The geochemical evolution of basalt Enhanced Rock Weathering systems quantified from a natural analogue

• DOI: 10.1016/j.gca.2024.02.005
• Publication Date: 2024-02-16T13:37:41Z
• Authors: T. Linke; E.H. Oelkers; K. Dideriksen; S.C. Möckel; S. Nilabh; F. Grandia; S.R. Gislason
• Keywords: Alkalinity

Substantial quantities of fine-grained basaltic dust have fallen on South Iceland soils over at least the past 3300 years, making this region an ideal natural analogue to define long-term consequences current Enhanced Rock Weathering efforts. A relatively pristine Gleyic/Histic Andosol, 3 m in height, receiving approximately 1250 mm rainfall annually was selected for study. This soil receives estimated 500–800 g m−2 y−1 dust. The waters system were regularly sampled as a function depth from May November 2018. fluid pH, alkalinity and concentrations most major elements increased with fluids became more reduced. In contrast, whereas numerous toxic trace metals are initially released by dissolution basalt near surface they scavenged likely due their uptake secondary minerals. Equilibrium reaction path modelling suggests that 1) added airborne dissolves throughout column 2) total 0.26 cm3 per kg water soil–water system. Mass balance calculations indicate annual mass dissolved is less than 60 % system, such material increases continuously time. Basalt maintained precipitation Al-Si-minerals allophane, organic anion ligands decay. These processes limit aqueous Al3+ activity keep undersaturated respect primary minerals glass. pH ∼6 has higher both Icelandic ocean. if no present, solutions would be 4.4, zero alkalinity, illustrating role drawing CO2 out atmosphere.