Browsing by Author "Holsen, Thomas M."

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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.
Gas-phase deposition of polychlorinated biphenyls (PCBs) to a water surface sampler
(Taylor & Francis, 2006) Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Mimarlık Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021; 6603118338
In this study a water surface sampler (WSS) was utilized to directly measure gas phase deposition of polychlorinated biphenyls (PCBs). The measured gas phase PCB fluxes averaged about 880 +/- 660 ngm(-2)d(-1), which was higher than the fluxes calculated using simultaneously measured air and water concentrations for natural surface waters. These large fluxes were due to fact that the measured fluxes were only in the absorption direction since deposited PCBs were continuously removed from the system using an XAD column resulting in the maximum possible flux rate from the air to the WSS water. Ambient air PCBs were also sampled simultaneously with a modified high volume sampler. The gas phase PCB concentrations changed between 0.90 and 4.46 ngm(-3) (2.18 +/- 1.16 ngm(-3)). The mass transfer coefficients (MTCs), calculated by dividing the fluxes by the gas phase concentrations was 0.40 +/- 0.36 cms(-1). The average MTC was comparable with those calculated using a similar configuration of a WSS.
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.
Measurement of particle phase dry polychlorinated biphenyls (PCBs) with deposition fluxes of a water surface sampler
(Pergamon-Elsevier Science, 2005-03) Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Mimarlık Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021
It has been shown that the atmospheric pathways including dry deposition are an important source of polychlorinated biphenyls (PCBs) entering surface waters in many locations. To assess how important this pathway is, accurate measurements or modeled estimates of dry deposition are needed. However, dry deposition is not well quantified because the direct measurement of dry deposition is difficult and indirect estimation techniques have substantial uncertainties associated with them. In this study, PCB dry deposition fluxes were directly measured with a water surface sampler (WSS) simultaneously with measurements of airborne concentrations in the Chicago urban area. The average particulate phase PCB flux to the WSS was 240 +/- 160 ng/m(2)-d, and the particulate phase airborne concentrations was 0.08 +/- 0.05 ng/m(3). Average overall dry deposition velocities, calculated by dividing the fluxes by total particle phase PCB concentrations were 4.2 +/- 2.7cm/s. This number is consistent with values determined using similar experimental techniques and higher than the values typically used to model PCB dry deposition. This difference may be due, in part, to the influence of PCBs associated with large particles being deposited onto the WSS. (c) 2005 Elsevier Ltd. All rights reserved.
Measurement of the vapor phase deposition of polychlorinated bipheyls (PCBs) using a water surface sampler
(Pergamon-Elsevier Science, 2005-02) Odabasi, Mustafa; Holsen, Thomas M.; Tasdemir, Yücel; Uludağ Üniversitesi/Mühendislik-Mimarlık Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021
A water surface sampler (WSS) was employed in combination with greased knife-edge surface deposition plates (KSSs) to measure the vapor phase deposition rates of PCBs to the sampler at an urban site, Chicago, IL. This sampler employed a water circulation system that continuously removed deposited PCBs. Total (gas + particle) and particulate PCB fluxes were collected with the WSS and KSSs, respectively. Gas phase PCB fluxes were then calculated by subtracting the KSS fluxes (particulate) from the WSS fluxes (gas + particle). The calculated gas phase PCB fluxes averaged 830 +/- 910 ng m(-2) d(-1). This flux value is, in general, higher than the fluxes determined using simultaneously measured air-water concentrations in natural waters and is in the absorption direction. This difference is primarily because the PCBs were continuously removed from the WSS water keeping the water PCB concentration near zero. Concurrently, ambient air samples were collected using a modified high volume air sampler. The gas phase PCB concentrations ranged between 1.10 and 4.46 ng m(-3) (average +/- SD, 2.29 +/- 1.28 ng m(-3)). The gas phase fluxes were divided by the simultaneously measured gas phase ambient concentrations to determine the overall gas phase mass transfer coefficients (MTCs) for PCBs. The average gas phase overall MTCs (K.) for each honiolog group ranged between 0.22 and 1.32 cm s(-1) (0.54 +/- 0.47cm s(-1)). The average MTC was in good agreement with those determined using similar techniques.
PCB mass transfer coefficients determined by application of a water surface sampler
(Pergamon-Elsevier Science, 2007-01) Odabaşı, Mustafa; Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021; 6603118338
A water surface sampler (WSS) was employed in combination with greased surface deposition plates (GSDPs) to measure the particulate dry deposition and gas exchange of polychlorinated biphenyls (PCBs) in Chicago, IL. Vapor phase PCB fluxes were calculated by subtracting the particulate fluxes obtained from GSDPs from total (particulate + gas) fluxes obtained from the WSS. Vapor phase PCB fluxes were divided by ambient air concentrations measured with a high volume sampler to calculate overall gas phase PCB mass transfer coefficients (KG). The calculated average PCB MTC was 0.54 +/- 0.47 cm s(-1). This experimentally determined average gas phase overall mass transfer coefficient, KG, agreed well with the ones reported from studies using similar techniques and agreed well with modeled values obtained using MTC correlations developed for the WSS.
Polycyclic aromatic hydrocarbons (PAHs) in Chicago air
(Elsevier Science BV, 1999-02-16) Odabaşı, Mustafa; Vardar, Nedin; Sofuoğlu, Aysun; Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre ve İnşaat Mühendisliği Bölümü.; AAG-9468-2021
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) Sigma(14)-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.
Temperature dependence of gas-phase polycyclic aromatic hydrocarbon and organochlorine pesticide concentrations in Chicago air
(Elsevier, 2001-12) Sofuoğlu, Aysun; Odabaşı, Mustafa; Khalili, Nasrin R.; Holsen, Thomas M.; Taşdemir, Yücel; Uludağ Üniversitesi/Mühendislik Fakültesi/Çevre Mühendisliği Bölümü.; AAG-9468-2021
The temperature dependence of gas-phase atmospheric concentrations of polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides measured in Chicago, IL between June and October 1995 were investigated using plots of the natural logarithm of partial pressures (in P) vs. reciprocal mean temperatures (1/T). For the eight lowest molecular weight PAHs, temperature dependence was statistically significant (at the 95% confidence level) and temperature accounted for 23-49% of the variability in gas-phase concentrations. The relatively higher slopes for most of the PAHs suggested that volatilization from local sources and short-range transport influenced their concentrations, For pesticides, temperature dependence was statistically significant for DDD and for trans-nonachlor (at the 95% and 90% confidence levels), and was not statistically significant for the other five compounds (2-18% of the variability in their gas-phase concentrations). The relatively lower slopes for individual pesticides suggested that they have mostly non-urban and distant sources. Results of back trajectory analyses suggested that the region, southwest of Chicago, might be an important local or regional source sector for PAHs and organochlorine pesticides. No statistically significant relationship was observed between wind speed and PAH or pesticide concentrations. None of the variables (temperature. wind speed, wind direction, local and regional sources) could fully explain the variation in their concentrations measured in Chicago, therefore, this variation can be attributed to the combined effect of those factors.