Age of Dissolved Organic Carbon across an Arctic Landscap

Abstract:

The Arctic is particularly vulnerable to climate change. Systems there currently experience a balance between frozen and thawed conditions and the proportion of frozen and thawed conditions are expected to change with increasing temperatures and changes in snowfall. Increased temperatures will make these frozen stocks of carbon, much of it labile, vulnerable to decomposition and translocation. Most studies on the carbon balance of terrestrial ecosystems have focused on gaseous fluxes of carbon to the atmosphere, but numerous studies have shown that production and loss of dissolved carbon can be a crucial mechanism for high-latitude ecosystem carbon loss that results in considerable export off the Arctic landscape and may reduce or eliminate terrestrial carbon sinks. In addition, hydrological vertical transport of DOC is an important process in permafrost areas. In collaboration with the NGEE-Arctic study, we measured 14C of DOC from surface waters and from shallow and deep subsurface porewater collected from various locations in the Barrow Arctic Ocean Observatory (BAO) including different drainage locations and thawed lake basins of varying age. Locations were sampled in July and September 2013 to assess changes in 14C-DOC across the landscape and from early and late summer. Preliminary results suggest that DOC in surface and pore water increases in age with depth and across the growing season. These patterns as well as patterns across the landscape will be presented and discussed.