HR: 11:50h
AN: B42A-06    [Abstracts]
TI: Biogeochemistry and nitrogen cycling in an Arctic, volcanic ecosystem
AU: * Fogel, M L
EM: fogel@gl.ciw.edu
AF: Geophysical Laboratory, Carnegie Institutio of Washington 5251 Broad Branch Rd NW, Washington, DC 20015, United States
AU: Benning, L
EM: liane@see.leeds.ac.uk
AF: University of Leeds, Earth and Biosphere Institute, Leeds, LS2 9JT, United Kingdom
AU: Conrad, P G
EM: pamela.g.conrad@jpl.nasa.gov
AF: JPL-Cal Tech, 4800 Oak Grove Drive MS183-301, Pasadena, CA 91109, United States
AU: Eigenbrode, J
EM: jennifer.eigenbrode@nasa.gov
AF: NASA Goddard Space Flight Center, Code 699.0, Greenbelt, MD 20771, United States
AU: Starke, V
EM: vstarke@ciw.edu
AF: Geophysical Laboratory, Carnegie Institutio of Washington 5251 Broad Branch Rd NW, Washington, DC 20015, United States
AB: As part of a study on Mars Analogue environments, the biogeochemistry of Sverrefjellet Volcano, Bocfjorden, Svalbard, was conducted and compared to surrounding glacial, thermal spring, and sedimentary environments. An understanding of how nitrogen might be distributed in a landscape that had extinct or very cold adapted, slow- growing extant organisms should be useful for detecting unknown life forms. From high elevations (900 m) to the base of the volcano (sea level), soil and rock ammonium concentrations were uniformly low, typically less than 1- 3 micrograms per gm of rock or soil. In weathered volcanic soils, reduced nitrogen concentrations were higher, and oxidized nitrogen concentrations lower. The opposite was found in a weathered Devonian sedimentary soil. Plants and lichens growing on volcanic soils have an unusually wide range in N isotopic compositions from –5 to +12‰, a range rarely measured in temperate ecosystems. Nitrogen contents and isotopic compositions of volcanic soils and rocks were strongly influenced by the presence or absence of terrestrial herbivores or marine avifauna with higher concentrations of N and elevated N isotopic compositions occurring as patches in areas immediately influenced by reindeer, Arctic fox ( Alopex lagopus), and marine birds. Because of the extreme conditions in this area, ephemeral deposition of herbivore feces results in a direct and immediate N pulses into the ecosystem. The lateral extent and distribution of marine- derived nitrogen was measured on a landscape scale surrounding an active fox den. Nitrogen was tracked from the bones of marine birds to soil to vegetation. Because of extreme cold, slow biological rates and nitrogen cycling, a mosaic of N patterns develops on the landscape scale.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0469 Nitrogen cycling
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 4817 Food webs, structure, and dynamics (0491)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting