Stable carbon isotopes as an indicator for soil degradation in an alpine environment (Urseren Valley, Switzerland)

Abstract

Analyses of soil organic carbon (SOC) content and stable carbon isotope signatures (delta(13)C) of soils were assessed for their suitability to detect early stage soil erosion. We investigated the soils in the alpine Urseren Valley (southern central Switzerland) which are highly impacted by soil erosion. Hill slope transects from uplands (cambisols) to adjacent wetlands (histosols and histic to mollic gleysols) differing in their intensity of visible soil erosion, and reference wetlands without erosion influence were sampled. Carbon isotopic signature and SOC content of soil depth profiles were determined. A close correlation of delta(13)C and carbon content (r > 0.80) is found for upland soils not affected by soil erosion, indicating that depth profiles of delta(13)C of these upland soils mainly reflect decomposition of SOC. Long-term disturbance of an upland soil is indicated by decreasing correlation of delta(13)C and SOC (r </= 0.80) which goes in parallel with increasing (visible) damage at the site. Early stage soil erosion in hill slope transects from uplands to adjacent wetlands is documented as an intermediate delta(13)C value (-27.5 per thousand) for affected wetland soil horizons (0-12 cm) between upland (aerobic metabolism, relatively heavier delta(13)C of -26.6 per thousand) and wetland isotopic signatures (anaerobic metabolism, relatively lighter delta(13)C of -28.6 per thousand). Carbon isotopic signature and SOC content are found to be sensitive indicators of short- and long-term soil erosion processes.

Geochemical Processes Leading to the Precipitation of Subglacial Carbonate Crusts at Bossons Glacier, Mont Blanc Massif (French Alps)

“…This process has been suggested by Refsnider et al (2014) to explain the low δ 13 C of around −9‰ (VPDB) in the SPCCs from the eastern Canadian Arctic. The carbon isotopic composition measured in organic material of sample STB1, around −24.1 ± 0.2‰ (1σ), is fully consistent with the range of the modern upland Alpine (Urseren Valley, southern central Switzerland) soil organic matter from −27 to −21‰ (Schaub and Alewell, 2009). As the soil dissolved gaseous CO 2 is usually enriched in 13 C by about 4.4‰ during diffusion compared to the soil organic matter (Davidson, 1995;Refsnider et al, 2014), if we hypothesize that the STB1 organic carbon δ 13 C is representative of the carbon source for the SPCCs, then we can calculate that the CO 2 produced during the oxidation of this organic carbon might have had an isotopic composition around −24.1 + 4.4 FIGURE 8 | Carbon and oxygen isotope values for the carbonate within samples BOS2-1A, BOS2-2, BOS3.…”

Progress and challenges in using stable isotopes to trace plant carbon and water relations across scales

“…The inherent complexity behind ecosystem respiration lies behind the many contributing sources. Nowadays, studies of these components have expanded to include stem CO 2 flux, mycorrhizal and microbial contributions (Esperschütz et al, 2009), litter decomposition (Bird et al, 2008;Rubino et al, 2010), dissolved organic carbon (Sanderman and Amundson, 2008;Müller et al, 2009), erosion (Schaub and Alewell, 2009), soil organic matter dynamics (Klumpp et al, 2007;Kayler et al, 2011) and CO 2 storage in soil air and solution (Gamnitzer et al, 2011). Labelling has also played a central role in achieving a higher level of certainty in observing single source temporal patterns (Ubierna et al, 2009;Powers and Marshall, 2011).…”

Combined use of stable isotopes and fallout radionuclides as soil erosion indicators in a forested mountain site, South Korea

“…δ 13 C) and nitrogen (i.e. δ 15 N) served as useful tools to determine sources and sinks of carbon, nitrogen or sediments (Alewell et al, 2008;Buck and Monger, 1999;Papanicolaou et al, 2003;Schaub and Alewell, 2009;Turnbull et al, 2008;Fox and Papanicolaou, 2007;Jacinthe et al, 2009). They are also useful for process identification and even process quantification (Conen et al, 2007(Conen et al, , 2008.…”