The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water–air and soil–air exchange

Abstract

The carbon dioxide evasion cycle of an intermittent first-order stream: contrasting water-air and soil-air exchange. Biogeochemistry, 132(1), pp. 87-102. (doi:10.1007/s10533-016-0289-2) This is the author's final accepted version.There may be differences between this version and the published version. You are advised to consult the publisher's version if you wish to cite from it.http://eprints.gla.ac.uk/133460/ Ephemeral streams and wetlands are characterized by complex cycles of submersion and 26 emersion, which influence the greenhouse gas flux rates. In this study we quantify the 27 spatiotemporal variability in CO 2 and CH 4 concentrations and fluxes of an intermittent 28 first-order stream over three consecutive wet and dry cycles spanning 56 days, to assess 29 how hydrologic phase transitions influence greenhouse gas evasion. Water column excess 30 CO 2 ranged from -11 to 1600 µM, and excess CH 4 from 1 to 15 µM. After accounting for 31 temporal changes in the ratio of wet versus dry streambed hydraulic radius, total CO 2 -C 32 fluxes ranged from 12 to 156 mmol m -2 d -1 , with an integrated daily mean of 61 ± 25 33 mmol m -2 d -1 . Soil-air evasion rates were approximately equal to those of water-air 34 evasion. Rainfall increased background water-air CO 2 -C fluxes by up to 780% due to an 35 increase in gas transfer velocity in the otherwise still waters. CH 4 -C fluxes increased 19-36 fold over the duration of the initial, longer wet-cycle from 0.1 to 1.9 mmol m -2 d -1 . 37Temporal shifts in water depth and site-specific ephemerality were key drivers of carbon 38 dynamics in the upper Jamison Creek watercourse. Based on these findings, we 39 hypothesize that the cyclic periodicity of fluxes of biogenic gases from frequently 40 intermittent streams (wet and dry cycles ranging from days to weeks) and seasonally 41 ephemeral watercourses (dry for months at a time) are likely to differ, and therefore these 42 differences should be considered when integrating transient systems into regional carbon 43 budgets and models of global change.

Sources and variability of CO2 in a prealpine stream gravel bar

“…The unsubmerged surface of GBs has been shown to have significantly higher CO 2 evasion fluxes, as compared with the equivalent area of its adjacent stream (Boodoo, Trauth, Schmidt, Schelker, & Battin, ). These observed CO 2 evasion flux patterns are similar to those of intermittent streams during periods of flow intermittency versus times of continuous flow (Gómez‐Gener et al, ; Looman, Maher, Pendall, Bass, & Santos, ; von Schiller et al, ). To fully understand the role of GBs on the carbon balance of stream corridors, it is thus important to quantify the spatio‐temporal variability in the sources and magnitude of CO 2 evasion fluxes.…”

Differential Response of Greenhouse Gas Evasion to Storms in Forested and Wetland Streams

“…This study showed that pCO 2 , pCH 4 , and pN 2 O increased with stream flow in the high wetland and one of the intermediate wetland, first‐order streams and either decreased or had no relationships in low wetland and forested, first‐order streams. Most previous work has shown dilution of CO 2 and CH 4 concentrations with increasing discharge (Billett & Harvey, ; Dinsmore & Billett, ; Dinsmore et al, , ; Looman et al, ; Wallin et al, ). The positive relationships in this study are probably due to sampling close to wetland sources.…”

“…When examining these mechanisms in the field, studies find both positive and negative relationships between pCO 2 and discharge. Most studies of this nature have occurred in headwater, peatland systems, and report negative relationships between instantaneous discharge and CO 2 (Billett & Harvey, 2013;Dinsmore et al, 2013Dinsmore et al, , 2010Dinsmore & Billett, 2008;Looman et al, 2017;Wallin et al, 2010) and CH 4 (Dinsmore et al, 2013(Dinsmore et al, , 2010Hope et al, 2001). However, a headwater stream in permafrost-influenced interior Alaska showed a positive relationship between pCO 2 and discharge during storms at a downstream site and a negative relationship at an upstream site (Crawford et al, 2013).…”

Carbon dioxide dynamics in an agricultural headwater stream driven by hydrology and primary production

“…Mediterranean areas or Australia (e.g. Gomez-Gener et al 2015;Looman et al 2017). Here we show that such stream intermittency can also cause high and rapid CO2 pulses in a Swedish agricultural setting, highlighting the need for expanding the geographical coverage of studies that investigate stream intermittency in relation to GHG dynamics and emissions.…”