Methane emissions from tundra environments in the Yukon‐Kuskokwim delta, Alaska

Abstract

Over a 6‐week period from July 3 to August 10, 1988, we made measurements of the flux of methane by enclosure techniques from major tundra environments in the Yukon‐Kuskokwim Delta of Alaska (60°45′N). Emissions from wet meadow tundra averaged 144 ± 31 mg CH4/m2/d and ranged from 15.6 to 426 mg CH4/m2/d, varying with soil moisture and temperature. Flux from the drier upland tundra was approximately 2 orders of magnitude lower and averaged 2.3 ± 1.1 mg CH4/m2/d. Consumption of ambient levels of methane was sporadically measured at these drier sites, and emissions ranged between −2.1 and 18.1 mg CH4/m2/d. Tundra lakes emit methane from the open water surface as well as from fringing aquatic vegetation. The presence of vegetation significantly enhanced flux over open water rates. Average fluxes from a variety of sites with vegetation ranged between 62.7 and 153.5 mg CH4/m2/d. Calculated diffusive fluxes from open water varied with lake size, the large lakes emitting 3.8 mg CH4/m2/d and small lakes emitting an average of 77 mg CH4/m2/d. An updated estimate of global emissions from tundra indicates an annual flux of approximately 11 ± 3 Tg CH4.

The growing season greenhouse gas balance of a continental tundra site in the Indigirka lowlands, NE Siberia

“…2.1.2 it was mentioned that near 20% of the area surrounding the site consists of surface water. As the carbon dioxide exchange between lakes and the atmosphere is probably smaller than between land and the atmosphere, whereas methane emissions from lakes may be larger than from dry land (Bartlett et al, 1992), the greenhouse gas balance of the larger area is probably more neutral than presented in Fig. 14. At present, information about which fraction of the larger area is covered with floodplain is lacking.…”

“…The water table effect is directly related to anaerobic conditions in the soil and has been documented by many authors (Bartlett et al, 1992;Friborg et al, 2000; Heikinnen et al, 2002; Oberlander et al, 2002;Wagner et al, 2003;Kutzbach et al, 2004). Statistical analysis shows that the spatial heterogeneity of the terrain mainly affects water table variation, and soil temperature to a much smaller extent.…”

Barriers to predicting changes in global terrestrial methane fluxes: analyses using CLM4Me, a methane biogeochemistry model integrated in CESM

“…Many field studies have concluded that the presence of vascular plants with aerenchyma leads to increased net CH 4 emissions (Morrissey et al, 1993;Schimel, 1995;Chanton et al, 1993;Bartlett et al, 1992;Frenzel and Karofeld, 2000;Grunfeld and Brix, 1999;Torn and Chapin, 1993) by providing an efficient escape mechanism for CH 4 . However, in large-scale CH 4 biogeochemical models, separate representations of aerenchyma area (and the attendant diffusive pathway) and methanogenesis substrate inputs are required.…”

Isoprene emissions from a tundra ecosystem

“…These ground-based experiments were complemented by airborne measurements of a variety of important reactive trace gases (Harriss et al, 1992b). While detailed knowledge of methane sources and sinks (Bartlett et al, 1992) as well as NO x and O 3 deposition fluxes (Jacob et al, 1992) were obtained during ABLE-3A, BVOC exchange measurements were not quantified. Non-methane hydrocarbon measurements on the NASA Electra research aircraft, however, indicated the abundance of important biogenic reactive trace gases in the Arctic (isoprene, Blake et al, 1992).…”