Table Of Content66
The
Silicon
Cycle
Human Perturbations
and Impacts
on Aquatic Systems
Venugopalan Ittekkot,
EDITED BY
Daniela Unger,
Christoph Humborg,
Nguyen Tac An
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The Silicon
Cycle
The Scientific Committee on Problems of the Environment(SCOPE)
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SCOPE 66: The Silicon Cycle: Human Perturbations and Impacts
on Aquatic Systems, edited by Venugopalan Ittekkot, Daniela Unger,
Christoph Humborg, and Nguyen Tac An
SCOPE 66
The Silicon
Cycle
Human Perturbations and
Impacts on Aquatic Systems
Edited by
Venugopalan Ittekkot
Daniela Unger
Christoph Humborg
Nguyen Tac An
A project of SCOPE, the Scientific Committee on
Problems of the Environment, of the
International Council for Science
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Library of Congress Cataloging-in-Publication Data
The silicon cycle : human perturbations and impacts on aquatic systems / Venugopalan
Ittekkot, Daniela Unger, Christoph Humborg, and Nguyen Tac An, editors.
p. cm. — (Scope ; 66)
ISBN 1-59726-114-9 (cloth : alk. paper) — ISBN 1-59726-115-7 (pbk. : alk. paper)
1. Silicon cycle (Biogeochemistry) 2. Aquatic ecology. I. Ittekkot, V. (Venugopalan),
1945- II. Series: SCOPE report ; 66.
QH344.S55 2006
577'.14—dc22 2006012462
British Cataloguing-in-Publication data available.
Printed on recycled, acid-free paper
Manufactured in the United States of America
10 9 8 7 6 5 4 3 2 1
Contents
List of Figures and Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ix
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xvii
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xix
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
Venugopalan Ittekkot,Daniela Unger,Christoph Humborg,and
Nguyen Tac An
2. Silicate Weathering in South Asian
Tropical River Basins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Vaidyanatha Subramanian,Venugopalan Ittekkot,Daniela Unger,and
Natarajan Madhavan
3. Silicon in the Terrestrial Biogeosphere . . . . . . . . . . . . . . . . . . . . .13
Daniel J.Conley,Michael Sommer,Jean Dominique Meunier,
Danuta Kaczorek,and Loredana Saccone
4. Factors Controlling Dissolved Silica in
Tropical Rivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Tim C.Jennerjahn,Bastiaan A.Knoppers,Weber F.L.de Souza,
Gregg J.Brunskill,E.Ivan,L.Silva,and Seno Adi
5. Dissolved Silica Dynamics in Boreal and Arctic Rivers:
Vegetation Control over Temperature? . . . . . . . . . . . . . . . . . .53
Christoph Humborg,Lars Rahm,Erik Smedberg,
Carl-Magnus Mörth,and Åsa Danielsson
6. Dissolved Silica in the Changjiang (Yangtze River)
and Adjacent Coastal Waters of the East China Sea . . . . . . . . . .71
Jing Zhang,Su Mei Liu,Ying Wu,Xiao Hong Qi,
Guo Sen Zhang,and Rui Xiang Li
viii | Contents
7. Atmospheric Transport of Silicon . . . . . . . . . . . . . . . . . . . . . . . . .81
Ina Tegen and Karen E.Kohfeld
8. Estuarine Silicon Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93
Lei Chou and Roland Wollast
9. Physiological Ecology of Diatoms Along the
River–Sea Continuum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121
Pascal Claquin,Aude Leynaert,Agata Sferratore,
Josette Garnier,and Olivier Ragueneau
10. Modeling Silicon Transfer Processes in
River Catchments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .139
Josette Garnier,Agata Sferratore,Michel Meybeck,
Gilles Billen,and Hans Dürr
11. Role of Diatoms in Silicon Cycling and Coastal
Marine Food Webs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .163
Olivier Ragueneau,Daniel J.Conley,Aude Leynaert,
Sorcha Ni Longphuirt,and Caroline P.Slomp
12. Responses of Coastal Ecosystems to Anthropogenic
Perturbations of Silicon Cycling . . . . . . . . . . . . . . . . . . . . . . . . .197
Olivier Ragueneau,Daniel J.Conley,Aude Leynaert,
Sorcha Ni Longphuirt,and Caroline P.Slomp
13. Silicon Isotope–Based Reconstructions
of the Silicon Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215
Christina L.De La Rocha
14. Long-Term Oceanic Silicon Cycle and the
Role of Opal Sediment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
Christoph Heinze
15. The Perturbed Silicon Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . .245
Venugopalan Ittekkot,Daniela Unger,Christoph Humborg,
and Nguyen Tac An
List of Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253
SCOPE Series List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259
SCOPE Executive Committee 2005–2008 . . . . . . . . . . . . . . . . . . . . . . . . . . .263
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .265
List of Figures and Tables
Figures
2.1. Correlation of alkalinity and total Ca and Mg. 7
2.2. Correlation of total alkalinity and silicate alkalinity. 9
2.3. Computed values for pCO plotted against silicate alkalinity. 9
2
3.1. Small amorphous silica spheres in beech leaves. 17
3.2. The biogeochemical Si cycle in a loblolly pine forest. 22
3.3. The benefits of Si for plants under various stresses. 24
4.1. DSi concentrations in large tropical rivers, nontropical rivers,
and small tropical rivers related to catchment size and discharge. 33
4.2. DSi yield and load versus catchment features: DSi yield versus runoff,
DSi load versus catchment size, DSi load versus runoff, and DSi yield
versus total suspended solid yield. 34
4.3. DSi concentration, yield, and load of tropical rivers by continent. 35
4.4. DSi load versus land use features in the catchment: DSi load versus
developed land, DSi load versus cropland, and DSi load versus
forest loss. 42
4.5. Ratios of DSi to N in large tropical rivers, nontropical rivers, and
small tropical rivers related to population density and number
of dams. 44
