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Needles of two conifer species, Picea abies and Pinus nigra, were used as passive samplers for monitoring air contamination by sampling at increasing distances from a suspected point source of DDT. Needle concentrations declined with increasing distance downwind of the point source allowing to identify spatial and temporal trends of accumulation. This suggested that conifer needles are effective biomonitors of contamination levels in areas characterized by the presence of semi-volatile substances. Differences in uptake were apparent between the species. Needle morphology and structure were studied with scanning electron microscope (SEM) as were dimensional parameters (surface area, volume). The results suggest that the concentrations depend on a mechanism involving the inner structure of the needles, specifically the number and accessibility of resin channels rather than their surface area. Pine needles have more channels with greater accessibility than spruce. The results suggest that spruce is more suitable for short term measurement while pine for determining long term cumulative exposure.  相似文献   
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Fetal ovarian cysts can be managed in different ways, depending upon their size and clinical course: conservatively, by open surgery or by postnatal transabdominal puncture. However, in cases of large cysts detected antenatally and affecting the ongoing pregnancy, in utero transabdominal puncture can be undertaken, without increase of risk. A case of such a puncture at 30 weeks gestation is reported.  相似文献   
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Environmental Science and Pollution Research - Environmental monitoring in Northern Italy, one of the most polluted areas in Europe, is of paramount importance. Leaf monitoring throughout magnetic...  相似文献   
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