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Streambed Organic Matter Controls on Carbon Dioxide and Methane Emissions from Streams
Version 2 2019-10-17, 17:03
Version 1 2019-02-15, 15:49
journal contribution
posted on 2019-10-17, 17:03 authored by Paul Romeijn, Sophie A. Comer-Warner, Sami Ullah, David M. Hannah, Stefan KrauseGreenhouse
gas (GHG) emissions of carbon dioxide (CO2) and methane
(CH4) from streambeds are currently understudied.
There is a paucity of research exploring organic matter (OM) controls
on GHG production by microbial metabolic activity in streambeds, which
is a major knowledge gap given the increased inputs of allochthonous
carbon to streams, especially in agricultural catchments. This study
aims to contribute to closing this knowledge gap by quantifying how
contrasting OM contents in different sediments affect streambed GHG
production and associated microbial metabolic activity. We demonstrate,
by means of an incubation experiment, that streambed sediments have
the potential to produce substantial amounts of GHG, controlled by
sediment OM quantity and quality. We observed streambed CO2 production rates that can account for 35% of total stream evasion
estimated in previous studies, ranging between 1.4 and 86% under optimal
conditions. Methane production varied stronger than CO2 between different geologic backgrounds, suggesting OM quality controls
between streambed sediments. Moreover, our results indicate that streambed
sediments may produce much more CO2 than quantified to
date, depending on the quantity and quality of the organic matter,
which has direct implications for global estimates of C fluxes in
stream ecosystems.