Friday, April 19, 2013

More cores...from drained thaw lake basins

Our team has spent the last year and a half sampling permafrost soils in polygons that represent the major geomorphological feature in the vicinity of our field plots. We have been working in an area occupied by low-, flat-, and high-centered polygons and studying how these different landforms might impact the distribution of water across the landscape. In turn, this water influences carbon cycle processes that are important to climate.

Our intent has always been to study feedbacks between climate and Arctic ecosystems, beginning with polygonal ground and then broadening our scope of work to include other features like drained thaw lake basins (DTLBs). These are what remain when thaw lakes on the Arctic Coastal Plain drain, leaving vegetated areas that can be of various ages and have carbon cycle dynamics that are different than those of the surrounding landscape. Ken Hickel, from the University of Cincinnati, has been active in identifying these areas and we have used his maps to locate the types of DTLBs that we would now like to study just south of our current field site.

Craig, Ken, and Taniya used a GPS system to guide us to one of DTLB sites that we had identified early in the week. This was straightforward since, before he left California, Craig downloaded one of the Hinkel et al. maps into the system so that we could easily navigate to the desired location. It was, fortunately, just a few hundred meters off a spur road south of the Barrow Environmental Observatory. A land-use permit from the North Slope Borough had been approved last fall and allowed us to now conduct our research in this area.

Once we located our sampling points, Larry and Bob positioned the drill rig into place. Ken took over and began drilling what would be our final two or three cores of the trip. Having drilled dozens of cores in the last two years, Ken was able to notice that drilling these soils was a little different than those we drilled on the BEO. Here, the soil seemed finer in texture and harder to drill. We will analyze the sand, silt, and clay content, and fractional ice content on all samples...this should be sufficient to confirm this observation.

The permafrost cores, although harder to obtain than those from polygonal ground, were of a high quality. Several layers of fine sediment and organic rich layers were quite obvious. We are keen to get these samples back to ORNL and LBNL where our groups will be able to conduct studies on the fate and chemical characteristics of organic matter on the many cores we have collected.

Finally, Larry and I had agreed earlier in the week to give an informal science presentation to the local community. Nok Ackers, who works for the Barrow Arctic Science Consortium (BASC), extended the initial invitation. I met Nok several years ago during one of my first trips to Barrow. As it turns out, Larry returned to Fairbanks earlier this afternoon and thus the presentation was mine to make. I spoke about the integration knowledge gained through field and laboratory studies into climate models. The NGEE Arctic project served as an example. The presentation was at the Inupiat Heritage Center and was attended by several dozen residents. There was a good Q&A session afterwards.