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Abstrakt

A two-year-long data set of air temperature from four different altitudes above Petuniabukta, central Spitsbergen, was analysed in order to assess the near-surface temperature lapse rates and the relative frequency of air temperature inversion occurrence. From August 2013 to July 2015, air temperatures at adjacent altitudes in Petuniabukta were strongly correlated. The near-surface lapse rates in all three layers differed significantly both from the average lapse rate in the international standard atmosphere (0.65°C 100 m-1) and the lapse rate calculated by linear regression. A pronounced annual cycle was detected in the lowermost air layer (from 23 to 136 m a.s.l.) with a variable near-surface lapse rate in the winter months, while an annual cycle was not apparent in the air layers above 136 m a.s.l. The lowermost layer was also characterized by a notable daily cycle in near-surface lapse rate in spring and autumn. Air temperature inversions occurred in up to 80% of the study period in the air layer below 136 m a.s.l., with the relative frequency being much lower in the other two air layers. The air temperature inversions lasted as long as 139 hours. A case study revealed that one of the strongest air temperature inversions was connected to an area of lower pressure gradients at the 850-hPa pressure level.
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Abstrakt

This paper presents the first results of measurements of global solar radiation, albedo, ground surface and 2−m air temperature, relative humidity, and wind speed and direction carried out in the central part of Spitsbergen Island in the period 2008–2010. The study site was located on the coastal ice−free zone of Petuniabukta (north−western branch of Billefjorden), which was strongly affected by local topography, character of the ground surface, and sea ice extent. Temporal analysis of the selected meteorological parameters shows both strong seasonal and inter−diurnal variation affected by synoptic−scale weather systems, channelling and drainage effects of the fjords and surrounding glaciers. The prevailing pattern of atmospheric circulation primarily determined the variation in global solar radiation, wind speed, ground surface and 2−m air temperatures. Furthermore, it was found that thermal differences between Petuniabukta and the nearest meteorological station (Svalbard Lufthavn) differ significantly due to differences in sea ice concentrations and ice types in the fjords during the winter and spring months.
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Abstrakt

In order to simulate the warming effects on Arctic wetlands, three passive open−top chambers (OTCs) and three control cage−like structures (CCSs) equipped with soil temperature and soil volumetric water content (VWC) probes for continuous micro− climatic measurements were installed in a wet hummock meadow, Petuniabukta, Billefjorden, central Spitsbergen, in 2009. The warming effects on primary productivity were investigated during summer seasons 2009 and 2010 in cyanobacterial colonies of Nostoc commune s.l., which plays an important role in the local carbon and nitrogen cycles. The microclimatic data indicated that the effect of OTCs was dependent on microtopography. During winter, two short−term snow−thaw episodes occurred, so that liquid water was available for the Nostoc communities. Because of the warming, the OTC hummock bases remained unfrozen three weeks longer in comparison to the CCSs and, in spring, the OTC hummock tops and bases exceeded 0 ° C several days earlier than CCS ones. Mean summer temperature differences were 1.6 ° C in OTC and CCS hummock tops, and 0.3 ° Cinthe OTC and CCS hummock bases. The hummock tops were drier than their bases; however the VWC difference between the OTCs and CCSs was small. Due to the only minor differences in the microclimate of OTC and CCS hummock bases, where the Nostoc colonies were located, no differences in ecophysiological characteristics of Nostoc colonies expressed as photochemistry parameters and nitrogenase activities were detected after two years exposition. Long−term monitoring of Nostoc ecophysiology in a manipulated environment is necessary for understanding their development under climate warming.
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Abstrakt

We studied dynamic changes in anthropogenic bacterial communities at a summer−operated Czech research base (the Mendel Research Station) in the Antarctic during 2012 and 2013. We observed an increase in total numbers of detected bacteria between the beginning and the end of each stay in the Antarctic. In the first series of samples, bacteria of Bacillus sp. predominated. Surprisingly, high numbers of Gram−positive cocci and coli − forms were found (including opportunistic human pathogens), although the conditions for bacterial life were unfavourable (Antarctic winter). In the second series of samples, coliforms and Gram−positive cocci predominated. Dangerous human pathogens were also detected. Yersinia enterocolitica was identified as serotype O:9. Antibiotic susceptibility testing showed medium−to−high resistance rates to ampicillin, cefalotin, cefuroxime, amoxicillin−clavulanate and gentamicin in Enterobacteriaceae. 16S rRNA sequencing showed high rates of accordance between nucleotide sequences among the tested strains. Three conclusions were drawn: (1) Number of anthropogenic bacteria were able to survive the harsh conditions of the Antarctic winter (inside and outside the polar station). Under certain circumstances ( e.g. impaired immunity), the surviving bacteria might pose a health risk to the participants of future expeditions or to other visitors to the base. (2) The bacteria released into the outer environment might have impacts on local ecosystems. (3) New characteristics ( e.g. resistance to antibiotics) may be introduced into local bacterial communities.
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