Ge/Si Ratio and Germanium Isotope Fractionation Mechanism in the Zhanjiang Basalt Weathering Profile

Key Points

• To investigate the variation of Ge/Si ratios and the mechanisms of germanium isotope fractionation during basalt chemical weathering under tropical conditions.
• Analyzed samples from surface soil, residual soil, and bedrock for Ge/Si ratios and δ74Ge values.
• Conducted sequential extraction experiments to study the form of germanium in samples.
• Evaluated correlations between Ge content, migration coefficients, and Ge/Si ratios.
• Surface and residual soils exhibited higher Ge/Si ratios (3.12~5.89 μmol/mol) compared to bedrock (1.87 μmol/mol).
• The δ74Ge values in soil samples were lower overall, ranging from −0.09±0.21‰ to 0.71±0.06‰.
• 69%~98% of germanium is found in residual forms predominantly as aluminosilicate minerals.
• The germanium isotope fractionation factor during basalt weathering is −1.69 ± 0.24‰ (1σ).