Thursday, July 31, 2014

Geochemistry in a Bottle…

One of several tasks that I had this week while in Barrow was to collect water samples for geochemical analysis. Baohua Gu and his colleagues at ORNL have been analyzing surface and pore water samples for two years, looking to identify relationships between pH and soil constituents like iron and their control on methane production.

Yesterday I installed access tubes (e.g., piezometers) at various locations among low- and high-centered polygons, placing them in dry edges and wet, saturated troughs. They were also installed to several depths from the upper organic layer to near the permafrost table. Today I returned to those and used a syringe to extract a sample of water. The water tends to be full of sediment, but these samples will be filtered prior to analysis back in the laboratory. Surface water samples were collected as well for comparison and they contained far less suspended sediments than the pore water samples.
Baohua, David Graham, and several others from ORNL will return in late August to collect another set of samples. Patterns of geochemistry over the season and across years will help us to understand controls on methane production and improve the way these processes are represented in models.