engleski

Persistent organochlorine compounds in soil of Plitvice Lakes National Park and the city of Varaždin

Organochlorine (OC) pesticides and polychlorinated biphenyls (PCBs) are widespread, highly persistent, and hydrophobic environmental pollutants. They strongly bind to soil/sediment particles, which then may become secondary sources of environmental pollution and animal and human exposure. We studied the occurrence and mass fractions of OC pesticides and PCBs in 16 surface soils collected at four sites within the protected area of the Plitvice Lakes National Park and 16 soils collected at urban and suburban sites of the city of Varaždin. The soils were analysed for 15 pesticides [hexachlorobenzene (HCB), hexachlorocyclohexane isomers (α-, β-, and γ- HCH), DDT-type compounds (4, 4’-DDT, 4, 4’-DDE, 4, 4’-DDD, 2, 4’-DDT), aldrin, dieldrin, endrin, isodrin, heptachlor, heptachlor epoxide, α-endosulfan] and 17 PCBs including seven indicator congeners (no. 28, 52, 101, 118, 138, 153, 180). The air-dried samples were extracted with 1:1 acetone:n-hexane mixture using a microwave-assisted extraction procedure. The extracts were analysed by gas chromatography with electron capture and mass spectrometric detection. Unlike soils from Plitvice, where PCBs were not detected at quantifiable levels in any of the samples, the Varaždin soils contained from one up to nine PCB congeners in a total mass fraction of 0.22 μg/kg to 5.88 μg/kg. The most frequently detected pesticide compounds at both locations were 4, 4’-DDE, HCB, γ-HCH, and 4, 4’-DDT. The highest pesticide mass fraction in the Plitvice soils (35.17 μg/kg) was measured for dieldrin (not detected in any Varaždin soil) and in Varaždin soils for 4, 4’-DDE (5.66 μg/kg). The sum of DDT-type compound mass fractions was significantly higher in Varaždin (0.61 to 14.7 μg/kg, median 2.31 μg/kg) than in Plitvice (0.10 to 2.60 μg/kg, median 0.94 μg/kg) soils. In most soil samples, the 4, 4’-DDE/4, 4’-DDT ratio was higher than one indicating an old input of 4, 4’-DDT, which was largely converted to 4, 4’-DDE. The predominance of γ-HCH over α- HCH in soils at both locations may be a consequence of the locally preferred usage of the former isomer formulation in the past (banned in Croatia more than a decade ago), but also of the new inputs to surface soil via atmospheric transport from remote areas. This work has been supported by Plitvice Lake National Park within the project "Monitoring of Organic and Inorganic Pollutants in the Environment of Plitvice Lake National Park" and by Croatia Science Foundation within the project OPENTOX.

organochlorine pesticides ; polychlorinated biphenyls ; soil

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