Evaluation of rock resources for carbon dioxide removal by enhanced weathering: A South China case

[Geoengineering News]

https://www.sciencedirect.com/science/article/abs/pii/S0883292726001368

Authors: Shan Qi, Xing Jian

https://doi.org/10.1016/j.apgeochem.2026.106812

04 April 2026

Highlights

•A robust geochemical database of > 7000 mafic and ultramafic rock samples across South China was established.

•ERW suitability was evaluated by weathering potential, nutrients and heavy metals, climate and transport distance.

•Environmental risks of ERW could not be overlooked, and should be considered for elements like Cr, Ni, Zn, Co, Cu, Cd, etc.

•Fujian Province is rated as the most promising province and should be the first to carry out the field trials.

•Sichuan/Yunnan, Hainan and Henan are promising ERW candidates, but potential environmental impacts require monitoring.

Abstract

With the challenge of rising atmospheric CO2, Enhanced Rock Weathering (ERW) has emerged as a promising climate mitigation strategy. By spreading ground weatherable rocks (mostly mafic and ultra-mafic silicate rocks) to cropland, forest and coast in climatically favorable regions, ERW is thought to involve both benefits and environmental risks. While previous studies have mainly focused on carbon removal abilities and efficiencies of the most favorable minerals and rocks, high-potential rock resource surveys and comprehensive regional assessments integrating diverse beneficial and risk factors are poorly reported. In this contribution, we bridged this gap by first establishing a robust geochemical database of 7037 mafic and ultramafic rock samples across South China. Using this database, we developed a multi-criteria evaluation framework considering weathering potential, nutrients, heavy metals, and local climatic factors. The weight allocation in the system was determined by the Inter-criteria Correlation (CRITIC) method and subjective adjustment to assess the ERW potential of these rocks. The evaluation results reveal significant potential in Fujian Province, which we identify as the optimal location, with Guangdong, Jiangxi, and Hainan provinces being highly suitable alternatives. The coastlines of Guangdong, Hainan and southwestern Guangxi provinces are also ideal sites for coastal ERW deployment. Furthermore, high-potential rocks are often characterized by metamorphism and high iron oxide content, such as metamorphosed harzburgite from the Fujian coast, gabbro from the Emeishan Large Igneous Province (ELIP) in southwestern China, and pyroxenite from Henan Province. These findings offer actionable insights for policymakers and developers, enabling targeted resource allocation and accelerating ERW adoption. While heavy metal elements like copper, cadmium, and lead require careful environmental monitoring, the study provides a practical roadmap for ERW deployment. Our multi-criteria assessment framework serves as a standardized approach for a local or regional ERW resource assessment that can contribute to global CO2 removal strategies. Future work should refine this methodology by incorporating mineralogical compositions for greater precision and validating findings through in-situ field trials to assess real-world CO2 removal rates and heavy metal bioavailability. The comprehensive database established here provides a foundational resource for these future endeavors and other geological applications.

Source: ScienceDirect