Carbon emissions from fluvial systems are a key component of local and regional carbon cycles. We used floating chambers to investigate the CO2 flux from stream water to air (fCO2
In light of current climate change challenges, the quantification of Earth’s global carbon (C) cycle is critical for a sustainable future. There is a growing consensus that inland waters may represent a significant carbon dioxide (CO2) source to the atmosphere (Cole et al. 2007; Raymond et al. 2013), and degassing of CO2 from streams and rivers has received significant attention in recent years (e.g., Billett and Moore 2008; Butman and Raymond 2011; Campeau et al. 2014; Hope et al. 2001; Hotchkiss et al. 2015; Jonsson et al. 2007; Richey et al. 2002; Striegl et al. 2012; Teodoru et al. 2015). Despite the increased interest in understanding biogeochemical mechanisms driving fluvial emissions of CO2, the role of old regional groundwater, including its interaction with surface water, has been largely overlooked. Regional groundwater flow is a hydrogeological process by which groundwater moves long distances through deep subsurface pathways beneath surface topographic divides, possibly recharging in one watershed and discharging in another many kilometers away (Tóth 2009; Schaller and Fan 2009; Smerdon et al. 2012; Pacheco 2015), thus creating the potential for long-distance subsurface transport of C between watersheds and ecosystems. However, little is known about CO2 emissions from streams and rivers affected by regional groundwater discharge and the potential effects on C balances of the aquatic and surrounding terrestrial ecosystems.
