Field evidence for rapid precipitation of non-crystalline secondary phases during enhanced rock weathering
Year: 2026
Type: preprint
Abstract: Terrestrial enhanced rock weathering (ERW) is a proposed carbon dioxide removal strategy based on the application of silicate rock powder to soils. By introducing fresh mineral surfaces into soils, ERW can lead to the formation of reactive secondary phases, including poorly crystalline aluminosilicates such as allophane and imogolite. Despite their potential impact on both soil properties and the effectiveness of ERW, direct field evidence for the formation of these secondary phases remains elusive. Here we applied a basaltic rock powder (20 t ha − 1 ) to three temperate fields and investigated the formation of secondary phases using selective dissolution and scanning electron microscopy. We show that secondary phases formation occurs as early as seven months after rock powder application. In surface soils (0–3 cm), oxalate-extractable aluminum and silicon increased by 108% ± 30% and 682% ± 302%, respectively, suggesting a rapid formation of poorly crystalline aluminosilicate phases. Imaging further revealed the presence of allophane-like spherules and smectite precursors on the weathering rock powder surfaces. These findings demonstrate that ERW initiates rapid pedogenic transformations on annual timescales, highlighting the need to consider secondary phase formation when assessing the effectiveness and soil impacts of ERW-based CO 2 removal.
Source: Research Square
Authors: Emma Bonvin, Xavier Dupla, Stéphanie Grand
Institutions: ETH Zurich, University of Lausanne
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W7220653359