CO2 diffusion into pore spaces limits weathering rate of an experimental basalt landscape

Geology
By: , and 

Links

Abstract

Basalt weathering is a key control over the global carbon cycle, though in situ measurements of carbon cycling are lacking. In an experimental, vegetation-free hillslope containing 330 m3 of ground basalt scoria, we measured real-time inorganic carbon dynamics within the porous media and seepage flow. The hillslope carbon flux (0.6–5.1 mg C m–2 h–1) matched weathering rates of natural basalt landscapes (0.4–8.8 mg C m–2 h–1) despite lacking the expected field-based impediments to weathering. After rainfall, a decrease in CO2 concentration ([CO2]) in pore spaces into solution suggested rapid carbon sequestration but slow reactant supply. Persistent low soil [CO2] implied that diffusion limited CO2 supply, while when sufficiently dry, reaction product concentrations limited further weathering. Strong influence of diffusion could cause spatial heterogeneity of weathering even in natural settings, implying that modeling studies need to include variable soil [CO2] to improve carbon cycling estimates associated with potential carbon sequestration methods.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title CO2 diffusion into pore spaces limits weathering rate of an experimental basalt landscape
Series title Geology
DOI 10.1130/G38569.1
Volume 45
Issue 3
Year Published 2017
Language English
Publisher Geological Society of America
Contributing office(s) Earthquake Science Center
Description 4 p.
First page 203
Last page 206
Google Analytic Metrics Metrics page
Additional metadata about this publication, not found in other parts of the page is in this table