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Studies were carried out in 2004-2007 in two apiaries which varied in flow terms. In the midsummer, bees from P apiary collected pollen and nectar from mixed forest, pastures and fields, while bees from NJ apiary worked white mustard and weeds on wastelands. The winter scatters were collected for investigations every year, after the first bees’ flight. HCH concentration in bees from P apiary ranged from 0.00102 μg/g of lipid matter (l.m.) to 0.00170 μg/g l.m. and the total amount of DDT was 0.00970-0.03530 μg/g l.m. In the bees’ scatter from NJ apiary the HCH level was 0.00091-0.00530 μg/g l.m. and the total amount of DDT was 0.00171-0.00424 μg/g l.m. Between 2004 and 2007 the level of chlorinated hydrocarbons, mostly HCH, in both apiaries (especially in NJ) was reduced. It shows a progressive decomposition of this compound in the environment. However, the DDT content in the scatter from P apiary in the first two years of investigations as well as in 2007 was 0.00970-0.01280 μg/g l.m., whereas in 2006 it increased up to 0.03530 μg/g l.m. So significant an increase (2.7-3.6 times) in the DDT content towards the end of the investigated period seems to indicate a periodical infiltration of this compound into the region of the Pisz forest, probably from Africa, where this pesticide is still applied for mosquito control.
The aim of this paper was to compare the residues of chlorinated hydrocarbons in bees from one of the apiaries of Piska Forest in 1996-2005. Furthermore, the content of HCH and DDT was examined in bees from this apiary where, in 2005, a very intensive cultivation of rape seed took place and by 1989 a large amount of pesticides had been applied. It was ascertained that in bees from P. apiary, which for more than ten years had been users of the same field crops (berries, lime-tree), the HCH level decreased from 0.0127 µg/g of l.s. (1996) to 0.0016 µg/g of l.s. (2005), whereas the DDT content was not reduced. This fact seems to indicate a considerably more rapid HCH decomposition in the environment. In bees staying nearly 3 weeks at the site of rape cultivation and examined after their return to the maternal apiary the content of HCH was 0.0236 µg/g of l.s. which was 15 times higher than in bees staying at the same place. The obtained results indicate that chlorinated hydrocarbons are still occurring in the environment and their amount depends on the type of pesticide used. It seems that on sandy soils the decomposition of HCH is considerably more rapid than on heavy clay soils. The diverse level of DDT in bees in P. apiary testifies to a considerable concentration of this pesticide in Piska Forest and to its slow decomposition in the environment or its permanent penetration with air streams from other regions of the world.
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