科研之友
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摘要
Freezing temperatures, desiccation and high levels of solar radiation make the surface of the Antarctic ice sheet one of Earth%26apos;s harshest habitats. However, our study in the Vestfold Hills area of East Antarctica shows that favourable conditions for microbial production become established just beneath the surface of blue-ice areas, which collectively cover about 2% of the ice-sheet periphery. Their translucent, wind-polished surface allows solar heating to create meltwater in a greenhouse-type environment at depths of up to 1 m. Melting is intensified around dark debris particles, or cryoconite, where we found microbiological activity to be greatest. Rates of photosynthesis (average 2060 ng C (g cryoconite)(-1) d(-1)) were adapted to low light intensities (similar to 10% of surface irradiance values) and most likely dominated by cyanobacteria and Chloroplastida. A heterotrophic bacterial community was also found to be active within the cryoconite, although average bacterial growth rates (5.7 ng C (g cryoconite)(-1) d(-1)) were far lower than average community respiration (1870 ng C (g cryoconite)(-1) d(-1)). The majority of the respired carbon was most likely associated with the autotrophs and several protists. Therefore, blue-ice areas constitute oases for microbial life around the periphery of Earth%26apos;s coldest ice sheet.
- 出版日期2013
