Constraining silicon isotope exchange kinetics and fractionation between aqueous and amorphous Si at room temperature

Summary

This experimental geochemistry study constrains silicon isotope exchange kinetics and fractionation between aqueous solutions and amorphous silica at room temperature through controlled laboratory measurements. The quantitative parameters derived—exchange rates and fractionation factors—provide a foundation for interpreting silicon isotope signatures in soil pore waters, plant tissues, and pedogenic minerals. Such constraints are essential for using silicon isotopes as tracers of weathering, nutrient cycling, and soil formation processes in terrestrial systems.

UK applicability

The fundamental kinetic parameters established may be incorporated into interpretations of silicon isotope ratios in UK soils and silicate weathering studies, though direct field validation under UK soil and climatic conditions would strengthen applicability. UK soil scientists using silicon isotopes for pedogenesis or nutrient tracer studies would benefit from these quantified exchange kinetics.

Key measures

Silicon isotope fractionation factors (Δ30Si values), exchange rate constants, equilibrium isotopic composition differences between aqueous and amorphous silica phases

Outcomes reported

The study experimentally quantified silicon isotope fractionation factors and exchange kinetics between aqueous solutions and amorphous silica phases at ambient temperature. Results provide rate constants and equilibrium fractionation parameters applicable to tracing silicon cycling in pedogenic and biological systems.

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