 |
| Titel |
Sources of dissolved organic matter during storm and inter-storm conditions in a lowland headwater catchment: constraints from high-frequency molecular data |
| VerfasserIn |
L. Jeanneau, M. Denis, A.-C. Pierson-Wickmann, G. Gruau, T. Lambert, P. Petitjean |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 14 ; Nr. 12, no. 14 (2015-07-24), S.4333-4343 |
| Datensatznummer |
250118032
|
| Publikation (Nr.) |
 copernicus.org/bg-12-4333-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| The transfer of dissolved organic matter (DOM) at soil–river interfaces
controls the biogeochemistry of micropollutants and the equilibrium between
continental and oceanic C reservoirs. Understanding the mechanisms
controlling this transfer is fundamental to ecology and geochemistry. DOM
delivery to streams during storms is assumed to come from the flushing of
preexisting soil DOM reservoirs mobilized by the modification of water flow
paths. We tested this hypothesis by investigating the evolution of the
composition of stream DOM during inter-storm conditions and five storm
events monitored with high-frequency sampling. The composition of DOM was
analyzed using thermally assisted hydrolysis and methylation (THM) with
tetramethylammonium hydroxide (TMAH) coupled to a gas chromatograph and mass
spectrometer. In inter-storm conditions, stream DOM is derived from the
flushing of soil DOM, while during storm events, the modification of the
distribution of chemical biomarkers allows the identification of three
additional mechanisms. The first one corresponds to the destabilization of
microbial biofilms due to the increase in water velocity, resulting in the
fleeting export of a microbial pool. The second mechanism corresponds to the
erosion of soils and river banks, leading to a partition of organic matter between particulate and dissolved phases. The third mechanism is linked to the
increase in water velocity in soils that could induce the erosion of
macropore walls, leading to an in-soil partition between soil microparticles and dissolved phase. The contribution of this in-soil erosive
process would be linked to the magnitude of the hydraulic gradient following
the rise of the water table and could persist after the recession, which could
explain why the return to inter-storm composition of DOM does not follow the
same temporal scheme as the discharge. These results are the most important factors
in understanding the transfer of nutrients and micropollutants at the soil–river
interfaces during the hot moments that are storm events. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|