Geochemical Drivers of Carbon Dioxide and Methane Production

NGEE Arctic researchers at ORNL are investigating how soil geochemistry can drive production of greenhouse gases in Arctic tundra. Releases of carbon dioxide (CO2) and methane (CH4) are likely to change as Arctic environments adapt to changing climate, and understanding geochemical controls on these shifts in microbial CO2 and CH4 production is important for modeling land-atmosphere climate feedbacks. ORNL postdoctoral researcher Elizabeth Herndon along with senior scientists Liyuan Liang, Baohua Gu, and Stan Wullschleger, and SSRL collaborator John Bargar sampled surface and soil pore waters from the Barrow Environmental Observatory (BEO) in early and late summer 2013.  Water samples were subsequently analyzed for solute and gas concentrations, and dissolved organic carbon (DOC) chemistry was investigated with analytical techniques including X-ray absorption spectroscopy.

Soil pore waters were characterized by sharp vertical gradients with solute and dissolved gas concentrations increasing with depth. In both surface and soil pore waters, DOC and Fe(2+) were dominant ionic species. Read more...

Water collection technique demonstration

 

Figure 1. ORNL postdoc Elizabeth Herndon (left) and UAF research associate Allessio Gusmeroli (right) demonstrate water collection techniques to regional middle school students during a sampling trip to Barrow AK on July 2, 2013.

 

Carbon Cycle Models Require Reliable Representation of Soil Moisture Dynamics

Water in soils does not freeze completely at the nominal freezing temperature because capillary forces suppress the energy state of water in small pores, thus allowing some fraction of the water to remain unfrozen. Classical constitutive models that represent that phase partitioning are strictly applicable only to gas-free soils and are thus not adequate for general numerical models that must represent unsaturated conditions scientists at LANL have overcome that limitation. In a recent paper accepted for publication in Vadose Zone Journal, Painter and Karra [1] developed phase-partitioning models that are applicable to unsaturated conditions. They show that the new model accurately represents laboratory measurements of unfrozen water content below the nominal freezing temperature of water (Figure 2).  Read more...

Comparison of lab measurements Gas saturation model
Figure 2. Comparison of laboratory measurements of unfrozen water content with the new constitutive model (curves) as a function of temperature for different values of the total water content. Figure 3.Gas saturation index in the summer in a high-resolution 3-D PFLOTRAN simulation [2] of active layer dynamics at the Barrow Environmental Observatory. The PFLOTRAN implementation used the new constitutive model [1] and the new three-phase mass and energy balance formulations [2]. Note that the soil is unsaturated on the polygon rims.

NGEE Arctic Data Policies and Data Management Guidance

NGEE Arctic data team has posted final drafts of three Data Policies for data sharing, fair-use, and collaboration at http://ngee-arctic.ornl.gov/content/ngee-arctic-data-management-policies-and-plans. Implementing these policies is critical to meeting the scientific goals and objectives of NGEE Arctic.
In addition, the data team has prepared a series of guides/help files for use by investigators for reporting, processing, and archiving data for both project and public sharing. We answer the burning questions -- What is a data set? How do I organize my data files for sharing? And more, at http://ngee-arctic.ornl.gov/content/metadata-entry-data-upload-and-data-management-help.

 

Safety Training Requirements -- New April 24, 2014

NGEE-Arctic participants and collaborators must complete the required viewing of safety videos and reading of safety manuals to be approved for field and laboratory work at NGEE-Arctic facilities in Barrow, Alaska.  The annual review of the manuals has been completed and resulted in only minor changes to the manuals:

  • The ATV job aid was deleted from the Field Safety Manual and fueling and hazardous material trasport was added.
  • Both manuals were updated with additional contact information.

 

Participants and collaborators are strongly encouraged to complete all training requirements prior to travel because computers and internet connectivity are limited in Barrow.

Training materials are only available on the NGEE-Arctic project website (https://ngee-arctic.ornl.gov/content/ngee-safety).

Access to training materials requires NGEE-Arctic website login. After login, the Safety tab will appear.

  • ORNL participants may access Training Materials with their ORNL UCAMS login UID and PWD.
  • Other participants and collaborators may access Training Materials with their website UID and PWD.
    • If you are not a registered website user, please request an account (Login tab). You will receive e-mail notification with your account information.
    • Note that it may take 24 to 48 hours for your account to be established.

Upon successful completion of the training requirements you will receive e-mail notification from NGEE-Arctic Management that you are approved for field and laboratory work at the NGEE-Arctic facilities in Barrow.