Temporal and spatial variability of dissolved inorganic carbon in a boreal stream network: Concentrations and downstream fluxes

• Carbon dioxide (CO(2)) and dissolved inorganic carbon (DIC) concentrations and export were analyzed throughout a 67 km(2) boreal stream network in northern Sweden. 700 DIC and CO(2) samples from 14 subcatchments were collected in 2006 and 2007. All sites were consistently supersaturated in CO(2) with respect to the atmosphere. Temporal variability of DIC and CO(2) concentration was best correlated with discharge, with concentrations generally diluting at high discharge. However, the variability in CO(2) concentration was also dependent on the specific pH range of the stream, as variability was greatest in acidic headwater streams and lowest in larger circumneutral streams. In the larger ones the increase in the CO(2) proportion of DIC at increased discharge counteracts the dilution of CO(2). The shift toward proportionally more CO(2) of the DIC at higher discharge is caused by decline in pH. Spatial patterns showed that DIC and CO(2) concentrations were best correlated with peatland coverage of the subcatchment. The highest concentrations were found in headwater streams draining peatlands. The downstream export of DIC from the catchment outlet constitutes 19% of the total downstream export of carbon (DIC + DOC), or 0.7 (+/-0.09) g C m(-2) yr(-1). This study demonstrates the importance of including fluvial fluxes of inorganic carbon in landscape carbon budgets via runoff, and also highlights the need to account for stream evasion of CO(2) to the atmosphere in such estimates since it can be larger than the downstream DIC export.

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Fisk- och akvakulturforskning (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Fish and Aquacultural Science (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

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