Experiment was carried out using 12 colonies of honey bees bred in hives located near an extraurban crossroad. We analyzed the Pb, Cd and Zn deposited on the bee's surfaces and the heavy metal accumulation in the foragers, dead bees, honey products and some environmental markers during nine weeks of the experiment. Results showed a large amount of Zn and Cd on the bee's surface as a consequence of atmospheric fallout, whereas Pb seems to be either water-extractable and/or likely accumulated in the body of the insect. Dead bees expelled from the hives displayed a progressive accumulation of all heavy metals during the experimental period. Royal jelly and honey contained large amounts of heavy metals. In particular, we found a linear relationship between Cd in the honey and that found in flowers of Trifolium pratense L. Results obtained suggested that honey bee products and the examined environmental markers may be considered useful parameters to assess the presence of environmental contaminants, whereas the measurements of heavy metals in the dead bees may be considered a suitable tool also to verify a possible dynamics of accumulation of pollutants.
We studied the long-term effects (12 years) of municipal refuse compost addition on the total organic carbon (TOC), the amount and activity of the microbial biomass (soil microbial biomass C, B(C) and metabolic quotient qCO2) and heavy metal bioavaiability in soils as compared to manuring with mineral fertilizers (NPK) and farmyard manure (FYM). In addition, we studied the relationships between among the available fraction [Diethylenetriaminopentacetic acid (DTPA) extractable] of heavy metals and their total content, TOC and B(C). After 12 years of repeated treatments, the TOC and B(C) of control and mineral fertilized plots did not differ. Soils treated with FYM and composts showed a significant increase in TOC and B(C) in response to the increasing amounts of organic C added. Values of the B(C)/TOC ratio ranged from 1.4 to 2, without any significative differences among soil treatments. The qCO2 increased in the organic-amended soil and may have indicated microbial stress. The total amounts of metals in treated soils were lower than the levels permitted by the European Union in agricultural soils. DTPA-extractable metals increased in amended soils in response to organic C. A multiple regression analysis with stepwise selection of variables was carried out in order to discriminate between the influence exerted on DTPA-extractable metals by their total content. TOC and B(C). Results showed that each metal behaved quite differently, suggesting that different mechanisms might be involved in metal bioavailability
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