| 28 Jul 2026
Effects of enhanced rock weathering on soil gas fluxes across UK land uses
Abstract. Enhanced rock weathering (ERW) is a proposed carbon dioxide (CO2) removal strategy via the application of crushed silicate rocks to accelerate the natural breakdown of silicate minerals, permanently trapping atmospheric CO2. Application of rock dust may alter soil properties, such as pH, with potential consequences for soil trace gases fluxes relevant to climate forcing and air quality. However, previous ERW studies have focused mainly on the principal greenhouse gases, while broader trace gas responses remain poorly constrained. This laboratory study presents measurements of nitric oxide (NO), ammonia (NH3), carbon monoxide (CO), hydrogen (H2) and volatile organic compounds (VOCs), as well as CO2, methane (CH4) and nitrous oxide (N2O), from control and ERW-treated soils collected from arable, grassland and newly planted broadleaf and conifer forest field trials in the UK. Soils were sieved, repacked and rewetted for laboratory measurements. A dynamic air-flow-through chamber system, equipped with a high-resolution multi-gas analyser and a proton-transfer-reaction mass spectrometer, was used to measure N2O, NO, NH3, CO, and VOCs between 5 and 25 °C. CO2 and CH4 fluxes were measured online at 20 °C using a closed-loop chamber method, and H2 fluxes were measured by discrete sampling from static chamber headspace using gas chromatography. ERW-associated differences varied among gases and soils, with no consistent response across all incubated samples. The reported treatment differences included lower CO2 emissions in both forest soils, greater CH4 uptake in broadleaf forest soil, higher NO emissions in grassland soil, and changes in CO and hydrocarbon fluxes in forest soils. NH3 and H2 fluxes showed no statistically significant treatment responses, and no individual VOC remained significantly different after correction for multiple testing. Overall, rock dust application had limited and inconsistent impacts on trace gas fluxes across the soils examined in this snapshot study. Longer-term measurements at ERW field trials are needed to examine how these responses vary seasonally and evolve as the applied materials continued to weather. These measurements should be accompanied by in-depth soil characterisation and microbial analyses to elucidate the complex relationships between ERW treatment and trace gas fluxes. This evidence is needed to assess the full climate, air-quality and environmental implications of large-scale ERW deployment.
Competing interests: At least one of the (co-)authors is a member of the editorial board of Biogeosciences.
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