Towards an Integrated Model of Weathering, Climate, and Biospheric Processes
Towards an Integrated Model of Weathering, Climate, and Biospheric Processes
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建立风化、气候和生物圈过程的综合模型
DOI：
10.2138/rmg.2009.70.9
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发表时间：
2009
影响因子：
--
通讯作者：
L. François
中科院分区：
文献类型：
--
作者：
Y. Goddéris;C. Roelandt;J. Schott;M. Pierret;L. François
Subaerial weathering of the continental rocks is an important component of global biogeochemical cycles. During the dissolution of continental rocks, atmospheric CO2 is consumed resulting in alkalinity production and its transfer to the ocean via river transport. Atmospheric carbon is also consumed during the dissolution reaction itself, as illustrated by the dissolution equation of plagioclase:
\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \begin{eqnarray*}&&4Na\_{0.5}Ca\_{0.5}Al\_{1.5}Si\_{2.5}O\_{8}\ +\ 17H\_{2}O\ +\ 6CO\_{2}\ {\rightarrow}\\&&3Al\_{2}Si\_{2}O\_{5}(OH)\_{4}\ +\ 2Na^{+}\ +\ 2Ca^{2+}\ +\ 6HCO\_{3}^{{-}}\ +\ 4H\_{4}SiO\_{4}\end{eqnarray*} \end{document}(1)
Plagioclase dissolution produces dissolved species (basic cations, bicarbonate ions, and silica) and clay minerals which can precipitate locally. Dissolution of carbonate minerals also consumes atmospheric carbon, for example:
\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[CaCO\_{3}\ +\ H\_{2}O\ +\ CO\_{2}\ {\rightarrow}\ Ca^{2+}\ +\ 2HCO\_{3}^{{-}}\] \end{document}(2)
Bicarbonate ions generated from either reaction can be transported to the ocean where it is mixed by the oceanic thermohaline circulation. Both reactions (1) and (2) thus remove carbon from the atmosphere and store it into the oceanic dissolved inorganic carbon reservoir at a timescale of the oceanic mixing (around 5000 yrs today). The total amount of atmospheric carbon being removed through this process has been estimated from the inventory of the amount of bicarbonate ions carried by the world major rivers. It reaches today 0.288 gigatons of carbon per year (GtC/yr) (Gaillardet et al. 1999), 0.14 GtC/yr being consumed by silicate weathering (a number updated to 0.163 GtC/yr by Dessert et al. 2003), and 0.148 GtC/yr by carbonate minerals dissolution. These fluxes are comparable to the net exchange fluxes between the ocean and the atmosphere (0.6 GtC/yr, pre-industrial state) and between the atmosphere and the land biosphere (0.4 GtC/yr, pre-industrial state), making continental weathering a potentially important component of the short term anthropogenic global carbon cycle. This importance has been recently stressed in two studies showing that continental weathering is strongly affected by human activities. Indeed, the HCO3− discharge of the Mississippi river has increased by about 25% over the last 40 years probably in response to anthropogenic land use change …
Subaerial weathering of the continental rocks is an important component of global biogeochemical cycles. During the dissolution of continental rocks, atmospheric CO2 is consumed resulting in alkalinity production and its transfer to the ocean via river transport. Atmospheric carbon is also consumed during the dissolution reaction itself, as illustrated by the dissolution equation of plagioclase:
\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \begin{eqnarray*}&&4Na\_{0.5}Ca\_{0.5}Al\_{1.5}Si\_{2.5}O\_{8}\ +\ 17H\_{2}O\ +\ 6CO\_{2}\ {\rightarrow}\\&&3Al\_{2}Si\_{2}O\_{5}(OH)\_{4}\ +\ 2Na^{+}\ +\ 2Ca^{2+}\ +\ 6HCO\_{3}^{{-}}\ +\ 4H\_{4}SiO\_{4}\end{eqnarray*} \end{document}(1)
Plagioclase dissolution produces dissolved species (basic cations, bicarbonate ions, and silica) and clay minerals which can precipitate locally. Dissolution of carbonate minerals also consumes atmospheric carbon, for example:
\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[CaCO\_{3}\ +\ H\_{2}O\ +\ CO\_{2}\ {\rightarrow}\ Ca^{2+}\ +\ 2HCO\_{3}^{{-}}\] \end{document}(2)
Bicarbonate ions generated from either reaction can be transported to the ocean where it is mixed by the oceanic thermohaline circulation. Both reactions (1) and (2) thus remove carbon from the atmosphere and store it into the oceanic dissolved inorganic carbon reservoir at a timescale of the oceanic mixing (around 5000 yrs today). The total amount of atmospheric carbon being removed through this process has been estimated from the inventory of the amount of bicarbonate ions carried by the world major rivers. It reaches today 0.288 gigatons of carbon per year (GtC/yr) (Gaillardet et al. 1999), 0.14 GtC/yr being consumed by silicate weathering (a number updated to 0.163 GtC/yr by Dessert et al. 2003), and 0.148 GtC/yr by carbonate minerals dissolution. These fluxes are comparable to the net exchange fluxes between the ocean and the atmosphere (0.6 GtC/yr, pre-industrial state) and between the atmosphere and the land biosphere (0.4 GtC/yr, pre-industrial state), making continental weathering a potentially important component of the short term anthropogenic global carbon cycle. This importance has been recently stressed in two studies showing that continental weathering is strongly affected by human activities. Indeed, the HCO3− discharge of the Mississippi river has increased by about 25% over the last 40 years probably in response to anthropogenic land use change …