Dynamics of deep soil carbon – insights from 14C time series across a climatic gradient

van der Voort, T. S., Mannu, U., Hagedorn, F., McIntyre, C. , Walthert, L., Schleppi, P., Haghipour, N. and Eglinton, T. I. (2019) Dynamics of deep soil carbon – insights from 14C time series across a climatic gradient. Biogeosciences, 16(16), pp. 3233-3246. (doi: 10.5194/bg-16-3233-2019)

Abstract

Quantitative constraints on soil organic matter (SOM) dynamics are essential for comprehensive understanding of the terrestrial carbon cycle. Deep soil carbon is of particular interest as it represents large stocks and its turnover times remain highly uncertain. In this study, SOM dynamics in both the top and deep soil across a climatic (average temperature ∼ 1–9 ∘C) gradient are determined using time-series (∼20 years) 14C data from bulk soil and water-extractable organic carbon (WEOC). Analytical measurements reveal enrichment of bomb-derived radiocarbon in the deep soil layers on the bulk level during the last 2 decades. The WEOC pool is strongly enriched in bomb-derived carbon, indicating that it is a dynamic pool. Turnover time estimates of both the bulk and WEOC pool show that the latter cycles up to a magnitude faster than the former. The presence of bomb-derived carbon in the deep soil, as well as the rapidly turning WEOC pool across the climatic gradient, implies that there likely is a dynamic component of carbon in the deep soil. Precipitation and bedrock type appear to exert a stronger influence on soil C turnover time and stocks as compared to temperature.

• Item Type: Articles
• Additional Information: This research has been supported by the Swiss National Science Foundation NRP 68 (grant no. SNF 406840_143023/11.1.13-31.12.15).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Mcintyre, Dr Cameron
• Authors: van der Voort, T. S., Mannu, U., Hagedorn, F., McIntyre, C., Walthert, L., Schleppi, P., Haghipour, N., and Eglinton, T. I.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Biogeosciences
• Publisher: Copernicus Publications
• ISSN: 1726-4170
• ISSN (Online): 1726-4189
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Biogeosciences 16(16):3233-3246
• Publisher Policy: Reproduced under a Creative Commons License