This study aimed at providing a thorough understanding of temporal and spatial variations of VOCs and underlying factors in different microenvironments in two different urban atmospheres, with different degrees of regulatory enforcement. The VOC data were collected in field campaigns conducted in Ankara, Turkey, and Ottawa, Canada over the years 2000-2004. Insight into the sources of VOCs in different urban atmospheres was sought by using three commonly used receptor models namely / Positive Matrix Factorization (PMF), Chemical Mass Balance (CMB) Model and Conventional Factor Analysis (CFA). Motor vehicle related source profiles were developed to use in receptor modeling. Motor vehicles are the most abundant VOC sources with about 60% and 95% contributions to ambient levels in Ankara and Ottawa, respectively. Residential heating (31%) during winter season, biogenic (9%) and architectural coating (12%) emissions during summer season and solvent use (about 12%) emissions are the next abundant VOC sources in Ankara. In addition, a new method to estimate the contribution of sources from wind sectors in urban atmosphere was developed and implemented in this study. The comparison of the results of these two cities demonstrated the influence of control measures on ambient levels and sources of VOCs observed in different urban atmospheres. VOC levels in Ankara exceed EU levels and they are about factor of two higher than that are measured in Ottawa owing to lack of implementation of emission control regulations for VOCs in Ankara compared to well adopted regulations in Ottawa.

In this study, regularly measured long-term leachate data from Bursa Municipal Solid Waste Landfill (MSWL) were analyzed using conventional statistical, time series and factor analyses to investigate in detail the temporal variability of leachate quality and quantity, trend, randomness, seasonality and the auto- and cross- correlations of leachate pollutants. Evaluating the results of data analyses, leachate management recommendations, including sampling strategies in monitoring programs and treatment alternatives for old and fresh leachates, were developed. Statistically analyzed leachate parameters included BOD, COD, pH, SS, electrical conductivity, total CrO4, Cr6+, Fe, Cu, Zn, Pb, Cd, CN-, Cl, F, total P, NH4-N, total N, SO4, S2-, total alkalinity and leachate flow rate. Results indicated that the majority of pollutant concentrations varied in large ranges. Leachate parameters usually showed non-normal distributions and high variability in the closed T Valley compared to the open Main Valley. The majority of leachate parameters was autocorrelated and had statistically significant correlations amongst themselves. Factor analysis showed that different inter-relationships were present between leachate parameters for closed and open valleys. The sampling frequency and the number of leachate parameters need to be measured were determined to be higher for open landfills than for closed landfills. It was recommended that leachates, having high organic strength, in open landfill be treated using biological and physical/chemical processes. However, after the closure of the landfill, physical/chemical processes were recommended for leachate treatment, as it gradually completes transition from fresh to old leachate.

Natural zeolites, especially clinoptilolite, have the ability of removing certain cations from wastewater by utilizing ion exchange and adsorption. In this study, clinoptilolite originated from Bigadi&ccedil / , Balikesir deposit was investigated in its natural and conditioned form for its effectiveness in removing Zn2+ and Pb2+ ions from aqueous solutions. In addition, relevant mechanisms involved in heavy metal removal by clinoptilolite were examined in this study. Throughout this work, equilibrium and kinetic studies were performed with as-received and conditioned clinoptilolite, having particle size of 0.15 &ndash / 0.80 mm. Conditioning aimed to replace exchangeable cations (Na+, K+, Ca2+, Mg2+) on clinoptilolite with a cation that is more willing to undergo ion exchange. The results of equilibrium studies revealed that clinoptilolite had different capacities for Zn2+ and Pb2+ ions. Clinoptilolite had high capacity for Pb2+ ions, whereas lower capacities were attained for Zn2+. Conditioning with concentrated NaCl solution increased the removal capacity for both metals. Maximum capacities attained were 0.14 meq/g (as-received) and 0.39 meq/g (conditioned) for Zn2+, and 0.51 meq/g (as-received) and 1.10 meq/g (conditioned) for Pb2+. Furthermore, kinetic studies performed under pH-uncontrolled and pH-controlled conditions revealed that heavy metal removal can not only be explained by ion exchange. These studies also indicated that Zn2+ ions were weakly bound to clinoptilolite structure, whereas there was a strong bonding between Pb2+ ions and clinoptilolite structure. To examine possible removal mechanisms, relationship between exchangeable ions released from clinoptilolite structure and Zn2+ and Pb2+ ions removed from aqueous solutions were investigated during equilibrium and kinetic studies. For equilibrium studies, it was observed that the higher the heavy metal equilibrium concentration, the higher is the amount of exchangeable ions released. However, the results indicated that the release of exchangeable ions were not only due to ion exchange. Examination of Si4+, the main central metal ion of clinoptilolite, during kinetic studies showed that destruction of clinoptilolite framework was partly responsible for the release of exchangeable ions. Release of Si4+ was more pronounced in Pb2+ removal studies, indicating dependency of framework destruction on the type of heavy metal species.

Heavy metals are well known toxic priority pollutants. Hence, wastewaters containing these species must be treated prior to discharge into receiving bodies. In this study, the potential of Bigadi&ccedil / clinoptilolite for Cu2+ and Ni2+ removal from wastewaters was investigated in batch and continuous reactors. Results of the preliminary experiments revealed the optimum operating conditions, namely, initial solution pH of 5 and 4 for Cu2+ and Ni2+, respectively and contact time of 48 hours. Additionally, conditioning of clinoptilolite with 2M NaCl solution for 24 hours was found to considerably improve the capacity utilized at breakthrough. Maximum removal capacities and prevailing mechanisms in the system were investigated via equilibrium studies under preliminary determined optimum operating conditions. Langmuir and Freundlich models were fitted to the experimental data and Langmuir model was found to be better in describing the system behavior. Maximum removal capacities obtained from non-linear regression of Langmuir model are almost the same for Cu2+ and Ni2+ removal using as received clinoptilolite samples (0.31 and 0.32 meq/g respectively). However, conditioned clinoptilolite samples exhibit higher capacity for Cu2+ over Ni2+ (0.5 and 0.43 meq/g, respectively). Analyses of exchangeable cations in the aqueous phase were carried out to examine the prevailing mechanisms in the system. As a result, adsorption, dissolution of clinoptilolite and surface precipitation (particularly in the case of Cu2+ removal) are considered to accompany ion exchange. Finally, fixed-bed column studies were conducted with conditioned clinoptilolite samples for Cu2+ removal. An improvement in Cu2+ uptake was observed with decreasing volumetric flow rate (from 8 BV/h to 2-4 BV/h) and decreasing particle size (from 1.180-1.400 mm to 0.833-1.180 mm). Analyses of exchangeable cations as well as Si4+, Fe(total) and Al3+ were also carried out to examine the prevailing mechanisms. Ion exchange was discussed as the predominant mechanism in the system with minor contributions from adsorption and dissolution of clinoptilolite to the total amount of Cu2+ uptake and to the total amount of exchangeable cations release, respectively.

Natural Attenuation can be an effective cleanup option for remediation of Groundwater contamination by BTEX. One of the important aspects of the methodology that has been recognized recently is that mass removal rates, the most important parameters used to determine effectiveness of the methodology, is controlled by groundwater flow regime, which to a large extent controlled by aquifer heterogeneity. Considering this recognition, the primary objective of this research is to quantitatively describe the relationship between natural attenuation rates of BTEX and aquifer heterogeneity using numerical solution techniques. To represent different levels of aquifer heterogeneity, hydraulic conductivity distributions are simulated using Turning Bands Algorithm, changing statistical parameters Coefficient of Variation (CV) and correlation length (h). Visual MODFLOW is used to model the transport of BTEX contamination, at different hydraulic conductivity fields. Degradation rates are calculated by Buscheck&amp / Alcantar and Conservative Tracer Methods. The results show that, for a given h, as CV increases, the plume slows down and stays longer at the domain, so areal extent of plume decreases. For anisotropic field, plumes are more dispersed along x and y-direction, and areal extents of the plumes are greater. During MNA feasibility studies, for the aquifer heterogeneity level of CV and h smaller than 100 % and 10 m, respectively, a minimum recommended biodegradation rate constant of 0.02 d-1 can be used, whereas for the aquifer heterogeneity level of CV and h greater than 100 % and 10 m, respectively, using a minimum biodegradation rate constant of 0.06 d-1 can be recommended.

Monitored natural attenuation has been particularly used at sites where petroleum hydrocarbons and chlorinated solvents have contaminated soil and groundwater. One of the important aspects of the methodology that has been recognized recently is that the mass removal rates, the most important parameter to determine effectiveness of the methodology, is controlled by the groundwater flow regime and the aquifer heterogeneity. Considering this recognition, the primary objective of this study is to quantitatively describe the relationship between the natural attenuation rates and aquifer heterogeneity using numerical simulation techniques. To represent different levels of aquifer heterogeneity, the hydraulic conductivity distribution (ln K) is statistically simulated with the numerical algorithm, Turning Bands Random Field Generator, by changing the statistical parameters, Coefficient of Variation (CV) and correlation length (h) and Visual MODFLOW and RT3D software programs are used for the simulation of groundwater flow and chlorinated solvent transport. Simulation results showed that degradation rates and the shape of the contaminant plumes show variations for different heterogeneity levels. Increasing CV resulted in the decrease in the transport of the plume and shrinkage in the areal extend. On the other hand, &ldquo / h&rdquo / determined the shape and the size of the plume through its affect on mechanical dispersion. For a given &ldquo / h&rdquo / , degradation rates increased with increasing CV, but change in &ldquo / h&rdquo / did not show a regular trend. Such findings are expected to be beneficial when assessing the effectiveness of natural attenuation process for a selected site during the feasibility studies without need for detailed site characterization.

This study was carried out to investigate performance of a Vacuum Rotating Membrane (VRM) type membrane bioreactor (MBR). During the study, the VRM plant was erected from scratch and operated in METU campus. The plant was composed of two tanks. First one was about 100 m3 and it was used for biological treatment / the second tank, about 30 m3, was used as filter chamber. The permeate flow rate was adjusted between 6 and 8.5 m3/h giving a hydraulic retention time (HRT) of 18 hours during the study. In the aeration tank, dissolved oxygen (DO) was adjusted to between 4 and 0.1 mg/L to see the effect of the dissolved oxygen concentration on the process. In the filter chamber, total of 540 m2 flat sheet membrane surface were used for the separation of the treated wastewater from the activated sludge. During the 140 days of operation, MLSS concentration increased from 2.5 g/L to 20 g/L. A 99.99% BOD removal and above 95% COD removal were achieved most of the time during the study. At the time when organic loading rate was between 0.35 and 0.1 kg COD/ kgVSS-day, sludge production was very low. Therefore, sludge retention time (SRT) was taken as infinite. The turbidity in the effluent was less than 1 NTU at all the time, and was below that of the tap water. In the aeration tank, 100% Total-N removal was observed when DO was 2 mg/L and MLSS was 8.36 mg/L on 80th day of operation. This indicates that simultaneous nitrification and denitrification was taking place at these conditions. Later, N-removal decreased when DO was deliberately decreased to 0.1 mg/L in the aeration tank to prevent nitrification / for treated wastewaters were intended to be used for irrigation. Since the pores of the membrane were 0.038 &amp / #956 / m, treated wastewaters were sterile with respect to bacteria

In this thesis we develop and use a continuum random walk framework to solve problems that are usually studied using a discrete random walk on a discrete lattice. Problems studied include; the time it takes for a random walker to be absorbed at a trap on a fractal lattice, the calculation of the spectral dimension for several different classes of networks, the calculation of the density of states for a multi-layered Bethe lattice and the relationship between diffusion exponents and a resistivity exponent that occur in relevant power laws. The majority of the results are obtained by deriving an expression for a Laplace transformed Green’s function or first passage time, and then using Tauberian theorems to find the relevant asymptotic behaviour. The continuum framework is established by studying the diffusion equation on a 1-d bar with non-homogeneous boundary conditions. The result is extended to model diffusion on networks through linear algebra. We derive the transformation linking the Green’s functions and first passage time results in the continuum and discrete settings. The continuum method is used in conjunction with renormalization techniques to calculate the time taken for a random walker to be absorbed at a trap on a fractal lattice and also to find the spectral dimension of new classes of networks. Although these networks can be embedded in the d- dimensional Euclidean plane, they do not have a spectral dimension equal to twice the ratio of the fractal dimension and the random walk dimension when the random walk on the network is transient. The networks therefore violate the Alexander-Orbach law. The fractal Einstein relationship (a relationship relating a diffusion exponent to a resistivity exponent) also does not hold on these networks. Through a suitable scaling argument, we derive a generalised fractal Einstein relationship which holds for our lattices and explains anomalous results concerning transport on diffusion limited aggregates and Eden trees.

Exhaled breath is a rich and complex matrix containing many hundreds of compounds. Every breath offers the potential of a non-invasive measurement of the biochemical processes occurring in the human body and it is this notion that has led to the application of breath analysis for the detection of disease. With the majority of research in the field being focused on the detection of biomarkers, little has been presented on how the seemingly homeostatic matrix of breath varies during the course of normal life events. The research in this thesis describes how a subject's emotional state, physical state, and daily activities can alter the composition of exhaled breath.

Radioisotopes of caesium (Cs) and strontium (Sr) have been distributed in the environment due to weapons testing, nuclear power production and accidents at nuclear facilities. Radiocaesium and radiostrontium are of major concern in the medium to long term following accidental releases as they have high energies, long half lives (137Cs≈30 years; 90Sr≈29 years) and their easy assimilation into biological systems due to their similarity to the biologically important elements potassium (K) and calcium (Ca), respectively. Radio-caesium and -strontium are transferred to humans primarily via plant root uptake, and therefore minimising this uptake has been the focus of a number of remediation strategies, such as ploughing and fertiliser application. Species or cultivar substitution, where a species/cultivar that has higher uptake is replaced by a species/cultivar that has lower uptake, has been proposed as an effective and socially acceptable remediation strategy for contaminated agricultural land, but not enough is known about its efficacy for it to be recommended internationally. The aim of this thesis is to evaluate the potential of species or cultivar substitution as a remediation strategy for contaminated agricultural areas. Chapter 2 consists of meta-analysis of the available data (115 experiments) on the inter-cultivar variation in Cs and Sr accumulation by 27 plant species. Chapter 3 includes experiments conducted in the laboratory (UK) and two experiments in the field (Ukraine) investigating inter-cultivar variation in radiocaesium and radiostrontium accumulation in Brassica oleracea, and whether consistently lower-accumulating cultivars could be identified. Chapter 4 details analysis of samples from grass breeding experiments in Aberystwyth and Edinburgh (UK) from four forage grass species; hybrid ryegrass (Lolium perenne L. x Lolium multiflorum Lam.), L. perenne, L.multiflorum and Festuca arundinacea Shreb., and investigates inter-species and inter-cultivar variation in uptake of stable Cs and Sr. Hybrid ryegrass cultivars that were lower-accumulating in Cs and/or Sr were also identified. Chapter 5 compares the stable Cs and Sr uptake in six L. perenne and two F. arundinacea cultivars grown in Aberystwyth and Narodychi (Ukraine). Chapter 6 compares the performance in terms of yield and forage quality (elemental concentrations, digestibility and water soluble carbohydrate content) of six hybrid ryegrass cultivars and ten F. arundinacea cultivars identified as consistently lower-accumulating in Cs and/or Sr against the performance of two commercial hybrid ryegrass cultivars. The mean inter-cultivar variation in Cs and Sr was 1.8-fold and 2.0-fold,respectively when 27 plant species were studied. Thirty-five-fold variation in radiocaesium and 23-fold variation in radiostrontium was found between c.70 Brassica oleracea cultivars. In two field experiments in Ukraine, five cultivars had consistently lower radiocaesium concentration ratios and two cultivars consistently lower radiostrontium concentration ratios. One cultivar had lower radiocaesium and radiostrontium concentration ratios. Festuca arundinacea cultivars had lower Cs and Sr concentration ratios than cultivars of hybrid ryegrass, L. perenne and L. multiflorum. Three out of 17 hybrid ryegrass cultivars had consistently lower Cs concentration ratios, two cultivars consistently lower Sr and one consistently lower Cs and Sr. Despite differences in soil properties and environmental conditions, F. arundinacea cultivars grown in Aberystwyth and Narodychi accumulated less stable and radioactive Cs and Sr than L. perenne cultivars. One L. perenne cultivar also accumulated less Cs and Sr at both sites. F. arundinacea cultivars accumulated less Cs and Sr than commercial hybrid ryegrass cultivars, but alsohad up to 59% lower yield and a reduction of up to 19% in K accumulation, up to 46% in Ca accumulation, up to 7% in dry matter digestibility and up to 17% in water soluble carbohydrate content. Selecting lower accumulating cultivars was found to reduce Cs and Sr accumulation less, but with a smaller yield penalty and a smaller reduction in digestibility and water soluble carbohydrate content. It is concluded that species and cultivar substitution could be an effective remediation strategy in contaminated agricultural land provided implications for yield and quality are considered.