Yücel Tasdemir

Polycyclic aromatic hydrocarbons (PAHs) in Chicago air

Ambient air samples were collected in Chicago, IL between June and October 1995 as part of a study to investigate the dry deposition and air–water exchange of polycyclic aromatic hydrocarbons (PAHs). A modified high-volume sampler (PS-1 sampler) was used to collect airborne PAHs in both the particulate and gas phases. The average total (gas+particulate) Σ14-PAH concentration was 428±240 ng m−3, similar to those previously observed in Chicago, IL and other urban areas. The particle/gas phase distribution varied widely. The gas phase percentage ranged from 1.1 to 99.4%, and generally decreased with increasing molecular weight. The amount of PAHs associated with the particulate phase increased with decreasing temperature, probably due to the temperature dependence of gas/particle partitioning. Concentrations of PAHs with molecular weights between 154 and 202 were correlated well with phenanthrene concentrations while compounds with molecular weights higher than 202 had little or no correlation with phenanthrene concentration, probably due to the different partitioning, transport and removal characteristics of low and high molecular weight compounds.

Seasonal concentrations and partitioning of PAHs in a suburban site of Bursa, Turkey.

Effects of space heating on atmospheric concentrations and gas-particle partitioning of PAHs were investigated in a suburban site of Bursa, Turkey. The average concentrations of summation operator(15)-PAHs in heating season samples were approximately 10 times higher than those of non-heating season samples. The plot of log K(p) versus log P(L)(0) for all the data set gave significantly different slopes. The slope for the heating season (-0.75) samples was steeper than the one for the non-heating season (-0.64) samples. It was also observed that partitioning of PAHs for the non-heating season samples showed different characteristics depending on air parcel trajectories. Generally steeper slopes were obtained for the air parcels traveled across the Black sea and arrived to the sampling site from northern sector. On the other hand, the variations in slopes according to air mass origin were insignificant for the heating season samples. Local contributions from space heating are the reason for this observation.

Ambient Concentrations and Gas/Particle Partitioning of Polycyclic Aromatic Hydrocarbons in an Urban Site in Turkey

Atmospheric samples were collected between July 2004 and May 2005 in Bursa, Turkey, when there was no rain, and analyzed for gas and particle concentrations of polycyclic aromatic hydrocarbons (PAHs). This study targeted 15 PAH compounds. Vapor-phase PAH compositions were dominated by the more volatile PAHs, relative to the particle phase. On average, 76% of the total (gas + particulate) PAH concentration was in the vapor phase. Average total PAH concentration was 298 ± 418 ng/m3. The large seasonal concentration fluctuation was attributed to residential heating, vaporization, industrial activities, and meteorological conditions. The measured average seasonal concentrations were 55 ± 40, 187 ± 202, 645 ± 588 and 148 ± 132 ng/m3 for summer, fall, winter, and spring, respectively. The partitioning of PAHs between gas and particle phases was investigated employing the Junge-Pankow model. Plots of log gas/particle partition coefficient (K p ) versus log liquid vapor pressures (PL o) had reasonable correlations for individual samples. Experimentally determined K p values were compared with the result obtained using absorption (octanol–air partition coefficient [K OA ]) into aerosol organic matter and adsorption (K SA + K OA ) onto soot carbon models. Experimentally determined K p values were generally in the same range with the ones obtained from the models.

Air and seawater pollution and air-sea gas exchange of persistent toxic substances in the Aegean Sea: spatial trends of PAHs, PCBs, OCPs and PBDEs

Near-ground air (26 substances) and surface seawater (55 substances) concentrations of persistent toxic substances (PTS) were determined in July 2012 in a coordinated and coherent way around the Aegean Sea based on passive air (10 sites in 5 areas) and water (4 sites in 2 areas) sampling. The direction of air–sea exchange was determined for 18 PTS. Identical samplers were deployed at all sites and were analysed at one laboratory. hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs) as well as dichlorodiphenyltrichloroethane (DDT) and its degradation products are evenly distributed in the air of the whole region. Air concentrations of p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) and o,p′-DDT and seawater concentrations of p,p′-DDE and p,p′-DDD were elevated in Thermaikos Gulf, northwestern Aegean Sea. The polychlorinated biphenyl (PCB) congener pattern in air is identical throughout the region, while polybrominated diphenylether (PBDE)patterns are obviously dissimilar between Greece and Turkey. Various pollutants, polycyclic aromatic hydrocarbons (PAHs), PCBs, DDE, and penta- and hexachlorobenzene are found close to phase equilibrium or net-volatilisational (upward flux), similarly at a remote site (on Crete) and in the more polluted Thermaikos Gulf. The results suggest that effective passive air sampling volumes may not be representative across sites when PAHs significantly partitioning to the particulate phase are included.

Removal of polycyclic aromatic hydrocarbons from municipal sludge using UV light

Abstract This study includes research into using UV light to remove Polycyclic Aromatic Hydrocarbons (PAHs) from municipal sludge. The effectiveness of TiO2 as a photocatalyst on this UV application was also determined. Sludge samples that were taken from an urban wastewater treatment plant (UWWTP) were exposed to UV-C light in a specially designed setup. The total concentration of Σ12 PAH in the sludge, which was 1339 ng g−1 of dry matter initially, decreased by 2–77% after 24 h of UV application. The concentrations of some PAH isomers increased after the UV application, which revealed that isomer transformations could emerge due to the effects of temperature and photodegradation. UV light was found to remove 3-ring light compounds more effectively than 4–6-ring heavy compounds. A total PAH decrease of 77% was achieved by adding an amount of TiO2 equal to 0.5% of the dry weight of the sludge although the removal rate of PAHs from the sludge decreased when the TiO2 dosage was increased. It is possible tha...

Prediction of the PCB pollution in the soils of Bursa, an industrial city in Turkey.

The purpose of this study was to predict the equilibrium soil concentrations and distributions of Sigma(41)Polychlorinated Biphenyl (PCB) congeners from the air data measured at 4 sites (urban, suburban, residential, and industrial) in Bursa between 2004 and 2005. The soil-air partition coefficient (K(SA)) was used for the predictions. Predicted soil concentrations ranged from 25 pg/g to 690 pg/g, while the atmospheric concentrations fluctuated between 35 pg/m(3) and 1112 pg/m(3). The soil concentrations were found to be in agreement with the lower range of European and global values, and below the regulatory limits. The urban and residential sites yielded higher PCB concentrations and a higher degree of heavier congeners than the sites characterized as suburban. The urban and residential sites were dominated by hexa-chlorinated biphenyls (CBs), followed by tri-CBs, while the industrial site was dominated by tri-CBs, followed by tetra-CBs. PCB congeners of 153, 180, 138, 118, and 101 were higher in all locations. The effect of the temperature changes on the concentrations was found to be insignificant, as the correlations ranged between 0.0009 and 0.22 for all sites. The K(SA) approach yielded reasonable results, and it is recommended to use this approach when there is limited data about the pollution levels of a certain media such as soil by using the measured levels of the other media such as air.

Air-soil exchange of PCBs: seasonal variations in levels and fluxes with influence of equilibrium conditions.

The variations in the occurrences of PCB congeners both in soil and air were investigated in conjunction with each other, and the changes in the fugacity fractions and flux levels were examined on a seasonal basis. Air and soil samples were collected concurrently two or three times in a month during a one-year monitoring at two different locations in Bursa, located in the northwestern Turkey. Fugacity fractions and net flux levels of PCB congeners were calculated. Air and soil PCB levels increased together as the soil temperature increased, suggesting the influence of instantaneous air-soil exchange towards the equilibrium conditions. The flux levels and fugacity fractions also showed a positive significant correlation with soil temperature. Flux levels were positive for the dates with fugacity fractions above 0.5, indicating volatilization from soil to air.

Measurement of atmospheric deposition of polychlorinated biphenyls and their dry deposition velocities in an urban/industrial site in Turkey.

Dry deposition fluxes and total (gas+particle) concentrations of polychlorinated biphenyls (PCBs) were measured between August 2004 and May 2005. Samples were collected from an urban-industrial site of Bursa, Turkey. A stainless steel pot and a high volume air sampler (HVAS) were employed to collect deposition and ambient air samples, respectively. The dry deposition fluxes of PCBs ranged from 3600 to 56,000 pg m−2 d−1 while the total PCB concentrations collected simultaneously were between 35 and 348 pg m−3. The average dry deposition flux value was in line with the previously reported values. Possible variations in PCB fluxes were likely due to PCB and total suspended particle (TSP) concentrations, and meteorological conditions. No seasonal trends were observed for the bulk deposition samples. The 3- and 4- chlorobiphenyls (CBs) were abundant homolog groups in bulk and concentration samples with ratios of 67% and 90%, respectively. Apparent bulk deposition velocities were calculated by dividing the dry deposition flux value by particle phase air concentration values of PCBs measured with HVAS. The calculated apparent dry deposition velocities ranged from 0.23 cm s−1 to 3.09 cm s−1 (aver ± SD, 0.74 ± 0.23 cm s−1).

Atmospheric Gas and Particle Phase Concentrations of Polychlorinated Biphenyls (PCBs) in a Suburban Site of Bursa, Turkey

Ambient air samples were collected between July 2004 and May 2005 with a high-volume air sampler (HVAS) in order to investigate the gas and particle concentration levels of polychlorinated biphenyls (PCBs) in a suburban site (the Uludag University Campus) in Bursa, Turkey. Average particle and gas-phase PCB concentrations (average ± standard deviation) were 85.8 ± 127.8 pg m−3 and 328.1 ± 284.2 pg m−3, respectively. Total (gas+particle) PCB concentrations were higher in the warmer periods, while an opposite case was observed for the colder periods. The application of the Clausius-Clapeyron equation representing the relationship between gas-phase PCB concentrations and air temperature yielded a significant correlation. Moreover, the relationships between PCB congeners and meteorological variables were investigated. Based on meteorological variables and back trajectory results, evaporation and atmospheric transport were assumed to be the major sources of PCBs in the sampling site. PCBs are partitioned between gas and particle phases, and this fate was examined using different available approaches such as logKP-logPLo , logKP-logKOA, and Junge-Pankow model. Shallow slopes between −0.18 and −0.48 were obtained from the logKP-logPLo plot, while the slope of logKP-logKOA ranged from 0.2 to 0.42. PLo and KOA values obtained from the literature were both considered good descriptors for determination of KP experimental partitioning coefficient in the site. Correlations were significant at p < 0.01 for all approaches.

Evaluation of NOx and O3 Concentrations in the Atmosphere of Bursa, Turkey

This study summarizes seasonal variations of NOx and O3 concentration levels. Samples were taken between May 2001 and April 2002 in a monitoring site located in the city center of Bursa, Turkey. Owing to the emission rates and meteorological conditions, air pollutant concentrations varied. The annual average NOx and O3 concentrations were found to be 78.96 ± 70.39 μ g/m3 and 55.10 ± 32.53 μg/m3, respectively. In general, the maximum NOx concentrations (115.35 ± 38.83) occurred during the winter while minimum values (44.86 ± 17.10) were observed during the summer. This fluctuation probably caused by the residential heating, mixing height and photochemical activity in the region. On the other hand, ozone concentrations were higher in the summer by the effect of photochemical oxidation. This study may help in forensic investigations dealing with O3 sources in the atmosphere.