High nitrate variability on an Alaskan permafrost hillslope dominated by alder shrubs

• Published in: The Cryosphere
• Main Authors: R. E. McCaully, C. A. Arendt, B. D. Newman, V. G. Salmon, J. M. Heikoop, C. J. Wilson, S. Sevanto, N. A. Wales, G. B. Perkins, O. C. Marina, S. D. Wullschleger
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2022
• Subjects: Environmental sciences; GE1-350; Geology; QE1-996.5; Arctic; permafrost; Seward Peninsula; The Cryosphere; Tundra; Alaska
• Online Access: https://doi.org/10.5194/tc-16-1889-2022; https://doaj.org/article/2d3d55796ce04f9a93855b6fd08410e4

In Arctic ecosystems, increasing temperatures are driving the expansion of nitrogen (N) fixing shrubs across tundra landscapes. The implications of this expansion to the biogeochemistry of Arctic ecosystems are of critical importance and more work is needed to better understand the form, availability, and transportation potential of N from these shrubs across a variety of Arctic landscapes. To gain insights into the processes controlling N within a permafrost hillslope system, the spatiotemporal variability of nitrate (NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="53e1f98be2cdf70dbe180d95894fc6b5"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-16-1889-2022-ie00002.svg" width="9pt" height="16pt" src="tc-16-1889-2022-ie00002.png"/></svg:svg> ) and its environmental controls were investigated at an alder ( Alnus viridis spp. fruticosa ) dominated permafrost tundra landscape in the Seward Peninsula, Alaska, USA. Soil pore water was collected from locations within alder shrubland growing along a well-drained hillslope and was compared to soil pore water collected from locations outside ( upslope , downslope , and between ) the alder shrubland. Soil pore water collected within alder shrubland had an average NO 3 -N (nitrogen from nitrate) concentration of 4.27±8.02 mg L −1 and differed significantly from locations outside alder shrubland ( 0.23±0.83 mg L −1 p <0.05 ). Temporal variation in NO 3 -N within and downslope of alder shrubland co-occurred with precipitation events where NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn ...