performance followed by solid content and mixing rate. Temperature has been also most effective parameter on degradation of OTC. Mixing rate also helped degradation of OTC slightly. Also solid content was in negative relation with OTC inhibition. It has been found that half-life of OTC was ranging from 22-28 days in mesophilic and 16-18 days in thermophilic digesters, respectively. Molecular analyses showed that bacterial community of digesters was dominated by fermentative and hydrolytic bacteria belonging groups of Firmicutes and acidogenic Proteobacteria. Methanobacteriales, Methanomicrobiales and Methanosarcina spp. were found as methanogenic community. FISH analyses indicated an increase in microbial activity after 20 days; after that activity dropped significantly. Manure and digestate were amended to soil to monitor the elimination of antibiotic and its effects on microbial structures. It has been found that the half-life of OTC is far longer (135 days) in soil than in digesters (18-24 days) and microbial structures were changed after amendment. Tetracycline resistance gene analyses showed presence of 104-106 resistance gene copies in digester studies and 103-105 resistance gene copies in soil studies Analyses also showed that ratio of antibiotic resistance genes to bacterial 16S rRNA genes were increased 50 fold in mesophilic digesters and 100 fold in thermophilic digesters. In soil studies ratio don’t showed a significant change.
Contribution of Anatolian bats to genetic diversity of western palaearctic with a particular focus on Kuhl's pipistrelle
(Thesis (Ph.D.) - Bogazici University. Institute of Environmental Sciences, 2014., 2014.) Çoraman, Emrah.; Furman, Andrzej.
Identification of intraspecific conservation units and incorporating the distribution of genetic diversity into management plans are crucial requirements for assessing effective protection strategies. The first part of this study investigates the phylogeographic structures of 33 bat species present in the Near East in order to evaluate the conservation implications of their intraspecific genetic diversity. The management requirements of the identified clades and their taxonomical relations were evaluated by analysing their distributions and the levels of their genetic differentiations in mtDNA markers. In 12 species and the large Myotis complex, a total of 15 genetically distinct populations were identified. Comparing the phylogeographic patterns of different taxa indicates that three regions, the Balkans, the Caucasus, and the southern Anatolia, harbour genetically divergent populations and should have higher priority in conservation practices. In the second part, the response of the Pipistrellus kuhlii lineages to climate change was evaluated by analysing their phylogeographical patterns in association to ecological niche models (ENM). The results show that the P. kuhlii clades evolved in separate Pleistocene refugia located in Iberia, the North Africa, and the Middle East, and subsequently colonized Europe. These clades differ on mtDNA and microsatellites, though, are not reproductively isolated. Comparing both the current and the past predictions of ENMs with the observed genetic diversity indicate that the clades had distinct niche identities and should be analysed separately. Apparently, these differences are conserved for long periods of time and will likely to affect their response to current climate change. Nevertheless, we show that the future predictions of the ‘clade only’ models are consistent with the currently observed population expansions. Considering that Turkey has one of the richest bat fauna in the Mediterranean region and the Anatolian populations of various species are genetically distinct, protecting populations in Turkey is critically important for preserving the genetic diversity of the bats in the Western Palaearctic. Both regional and large-scale conservation strategies should incorporate potential differences in climate tolerance among lineages.

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