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Tracer for the Global Biogeochemical Cycle of Magnesium Past and Present or Archive of Alteration?
Edward T. Tipper
Published online:

07 February 2022

Print publication:

03 March 2022
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Magnesium is a major constituent in silicate and carbonate minerals, the hydrosphere and the biosphere. Magnesium is constantly cycled between these reservoirs. Since each of the major planetary reservoirs of magnesium have different magnesium isotope ratios, there is scope to use magnesium isotope ratios to trace 1) the processes that cycle Magnesium at a spatial scales from the entire planet to microscopic and 2) the relative fluxes between these reservoirs. This review summarises some of the key motivations, successes and challenges facing the use of magnesium isotopes to construct a budget of seawater magnesium, present and past.

6 - Equilibrium Models of NaturalWaters
from PART I - EQUILIBRIUM IN NATURAL WATERS
Craig M. Bethke, University of Illinois, Urbana-Champaign
Book:

Geochemical and Biogeochemical Reaction Modeling

Published online:

09 December 2021

Print publication:

06 January 2022, pp 67-86
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Summary

Calculated models of the chemistry of natural waters show how mass is distributed among aqueous species, minerals, and gases, whether individual minerals are undersaturated or supersaturated, and gas partial pressures within the waters. This chapter explores how to construct and interpret computed models of water chemistry, using seawater, river water, and deep-sea brines as examples.

Tracer of Ocean Productivity and a Recorder of Isotopic Compositions of Seawater S, O, Sr, Ca and Ba
Weiqi Yao, Elizabeth Griffith, Adina Paytan
Published online:

23 December 2020

Print publication:

28 January 2021
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Reconstruction of ocean paleoproductivity and paleochemistry is paramount to understanding global biogeochemical cycles such as the carbon, oxygen and sulfur cycles and the responses of these cycles to changes in climate and tectonics. Paleo-reconstruction involves the application of various tracers that record seawater compositions, which in turn may be used to infer oceanic processes. Several important tracers are incorporated into pelagic barite, an authigenic mineral that forms in the water column. Here we summarize the utility of pelagic barite for the reconstruction of export production and as a recorder of seawater S, O, Sr, Ca and Ba.