engleski

PCB and organochlorine pesticides in one-year and two-year old pine needles

Pine needles are covered with wax which acts as a passive sampler for lipophilic compounds from surrounding air. Therefore needles can be used to monitor atmospheric pollution on global, regional and local scales. Intraspecies comparison is important because different plant species accumulate pollutants differently. It is likely that needles of different ages have different pollutant concentrations. The aim of this study was to investigate a pattern and levels of organochlorine pesticides and PCBs in one- and two-year old pine needles from the same branch. Nineteen pine needle samples were collected in urban and semiurban areas across Croatia during January-March 1998. Branches were collected at approximately 1.5 m above the ground level and one- and two-year old needles from the same branch were separated. The following organochlorine comounds were measured: HCB (hexachlorobenzene), alpha-, beta-, gamma-HCH (alpha-, beta-, gamma-hexachlorocyclohexane), DDE (1, 1-dichloro-2, 2-di(4-chlorophenyl)ethene), DDD (1, 1-dichloro-2, 2-di(4-chlorophenyl)ethane, DDT (1, 1, 1-trichloro-2, 2-di(4-chlorophenyl)ethane and seventeen PCB congeners (PCB-28, PCB-52, PCB-60, PCB-74, PCB-101, PCB-105, PCB-114, PCB-118, PCB-123, PCB-138, PCB-153, PCB-156, PCB-157, PCB-167, PCB-170, PCB-180, PCB-189). The method used was described in full by Herceg Romanić and Krauthacker (Bulletin of Environmental Contamination and Toxicology 72 (2004)1203-1210). Breafly, the method consisted in dichloromethane extraction, precipitation of waxes from cooled extracts, saponification under alkaline conditions and adsorption chromatography on multilayer silica column (containing silica gel impregnated with sulphuric acid and silica gel with sodium hydroxide). Qualitative and quantitative analysis was done by HRGC/ECD on two different capillary columns. Each sample was analysed on both columns. Only compounds identified on both columns were evaluated. The detection limit was 0.4 ng/ml for each compound. In both, one- and two-year old needles medians follow the same order: 1) for organochlorine pesticides: gamma-HCH>DDE>HCB>beta-HCH>alpha-HCH>DDT>DDD ; 2) for indicator PCBs: PCB-28>PCB-101>PCB-138>PCB-52>PCB-153>PCB-180 ; 3) for other PCB congeners: PCB-118, PCB-123>PCB-60>PCB-74>PCB-105>PCB-170. The medians of the remaining PCB congeners are 0 with exception of PCB-156 and PCB-114 whose medians in two-year old needles are higher than 0. The incidence and median of all compounds are higher in two-year old needles. Levels of organochlorine compounds in two year old needles are higher due to longer exposure to air pollution. It is therefore necessary to collect samples of the same age, to be able to make a reliable comparison between sites. However, it is sometimes difficult to compare organochlorine compound levels from samples of the same age on a large regional (or global) scale. An alternative could be a comparison of compound pattern.

PCB congeners; organochlorine pesticides; pine needles

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