Isotopes as Tracers of Elements Across the Geosphere-Biosphere Interface

Isotopes as Tracers of Elements Across the Geosphere-Biosphere Interface 

Recent advances in isotope ratio mass spectrometry, particularly the advent of multi-collector (MC) inductively coupled plasma mass spectrometry (ICP-MS), 

The mass of the geosphere and the diversity of its chemical and mineral composition are the most substantial of all reservoirs [5] and it is the ultimate source of all elements. The mass of the entire geosphere dovm to 2 km depth is about 10 kg. The hydrosphere holds 1.4 X 10 kg of water, with 97.5% of it in the oceans. The hydrosphere amounts to 15% of the mass of the geosphere and hosts only about 5 X 10 kg of dissolved solids. The mass of the atmosphere is only 5 x 10 kg, which is a small fraction of the geosphere. The mass of dry organic matter in the biosphere is about 1.5 x 10 kg, contained mostly in land plants, with animals accounting for only 1% of the total and marine life for an even smaller fraction [6]. 

Elements That Typify the Ceospheie-Biosphere Interface 

Among the benefits from using isotopic analysis to study trace element movement across the geosphere and biosphere is the realization that Hg shows mass-independent fractionation that enhances our ability to define the sources of this toxic element [13]. Isotopes of Ca and Mg in biogenic carbonates indicate that there are both equilibrium mineralogical controls and kinetic controls on how these elements are incorporated by organisms from the geosphere and 

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