Sema Yurdakul

Temporal variations of BTX compounds in Bursa/Turkey atmosphere

Ambient concentrations of C2-C12 volatile organic compounds (VOCs) were measured at Bursa, which is the fourth largest city of Turkey. Two measurement campaigns were carried out between September 14 to November 6, 2005 and March 17 to May 10, 2006. Fifty one VOCs were regularly determined in each chromatogram. However, only BTX compounds are discussed in this study. Concentrations of BTX compounds showed well-defined diurnal cycles. Concentrations increased starting at 06:00 am in the morning, reaching to a maximum somewhere between 9:00 to 11:00 am. Then concentration decreased, until the evening rush hour, owing to increasing mixing height during day time. Then concentrations of BTX increased in the afternoon rush hour which extended to 08:00 pm. BTX concentrations remained low throughout the night. High binary correlations between BTX compounds suggest a common source, which are traffic emissions. However, other non-traffic sources were also found to be effective, for benzene in the November to March c...

Sources of Volatile Organic Compounds in a University Building

A total of 34 volatile organic compounds (VOCs) were measured in the indoor of laboratories, offices and classrooms of the Chemical Engineering Department of Hacettepe University in Ankara in 2 week-day passive sampling campaigns. The average concentrations ranged from 0.77 to 265 μg m−3 at the different indoor sites, with the most abundant VOC found to be toluene (119.6 μg m−3), followed by styrene (21.24 μg m−3), 2-ethyltoluene (17.11 μg m−3), n-hexane (10.21 μg m−3) and benzene (9.42 μg m−3). According to the factor analysis, the evaporation of solvents used in the laboratories was found to be the dominant source.

Spatio-temporal variations of atmospheric and soil polybrominated diphenyl ethers (PBDEs) in highly industrialized region of Dilovasi

Polybrominated diphenyl ethers (PBDEs) were investigated in ambient air of a highly industrialized region at 23 different sampling sites for 12 months. Total concentrations of 8 PBDE congeners (Σ8PBDE) were found to be between 5.73 and 520 pg m-3 (94.7 ± 78.9; average ± SD) and BDE-209 was the predominant congener, followed by BDE-47 and/or BDE-99. Their contributions to Σ8PBDE were 71 ± 13, 9 ± 4% and 8 ± 4%; respectively. Compared to previous studies around the world, high concentrations detected in Dilovasi demonstrated the severity of atmospheric PBDE pollution in the area. For all sampling sites, average PBDE concentration obtained in summer (118.5 ± 98.7 pg m-3) was higher than one found in winter period (79.7 ± 59.1 pg m-3) and this seasonal difference was more obvious in industrial/urban sites (p < 0.05), probably due to enhanced volatilization from ongoing PBDE sources such as waste incineration and iron-steel plants. The soil-air exchange tendencies of PBDEs did not show substantial differences between the sampling periods with small variations for each congener. All congeners either tend to deposit to soil or to be within the equilibrium range for all seasons. This reflects the impact of local ongoing sources rather than temperature on the direction of soil-air exchange of PBDEs in this region. Specific congener ratios such as BDE-47/-99 and -99/-100 confirmed the impact of local sources rather than long-range transport on PBDE congeners in the study area. According to the Positive Matrix Factorization (PMF) results, the BDE-209 content of the first factor was found to be 91.7% and this factor was attributed to the deca-BDE technical formulations. The second factor was highly rich with both BDE-183 (%61) and BDE-28 (%52) and identified as octa-BDE technical products. The last factor was highly loaded with BDE-99, BDE-47, BDE-100, BDE-154 and BDE-153 and has been determined as the penta-BDE commercial formulations.

Source apportionment and carcinogenic risk assessment of passive air sampler-derived PAHs and PCBs in a heavily industrialized region

Cancer has become the primary reason of deaths in Dilovasi probably due to its location with unique topography under the influence of heavy industrialization and traffic. In this study, possible sources and carcinogenic health risks of PAHs and PCBs were investigated in Dilovasi region by Positive Matrix Factorization (PMF) and the USEPA approach, respectively. PAHs and PCBs were measured monthly for a whole year at 23 sampling sites using PUF disk passive samplers. Average ambient air concentrations were found as 285±431ng/m3 and 4152±6072pg/m3, for Σ15PAH and Σ41PCB, respectively. PAH concentrations increased with decreasing temperature especially at urban sites, indicating the impact of residential heating in addition to industrial activities and traffic. On the other hand, PCB concentrations mostly increased with temperature probably due to enhanced volatilization from their sources. Possible sources of PAHs were found as emissions of diesel and gasoline vehicles, biomass and coal combustion, iron and steel industry, and unburned petroleum/petroleum products, whereas iron-steel production, coal and biomass burning, technical PCB mixtures, and industrial emissions were identified for PCBs. The mean carcinogenic risk associated with inhalation exposure to PAHs and PCBs were estimated to be >10-6 and >10-5, respectively, at all sampling points, while the 95th percentile was >10-5 at 15 of 23 and >10-4 at 8 of 23 sampling locations, respectively. Probabilistic assessment showed, especially for PCBs, that a majority of Dilovasi population face significant health risks. The higher risks due to PCBs further indicated that PCBs and possibly other pollutants originating from the same sources such as PBDEs and PCNs may be an important issue for the region.

Comparison of Thermal Properties and Kinetics of Selected Waste Wood Samples in Two Different Atmospheres

Knowledge of the kinetics and thermal decomposition properties of woods are of great importance. Successful design and control of technologies for the pyrolysis and combustion of lignocellulosic raw materials require a good understanding of the kinetics of the thermochemical processes. In this chapter, thermal properties and kinetic constants of selected waste wood samples (pine, medium-density fiberboard, and plywood) are examined in two different atmospheres, nitrogen and air, by thermogravimetric analysis. Samples were sieved to 3 mm and a heating rate of 10 °C/min was used. In nitrogen atmosphere, two peaks were observed for all samples due to moisture and volatile content of the samples. However, in air atmosphere three peaks were observed owing to removal of moisture, active oxidation of volatile matter, and char combustion. Activation energies of the samples in air atmosphere were higher than in the nitrogen atmosphere. Consequently, it can be said that all samples were more thermally stable in an air atmosphere than in a nitrogen atmosphere. Furthermore, a diffusion-controlled reaction starting on the exterior of spherical particles was found to be the main mechanism for all waste wood samples.