engleski

Distribution of pyrolytic and diagenetic polycyclic aromatic hydrocarbons in a municipal solid waste landfill

The composition of contaminants in municipal landfills and underlying soils is rather complex and comprises numerous specific organic compounds of xenobiotic and biological origin as well as their transformation products that are formed in the landfill. The present study was conducted on the main landfill of the city of Zagreb, Croatia, which contains over 5 million tons of mixed waste, mostly domestic refuse, but with a significant contribution of industrial waste. The polycyclic aromatic hydrocarbons (PAH), which belong to the most common classes of organic contaminants in the landfill, were applied as molecular markers to differentiate contributions of biological and anthropogenic waste and to indicate the characteristic redox zones in the landfill. The aromatic hydrocarbon fraction from the solid waste, as assessed by gas chromatography/mass spectrometry, was strongly dominated by anthropogenic hydrocarbons having fossil and/or pyrolytic origins, however, soil and aquifer sediment below the landfill had a markedly different hydrocarbon composition with derivatives of abietic acid as the most prominent constituents. A strong reduction of anthropogenic PAH indicated a high efficiency of biological transformations during the vertical infiltration, encompassing a sequence of different redox zones in the landfill. In contrast, the concentration of abietane hydrocarbons, which comprised a whole suite of increasingly aromatic intermediates, including the final product retene, strongly increased in the lower sections of the landfill as a consequence of their formation under methanogenic conditions. Nevertheless, the concentration of retenoid compounds in the aquifer, immediately below the landfill, was low, most probably due to a very strong adsorption to the soil.

polycyclic aromatic hydrocarbons; diagenesis; organic matter; landfill

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