Browsing by Author "Vardar, Nedim"

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Assessment of trace element concentrations and their estimated dry deposition fluxes in an urban atmosphere
(Elsevier Science, 2006) Vardar, Nedim; Taşdemir, Yücel; Kural, Can; Cindoruk, Sıddık S.; Uludağ Üniversitesi/Mühendislik Mimarlık Fakültesi/Çevre Mühendisliği Bölümü.; 0000-0001-7536-0332; AAG-9468-2021; 6603118338; 8551608000; 10339194600
Thirty-three ambient air samples were collected during spring and summer (2003) in the metropolitan area of Bursa, Turkey. All airborne samples were analyzed for crustal (Mg, Ca, Mn, Fe) and anthropogenic (Cr, Co, Ni, Cu, Zn, Cd, Ph) trace metals. A TSP sampler was employed using glass and quartz fiber filters to collect air samples. Average individual trace element concentrations fluctuated between 4896.3 +/- 3754.3 ng/m(3) (Ca) and 0.7 +/- 0.9 ng/m(3) (Cd). The measured concentrations of the trace elements were within the ranges of previously reported values obtained from different places including Turkey, Argentina, Spain, Korea, and Brasil. The concentrations were arranged according to day and night, weekend and weekdays, spring and summer samples. Concentrations were also evaluated based on the filter types used, glass fiber and quartz filters. Enrichment factors (EFs) were calculated to identify anthropogenic versus natural emission sources of trace elements. The prevailing winds from various sectors were examined to determine the transport of metal particles from different districts. Principal component analysis (PCA) was employed to define the possible origins of trace elements in airborne particulate matter. The result suggested that industrial activities along with traffic emissions and suspension of street dusts have important effects on ambient air concentrations of trace metals. Dry deposition fluxes were estimated using documented dry deposition velocities in the literature and concentrations measured in this study.
Atmospheric concentrations of PAHs, their possible sources and gas-to-particle partitioning at a residential site of Bursa, Turkey
(Elsevier Science, 2008-06) Vardar, Nedim; Esen, Fatma; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-8469-2021; AAG-9468-2021; 10340657500; 6603118338
Atmospheric PAH concentrations were determined in Gulbahce district of Bursa, Turkey between August 2004 and April 2005. Measured PAH concentrations were classified as heating and non-heating season samples. The concentrations of total PAHs in heating season were almost ten times higher than those in non-heating season. Diagnostic ratios and factor analysis results show that in the heating season traffic along with residential heating emissions heavily influence PAH concentrations. The plot of logK, versus logP(L)(0) for all the data set of heating and non-heating season samples gave significantly different slopes. The slope for the heating season samples (-0.92) was steeper than the one for the non-heating season samples (-0.78). The partitioning results for individual samples further indicated that slope values varied depending on air parcel trajectories. Air parcels traveled over water (either over the Black Sea or Aegean Sea) prior to arriving at the sampling site had less steep slopes. Partitioning of PAHs was also investigated by comparing experimentally determined K-p values with the results obtained both from octanol-based model (K-p(Oct.)) and soot and octanol-based model (K-p (Soot+Oct.)). Both models were useful in predicting the experimental K-p values. However, they did not explain the observed variability in the experimental K-p values.
Characterization of atmospheric concentrations and partitioning of PAHs in the Chicago atmosphere
(Elsevier Science BV, 2004-07-05) Vardar, Nedim; Odabaşı, Mustafa; Noll, Kenneth E.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021
An intensive sampling program has been undertaken in the absence of precipitation at an urban site, Chicago, to characterize the atmospheric concentration and partitioning of PAHs. Two different sampling programs have been carried out with a large number of samples. Measured ambient concentrations of PAHs were classified as Land and Lake samples based on wind direction and back trajectory calculations. Differences in ambient concentrations of PAHs were observed between Land and Lake samples. The concentrations of PAHs when air originated over the Land were approximately two-four times higher than the concentrations measured when air originated over the Lake. It has been demonstrated that partitioning of PAHs shows a consistent difference between samples taken when wind came from off the land rather than off the water. This was most evident by more shallow slopes for Lake samples compared to the slopes for Land samples, when partition coefficient (K-p) is plotted on a log-log scale vs. the subcooled liquid vapor pressure (P-L(0)). Experimentally, determined K-p values were compared with the results obtained using two different models, one based on absorption into aerosol organic matter and the other adsorption onto soot carbon. Experimental K-p values generally agreed well with the soot+ octanol based model predictions.
Concentrations and gas/particle partitioning of PCBs in Chicago
(Elsevier Science, 2004-09) Vardar, Nedim; Odabaşı, Mustafa; Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021
Thirty seven air samples were collected in Chicago, IL from June to October 1995 and analyzed for gas and particle concentrations of polychlorinated biphenyls (PCBs). Lower molecular weight (MW) PCBs dominated the samples and on average 95% of the Sigma(50)PCB concentration (gas + particulate) was in the vapor phase. Sigma(50)PCB concentrations were classified based on prevailing winds (lake and land). The Sigma(50)PCB concentration varied between 0.42 and 5.21 ng/m(3) (1.80 +/- 1.70 ng/m(3)) for lake and 0.53 and 8.31 ng/m(3) (2.41 +/- 2.15 ng/m(3)) for land wind directions. Back trajectory analyses suggested that SW of Chicago can be an important local or regional source sector for PCBs. Partitioning between gas and particulate phases was modeled using the Junge-Pankow model. The measured particle phase concentrations for low MW PCBs were lower than those predicted by the model while the opposite was observed for high MW PCBs. Plots of gas/particle partition coefficient (log K-p) vs. subcooled liquid vapor pressure (log p(L)(0) had reasonable correlations for individual samples but the slope varied among the samples. Samples that originated from over the lake had higher slopes than samples that originated from over the land.
Dry deposition fluxes and velocities of polychlorinated biphenyls (PCBs) associated with particles
(Pergamon-Elsevier Science, 2004-05) Odabaşı, Mustafa; Vardar, Nedim; Sofuoğlu, Aysun; Murphy, Thomas J.; Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021
The interest in atmospheric deposition by the scientific community has increased a great deal over the past several years because of its significant contribution to the pollution budget of many natural waters. Dry deposition is an effective removal mechanism for polychlorinated biphenyls (PCBs) from the atmosphere. This study focuses on the understanding of the particulate dry deposition of PCBs in urban areas. In this paper, 43 chromatographic PCB congener peaks which represent 50 individual or coeluting congeners were evaluated. The PCB dry deposition fluxes were measured using a smooth, greased, knife-edge surrogate surface holding greased Mylar strips in Chicago, IL. The average PCB dry deposition flux measured (190 +/- 80 ng m(-2) day(-1)) was similar to those measured in other urban areas. Ambient air samples were also collected simultaneously with flux samples. The average apparent dry deposition velocity, calculated by dividing the fluxes to the particle phase concentrations was 5.2 +/- 2.9 cm s(-1). This value is in good agreement with the values calculated using similar techniques.
Measurement of atmospheric deposition of polychlorinated biphenyls and their dry deposition velocities in an urban/industrial site in Turkey
(Taylor & Francis, 2008) Vardar, Nedim; Cindoruk, Sabahattin Sıddık; Esen, Fatma; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; 0000-0001-7536-0332; AAG-9468-2021; 10339194600; 10340657500; 6603118338
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)).
Measurement of dry deposition and air-water exchange of polycyclic aromatic hydrocarbons with the water surface sampler
(American Chemical Society, 1999-02-01) Odabaşı, Mustafa; Sofuoğlu, Aysun; Vardar, Nedim; Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021; 6603118338
Recent work has shown that dry deposition and gas exchange of semivolatile organic compounds in the Great Lakes is important. However, there is no generally accepted method for collecting particulate dry deposition or gas exchange. in this work the Water Surface Sampler (WSS) was modified and used in combination with dry deposition plates to measure the particulate dry deposition and gas exchange of PAHs. Simultaneous dry deposition and ambient air samples were collected between June and October 1995 in Chicago, II. Total (particulate + gas) fluxes were measured with the WSS, while particulate fluxes were measured with dry deposition plates. Average Sigma(14)-PAH and particulate Sigma(14)-PAH fluxes were 360 +/- 146 mu g/m(2) d and 144 +/- 60 mu g/m(2) d, respectively. Gas-phase fluxes, determined by subtracting the dry deposition plate fluxes (particulate) from WSS fluxes (particulate + gas), averaged 170 +/- 72 mu g/m(2) d. The measured particulate dry deposition and gas exchange fluxes were substantially higher than those previously reported for the Great Lakes and nonurban areas, probably due to the significantly higher ambient PAH concentrations found in Chicago. Particulate phase overall dry deposition velocities calculated using the dry de position fluxes and ambient concentrations averaged 6.7 +/- 2.8 cm/s. This value is higher than values estimated using dry deposition models; however, it is in good agreement with values determined using similar techniques.
Seasonal concentrations and partitioning of PAHs in a suburban site of Bursa, Turkey
(Elsevier, 2008-09) Vardar, Nedim; Esen, Fatma; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-8469-2021; AAG-9468-2021; 10340657500; 6603118338
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 Sigma(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.