 |
| Titel |
Tracing the sources of organic carbon in freshwater systems |
| VerfasserIn |
Miriam Glendell, Jeroen Meersmans, Rachel Barclay, Gabriel Yvon-Durocher, Sam Barker, Richard Jones, Iain Hartley, Jennifer Dungait, Timothy Quine |
| Konferenz |
EGU General Assembly 2016
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123617
|
| Publikation (Nr.) |
 EGU/EGU2016-2903.pdf |
|
|
|
|
|
| Zusammenfassung |
| Quantifying the lateral fluxes of carbon from land to inland waters is critical for the
understanding of the global carbon cycle and climate change mitigation. However, the crucial
role of rivers in receiving, transporting and processing the equivalent of terrestrial net primary
production in their watersheds has only recently been recognised. In addition, the fluxes of
carbon from land to ocean, and the impact of anthropogenic perturbation, are poorly
quantified. Therefore, a mechanistic understanding of the processes involved in
the loss and preservation of C along the terrestrial-aquatic continuum is required
to predict the present and future contribution of aquatic C fluxes to the global C
budget.
This pilot study examines the effect of land use on the fate of organic matter within two
headwater catchments in Cornwall (UK) in order to develop a methodological framework for
investigating C-cycling across the entire terrestrial-aquatic continuum. To this end, we aim to
characterise the spatial heterogeneity of soil erosion driven lateral fluxes of SOC to identify
areas of erosion and deposition using 137Cs radio-isotope and trace the terrestrial versus
aquatic origin of C along the river reaches and in lake sediments at the catchment
outlet.
The 3D spatial distribution of SOC has been investigated by sampling three depth increments
(i.e. 0-15cm, 15-30cm and 30-50cm) along 14 hillslope transects within two sub-catchments
of ∼km2 each. In total, 80 terrestrial sites were monitored and analysed for total C and N, and
bulk stable 13C/15N isotope values, while 137Cs was used to obtain a detailed understanding
of the spatial – temporal variability in erosion driven lateral fluxes of SOC within the
catchments. The relative contribution of terrestrial and aquatic C was examined along the
river reaches as well as in lake sediments at the catchment outlet by considering n-alkane
signatures.
By linking the C accumulation rates in lake sediments over decadal timescales from
both terrestrial and aquatic sources as recorded in lake sediments to the measured
rates of soil erosion and terrestrial & aquatic CO2 respiration rates, this study has
paved a way towards a novel and cross-disciplinary approach to investigate and
further improve current status of knowledge as regards C-cycling across the entire
terrestrial-aquatic continuum. 137Cs was found to be useful to understand the dynamics and
spatial pattern of lateral fluxes of sediment & C at the catchment scale, while tracing
chemical composition of C using n-alkanes and stable isotopes (δ13C, δ15N) allowed
distinguishing between the terrestrial vs. aquatic origin of C and determining main
sources of particulate organic carbon in the aquatic environment within the two study
catchments. |
|
|
|
|
|
|