USAP-DC

Aquatic-terrestrial transition zones are crucial environments in understanding the biogeochemistry of landscapes. In temperate watersheds, these areas are generally dominated by riparian zones, which have been identified as regions of special interest for biogeochemistry because of the increased microbial activity in these locations, and because of the importance of these hydrological margins in facilitating and buffering hydrologic and biogeochemical exchanges between terrestrial and aquatic ecosystems. In the Antarctic Dry Valleys, terrestrial-aquatic transition zones are intriguing landscape features because of the vast importance of water in this polar desert, and because the material and energy budgets of dry valley ecosystems are linked by hydrology. Hydrological margins in aquatic-terrestrial transition zones will be studied in the Dry Valleys of Antarctica to answer two overarching questions: (1) what are the major controls over hydrologic and biogeochemical exchange across aquaticterrestrial transition zones and (2) to what extent do trends in nutrient cycling (e.g. nitrogen cycling) across these transition zones reflect differences in microbial communities or function vs. differences in the physical and chemical environment (e.g., redox potential)? The hydrologic gradients that define these interfaces provide the opportunity to assess the relative influence of physical conditions and microbial biodiversity and functioning upon biogeochemical cycling. Coordinated hydrologic, biogeochemical, and molecular microbial studies will be executed within hydrologic margins with the following research objectives: to determine the role of sediment characteristics, permafrost and active layer dynamics, and topography on sub-surface water content and distribution in hydrologic margins, to determine the extent to which transformations of nitrogen in hydrological margins are influenced by physical conditions (i.e., moisture, redox potential and pH) or by the presence of specific microbial communities (e.g., denitrifiers), and to characterize the microbial community structure and function of saturated zones.

This proposed research will provide an improved understanding of the interaction of liquid water, soils, microbial communities, and biogeochemistry within the important hydrologic margin landscape units of the dry valleys. Dry valleys streams and lakes are unique because there is no influence of higher vegetation on the movement of water and may therefore provide a model system for understanding physical and hydrological influences on microbial ecology and biogeochemistry. Hence the findings will contribute to Antarctic science as well as the broader study of riparian zones and hydrologic margins worldwide. Graduate students and undergraduate students will be involved with fieldwork and research projects. Information will be disseminated through a project web site, and outreach activities will include science education in local elementary, middle and high schools near the three universities involved.

Person	Role
Gooseff, Michael N.	Investigator
Barrett, John	Investigator
Takacs-Vesbach, Cristina	Investigator

Antarctic Organisms and Ecosystems

Award # 0338267

B268_hydrol_margins_dvs_proj_1.0

None in the Database

Repository	Title (link)	Format(s)	Status
PI website	Antarctic Hydrologic Margin Microbiology and Biogeochemistry - data	None	bad_url
USAP-DC	Hydrologic Margins Research Project, 2004-2008, McMurdo Dry Valleys	None	exist