Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1029/2019JG005604
Licence creative commons licence
Title (Primary) Sources, transformation and fate of dissolved organic matter in the gravel bar of a prealpine stream
Author Boodoo, K.S.; Fasching, C.; Battin, T.J.
Source Titel Journal of Geophysical Research-Biogeosciences
Year 2020
Department BOOEK
Volume 125
Issue 8
Page From e2019JG005604
Language englisch
Data and Software links
Keywords Gravel bar; hyporheic zone; Dissolved organic matter; retention time; hydrodynamic mixing; streamwater
Abstract Gravel bars (GBs) are hotspots of biogeochemical activity, likely impacting carbon dynamics in streams and rivers. However, it remains unclear how GBs process dissolved organic matter (DOM) received from streamwater and groundwater. Here we investigate the spatial and temporal variability of DOM concentration and composition within a GB using DOM absorbance and fluorescence measurements. We found clear seasonal and diurnal patterns in DOM composition within the GB, indicating changing contributions of DOM sources and transformation processes. While DOM composition was characterized by more protein‐like DOM in summer, with increasing contributions of humic‐like DOM toward winter within the streamwater and GB, groundwater DOM exhibited a strong aromatic and humic‐like character year‐round. DOM composition and concentration varied diurnally during autumn and winter within the GB and streamwater, while seasonally higher groundwater inputs in summer likely muted the diurnal pattern, pointing to the importance of seasonal hydrological controls on DOM dynamics. Mixing model analysis showed GB DOM characteristics to differ from that predicted by streamwater‐groundwater mixing within the GB, particularly in summer. Dissolved organic carbon (DOC) concentration decreased along flowpaths through the GB with increasing residence time, likely pointing to microbial uptake and/or adsorption to sediment surfaces within the GB, with concurrent clear shifts in DOM composition. While freshly produced and more humified DOM increased along GB flowpaths, protein‐like fluorescence (C3) was removed, indicating the simultaneous production and removal of DOM. Together our findings highlight the role of GBs in DOM removal and transformation, influenced by seasonal shifts in temperature and hydrodynamics.
Persistent UFZ Identifier
Boodoo, K.S., Fasching, C., Battin, T.J. (2020):
Sources, transformation and fate of dissolved organic matter in the gravel bar of a prealpine stream
J. Geophys. Res.-Biogeosci. 125 (8), e2019JG005604 10.1029/2019JG005604