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Annual Variations of the 14C Content of Soil CO2

Published online by Cambridge University Press:  18 July 2016

Helmut Dörr  and
K O Münnich
Helmut Dörr
Affiliation:
Institut für Umweltphysik, University of Heidelberg Im Neuenheimer Feld 366, D-6900 Heidelberg, FRG
K O Münnich
Affiliation:
Institut für Umweltphysik, University of Heidelberg Im Neuenheimer Feld 366, D-6900 Heidelberg, FRG
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Abstract

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A 6-year and a 2-year record of 14C measurements of soil CO2 in two soils are presented and discussed. The annual 14C variation of soil CO2 is controlled by the seasonally varying contribution of root respiration and of microbial decomposition of organic matter producing soil CO2. The Δ14C soil CO2 difference between summer and winter is ca 50‰ in a soil where turnover of organic matter is fast (τ = 2.5a) and ca 100‰ in a soil of slow turnover (τ = 60a). A simple model describing the movement and turnover of organic matter is derived, giving the depth distributions of organic carbon and of 14C. The model needs a subdivision of the carbon reservoir into at least two reservoirs with residence times of τ1 = la and τ2 = 100a, respectively, and with a vertical transfer velocity in the order of 0.6mm/a.

Type
III. The Carbon Cycle
Information
Radiocarbon , Volume 28 , Issue 2A , 1986 , pp. 338 - 345
Copyright
Copyright © The American Journal of Science 

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