Collaborative Research: geophysical evaluation of biogenic gases in peatlands

0510370 0510545 0510004

Slater Glaser Reeve

Biogenic gas emission from northern peatlands, by wicking from vascular plants and by

episodic ebullition events, accounts for approximately 7% of the global annual emission

of methane to the atmosphere. This proposal involves experiments to apply ground

penetrating radar (GPR) for (1) estimating the amount of biogenic gas stored in peatlands,

(2) determining the spatial distribution of biogenic gas within the peat, and (3)

monitoring biogenic gas release to the atmosphere. Data from a large northern peatland in

Maine (EAR-0242353) show that (1) higher CH4 and CO2 concentrations correlate with

high velocity/high attenuation zones in cross-borehole GPR data as well as shadow zones

(loss of reflections) in surface GPR data, (2) shadow zones (indicative of high gas

content) are frequently observed in the +11 km of surface GPR data collected in this

peatland. The experimental objectives are: (1) a laboratory evaluation of the relationship

between dielectric permittivity and gas content for a profile of peat cores from the surface

to the mineral soil; (2) a cross-hole GPR and surface GPR monitoring experiment,

supported by measurements of water levels, hydraulic conductivity and time domain

reflectometry, to observe rates of biogenic gas release to the atmosphere; (3) a surface

GPR study, supported by in situ measurements of biogenic gas concentration, to estimate

the volume of biogenic gas stored in two well studied northern peatlands (Caribou Bog,

ME and Glacial Lake Agassiz, MN). Important milestones include (a) a predictive

equation for gas content estimation in peat as a function of depth from dielectric

permittivity measurements, (b) new insight into the temporal pattern of gas release and

ebullition flux from peatlands, and (c) new estimates of the free gas content of peatland

carbon reservoirs accounting for the spatial/depth distribution of the gas.

Broader Impacts

This proposal incorporates educational activities, curriculum development, community

outreach and international collaboration within an applied research framework. Honors

UnderGraduate (HUG) researchers from the Rutgers-Newark Honors College (HC) will

partner with a postdoctoral scientist to obtain the research training required to complete

four of the primary research tasks. Each HUG will complete a yearlong senior project on

their research and contribute to a publication. The status of Rutgers-Newark as the topranked

National US University with respect to campus UG diversity facilitates HUG

opportunities to minority students. Students in Earth/Environmental Sciences at Rutgers-

Newark frequently express interest in fieldwork experiences. Part of the fieldwork will be

conducted by students participating in a new class, Summer Field Camp in Applied

Geophysics, developed as part of this project. Community outreach will occur via guided

tours, poster boards and presentations on the hydrology, ecology and carbon cycle in

Caribou Bog, facilitated by the recently opened 2 km long Orono boardwalk that now

provides public access to this bog. Finally, collaboration with a prominent peatland

scientist in Europe will draw international attention to our work and provide an

opportunity to conduct comparative work on a unique European peat bog.