Friday, August 29, 2014

Geochemistry of Methane Formation in Surface and Pore Water Samples…

Today we had 15 people working on the Barrow Environmental Observatory (BEO). Researchers from three DOE national laboratories, the University of Alaska, and scientists from China, Japan, and Germany were collecting data on various topics; soil carbon dynamics, hydrology, and energy balance. It is always rewarding to see this many people working on so many integrated components of the NGEE Arctic project.

David, Baohua, Mallory, Ziming, and I left our apartment in Barrow shortly before 8:00am and stopped by the Barrow Arctic Research Center (BARC) and our storage room in Building 553 before heading to the field. Once we made the 2 km hike to our field site, Baohua and Ziming got busy collecting surface and pore water samples. They used a combination of techniques to obtain water samples from various depths in the soil using macrorhizons, etc. These were inserted into the soil of low- and high-centered polygons yesterday, placed under modest suction, and by this morning had accumulated 40 to 50 cubic centimeters of water. It was necessary to filter the samples to remove suspended sediments and then Ziming and Baohua analyzed them in the field for electrical conductivity, pH, temperature, and concentration of ferrous iron. One of the primary objectives in collecting these samples is to better understand the process of methanogenesis. Methanogenesis is the formation of methane, a potent greenhouse gas, by microbes known as methanogens. These microbes, under anaerobic conditions, use ferric iron as an electron acceptor. This gives rise to ferrous iron which indicates anoxic conditions that may support methanogenesis. Data from the work of Ziming, Baohua, and David will be integrated with field and laboratory experiments to better understand the geochemical controls on methane formation. Improvements in how models represent this important process are one outcome of this research and an important goal of the NGEE Arctic project.