Crustal Geophysics and Geochemistry Science Center

Critical Zone Processes Across Landscapes

Critical Zone Processes in the Prairie Potholes Region of the North-Central U.S.

Task Objectives

The Prairie Pothole ecosystem occupies over 700,000 square kilometers in the north central U.S.and southern Canada. It contains over four million small wetlands that are critical habitat for wildlife, particularly birds. Geology controls the hydrology, geochemistry, and biology of the wetlands because they are formed on glacial till. Hydrology is dominated by the low permiability of the till and wetland chemistry by the presence of reactive sulfide and carbonate phases in the till. We are integrating geologic, geophysical, hydrologic, and geochemical studies with collaborative ecological research from the northern Plains wildlife center, USGS hydrolgists in Denver, and the Univeristy of Minnosota, to enable prediction of impacts of climate change on this system.

Task objectives:

  1. Conduct a study in the Cottonwood lakes ara of North Dakota. We will characterize the geochemical-hydrologic-bioloic controls on the extreme local chemical variability of the pothole wetlands. These wetlands can range from dilute compositions similar to rainwater, to saline fluids over distances as small as 200 meters or less.
  2. Expand the understanding developed in the Cottonwood Lakes area to a much wider portion of the Praire Pothole region by conducting studies in other parts of the ecosystem.
  3. Develop a mathematical model that predicts the chemical composition.

Planned Work

Conduct geochemical studies on water and soils to evaluate geochemical evolution of the Praire Pothole region and the role of microrganisms in carbon cycling in study area.

  1. Investigate microbial communities associated with water column and sediments of Prairie Potholes lakes.
  2. Couple microbial investigations with current greenhouse gas flux measurements or arrange to make flux measurements during microbial sampling.
  3. Couple microbial investigations with groundwater/surface water modeling
    1. H1: unique geochemistry of recharge - flow through - and discharge wetlands will affect biogeochemistry of anaerobic sediments
    2. H2: varied biogeochemistry will result in varied greenhouse gas flux and carbon storage/sequestration regimes in different types of wetlands
    3. H3: varied biogeochemistry will affect cycling/fate of trace/toxic elements
  4. Continue to develop Gas Chromatography-Flame Ionization Detector (GC-FID), -Thermal-Conductivity Detector (-TCD), and -Mass Spectrometry (-MS) methods for the lab
    1. Methane, CO2, and O2 concentrations
    2. Ether phospholipids (i.e. methanogen lipids)
    3. Low molecular weight fatty acids
    4. Polyaromatic Hydrocarbons (PAHs)

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