@article {4489, title = {Nutrient uptake in the supraglacial stream network of an Antarctic glacier}, journal = {Journal of Geophysical Research: Biogeosciences}, year = {2020}, month = {08/2020}, abstract = {

In polar regions, where many glaciers are cold-based (frozen to their beds), biological communities on the glacier surface can modulate and transform nutrients, controlling downstream delivery. However, it remains unclear whether supraglacial streams are nutrient sinks or sources and the rates of nutrient processing. In order to test this, we conducted tracer-injections in three supraglacial streams (62 to 123 m long) on Canada Glacier in the Taylor Valley, of the McMurdo Dry Valleys, Antarctica. We conducted a series of additions including: nitrate (N), N + phosphate (P), N+ P + glucose (C), and N+C. In two reaches, N-only additions resulted in N uptake. The third reach showed net N release during the N-only addition, but high N uptake in the N+P addition, indicating P-limitation or N+P co-limitation. Co-injecting C did not increase N-uptake. Additionally, in these systems at low N concentrations the streams can be a net source of nitrogen. We confirmed these findings using laboratory-based nutrient incubation experiments on sediment collected from stream channels on Canada Glacier and two other glaciers in the Taylor Valley. Together, these results suggest there is active biological processing of nutrients occurring in these supraglacial streams despite low sediment cover, high flow velocities and cold temperatures, modifying the input signals to proglacial streams. As glaciers world-wide undergo rapid change, these findings further our understanding of how melt generated on glacier surfaces set the initial nutrient signature for subglacial and downstream environments.

}, keywords = {LTER-MCM, McMurdo Dry Valleys, nitrogen, nutrient tracers, nutrient uptake, sediments, supraglacial streams}, doi = {10.1029/2020JG005679}, url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005679}, author = {Bergstrom, Anna J. and Michael N. Gooseff and Singley, Joel G. and Cohen, Matthew J. and Kathleen A. Welch} } @article {4106, title = {The impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited}, journal = {Elementa: Science of the Anthropocene}, volume = {6}, year = {2018}, month = {04/2018}, abstract = {

Fossil fuel use associated with scienti c activities in the Taylor Valley, Antarctic has been examined to determine the fluxes of particulate organic and elemental carbon and nitrogen as well as NOx\ for the 2015\–2016 austral summer field season. These carbon and nitrogen fluxes are compared to our previously published calculations for the 1997\–1998 austral summer. In addition, we compile fossil fuel usage and resulting C and N fluxes from the major field camp in Taylor Valley, Lake Hoare Camp (LHC) from the late 1990\’s through 2017. In general, the annual fluxes do vary from year to year, but there is no significant trend, at least during the primary summer field season. There is indication that increasing the length of scientific operations does increase the C and N inputs via fossil fuel burning. This works supports our original results demonstrating that over long periods of time the anthropogenic flux of N from local fossil fuel burning could become quantitatively important in the region. Although the particulate C fluxes remain very low, the recent finding of black carbon in the Taylor Valley landscape indicates more on-going monitoring of the source of this material is merited.

}, keywords = {LTER-MCM, carbon dynamics, emissions, fossil fuels, helicopter, management, McMurdo Dry Valleys, nitrogen, science activites}, doi = {10.1525/elementa.288}, url = {https://www.elementascience.org/article/10.1525/elementa.288/}, author = {W. Berry Lyons and Saelens, Elsa D. and Kathleen A. Welch} }