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Title: Temperature dependence of silicate weathering in nature estimated from geochemical mass balances in two forested Blue Ridge watersheds

Abstract

A comparison of two virtually identical watersheds in the southern Blue Ridge of North Carolina provides a unique opportunity for estimating the temperature dependence of natural feldspar weathering. Elevation (and consequently temperature) is the only factor which differs between the two watersheds; parent rock-type (Upper Precambrian Tallulah Falls Formation), aspect (south-facing), and vegetation type and successional stage are the same in both watersheds. The temperature dependence is estimated using the Arrhenius equation to calculate the apparent Arrhenius activation energy from (1) the ratio of feldspar weathering rates (determined from geochemical mass balance) and (2) the mean annual temperatures at the watersheds' midpoints (determined from measured temperatures at a known elevation and the mean atmospheric thermal lapse rate). The apparent Arrhenius activation energy of 18.4 kcal/mole is significantly higher than laboratory values; mineral weathering in nature increases more rapidly with temperature than predicted by extrapolating from experimental data. Hydrolysis of silicate minerals during weathering may thus be a stronger negative feedback on greenhouse warming than presently recognized; hydrolytic weathering reactions consume carbonic acid and thereby remove atmospheric carbon dioxide more rapidly with increasing temperature than is presently assumed in most models of global carbon cycling.

Authors:
 [1]
  1. Michigan State Univ., East Lansing, MI (United States). Dept. of Geological Sciences
Publication Date:
OSTI Identifier:
5725799
Report Number(s):
CONF-921058-
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Journal Name:
Geological Society of America, Abstracts with Programs; (United States)
Additional Journal Information:
Journal Volume: 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; Journal ID: ISSN 0016-7592
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; NORTH CAROLINA; WATERSHEDS; SILICATE MINERALS; WEATHERING; GEOCHEMISTRY; ACTIVATION ENERGY; CARBON CYCLE; CARBONIC ACID; CLIMATIC CHANGE; HYDROLYSIS; LEVELS; TEMPERATURE DEPENDENCE; CARBON COMPOUNDS; CHEMICAL REACTIONS; CHEMISTRY; DECOMPOSITION; DEVELOPED COUNTRIES; ENERGY; HYDROGEN COMPOUNDS; INORGANIC ACIDS; LYSIS; MINERALS; NORTH AMERICA; OXYGEN COMPOUNDS; SOLVOLYSIS; USA; 580000* - Geosciences

Citation Formats

Velbel, M A. Temperature dependence of silicate weathering in nature estimated from geochemical mass balances in two forested Blue Ridge watersheds. United States: N. p., 1992. Web.
Velbel, M A. Temperature dependence of silicate weathering in nature estimated from geochemical mass balances in two forested Blue Ridge watersheds. United States.
Velbel, M A. Wed . "Temperature dependence of silicate weathering in nature estimated from geochemical mass balances in two forested Blue Ridge watersheds". United States.
@article{osti_5725799,
title = {Temperature dependence of silicate weathering in nature estimated from geochemical mass balances in two forested Blue Ridge watersheds},
author = {Velbel, M A},
abstractNote = {A comparison of two virtually identical watersheds in the southern Blue Ridge of North Carolina provides a unique opportunity for estimating the temperature dependence of natural feldspar weathering. Elevation (and consequently temperature) is the only factor which differs between the two watersheds; parent rock-type (Upper Precambrian Tallulah Falls Formation), aspect (south-facing), and vegetation type and successional stage are the same in both watersheds. The temperature dependence is estimated using the Arrhenius equation to calculate the apparent Arrhenius activation energy from (1) the ratio of feldspar weathering rates (determined from geochemical mass balance) and (2) the mean annual temperatures at the watersheds' midpoints (determined from measured temperatures at a known elevation and the mean atmospheric thermal lapse rate). The apparent Arrhenius activation energy of 18.4 kcal/mole is significantly higher than laboratory values; mineral weathering in nature increases more rapidly with temperature than predicted by extrapolating from experimental data. Hydrolysis of silicate minerals during weathering may thus be a stronger negative feedback on greenhouse warming than presently recognized; hydrolytic weathering reactions consume carbonic acid and thereby remove atmospheric carbon dioxide more rapidly with increasing temperature than is presently assumed in most models of global carbon cycling.},
doi = {},
url = {https://www.osti.gov/biblio/5725799}, journal = {Geological Society of America, Abstracts with Programs; (United States)},
issn = {0016-7592},
number = ,
volume = 24:7,
place = {United States},
year = {1992},
month = {1}
}

Conference:
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