Reconstructing the impact of past land-use on soil degradation using compound-specific radiocarbon dating of sedimentary leaf waxes
Abstract
Accelerated soil erosion as a consequence of human land-use is a pervasive problem of global concern and recently became the focus of extensive research. Although sustainable land-use achieved significant awareness in the last decades, our knowledge of the long-term impact of soil degradation as well as its historical evolution is rather limited. This study seeks to address this issue by investigating past soil loss using radiocarbon dating of different OM fractions that are deposited in lake sediments.
During intensive land-use, such as deforestation or field cultivation, pre-aged soil organic carbon from deep soil horizons is mobilized and deposited in lakes. Depending on the intensity of human perturbation, the mobilization process leads to changes in soil carbon residence times. By measuring the age-difference between pre-aged, soil-derived leaf waxes and the sediment layers in which they were deposited (i.e. sedimentation age), we are able to reconstruct the soil retention of the molecular compounds. This time series of age-offsets allows an estimation of past soil degradation in the catchment. State-of-the-art compound-specific radiocarbon dating of terrestrial leaf waxes, such as n-alkanes and n-carboxylic acids, using a micro-scale accelerated mass spectrometer (AMS) system (MICADAS, ETH Hönggerberg), is key to reconstruct soil stability over time. We tested our hypothesis on different sediment records, recovered from three regions with different land-use histories, namely Lake Murten in Switzerland, lakes from the Vatnahverfi Peninsula in Southern Greenland, as well as lakes from Russian Karelia.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMPP31D1694H
- Keywords:
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- 0424 Biosignatures and proxies;
- BIOGEOSCIENCESDE: 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCESDE: 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHYDE: 4924 Geochemical tracers;
- PALEOCEANOGRAPHY