Journal of Chromatography A, 1122 (2006) 222–229 Chemical characterization of odorous gases at a landfill site by gas chromatography–mass spectrometry Faruk Dincer ∗ , Mustafa Odabasi, Aysen Muezzinoglu Department of Environmental Engineering, Dokuz Eylul University, Kaynaklar Campus, 35160 Buca-Izmir, Turkey Received 17 January 2006; received in revised form 12 April 2006; accepted 18 April 2006 Available online 12 May 2006 Abstract The composition of odorous gases emitted from a municipal landfill in the city of Izmir, Turkey was investigated using gas chromatography–mass spectrometry, and these data were examined in relation with the odor concentrations. Several volatile organic compounds (VOCs) were identified and quantified at five sampling sites in May and September 2005. Detected VOCs were monoaromatics (0.09–47.42 gm -3 ), halogenated compounds (0.001–62.91 gm -3 ), aldehydes (0.01–38.55 gm -3 ), esters (0.01–7.54 gm -3 ), ketones (0.03–67.60 gm -3 ), sulfur/nitrogen containing com- pounds (0.03–5.05 gm -3 ), and volatile fatty acids (VFAs) (0.05–43.71 gm -3 ). High levels of aldehydes (propanal up to 38.55 gm -3 ) and VFAs (formic acid up to 43.71 gm -3 ) were measured in May. However, VOC concentrations were relatively low in September. The monoaro- matics and halogenated compounds were the abundant VOCs in landfill air for the both sampling periods. The benzene-to-toluene (B:T) ratio at the landfill site was significantly lower than urban areas indicating the presence of higher amounts of toluene in landfills compared to traffic exhaust rich urban areas. A statistically significant linear relationship was found between odor concentrations determined by olfactometry and total VOC concentrations. The relationships of odor concentrations with the different groups of chemicals were also examined using a step-wise multiple regression analysis. It was found that the concentrations of aldehydes, ketones, and esters are the best estimators, explaining 96% of the variability in odor concentrations (r 2 = 0.96, n = 10, P< 0.01). © 2006 Elsevier B.V. All rights reserved. Keywords: Odor concentration; Olfactometry; Volatile organic compounds; Landfill odors; GC–MS; Benzene-to-toluene ratio 1. Introduction Municipal solid waste (MSW) landfills are potential sources of offensive odors creating annoyance in urban areas [1]. Odor pollution has become a growing concern during the last decades for urban communities located near or downwind of MSW landfills. The annoying odors released to the atmosphere from landfills may cause decreased quality of life and possibly more negative consequences on human health and welfare [2]. Landfill gases are generated naturally by anaerobic decompo- sition of wastes. Summer is the critical season for such processes as the higher temperatures and richer organic matter in the waste composition favor anaerobic processes leading to waste decom- position. Landfill gases are mainly composed of methane and carbon dioxide. They also include some non-methane volatile ∗ Corresponding author. Tel.: +90 232 453 0922; fax: +90 232 453 0922. E-mail address: fdincer@deu.edu.tr (F. Dincer). organic compounds (VOCs) [3]. Although the amounts of VOCs are usually below 1% (by volume) of the total emissions, their adverse effects on the environment are not negligible. For exam- ple, a range of chlorofluorocarbon compounds contribute to both stratospheric ozone depletion and greenhouse effect [4]. Prolonged exposure to the landfill gases containing benzene, toluene, and xylenes (BTX) and chlorinated hydrocarbons can cause severe health problems especially on landfill operators [5]. Alkylbenzenes, limonene, certain esters, and organosulfur compounds are mainly responsible for odor nuisance [6]. Odor measurement techniques have been based on sensory analysis using human nose as a detector. Compared to the human nose, many of the chemical detectors are not as sensitive for the odor active compounds [7]. Olfactometry based on the human perception capacity is the most common method for measur- ing odor concentrations. In this method, odor measurement is carried out by presenting a sample of odorous air in a range of dilutions using neutral air to an independent panel of selected and trained persons, and statistically treating the responses from 0021-9673/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2006.04.075