Chemical characterization of odorous gases at a landfill site by gas chromatography-mass spectrometry.

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 microg m(-3)), halogenated compounds (0.001-62.91microg m(-3)), aldehydes (0.01-38.55 microg m(-3)), esters (0.01-7.54 microg m(-3)), ketones (0.03-67.60 microg m(-3)), sulfur/nitrogen containing compounds (0.03-5.05 microg m(-3)), and volatile fatty acids (VFAs) (0.05-43.71 microg m(-3)). High levels of aldehydes (propanal up to 38.55 microg m(-3)) and VFAs (formic acid up to 43.71 microg m(-3)) were measured in May. However, VOC concentrations were relatively low in September. The monoaromatics 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 (r2 = 0.96, n = 10, P < 0.01).