@article {3206, title = {Spring thaw ionic pulses boost nutrient availability and microbial growth in entombed Antarctic Dry Valley cryoconite holes}, journal = {Frontiers in Microbiology}, volume = {5}, year = {2014}, month = {12/2014}, abstract = {

The seasonal melting of ice entombed cryoconite holes on McMurdo Dry Valley glaciers provides oases for life in the harsh environmental conditions of the polar desert where surface air temperatures only occasionally exceed 0\°C during the Austral summer. Here we follow temporal changes in cryoconite hole biogeochemistry on Canada Glacier from fully frozen conditions through the initial stages of spring thaw toward fully melted holes. The cryoconite holes had a mean isolation age from the glacial drainage system of 3.4 years, with an increasing mass of aqueous nutrients (dissolved organic carbon, total nitrogen, total phosphorus) with longer isolation age. During the initial melt there was a mean nine times enrichment in dissolved chloride relative to mean concentrations of the initial frozen holes indicative of an ionic pulse, with similar mean nine times enrichments in nitrite, ammonium, and dissolved organic matter. Nitrate was enriched twelve times and dissolved organic nitrogen six times, suggesting net nitrification, while lower enrichments for dissolved organic phosphorus and phosphate were consistent with net microbial phosphorus uptake. Rates of bacterial production were significantly elevated during the ionic pulse, likely due to the increased nutrient availability. There was no concomitant increase in photosynthesis rates, with a net depletion of dissolved inorganic carbon suggesting inorganic carbon limitation. Potential nitrogen fixation was detected in fully melted holes where it could be an important source of nitrogen to support microbial growth, but not during the ionic pulse where nitrogen availability was higher. This study demonstrates that ionic pulses significantly alter the timing and magnitude of microbial activity within entombed cryoconite holes, and adds credence to hypotheses that ionic enrichments during freeze-thaw can elevate rates of microbial growth and activity in other icy habitats, such as ice veins and subglacial regelation zones

}, keywords = {LTER-MCM}, doi = {10.3389/fmicb.2014.00694}, url = {http://journal.frontiersin.org/article/10.3389/fmicb.2014.00694/abstract}, author = {Telling, J. and Alexandre M. Anesio and Martyn Tranter and Andrew G Fountain and Thomas H. Nylen and Hawkings, Jon and Singh, Virendra B. and Kaur, Preeti and Musilova, Michaela and Wadham, J. L.} } @article {1166, title = {Snow in the McMurdo Dry Valleys, Antarctica.}, journal = {International Journal of Climatology}, volume = {30}, year = {2010}, month = {04/2010}, pages = {633-642}, type = {Journal}, abstract = {

Snowfall was measured at 11 sites in the McMurdo Dry Valleys to determine its magnitude, its temporal changes, and spatial patterns. Annual values ranged from 3 to 50 mm water equivalent with the highest values nearest the coast and decreasing inland. A particularly strong spatial gradient exists in Taylor Valley, probably resulting from local uplift conditions at the coastal margin and valley topography that limits migration inland. More snow occurs in winter near the coast, whereas inland no seasonal pattern is discernable. This may be due, again, to local uplift conditions, which are common in winter. We find no influence of the distance to the sea ice edge. Katabatic winds play an important role in transporting snow to the valley bottoms and essentially double the precipitation. That much of the snow accumulation sublimates prior to making a hydrologic contribution underscores the notion that the McMurdo Dry Valleys are indeed an extreme polar desert. Copyright \© 2009 Royal Meteorological Society

}, keywords = {LTER-MCM, Biggie}, doi = {10.1002/joc.1933}, author = {Andrew G Fountain and Thomas H. Nylen and Andrew Monaghan and Hassan J. Basagic and David Bromwich} } @article {1204, title = {Hydrologic response to extreme warm and cold summers in the McMurdo Dry Valleys, East Antarctica}, journal = {Antarctic Science}, volume = {20}, year = {2008}, month = {05/16/2008}, pages = {499-509}, type = {Journal}, keywords = {LTER-MCM, Climate Response, streams}, doi = {10.1017/S0954102008001272}, author = {Peter T. Doran and Christopher P. McKay and Andrew G Fountain and Thomas H. Nylen and Diane M. McKnight and Chris Jaros and John E. Barrett} } @article {1227, title = {Temporal variations in physical and chemical features of cryoconite holes on Canada Glacier, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Geophysical Research}, volume = {113}, year = {2008}, pages = {G01S92}, keywords = {LTER-MCM}, doi = {10.1029/2008JG000698}, author = {Andrew G Fountain and Thomas H. Nylen and Martyn Tranter and Bagshaw, Elizabeth} } @article {1259, title = {The aeolian flux of calcium, chloride and nitrate to the McMurdo Dry Valleys landscape: Evidence from snow pit analysis}, journal = {Antarctic Science}, volume = {18}, year = {2006}, pages = {497-505}, keywords = {LTER-MCM}, doi = {LTER}, author = {Witherow, R and Bertler, N and Kathleen A. Welch and W. Berry Lyons and Paul A. Mayewski and Sneed, S and Thomas H. Nylen and Handley, M and Andrew G Fountain} } @article {1267, title = {Experimental investigations into processes controlling stream and hyporheic temperatures, Fryxell Basin, Antarctica}, journal = {Advances in Water Resources}, volume = {29}, year = {2006}, pages = {130-153}, keywords = {LTER-MCM}, doi = {LTER}, author = {Cozzetto, K and Diane M. McKnight and Thomas H. Nylen and Andrew G Fountain} } @article {1270, title = {Glacier mass balances (1993-2001) Taylor Valley, McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {52}, year = {2006}, pages = {451}, keywords = {LTER-MCM}, doi = {LTER}, author = {Andrew G Fountain and Thomas H. Nylen and MacClune, K and Gayle L. Dana} } @article {1292, title = {The chemical composition of runoff from Canada Glacier, Antarctica: implications for glacier hydrology during a cool summer}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {15-19}, keywords = {LTER-MCM}, doi = {LTER}, author = {Martyn Tranter and Andrew G Fountain and W. Berry Lyons and Thomas H. Nylen and Kathleen A. Welch} } @article {1290, title = {An index model of stream flow at below freezing-temperatures in Taylor Valley, Antarctica}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, month = {01/2005}, pages = {76-82}, type = {Journal}, keywords = {LTER-MCM, Climate Response}, doi = {10.3189/172756405781813519}, url = {http://dx.doi.org/10.3189/172756405781813519}, author = {Ebnet, A and Andrew G Fountain and Thomas H. Nylen} } @article {1303, title = {The origin of channels on lower Taylor Glacier, McMurdo Dry Valleys Antarctica and their implication for water runoff}, journal = {Annals of Glaciology}, volume = {40}, year = {2005}, pages = {1-7}, keywords = {LTER-MCM}, doi = {LTER}, author = {Johnston, R and Andrew G Fountain and Thomas H. Nylen} } @article {1323, title = {The Biodiversity and Biogeochemistry of Cryoconite Holes from McMurdo Dry Valley Glaciers, Antarctica}, journal = {Arctic, Antarctic, and Alpine Research}, volume = {36}, year = {2004}, pages = {84-91}, keywords = {LTER-MCM}, author = {Porazinska, D and Andrew G Fountain and Thomas H. Nylen and Martyn Tranter and Ross A. Virginia and Diana H. Wall} } @article {1326, title = {Climatology of Katabatic Winds in the McMurdo Dry Valleys, Southern Victoria Land, Antarctica}, journal = {Journal of Geophysical Research}, volume = {109}, year = {2004}, keywords = {LTER-MCM}, author = {Thomas H. Nylen and Andrew G Fountain and Peter T. Doran} } @article {1327, title = {Cryoconite holes on polar glaciers and their importance for meltwater runoff}, journal = {Journal of Glaciology}, volume = {50}, year = {2004}, pages = {25-45}, keywords = {LTER-MCM}, author = {Andrew G Fountain and Martyn Tranter and Thomas H. Nylen and Booth, D and Karen J. Lewis} } @article {1321, title = {Evolution of cryoconite holes and their contribution to meltwater runoff from glaciers in the McMurdo Dry Valleys, Antarctica}, journal = {Journal of Glaciology}, volume = {50}, year = {2004}, month = {01/2004}, pages = {35-45}, keywords = {LTER-MCM}, doi = {10.3189/172756504781830312}, author = {Andrew G Fountain and Martyn Tranter and Thomas H. Nylen and Karen J. Lewis and Derek R. Mueller} } @article {1374, title = {Valley floor climate observations from the McMurdo Dry Valleys, Antarctica, 1986-2000}, journal = {Journal of Geophysical Research}, volume = {107}, year = {2002}, month = {12/2002}, pages = {4772-4784}, type = {Journal}, abstract = {

Climate observations from the McMurdo dry valleys, East Antarctica are presented from a network of seven valley floor automatic meteorological stations during the period 1986 to 2000. Mean annual temperatures ranged from \−14.8\°C to \−30.0\°C, depending on the site and period of measurement. Mean annual relative humidity is generally highest near the coast. Mean annual wind speed increases with proximity to the polar plateau. Site-to-site variation in mean annual solar flux and PAR is due to exposure of each station and changes over time are likely related to changes in cloudiness. During the nonsummer months, strong katabatic winds are frequent at some sites and infrequent at others, creating large variation in mean annual temperature owing to the warming effect of the winds. Katabatic wind exposure appears to be controlled to a large degree by the presence of colder air in the region that collects at low points and keeps the warm less dense katabatic flow from the ground. The strong influence of katabatic winds makes prediction of relative mean annual temperature based on geographical position (elevation and distance from the coast) alone, not possible. During the summer months, onshore winds dominate and warm as they progress through the valleys creating a strong linear relationship (r2\ = 0.992) of increasing potential temperature with distance from the coast (0.09\°C km\−1). In contrast to mean annual temperature, summer temperature lends itself quite well to model predictions, and is used to construct a statistical model for predicting summer dry valley temperatures at unmonitored sites.

}, keywords = {LTER-MCM, Biggie}, doi = {10.1029/2001JD002045}, author = {Peter T. Doran and Christopher P. McKay and Gary D. Clow and Gayle L. Dana and Andrew G Fountain and Thomas H. Nylen and W. Berry Lyons} } @inbook {1426, title = {Climate and hydrologic variations and implications for lake and stream ecological response in the McMurdo Dry Valleys, Antarctica}, booktitle = {Climate Variability and Ecosystem Response at Long Term Ecological Research Sites}, year = {2000}, pages = {174-195}, publisher = {Oxford University Press}, organization = {Oxford University Press}, keywords = {LTER-MCM}, author = {Kathleen A. Welch and W. Berry Lyons and Diane M. McKnight and Chris Jaros and Andrew G Fountain and Thomas H. Nylen and Peter T. Doran and Clive Howard-Williams}, editor = {D. Greenland and D. G. Goodin and R. C. Smith} }