US Long-Term Ecological Research Network
Ebullitive methane emissions from oxygenated wetland streams at North Temperate Lakes LTER 2013

Abstract

Stream and river carbon dioxide emissions are an important component of the global carbon cycle. Methane emissions from streams could also contribute to regional or global greenhouse gas cycling, but there are relatively few data regarding stream and river methane emissions. Furthermore, the available data do not typically include the ebullitive (bubble-mediated) pathway, instead focusing on emission of dissolved methane by diffusion or convection. Here, we show the importance of ebullitive methane emissions from small streams in the regional greenhouse gas balance of a lake and wetland-dominated landscape in temperate North America and identify the origin of the methane emitted from these well-oxygenated streams. Stream methane flux densities from this landscape tended to exceed those of nearby wetland diffusive fluxes as well as average global wetland ebullitive fluxes. Total stream ebullitive methane flux at the regional scale (103 Mg C yr-1; over 6400 km2) was of the same magnitude as diffusive methane flux previously documented at the same scale. Organic-rich stream sediments had the highest rates of bubble release and higher enrichment of methane in bubbles, but glacial sand sediments also exhibited high bubble emissions relative to other studied environments. Our results from a database of groundwater chemistry support the hypothesis that methane in bubbles is produced in anoxic near-stream sediment porewaters, and not in deeper, oxygenated groundwaters. Methane interacts with other key elemental cycles such as nitrogen, oxygen, and sulfur, which has implications for ecosystem changes such as drought and increased nutrient loading. Our results support the contention that streams, particularly those draining wetland landscapes of the northern hemisphere, are an important component of the global methane cycle.
Dataset ID
308

Data Citation Suggestion

Crawford, J., E. Stanley, and L. Loken. 2020. Ebullitive methane emissions from oxygenated wetland streams at North Temperate Lakes LTER 2013 ver 22. Environmental Data Initiative. https://doi.org/10.6073/pasta/7842765e6520b62af6fd4d95c838f177. Accessed 2021-08-05.

Date Range

-

Data Download

bubble composition adjacent to the traps
gas volume emitted in the form of bubbles over time. Trap 1- 30 were in Allequash Creek, 31 - 42 were in Mann Creek, Stevenson Creek, and North Creek
lat long and site description for gas traps
Bulk density and organic content of sediment measured in cores taken close to trap locations