| 1. |
- Agrell, Cecilia, et al.
(författare)
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PCB congeners in precipitation, wash out ratios and depositional fluxes within the Baltic Sea region, Europe
- 2002
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Ingår i: Atmospheric Environment. - 1352-2310. ; 36:2, s. 371-383
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Tidskriftsartikel (refereegranskat)abstract
- Concentrations of PCB congeners were determined in precipitation and the annual and seasonal depositional fluxes were calculated for 16 (mostly rural) stations around the Baltic Sea during 1990-1993. The concentrations of individual congeners in precipitation were found to be influenced by atmospheric concentrations of PCBs, ambient temperature, precipitation volume and physico-chemical properties of the compounds. Median levels of PCBs in precipitation differed one order of magnitude between stations. When analyzing all data together to obtain regional trends, concentrations of PCBs in precipitation decreased with increasing temperature. This relationship was the same for all stations but differed in the magnitude of the slope for individual congeners. Low chlorinated PCB congeners showed steeper slopes for the temperature relationship than did high chlorinated congeners, a result explained by high atmospheric concentrations of the low chlorinated congeners during low temperatures. Annual wash out ratios were between 31 and 72 x 103 and tended to be higher for the high chlorinated congeners. Wash out ratios decreased with increasing temperature for all congeners except PCB-33. At snow scavenging events, the wash out ratio of PCBs increased with a factor of 2. Latitudinal trends for PCB concentrations in precipitation and deposition were generally not statistically significant. The calculated yearly deposition of PCBs to the Baltic Sea was 390 and 5-18 kg for individual congeners, with PCB-138 having the highest flux. Deposition of PCB congeners varied seasonally, with a factor between 2 and 3, and was generally highest during fall. Relatively higher deposition of low chlorinated congeners compared to high chlorinated congeners was found during winter. (C) 2002 Elsevier Science Ltd. All rights reserved.
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| 2. |
- Jonsson, P, et al.
(författare)
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Effects of litter size on pup defence and weaning success of neighbouring bank vole females
- 2002
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Ingår i: Canadian Journal of Zoology. - 1480-3283. ; 80:1, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Reproductive success of territorial female mammals depends partly on their capability to defend their young from conspecific intruders. However, how this is related to the characteristics of females and their litter sizes is largely unknown. The defence activity of 25 female bank voles (Clethrionomys glareolus) in relation to the number of offspring was studied in a behavioural arena by manipulating litter sizes (-2 pups or +2 pups). Infanticidal male bank voles were used as intruders-predators. Moreover, the weaning success (weaned at least one offspring or none) of 15 pairs of neighbouring females was investigated in a large indoor runway system. In each pair of females, the litter size of one female was reduced (-2 pups) and the litter size of the other enlarged (+2 pups). Defence activity of females increased with the number of offspring and the mother's size. However, weaning success of neighbours was related only to their body mass, and litter-size manipulation did not affect weaning success. Present results indicate that, although bank vole females increase their defence intensity with an increase in the number of pups, the weaning success of neighbouring females may be primarily determined by their size and dominance rank.
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| 3. |
- Klaassen, M, et al.
(författare)
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Metabolic rate and thermal conductance of lemmings from high-arctic Canada and Siberia
- 2002
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Ingår i: Journal of Comparative Physiology B. - : Springer Science and Business Media LLC. - 0174-1578. ; 172:5, s. 371-378
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Tidskriftsartikel (refereegranskat)abstract
- The arctic climate places high demands on the energy metabolism of its inhabitants. We measured resting (RMR) and basal metabolic rates (BMR), body temperatures, and dry and wet thermal conductances in summer morphs of the lemmings Dicrostonyx groenlandicus and Lemmus trimucronatus in arctic Canada, and the BMR of D. torquatus, D. groenlandicus, L. sibiricus, L. bungei and L. trimucronatus in Siberia. In contrast to previous studies the data were collected on animals that had spent only a limited time in captivity. All parameters were analysed in relation to the variations in body mass (20-90 g). Body temperature and BMR were lower in D. groenlandicus than L. trimucronatus, which coincides with greater longevity in the former species. Wet and dry thermal conductances of both species were similar and comparable with those of other Myomorpha (mouse-type rodents), indicating no evidence for a previously claimed lower thermal conductance in lemmings. BMR in lemmings appeared to be higher than in other Arvicolidae (voles, lemmings and muskrats), which could relate to their typically high-latitude distribution. However, the more southerly living Lemmus species had higher BMR than the more northerly living Dicrostonyx species, which may be explained by the former having a relatively low-quality diet.
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