Chemical characteristics of hydrologically distinct cryoconite holes in coastal Antarctica

Abstract

Cryoconite holes play a significant role in the nutrient cycling on glaciers and can be regarded as a storehouse of nutrients that are generated through microbial and photochemical activities. In this work, the chemical characteristics of hydrologically connected and isolated cryoconite holes from three geographically distinct regions of coastal Antarctica, namely Larsemann Hills, Amery Ice Shelf and central Dronning Maud Land were studied. Major ions (Na + , K + , Mg 2+ , Ca 2+ , Cl − , SO 4 2− and NO 3 − ) andtotal organic carbon in the hydrologically isolated, closed cryoconite holes showed significantly higher enrichment (6-26 times and 9 times, respectively) over the conservative tracer ion Cl − possibly due to sediment dissolution and microbial synthesis during isolation period. In contrast, depletion of major ions and organic carbon were observed in the open, hydrologically connected holes due to their discharge from the cryoconite holes through interconnected streams. This study suggests that the contribution of cryoconite holes to the nutrient and microbial transport to downstream environments may vary with the extent of hydrological connectivity by virtue of the fact that nutrients and organic carbon which accumulate in the isolated cryoconite holes during isolation could get washed to downstream environments in the event that they get connected through surface or subsurface melt channels.

Cryoconite Hole Location in East-Antarctic Untersee Oasis Shapes Physical and Biological Diversity

“…For example the build-up of dark organic matter (OM) within CHs enhances local supraglacial melt rates (Takeuchi et al, 2001) and hence increases the water availability within CHs. Further, in comparison to hydrologically connected CHs, isolated ones promote recycling and production of nutrients and hence support downstream ecosystems once being re-connected to a hydrological system (Bagshaw et al, 2007;Samui et al, 2018). Such a nutrient flush can be caused by a warming event as recorded in the McMurdo Dry Valleys (MDVs) that led to a temporarily increased primary production in Lake Fryxell (Bagshaw et al, 2013).…”

“…Hence, compared to the "prime study sites" such as the MDVs, little is known about the microbial ecology in CHs from e.g., Queen Maud Land (East-Antarctica). There, only a handful of studies were conducted (e.g., Obbels et al, 2016;Samui et al, 2018;Lutz et al, 2019;Weisleitner et al, 2019b) although this pristine area exceeds the size of Greenland and hence is under-represented on a geographical scale. One of the main study areas in Queen Maud Land is Lake Untersee with the adjacent Anuchin glacier from which microbial diversity and various inoculation vectors have been investigated, however, there is no information about activity within their ice-sealed environments.…”

Fate of Dissolved Organic Carbon in Antarctic Surface Environments During Summer

“…Organic carbon in sediments was analyzed using a TOC analyzer (TOC‐V series SSM‐5000A from Shimadzu) with a nondispersive infrared detector (Samui et al, 2018). Glucose was used as the carbon standard, and 100 mg sample was used for analysis.…”

“…The experimental site at South Grovnes is located in a coastal valley surrounded by hills at the northern and southern regions, an ice wall on the eastern side and the Thala fjord on the western side. The CHs in this region are hydrologically connected with the supraglacial meltwater (Samui et al, 2018). Details of sampling location are provided in Table S1 in the supporting information.…”

Palaeoclimatic records from Antarctica and Southern Ocean: A review of Indian contributions

“…Biochemical and microbial characteristics of various supraglacial ecosystems such as, snow, meltwater streams, blue ice and cryoconite holes together with their role in biogeochemical cycling on the glacier surface was systematically studied during the past decade. The studies on cryoconite hole and surface snow samples collected from coastal Antarctica has shown that the supraglacial environments contain a substantial reservoir of organic carbon with inputs from microbial, marine and terrestrial sources (Antony et al, 2014;Samui et al, 2017Samui et al, , 2018. The dissolved organic matter (DOM) transformations by supraglacial microbes revealed that both autochthonous and allochthonous DOM is highly bioavailable and is transformed by resident microbial communities through parallel processes of degradation and synthesis .…”