Riparian zone processes and soil water total organic carbon (TOC): Implications for spatial variability, upscaling and carbon exports
(English)Manuscript (preprint) (Other academic)
Considerable amounts of groundwater inflows pass through riparian soils before discharging into stream networks. The interaction of groundwater inflows from adjacent hillslopes with riparian soils often changes the biogeochemical signature of the water. This mechanism often makes (near stream) riparian zones (RZs) key areas in the landscape that substantially influence stream water chemistry. Here we combine landscape analysis with total organic carbon (TOC) concentrations and groundwater levels measured at the riparian observatory in the boreal Krycklan catchment to investigate how terrain has shaped riparian processes and TOC characteristics. A considerable spatial variability of riparian TOC concentrations is presented in this system which can be related to variable groundwater levels and values of the topographic wetness index (TWI). Organic-rich riparian peat soils in forested areas emerged as hotspots exporting large amounts of TOC. These exports are subject to considerable temporal variations caused by variable flow conditions and changing TOC concentrations. Organic-poor riparian soils, on the other hand, exported only small and relatively time-invariant amounts of TOC. Organic-rich and organic-poor soils in RZs combine to a landscape mosaic that regulates much of spatial variability of stream water TOC. We finally present an empirical regression-model based on the TWI to predict spatially variable riparian TOC concentration profiles for areas in the Krycklan catchment that are underlain by glacial till.
total organic carbon, TOC, riparian zone, boreal headwater, topographic wetness index, upscaling
Oceanography, Hydrology, Water Resources
Research subject Physical Geography
IdentifiersURN: urn:nbn:se:su:diva-42728OAI: oai:DiVA.org:su-42728DiVA: diva2:351180
ProjectsSwedish Research Council (VR, grant no. 2005-4289)