Publications2008

CHEMOSPHERE 74 (2008) 797-803

Title: Performance of leaching bed reactor converting the organic fraction of municipal solid waste to organic acids and alcohols
Authors: Dogan E, Dunaev T, Erguder TH, Demirer GN
Abstract:A lab-scale leaching bed reactor (LBR) was operated to (1) investigate the potential of in-vessel solid-state anaerobic digestion of the organic fraction of municipal solid waste (MSW) and (2) examine the feasibility of using LBRs for hydrolysis/liquefaction and acidification of organic fraction of MSW for maximum total volatile fatty acid (tVFA) and alcohol production. A hydrolysis efficiency of 60% was achieved in the LBR, which was mainly affected by the solids content of organic fraction of MSW, the amount of water addition into the LBR and the channeling through the waste bed. The net mass of tVFA produced was 7000 mg at the end of 80 d. The main individual VFAs produced were acetic and butyric acids and the main alcohol was ethanol. The variations in the by-products of acidification were mainly due to the nature of feed and pH variations in the LBR. LBRs achieved rapid hydrolysis and acidification of organic fraction of MSW, consequently, high hydrolysis yield, chemical oxygen demand removal and tVFA production.

JOURNAL OF ENVIRONMENTAL ENGINEERING 134 (2008) 295-303

Title: Low-Strength Wastewater Treatment with Combined Granular Anaerobic and Suspended Aerobic Cultures in Upflow Sludge Blanket Reactors
Authors: Tuba Hande Ergüder and Göksel Niyazi Demirer
Abstract:Combined cultures were developed from anaerobic granular and suspended aerobic cultures in three upflow sludge blanket reactors aerated at 10 mL air/min 4 h/day (R2), every other day (R3), and 24 h/day (R4). The use of combined cultures was found to be advantageous compared to the anaerobic granules for the treatment of low-strength wastewaters. During municipal wastewater treatment at influent 5-day biochemical oxygen demand (BOD5) concentration of 53 — 118 mg/L (hydraulic retention time: 0.75 day), combined cultures in R2, R3, and R4 exhibited average BOD5 removal efficiencies of 52, 75, and 76%, respectively. The use of these cultures might be proposed as an alternative for municipal wastewater treatment due to their advantages such as achievement of required discharge standards, prevention of biomass loss/settleability problems unlike activated sludge systems and possible methanogenic activity, as well as high settling characteristics comparable to those of anaerobic granules.

BIOTECHNOLOGY and BIOENGINEERING Volume 100, (2008) 231-239

Title: Monovalent Cations and Their Influence on Activated Sludge Floc Chemistry, Structure, and Physical Characteristics
Authors: F. Kara, G.C. Gurakan, F.D. Sanin
Abstract:Multivalent cations have been known to be important components of activated sludge floc structure due to their bridging ability of the negatively charged sites on the biopolymer network. Recently in batch systems it was found that excess concentration of monovalent cations led to the deterioration in settleability, dewaterability of sludges and effluent quality of the system. In this study, effect of influent monovalent cations (potassium and sodium) on activated sludge floc structure was investigated in semi-continuous reactors. Results revealed that the increase in concentration of both ions correlated to the general increase in total EPS concentration. The zeta potential values were affected by the cation type and dose in such a way that sludge from sodium reactors had always higher zeta potential values (higher negative charge) than the sludges from potassium reactors. Flocs from sodium reactors were more fragile and weak and the capillary suction time values of these sludges were higher compared to those from potassium reactors. The findings of this research conclude that the floc structure is significantly weakened with the increase of monovalent cations. Even though EPS is produced, it is unable to bind the floc components together. With this, the physical properties of sludge deteriorate for both cations.© 2007 Wiley Periodicals, Inc.

Fuel Processing Technology 89(2008) 183–197

Title: Co-combustion of peach and apricot stone with coal in a bubbling fluidized bed
Authors: Aysel T. Atimtay, Burçak Kaynak
Abstract:In this study a bubbling fluidized bed combustor (BFBC) having an inside diameter of 102 mm and a height of 900 mm was used to investigate the co-combustion characteristics of peach and apricot stones produced as a waste from the fruit juice industry with coal. A lignite coalwas used for co-combustion. On-line concentrations of O2, CO, CO2, SO2, NOX and total hydrocarbons (CmHn) were measured in the flue gas during combustion experiments. Variations of emissions of various pollutants were studied by changing the operating parameters (excess air ratio, fluidization velocity, and fuel feed rate). Temperature distribution along the bed was measured with thermocouples. For co-combustion of apricot and peach fruit stones with a lignite coal, various ratios of biomass to coal ranging from 0 to 100 wt.% were tested. For the peach stone co-combustion tests, efficiencies are about 98% and for the apricot stone co-combustion tests, efficiencies ranged between 94.7% and 96.9% for 25%, 50% and 75% of apricot stone in the fuel mixture. The results of this study have shown that as the biomass ratio in the fuel mixture increases, the combustion takes place at the upper regions of the main column. This causes higher temperatures in the freeboard than the bed. Also the CO and hydrocarbon (CmHn) emissions increase as the biomass percentage increases in the fuel mixture. This causes decrease in the combustion efficiency. These results suggest that peach and apricot stones are potential fuels that can be utilized for clean energy production in small-scale fruit juice industries by using BFBC. The percentage of peach stones or apricot stones in the fuel mixture is suggested to be below 50 wt.% in order to obtain the emission limits of EU. During the design of the BFBC, one has to be careful about the volatile matter (VM) content of the biomass. For the complete combustion of the VM, longer freeboard or secondary air addition should be considered. © 2007 Elsevier B.V. All rights reserved.

Desalination 226 (2008) 289–297

Title: Impact of fertilizer usage on phosphorus loads to Lake Uluabat
Authors: Elif Bulut, Aysegul Aksoy
Abstract:This work investigated the role of fertilizer application rate on phosphorus (P) transport and loading to Lake Uluabat in Turkey. For this purpose ArcView Interface of Soil and Water Assessment Tool 2000 (AVSWAT) was used. Results showed that when the fertilizer amount applied to agricultural lands was doubled, the P load to Lake Uluabat increased by 32%. P transported to Lake Uluabat declined by about 6, 10 and 16%, when the fertilizer usage at the agricultural fields were decreased by 20, 30 and 50%, respectively. In general, a linear relationship was observed between the P load and the fertilizer application rates. The highest and lowest P losses were from the corn and wheat productions, respectively. 70% more P was carried to Lake Uluabat from corn, wheat, and tomato fields when the fertilizer amounts applied were doubled. When the fertilizer usage declined by 20, 30, and 50%, a total of 14, 21 and 35% less P were transported to the lake from the fields, respectively. For the threshold P loading, 56 of 78 subbasins were critical when the fertilizer usage was doubled. For 50% reduction in the fertilizer application rate, the number of critical subbasins decreased to 46. Nevertheless, this decrease was not sufficient to meet the goal P loading to Lake Uluabat.

Computers and Chemical Engineering 32 (2008) 2471–2478

Title: Modeling of the activated sludge process by using artificial neural networks with automated architecture screening
Authors: Hakan Moral, Aysegul Aksoy, Celal F. Gokcay
Abstract:In this study, a MATLAB script was developed to aid in the development of artificial neural network (ANN) models by screening out the better ANN architectures for the cases studied. Then, the script was applied for modeling of activated sludge process (ASP) for two different cases. In the first one, a hypothetical wastewater treatment plant (WWTP) was considered. The input and output data for the training of the ANN models were generated using a simulation model, which was an implementation of the Activated Sludge Model No. 1 (ASM1). The results indicated high correlation coefficient (R) between the observed and predicted output variables, reaching up to 0.980. In the second case, ANN modeling of ASP in the IskenderunWastewater Treatment Plant (IskWWTP) was studied. Resulting maximum R value was 0.795 for the predicted effluent chemical oxygen demand (CODeff) values. Moreover, CODeff was forecasted using another effluent parameter.

Waste Management 28 (2008) 112–119

Title: Anaerobic biogasification of undiluted dairy manure in leaching bed reactors
Authors: G.N. Demirer, S. Chen
Abstract:Dry anaerobic digestion of high solids animal manure is of increasing importance since conventional slurry digestion is not an effective system for these manures. The investment costs for large-size reactors, costs for heating these reactors, handling, dewatering, and the disposal of the digested residue decrease the benefits of conventional slurry anaerobic digestion for high solids animal manure. Even though leaching bed reactors (LBR) constitute a promising option for dry anaerobic biogasification of animal manure, no study is cited in the literature for animal manure, excluding a single study on cattle waste which utilized a similar concept in a different experimental set-up, namely a packed bed digester. Therefore, this work was undertaken to investigate the anaerobic biogasification of undiluted dairy manure in LBRs. To this purpose anaerobic leaching bed reactors (ALBR) packed with a mixture of dairy manure, anaerobic seed and wood powder/chips were operated. The ALBRs were fed with water, and the leachate that was collected from their effluents was subjected to biochemical methane potential (BMP) experiments to determine the biogas production. The results revealed that LBRs can successfully be applied to anaerobic digestion of undiluted dairy manure with around 25% improvement in biogas production relative to conventional (slurry) anaerobic digesters. © 2006 Elsevier Ltd. All rights reserved.

ENVIRONMENTAL ENGINEERING SCIENCE Volume 25, Number 3, 2008

Title: Improved Anaerobic Acidification of Unscreened Dairy Manure
Authors: Vedat Yılmaz and Göksel N. Demirer
Abstract:Even though several aspects of two-phase configuration might be very significant for efficient anaerobic digestion (AD) of dairy manure, its application has very been limited. Two sets of experiments daily-fed continuously mixed acidogenic anaerobic reactors with no recycle were conducted to investigate the optimum conditions on anaerobic acidification of unscreened dairy manure in terms of maximum acidification and VS reduction. Effect of solids and hydraulic retention time (SRT/HRT), organic loading rate (OLR), and pH control on anaerobic acidification in terms of volatile fatty acid (VFA) formation and volatile solids (VS) reduction were investigated. Results indicated that SRT/HRT and OLR of 2 days and 15 g VS/L ? day, respectively, yielded maximum acidification. The pH control was not effective on the acidification of dairy manure. The degree of acidification increases as HRT decreases, and also higher efficiency was determined in an uncontrolled reactor.

Clean 2008, 36 (9), 760 – 766

Title: Enhancing the Performance of Anaerobic Digestion of Dairy Manure through Phase-Separation
Authors: Vedat Yılmaz and Göksel N. Demirer
Abstract:Anaerobic digestion (AD) is an effective way to convert animal manures into profit-able by-products while simultaneously reducing the pollution of water, air, and soil caused by these wastes. Conventional high-rate anaerobic reactors cannot effectively process animal manures with high solids-containing wastes. The two-phase configuration for AD has several advantages over conventional one-phase processes, e. g., increased stability of the process, smaller size and cost efficient process configurations. In the present study, the experiments were carried out in a two-phase system composed of an acidogenic reactor and a methanogenic reactor, and in a one-phase system composed of only a methanogenic reactor. The reactors were operated as unmixed (without an external mixing aid), unsophisticated, and daily-fed mode. It was found that the two-phase configuration was more efficient than the one-phase system. The biogas production in the two-phase system at a hydraulic retention time (HRT) of 8.6 days (only methanogenic phase) was calculated to be 42% higher at an organic loading rate (OLR) of 3.5 g VS/L N day than that of the one-phase with a HRT of 20 days. This translates into significant performance improvement and reduced volume requirement. This finding represents a further step in the achievement of wider use of simple anaerobic reactor configurations for waste treatment in rural areas.

Journal of Environmental Engineering, Vol. 134, No. 4, April 1, 2008, 295–303

Title: Low-Strength Wastewater Treatment with Combined Granular Anaerobic and Suspended Aerobic Cultures in Upflow Sludge Blanket Reactors
Authors: Tuba Hande Ergüder and Göksel Niyazi Demirer
Abstract:Combined cultures were developed from anaerobic granular and suspended aerobic cultures in three upflow sludge blanket reactors aerated at 10 mL air/min 4 h/day (R2), every other day (R3), and 24 h/day (R4). The use of combined cultures was found to be advantageous compared to the anaerobic granules for the treatment of low-strength wastewaters. During municipal wastewater treatment at influent 5-day biochemical oxygen demand (BOD5) concentration of 53–118 mg/L (hydraulic retention time: 0.75 day), combined cultures in R2, R3, and R4 exhibited average BOD5 removal efficiencies of 52, 75, and 76%, respectively. The use of these cultures might be proposed as an alternative for municipal wastewater treatment due to their advantages such as achievement of required discharge standards, prevention of biomass loss/settleability problems unlike activated sludge systems and possible methanogenic activity, as well as high settling characteristics comparable to those of anaerobic granules.

Journal of Environmental Management 86 (2008) 193–200

Title: Anaerobic digestion of dairy manure with enhanced ammonia removal
Authors: S. Uludag-Demirer, G.N. Demirer, C. Frearc, S. Chen
Abstract:Poor ammonia-nitrogen removal in methanogenic anaerobic reactors digesting animal manure has been reported as an important disadvantage of anaerobic digestion (AD) in several studies. Development of anaerobic processes that are capable of producing reduced ammonia-nitrogen levels in their effluent is one of the areas where further research must be pursued if AD technology is to be made more effective and economically advantageous. One approach to removing ammonia from anaerobically digested effluents is the forced precipitation of magnesium ammonium phosphate hexahydrate (MgNH4PO4.6H2O), commonly called struvite. Struvite is a valuable plant nutrient source for nitrogen and phosphorus since it releases them slowly and has non-burning features because of its low solubility in water. This study investigated coupling AD and controlled struvite precipitation in the same reactor to minimize the nitrogen removal costs and possibly increase the performance of the AD by reducing the ammonia concentration which has an adverse effect on anaerobic bacteria. The results indicated that up to 19% extra COD and almost 11% extra NH3 removals were achieved relative to a control by adding 1750 mg/L of MgCl2.6H2O to the anaerobic reactor. © 2007 Elsevier Ltd. All rights reserved.

Journal of Cleaner Production 16 (2008) 422 - 431

Title: Cleaner production opportunity assessment study in SEKA Balikesir pulp and paper mill
Authors: E. Avşar, G.N. Demirer
Abstract:This study was designed to apply cleaner production concepts in a Turkish pulp and paper mill, for the first time in Turkey, to introduce the concept as well as to provide a framework for future initiatives. To achieve this objective a comprehensive waste reduction audit was conducted at SEKA Balikesir pulp and paper mill. First, audit schemes from different sources were examined and compiled that resulted in the methodology employed in this work. The audit covered water emissions and water usage. Then, the collected data were compared with international environmental performance indicators from other companies in the USA, Canada, Australia, and Europe. This comparison provided specific opportunities for improvement at different processes in the mill. For each viable opportunity, different waste reduction measures were analyzed and determined. Furthermore, the benefits of the identified waste reduction options were analyzed for increasing production efficiency and achieving target raw effluent pollution loads from the mill. © 2006 Elsevier Ltd. All rights reserved.

Journal of Hazardous Materials 152 (2008) 316–323

Title: A membrane-based co-treatment strategy for the recovery of print- and beck-dyeing textile effluents
Authors: G. Capar, L. Yilmaz, U. Yetis
Abstract:This paper describes the final part of a study on the recovery of print- and beck-dyeing wastewaters of the carpet manufacturing industry by membrane processes. These wastewaters had been previously treated separately where the print dyeing wastewaters were recovered by chemical precipitation followed by nanofiltration (NF) and beck-dyeing wastewaters were subjected to microfiltration (MF) and pH neutralization prior to NF. In this study, a co-treatment scheme after separate pre-treatment stages was adopted to simplify the overall process. The effect of mixing ratio on membrane fouling was also investigated. The co-treatment strategy was found advantageous since the number of NF units was minimized and the pH neutralization step in separate treatment of beck-dyeing wastewaters was eliminated, providing a reduction of chemical usage. © 2007 Elsevier B.V. All rights reserved.

Journal of Hazardous Materials 153 (2008) 1142–1148

Title: Biological treatment and nanofiltration of denim textile wastewater for reuse
Authors: Erkan Sahinkaya, Nigmet Uzal, Ulku Yetis, Filiz B. Dilek
Abstract:This study aims at coupling of activated sludge treatment with nanofiltration to improve denim textile wastewater quality to reuse criteria. In the activated sludge reactor, the COD removal efficiency was quite high as it was 91±2% and 84±4% on the basis of total and soluble feed COD, respectively. The color removal efficiency was 75±10%, and around 50–70% of removed color was adsorbed on biomass or precipitated within the reactor. The high conductivity of the wastewater, as high as 8 mS/cm, did not adversely affect system performance. Although biological treatment is quite efficient, the wastewater does not meet the reuse criteria. Hence, further treatment to improve treated water quality was investigated using nanofiltration. Dead-end microfiltration (MF) with 5 mm pore size was applied to remove coarse particles before nanofiltration. The color rejection of nanofiltration was almost complete and permeate color was always lower than 10 Pt–Co. Similarly, quite high rejections were observed for COD (80–100%). Permeate conductivity was between 1.98 and 2.67 mS/cm (65% conductivity rejection).Wastewater fluxes were between 31 and 37 L/m2/h at 5.07 bars corresponding to around 45% flux declines compared to clean water fluxes. In conclusion, for denim textile wastewaters nanofiltration after biological treatment can be applied to meet reuse criteria. © 2007 Elsevier B.V. All rights reserved.

Journal of Hazardous Materials 155 (2008) 385–392

Title: Removal of cadmium from aqueous solutions using clinoptilolite: Influence of pretreatment and regeneration
Authors: Kadir Gedik, Ipek Imamoglu
Abstract:In this study, Cd removal from aqueous solutions via clinoptilolite was investigated in terms of the effect of pretreatment and regeneration. Four different chemicals (NaCl, KCl, CaCl2 and HCl) were tested for this purpose. Samples treated by a total of 20 bed volume (BV) of 1MNaCl solution prepared in tap water with no pH adjustment were found to perform satisfactorily. Five exhaustion and regeneration cycles were then carried out, revealing an increasing Cd removal capacity, coupled with constant Cd elution efficiency in progressing cycles. Furthermore, the change of pH and the presence of exchangeable (Na, K, Ca and Mg) and framework cations (Si and Al) in the aqueous phase were investigated. Subsequently, these were discussed in terms of progressive conversion of clinoptilolite to its homoionic Na-form, and the presence of different Cd removal mechanisms in the system. This study emphasizes the potential of clinoptilolite to be a part of sustainable wastewater treatment technologies, enabling the recovery of both the sorbent and the metal, via demonstration of effective Cd removal and clinoptilolite recovery, besides successful concentration of metal in the regenerant solution. © 2008 Elsevier B.V. All rights reserved.

Separation Science and Technology, 43: 1191–1207, 2008

Title: Affinity of Clinoptilolite-based Zeolites towards Removal of Cd from Aqueous Solutions
Authors: K. Gedik and I. Imamoglu
Abstract:Cd removal from aqueous solutions using as-received and pretreated forms of two different clinoptilolite samples (denoted GC and BC) was investigated and dissimilar sorption affinities were revealed. Equilibrium behavior of systems were modeled using six different adsorption isotherms. The maximum sorption capacities, as obtained from the solubility-normalized Dubinin-Astakhov model for as-received samples, were determined as 0.18 meq/g and 0.12 meq/g for GC and BC, whereas 0.72 meq/g and 0.41 meq Cd/g was determined for their pretreated forms, respectively. Examination of the release of exchangeable cations into the solution at equilibrium and the change of pH were discussed in terms of varying prevalence of ion exchange, dissolution of the sorbent and adsorption.

Journal of the Air & Waste Management Association 58:543-552

Title: Effect of Meteorological Parameters on Fine and Coarse Particulate Matter Mass Concentration in a Coal-Mining Area in Zonguldak, Turkey
Authors: Tecer, L.H., Süren, P., Alagha, O., Karaca, F., Tuncel, G
Abstract:In this work, the effect of meteorological parameters and local topography on mass concentrations of fine (PM2.5) and coarse (PM2.5–10) particles and their seasonal behavior was investigated. A total of 236 pairs of samples were collected using an Anderson Dichotomous sampler between December 2004 and October 2005. The average mass concentrations of PM2.5, PM2.5–10, and particulate matter less than 10 m in aerodynamic diameter (PM10) were found to be 29.38, 23.85, and 53.23 g/m3, respectively. The concentrations of PM2.5 and PM10 were found to be higher in heating seasons (December to May) than in summer The increase of relative humidity, cloudiness, and lower temperature was found to be highly related to the increase of particulate matter (PM) episodic events. During non-rainy days, the episodic events for PM2.5 and PM10 were increased by 30 and 10.7%, respectively. This is a result of the extensive use of fuel during winter for heating purposes and also because of stagnant air masses formed because of low temperature and low wind speed over the study area.

Journal of Toxicology and Environmental Health, Part A, 71: 512-520, 2008

Title: Particulate Matter (PM2.5, PM10-2.5, and PM10) and Children's Hospital Admissions for Asthma and Respiratory Diseases: A Bidirectional Case-Crossover Study
Authors: Lokman Hakan Tecer, Omar Alagha, Ferhat Karaca, Gürdal Tuncel, and Nilufer Eldes
Abstract:Epidemiological studies reported adverse effects of air pollution on the prevalence of respiratory diseases in children. The purpose of this study was to examine the association between air pollution and admissions for asthma and other respiratory diseases among children who were younger than 15 yr of age. The study used data on respiratory hospital admissions and air pollutant concentrations, including thoracic particulate matter (PM10), fine (PM2.5), and coarse (PM10-2.5) particulate matter in Zonguldak, Turkey. A bidirectional case-crossover design was used to calculate odds ratios for the admissions adjusted for daily meteorological parameters. Significant increases were observed for hospital admissions in children for asthma, allergic rhinitis (AR), and upper (UPRD) and lower (LWRD) respiratory diseases. All fraction of PM in children showed significant positive associations with asthma admissions. The highest association noted was 18% rise in asthma admissions correlated with a 10-µg/m3 increase in PM10-2.5 on the same day of admissions. The adjusted odds ratios for exposure to PM2.5 with an increment of 10 µg/m3 were 1.15 and 1.21 for asthma and allergic rhinitis with asthma, respectively. PM10 exerted significant effects on hospital admissions for all outcomes, including asthma, AR, UPRD, and LWRD. Our study suggested a greater effect of fine and coarse PM on asthma hospital admissions compared with PM10 in children.

Atmospheric Research 89 (2008) 306-314

Title: Average mass concentrations of TSP, PM10 and PM2.5 in Erzurum urban atmosphere, Turkey
Authors: Bayraktar, H., Turalioğlu, F.S., Tuncel, G.
Abstract:In this study, particulate matters (TSP, PM10, PM2.5 and PM10–2.5) which are hazardous for environment and human health were investigated in Erzurum urban atmosphere at a sampling point from February 2005 to February 2006. During sampling, two low volume samplers were used and each sampling period lasted approximately 24 h. In order for detection of representative sampling region and point of Erzurum, Kriging method was applied to the black smoke concentration data for winter seasons. Mass concentrations of TSP, PM10 and PM2.5 of Erzurum urban atmosphere were measured on average, as 129, 31 and 13 µg/m3, respectively, in the sampling period. Meteorological factors, such as temperature, wind speed, wind direction and rainfall were typically found to be affecting PMs, especially PM2.5. Air temperature did not seem to be significantly affecting TSP and PM10 mass concentrations, but had a considerably negative induction on PM2.5 mass concentrations. However, combustion sourced PM2.5 was usually diluted from the urban atmosphere by the speed of wind, soil sourced coarse mode particle concentrations (TSP, PM10) were slightly affected by the speed of wind. Rainfall was found to be decreasing concentrations to 48% in all fractions (TSP, PM10, PM10–2.5, PM2.5) and played an important role on dilution of the atmosphere. Fine mode fraction of PM (PM2.5) showed significant daily and seasonal variations on mass concentrations. On the other hand, coarse mode fractions (TSP, PM10 and PM10–2.5) revealed more steady variations. It was observed that fine mode fraction variations were affected by the heating in residences during winter seasons.

Atmospheric Research 89 (2008) 306-314

Title: Comparison of sources affecting chemical compositions of aerosol and rainwater at different locations in Turkey
Authors: Ahmet Türküm, Beyhan Pekey, Hakan Pekey, Gürdal Tuncel
Abstract:In this study, concentrations of elements and ions were measured in atmospheric aerosol and rainwater samples collected at two rural stations on the Mediterranean and Black Sea coasts of Turkey. The relationship between chemical compositions of atmospheric aerosol and rainwater was investigated using receptor-oriented methods utilizing long-term data collected at the Antalya and Amasra stations in Turkey. Factor analysis performed on aerosol and rainwater data sets yielded that source types affecting chemical composition of rain and atmospheric particles were generally the same, but the contribution of each source type to rain and aerosol compositions showed differences. Potential source contribution function calculations were performed to determine if source regions affecting the chemical composition of rain and atmospheric particles were identical. The general pattern observed in distribution of source regions in rainwater and aerosol data sets showed some similarities at both stations, but there were substantial differences in detail. Source regions at the Antalya Station affecting the chemical composition of rainwater were local as compared to source regions affecting the composition of aerosol. The same difference was not observed in the Amasra Station. The source regions for crustal components of rainwater at the Antalya Station included western parts of Turkey, while European countries and North Africa were found to be the source regions affecting crustal components of aerosol at the Antalya Station. Potential source contribution function calculations indicated that major contributions to the anthropogenic components of aerosol at Antalya came mostly from the western parts of Turkey and European countries, while central Anatolia was the major source region contributing to anthropogenic components of rainwater at the Antalya Station. At the Amasra Station, the area north of the Black Sea and western parts of Turkey were the most important source regions affecting crustal and anthropogenic components for both aerosol and rainwater. It was observed that northern Europe, parts of Turkey, Ukraine, Russia, and some Balkan regions were the main source regions contributing to SO42- concentrations both in rainwater and aerosol samples collected at both sampling sites. © 2008 Elsevier B.V. All rights reserved.

Atmospheric Research 89 (2008) 315-323

Title: Investigating relationships between aerosol and rainwater compositions at different locations in Turkey
Authors: Ahmet Türküm, Hakan Pekey, Beyhan Pekey, Gürdal Tuncel
Abstract:Chemical compositions of atmospheric aerosol and rainwater samples collected at four different locations in Turkey were compared to investigate the relationship between aerosol and rainwater compositions. Results showed that aerosol composition could be reflected closely in rainwater composition if below-cloud processes dominate in-cloud processes. This was clearly observed for crustal elements at all stations and for most elements at the urban station. However, at rural stations there were differences in rain and aerosol that were attributed to significant contributions from in-cloud processes. Seasonal patterns observed in aerosol composition showed general agreement with the corresponding temporal variations observed in concentrations of elements in rainwater. These observations suggest that certain features of rainwater composition can be constructed if concentration data are available for aerosol. However, differences in the data observed at the different stations and among various elements or element groups showed that the composition of rainwater constructed from aerosol data can be only a crude effort. Similarities between rain and aerosol compositions were more pronounced at the urban station as compared to the rural stations. Scavenging ratios calculated using paired daily data were variable both among stations and within a single station. Long-term averaged data were found to be more reliable in calculating scavenging ratios of elements and ions at all stations. © 2008 Elsevier B.V. All rights reserved.

Microchemical Journal 88 (2008) 142–149

Title: Sources and source regions effecting the aerosol composition of the Eastern Mediterranean
Authors: G. Dogan, G. Güllü, G. Tuncel
Abstract:Positive matrix factorization (PMF) was used to deduce the aerosol sources at a rural site on the Mediterranean coast of Turkey, using sample collected between February 1992 and December 1993. Approximately 600 daily aerosol samples were collected and 40 elements and compounds were analyzed by atomic absorption spectrometry, instrumental neutron activation analysis, ion chromatography and colorimetry. Seven factors were identified with PMF, namely local dust, Saharan dust, sea salt, long range transport, smelter, arsenic and fertilizer factors. The non-parametric bootstrapped potential source contribution function (PSCF) was then used to help identify likely locations of the regional sources of pollution. Besides, explained variance, enrichment factors, seasonal variation of G-score values and back trajectories were used to define the source regions of the factors. Results demonstrated that there are major potential source areas, for the pollution-derived component in aerosol mass, on the Aegean coast, Northwest Turkey, Balkan countries, Ukraine and regions located northern part of Ukraine. © 2007 Elsevier B.V. All rights reserved.

Journal of Environmental Management 86 (2008) 581–594

Title: Multivariate statistics to investigate metal contamination in surface soil
Authors: Ozan D. Yaya, Omar Alagha, Gürdal Tuncel
Abstract:The modification of soil composition in the urbanized area of Ankara due to wet–dry deposition and pollution-derived particles from the atmosphere is investigated by analyzing 120 surface soil samples, collected from the urbanized area and its un-urbanized surrounding, for major, minor and trace elements. Concentrations of elements from human activity (e.g. Cd, Pb, Cr, Zn, Cu and Ca) in the urbanized area were higher than their corresponding concentrations in global average soil and soil in un-urbanized areas outside the urbanized area. Metal contents in soil were very high in densely populated districts and around some industrial facilities. The only exception was Pb distribution, which was more dispersed, due to the nature of motor vehicle emissions. Alteration of the Cd, Zn, Cu and Cr content of soil was confined to the inhabited and industrial areas, whereas enrichment factors of these elements were close to unity in the remaining study area. Factor analysis identified two polluted soil factor associations. One factor includes elements, such as Zn and Cd, which had high factor scores in inhabited areas and the other factor (high loading of Pb) represents soil polluted by motor vehicle emissions. © 2007 Elsevier Ltd. All rights reserved.

Atmospheric Research xxx (2008) xxx–xxx (in press)

Title: Comparison of sources affecting chemical compositions of aerosol and rainwater at different locations in Turkey
Authors: Ahmet Türküm, Beyhan Pekey, Hakan Pekey, Gürdal Tuncel
Abstract:In this study, concentrations of elements and ions were measured in atmospheric aerosol and rainwater samples collected at two rural stations on the Mediterranean and Black Sea coasts of Turkey. The relationship between chemical compositions of atmospheric aerosol and rainwater was investigated using receptor-oriented methods utilizing long-term data collected at the Antalya and Amasra stations in Turkey. Factor analysis performed on aerosol and rainwater data sets yielded that source types affecting chemical composition of rain and atmospheric particles were generally the same, but the contribution of each source type to rain and aerosol compositions showed differences. Potential source contribution function calculations were performed to determine if source regions affecting the chemical composition of rain and atmospheric particles were identical. The general pattern observed in distribution of source regions in rainwater and aerosol data sets showed some similarities at both stations, but there were substantial differences in detail. Source regions at the Antalya Station affecting the chemical composition of rainwater were local as compared to source regions affecting the composition of aerosol. The same difference was not observed in the Amasra Station. The source regions for crustal components of rainwater at the Antalya Station included western parts of Turkey, while European countries and North Africa were found to be the source regions affecting crustal components of aerosol at the Antalya Station. Potential source contribution function calculations indicated that major contributions to the anthropogenic components of aerosol at Antalya came mostly from the western parts of Turkey and European countries, while central Anatolia was the major source region contributing to anthropogenic components of rainwater at the Antalya Station. At the Amasra Station, the area north of the Black Sea and western parts of Turkey were the most important source regions affecting crustal and anthropogenic components for both aerosol and rainwater. It was observed that northern Europe, parts of Turkey, Ukraine, Russia, and some Balkan regions were the main source regions contributing to SO42- concentrations both in rainwater and aerosol samples collected at both sampling sites.

Atmospheric Research xxx (2008) xxx–xxx (in press)

Title: Investigating relationships between aerosol and rainwater compositions at different locations in Turkey
Authors: Ahmet Türküm, Beyhan Pekey, Hakan Pekey, Gürdal Tuncel
Abstract:Chemical compositions of atmospheric aerosol and rainwater samples collected at four different locations in Turkey were compared to investigate the relationship between aerosol and rainwater compositions. Results showed that aerosol composition could be rejected closely in rainwater composition if below-cloud processes dominate in-cloud processes. This was clearly observed for crustal elements at all stations and for most elements at the urban station. However, at rural stations there were differences in rain and aerosol that were attributed to signi cant contributions from in-cloud processes. Seasonal patterns observed in aerosol composition showed general agreement with the corresponding temporal variations observed in concentrations of elements in rainwater. These observations suggest that certain features of rainwater composition can be constructed if concentration data are available for aerosol. However, differences in the data observed at the different stations and among various elements or element groups showed that the composition of rainwater constructed from aerosol data can be only a crude effort. Similarities between rain and aerosol compositions were more pronounced at the urban station as compared to the rural stations. Scavenging ratios calculated using paired daily data were variable both among stations and within a single station. Long-term averaged data were found to be more reliable in calculating scavenging ratios of elements and ions at all stations. © 2008 Elsevier B.V. All rights reserved.

Environ Geol (2008) 54:759–776

Title: The effect of aquifer heterogeneity on natural attenuation rate of BTEX
Authors: Tuba Uçankus, Kahraman Ünlü
Abstract:Monitored natural attenuation can be a viable option for remediation of groundwater contamination by BTEX compounds. Under the field conditions, the rate of contaminant mass attenuation through natural processes, such as biodegradation, to a large extent affected by the groundwater flow regime, which is primarily controlled by the aquifer heterogeneity. Numerical simulation techniques were used to describe quantitatively the relationship between biodegradation rate of BTEX and aquifer heterogeneity. Different levels of aquifer heterogeneity were described by random hydraulic conductivity fields (K) having different statistical parameters, the coefficient of variation (CV) and the correlation length (h). The Turning Bands Algorithm was used to generate such K fields. Visual MODFLOW/RT3D was used to simulate the fate and transport of dissolved BTEX plume within heterogeneous aquifers. The multispecies reactive transport approach described BTEX degradation using multiple terminal electron-accepting processes. First-order biodegradation rate constants were calculated from simulated BTEX plumes in heterogeneous flow fields. The results showed that aquifer heterogeneity significantly affected biodegradation rate; it decreased with increasing CV when h was in the range of up to 12 m, whereas it increased with increasing CV when h was greater than about 12 m. For well characterized aquifers, this finding could be of great value in assessing the effectiveness of natural attenuation during feasibility studies at BTEX contaminated sites.

Waste Management xxx (2008) xxx–xxx (in press)

Title: Effect of vadose zone on the steady-state leakage rates from landfill barrier systems
Authors: B. Çelik, R.K. Rowe, K. Ünlü
Abstract:Leakage rates are evaluated for a landfill barrier system having a compacted clay liner (CCL) underlain by a vadose zone of variable thickness. A numerical unsaturated flow model SEEP/W is used to simulate the moisture flow regime and steady-state leakage rates for the cases of unsaturated zones with different soil types and thicknesses. The results of the simulations demonstrate that harmonic mean hydraulic conduc- tivity of coarse textured vadose zones is 3–4 orders of magnitude less than saturated hydraulic conduc- tivity; whereas, the difference is only one order of magnitude for fine textured vadose zones. For both coarse and fine textured vadose zones, the effective hydraulic conductivity of the barrier system and the leakage rate to an underlying aquifer increases with increasing thickness of the vadose zone and ulti- mately reaches an asymptotic value for a coarse textured vadose zone thickness of about 10 m and a fine textured vadose zone thickness of about 5 m. Therefore, the fine and coarse textured vadose zones thicker than about 5 m and 10 m, respectively, act as an effective part of the barrier systems examined. Although the thickness of vadose zone affects the effective hydraulic conductivity of the overall barrier system, the results demonstrated that the hydraulic conductivity of the CCL is the dominant factor controlling the steady-state leakage rates through barrier systems having single low permeability clay layers. Ó 2008 Elsevier Ltd. All rights reserved.