Abstract
Abstract. Peatlands store ∼ 20 %–30 % of the global soil organic carbon stock and are an important source of dissolved organic carbon (DOC) for inland waters. Recent improvements for in situ optical monitoring revealed that the DOC concentration in streams draining peatlands is highly variable, showing seasonal variation and short and intense DOC concentration peaks. This study aimed to statistically determine the variables driving stream DOC concentration variations at seasonal and event scales. Two mountainous peatlands (one fen and one bog) were monitored in the French Pyrenees to capture their outlet DOC concentration variability at a high-frequency rate (30 min). Abiotic variables including precipitation, stream temperature and water level, water table depth, and peat water temperature were also monitored at high frequency and used as potential predictors to explain DOC concentration variability. Results show that at both sites DOC concentration time series can be decomposed into a seasonal baseline interrupted by many short and intense peaks of higher concentrations. The DOC concentration baseline is driven, at the seasonal scale, by peat water temperature. At the event scale, DOC concentration increases are mostly driven by a rise in the water table within the peat at both sites. Univariate linear models between DOC concentration and peat water temperature or water table increases show greater efficiency at the fen site. Water recession times were derived from water level time series using master recession curve coefficients. They vary greatly between the two sites but also within one peatland site. They partly explain the differences between DOC dynamics in the studied peatlands, including peat porewater DOC concentrations and the links between stream DOC concentration and water table rise within the peatlands. This highlights that peatland complexes are composed of a mosaic of heterogeneous peat units distinctively producing or transferring DOC to streams.
Highlights
Aquatic carbon transfer from terrestrial ecosystems to inland waters is receiving increasing attention as it plays a major role in the watershed carbon balance (Webb et al, 2018) and in the global carbon cycle (Cole et al, 2007; Drake et al, 2017)
The average and minimum of the peat water table depth in the two piezometer networks were respectively −0.23 and −0.43 m at Ech and −0.15 and −0.45 m in Bernadouze
This study reports a statistical analysis of the stream Dissolved organic carbon (DOC) concentration variability at the outlet of two mountainous peatlands
Summary
Aquatic carbon transfer from terrestrial ecosystems to inland waters is receiving increasing attention as it plays a major role in the watershed carbon balance (Webb et al, 2018) and in the global carbon cycle (Cole et al, 2007; Drake et al, 2017). The origin of aquatic carbon has been tracked and wetlands have been shown to be the main organic carbon suppliers to rivers at both local (Hope et al, 1997; Laudon et al, 2004; Ledesma et al, 2017) and continental scales (Hope et al, 1994; Spencer et al, 2013). Stream outlets of peatlands have been monitored at different latitudes (Billett et al, 2006; Leach et al, 2016; Moore et al, 2013) in order to quantify and understand the aquatic carbon transfer between these organic-carbon-rich pools and their draining streams. Dissolved organic carbon (DOC) is a key component of these fluxes as it contributes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
