thumbnail

Mechanisms for chemostatic behavior in catchments: implications for CO2 consumption by mineral weathering

Chemical Geology

By:
and
DOI: 10.1016/j.chemgeo.2009.09.014

Links

Abstract

Concentrations of weathering products in streams often show relatively little variation compared to changes in discharge, both at event and annual scales. In this study, several hypothesized mechanisms for this “chemostatic behavior” were evaluated, and the potential for those mechanisms to influence relations between climate, weathering fluxes, and CO2 consumption via mineral weathering was assessed. Data from Loch Vale, an alpine catchment in the Colorado Rocky Mountains, indicates that cation exchange and seasonal precipitation and dissolution of amorphous or poorly crystalline aluminosilicates are important processes that help regulate solute concentrations in the stream; however, those processes have no direct effect on CO2 consumption in catchments. Hydrograph separation analyses indicate that old water stored in the subsurface over the winter accounts for about one-quarter of annual streamflow, and almost one-half of annual fluxes of Na and SiO2 in the stream; thus, flushing of old water by new water (snowmelt) is an important component of chemostatic behavior. Hydrologic flushing of subsurface materials further induces chemostatic behavior by reducing mineral saturation indices and increasing reactive mineral surface area, which stimulate mineral weathering rates. CO2 consumption by carbonic acid mediated mineral weathering was quantified using mass-balance calculations; results indicated that silicate mineral weathering was responsible for approximately two-thirds of annual CO2 consumption, and carbonate weathering was responsible for the remaining one-third. CO2 consumption was strongly dependent on annual precipitation and temperature; these relations were captured in a simple statistical model that accounted for 71% of the annual variation in CO2 consumption via mineral weathering in Loch Vale.

Study Area

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Mechanisms for chemostatic behavior in catchments: implications for CO2 consumption by mineral weathering
Series title:
Chemical Geology
DOI:
10.1016/j.chemgeo.2009.09.014
Volume
269
Issue:
1-2
Year Published:
2010
Language:
English
Publisher:
Elsevier
Publisher location:
Amsterdam, Netherlands
Contributing office(s):
Colorado Water Science Center
Description:
12 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Chemical Geology
First page:
40
Last page:
51
Country:
United States
State:
Colorado
Other Geospatial:
Loch Vale