@article {4856,
	title = {Differentiating physical and biological storage of nitrogen along an intermittent Antarctic stream corridor},
	journal = {Freshwater Science},
	volume = {42},
	year = {2023},
	month = {09/2023},
	abstract = {<p>In many temperate streams, biological uptake of N acts to attenuate the transport of excess N from allochthonous anthropogenic imports. Relatively few studies have determined how this N uptake relates to the magnitude of physical vs. biological N storage in the stream corridor, especially for intermittent systems where allochthonous N imports are often low and N transport may only occur during brief periods of streamflow. Glacial meltwater streams in the McMurdo Dry Valleys of Antarctica provide an excellent setting to quantify autochthonous N cycling and storage processes supported by abundant algal mats and well-connected hyporheic zones. We combined historic point-scale sediment and periphyton sample datasets with remote sensing-based modeling of periphyton coverage to estimate how much N was stored in periphyton biomass and the hyporheic zone of a 5-km long McMurdo Dry Valley stream corridor (\&gt;100,000 m<sup>2</sup>). We contextualized these N storage calculations by estimating the magnitude of annual N imports to and exports from the stream corridor based on \&gt;2 decades of streamflow and surface water data, source glacier ice cores and meltwater data, and past studies of local aeolian deposition and biological N fixation rates. We found that in this highly oligotrophic system, stream corridor-scale N storage was ~1000x that of total annual N import or export fluxes. More than 90\% of this temporarily stored N was autochthonous organic matter in the shallow (\&lt;10 cm) hyporheic zone, which acts as a reservoir that sustains N availability in the water column. Despite its location in a polar desert devoid of higher-order vegetation, area-normalized N storage (~40 g N/m<sup>2</sup>) was greater than that reported for streams at lower latitudes (~1\&ndash;22 g N/m<sup>2</sup>). We also demonstrated that NH<sub>4</sub><sup>+</sup> sorption to stream sediment may be an important physicochemical N storage mechanism that responds to short-term fluctuations in streamflow and governs the mobility of inorganic N. Altogether, this research illustrates the importance of quantifying N storage within stream corridors when evaluating the significance of internal cycling and physical retention processes that modulate N availability.</p>},
	keywords = {LTER-MCM, hyporheic zone, McMurdo LTER, nitrogen cycling, nutrient budget, organic matter, periphyton},
	issn = {2161-9549},
	doi = {10.1086/725676},
	url = {https://www.journals.uchicago.edu/doi/10.1086/725676},
	author = {Singley, Joel G. and Salvatore, Mark R. and Michael N. Gooseff and Diane M. McKnight and Eve-Lyn S. Hinckley}
}
@article {4942,
	title = {The distribution of surface soil moisture over space and time in eastern Taylor Valley, Antarctica},
	journal = {Remote Sensing},
	volume = {15},
	year = {2023},
	month = {06/2023},
	pages = {3170},
	abstract = {<p>Available soil moisture is thought to be the limiting factor for most ecosystem processes in the cold polar desert of the McMurdo Dry Valleys (MDVs) of Antarctica. Previous studies have shown that microfauna throughout the MDVs are capable of biological activity when sufficient soil moisture is available (~2\&ndash;10\% gravimetric water content), but few studies have attempted to quantify the distribution, abundance, and frequency of soil moisture on scales beyond that of traditional field work or local field investigations. In this study, we present our work to quantify the soil moisture content of soils throughout the Fryxell basin using multispectral satellite remote sensing techniques. Our efforts demonstrate that ecologically relevant abundances of liquid water are common across the landscape throughout the austral summer. On average, the Fryxell basin of Taylor Valley is modeled as containing 1.5 \&plusmn; 0.5\% gravimetric water content (GWC) across its non-fluvial landscape with ~23\% of the landscape experiencing an average GWC \&gt; 2\% throughout the study period, which is the observed limit of soil nematode activity. These results indicate that liquid water in the soils of the MDVs may be more abundant than previously thought, and that the distribution and availability of liquid water is dependent on both soil properties and the distribution of water sources. These results can also help to identify ecological hotspots in the harsh polar Antarctic environment and serve as a baseline for detecting future changes in the soil hydrological regime.</p>},
	keywords = {LTER-MCM, Dry valleys, ecology, hydrology, remote sensing, soil moisture},
	doi = {10.3390/rs15123170},
	url = {https://www.mdpi.com/2072-4292/15/12/3170},
	author = {Salvatore, Mark R. and Barrett, John E. and Fackrell, Laura E. and Sokol, Eric R. and Levy, Joseph S. and Kuentz, Lily C. and Gooseff, Michael N. and Adams, Byron J. and Power, Sarah N. and Knightly, J. Paul and Matul, Haley M. and Szutu, Brian and Doran, Peter T.}
}
