Chemical Engineering / Kimya Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/14

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Author: search.filters.author.Taşdemir, Yücel

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  • Article
    Citation - WoS: 65
    Citation - Scopus: 77
    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
    (Springer Verlag, 2015) Lammel, Gerhard; Audy, Ondrej; Besis, Athanasios; Efstathiou, Christos; Eleftheriadis, Kostas; Kohoutek, Jiri; Kukucka, Petr; Mulder, Marie D.; Pribylova, Petra; Prokes, Roman; Rusina, Tatsiana P.; Samara, Constantini; Sofuoğlu, Aysun; Sofuoğlu, Sait Cemil; Taşdemir, Yücel; Vassilatou, Vassiliki; Voutsa, Dimitra; Vrana, Branislav
    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.
  • Article
    Citation - WoS: 64
    Citation - Scopus: 65
    Dry Deposition Fluxes and Velocities of Polychlorinated Biphenyls (pcbs) Associated With Particles
    (Elsevier Ltd., 2004) Taşdemir, Yücel; Odabaşı, Mustafa; Vardar, Nedim; Sofuoğlu, Aysun; Murphy, Thomas J.; Holsen, Thomas M.
    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±80ngm-2day -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±2.9cms-1. This value is in good agreement with the values calculated using similar techniques.
  • Article
    Citation - WoS: 71
    Citation - Scopus: 76
    Temperature Dependence of Gas-Phase Polycyclic Aromatic Hydrocarbon and Organochlorine Pesticide Concentrations in Chicago Air
    (Elsevier Ltd., 2001) Sofuoğlu, Aysun; Odabaşı, Mustafa; Taşdemir, Yücel; Khalili, Nasrin R.; Holsen, Thomas M.
    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 (lnP) 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.