Controls on methane concentrations and fluxes in streams draining human-dominated landscapes

Ecological Applications
By:  and 

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Abstract

Streams and rivers are active processors of carbon, leading to significant emissions of CO2 and possibly CH4 to the atmosphere. Patterns and controls of CH4 in fluvial ecosystems remain relatively poorly understood. Furthermore, little is known regarding how major human impacts to fluvial ecosystems may be transforming their role as CH4 producers and emitters. Here, we examine the consequences of two distinct ecosystem changes as a result of human land use: increased nutrient loading (primarily as nitrate), and increased sediment loading and deposition of fine particles in the benthic zone. We did not find support for the hypothesis that enhanced nitrate loading down-regulates methane production via thermodynamic or toxic effects. We did find strong evidence that increased sedimentation and enhanced organic matter content of the benthos lead to greater methane production (diffusive + ebullitive flux) relative to pristine fluvial systems in northern Wisconsin (upper Midwest, USA). Overall, streams in a human-dominated landscape of southern Wisconsin were major regional sources of CH4 to the atmosphere, equivalent to ~20% of dairy cattle emissions, or ~50% of a landfill’s annual emissions. We suggest that restoration of the benthic environment (reduced fine deposits) could lead to reduced CH4 emissions, while decreasing nutrient loading is likely to have limited impacts to this ecosystem process.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Controls on methane concentrations and fluxes in streams draining human-dominated landscapes
Series title Ecological Applications
DOI 10.1890/15-1330
Volume 26
Issue 5
Year Published 2016
Language English
Publisher Ecological Society of America
Contributing office(s) National Research Program - Central Branch
Description 11 p.
First page 1581
Last page 1591
Country United States
State Wisconsin
County Dane
Online Only (Y/N) N
Additional Online Files (Y/N) N
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