Boron Proxies in Paleoceanography and Paleoclimatology

ISBN-13: 9781119010630 / Angielski / Twarda / 2019 / 248 str.

Barbel Hoenisch; Stephen Eggins

Opis

Anthropogenic carbon dioxide emissions do not only warm our planet but also acidify our oceans.

Spis treści

Preface viiAcknowledgments viiiAbout the Companion Website ix1 Introduction and Concepts 11.1 Why Are we Interested in Reconstructing Marine Carbonate Chemistry? 1Acknowledgments 8References 8Further Reading/Resources 122 Boron Systematics 132.1 Introduction 142.2 What Determines the Sensitivity of delta11B and B/Ca to Marine Carbonate Chemistry? 152.3 Boron Proxy Systematics in Synthetic Carbonates 212.4 Boron Isotopes in Biogenic Marine Carbonates 422.5 Secular Evolution of [BT] and delta¯11B in Seawater 812.6 The B/Ca Proxy in Foraminifera 88References 1053 Reconstructing Paleo-Acidity, pCO2 and Deep-Ocean [CO3²-] 1203.1 Introduction 1203.2 Estimating Paleoseawater pH from Boron Isotopes 1223.3 Estimating Marine Carbonate Chemistry from B/Ca Ratios 1503.4 Guidelines for Selecting Sediment Core Sites and Sample Sizes 155References 1564 Boron Concentration and Isotope Ratio Analysis 1654.1 Introduction 1654.2 Inter-Laboratory Comparison Studies 1704.3 Standard Reference Materials and Data Quality Assurance 1724.4 Boron Concentration and Isotope Ratio Analysis 1754.5 Sample Preparation and Cleaning 1794.6 Boron Separation and Purification 1834.7 Instrumental Techniques 1884.8 Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) 2014.9 Secondary Ion Mass Spectrometry (SIMS) 2044.10 Other Techniques 2064.11 Outlook and Future Directions 210References 211Index 224

O autorze

Bärbel Hönisch, Department of Earth and Environmental Sciences and Lamont–Doherty Earth Observatory of Columbia University, USA.

Stephen M. Eggins, Research School of Earth Sciences, The Australian National University, Australia.

Blurb

Anthropogenic carbon dioxide emissions do not only warm our planet but also acidify our oceans. It is currently unclear to which degree Earth s climate and marine life will be impacted by these changes but information from Earth history, particularly the geochemical signals of past environmental changes stored in the fossil remains of marine organisms, can help us predict possible future changes. This book aims to be a primer for scientists who seek to apply boron proxies in marine carbonates to estimate past seawater carbonate chemistry and atmospheric pCO ₂.
Boron proxies ( ¹¹B and B/Ca) were introduced nearly three decades ago, with subsequent strides being made in understanding their mechanistic functioning. This text reviews current knowledge about the aqueous systematics, the inorganic and biological controls on boron isotope fractionation and incorporation into marine carbonates, as well as the analytical techniques for measurement of boron proxies. Laboratory and field calibrations of the boron proxies are summarized, and similarities between modern calibrations are explored to suggest estimates for proxy sensitivities in marine calcifiers that are now extinct. Example applications illustrate the potential for reconstructing paleo–atmospheric pCO ₂ from boron isotopes. Also explored are the sensitivity of paleo–ocean acidity and pCO ₂ reconstructions to boron isotope proxy systematics that are currently less well understood, including the elemental and boron isotopic composition of seawater through time, seawater alkalinity, temperature and salinity, and their collective impact on the uncertainty of paleo–reconstructions.
The B/Ca proxy is based on the same mechanistic principles as the boron isotope proxy, but empirical calibrations suggest seawater pH is not the only controlling factor. B/Ca therefore has the potential to provide a second carbonate parameter that could be paired with ¹¹B to fully constrain the ocean carbonate system, but the associated uncertainties are large. This text reviews and examines what is currently known about the B/Ca proxy systematics. As more scientists embark on characterizing past ocean acidity and atmospheric pCO ₂, Boron in Paleoceanography and Paleoclimatology provides a resource to introduce geoscientists to the opportunities and complications of boron proxies, including potential avenues to further refine them.