Implications of the Riverine Response to Enhanced Weathering for CO2 removal in the UK

Harrington, K.J.; Hilton, Robert; Henderson, Gideon M.

doi:10.1016/j.apgeochem.2023.105643

Cited by 9 publications

(10 citation statements)

References 33 publications

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“…It is important to emphasize that the CDR rate estimated based on the time-integrated amount of feedstock dissolution and cation loss should be regarded as only an initial CDR value. There is potential for leakage of initially captured carbon downstream of a given field deployment, as alkalinity and dissolved inorganic carbon are transported from the soil column to the oceans (e.g., refs , , and − ). In addition, a large fraction of the dissolved cation load in any soil will be transiently hosted in soil exchange sites (e.g., refs − ; see also ref ).…”

Section: Resultsmentioning

confidence: 99%

“…However, this means that there is a variable lag time between feedstock dissolution and CO 2 capture that needs to be considered for accurate CDR quantification. Given these factors, a robust, “cradle-to-grave” MRV approach with TiCAT at its core will also require modeling the transport of weathering products through the soil ,,, and groundwater–river–ocean system ,− to determine potential leakage through re-release of CO 2 back to the atmosphere. In the near term, developing and testing these models should be done in conjunction with monitoring of aqueous geochemistry alongside soil-based approaches (such as TiCAT).…”

Section: Resultsmentioning

confidence: 99%

“…In cases in which the strong acid would have interacted with a silicate mineral already, this weathering needs to be discounted from initial CDR estimates (see Supporting Information section 1.10). The initial CDR rates calculated can be considered to be the maximum possible CDR from an ERW deployment and do not take into account downstream processes that will reduce the efficacy of carbon storage as bicarbonate in the river–ocean system, such as re-release of CO 2 via the precipitation of secondary clays and carbonates outside the soil column, or potential degassing of CO 2 after conversion of bicarbonate to carbonic acid by reequilibration in acidic solutions (e.g., refs , , and − ).…”

Section: Methodsmentioning

confidence: 99%

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Initial Validation of a Soil-Based Mass-Balance Approach for Empirical Monitoring of Enhanced Rock Weathering Rates

Reershemius,

Kelland,

Jordan

et al. 2023

Environ. Sci. Technol.

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Enhanced rock weathering (ERW) is a promising scalable and cost-effective carbon dioxide removal (CDR) strategy with significant environmental and agronomic co-benefits. A major barrier to large-scale implementation of ERW is a robust monitoring, reporting, and verification (MRV) framework. To successfully quantify the amount of carbon dioxide removed by ERW, MRV must be accurate, precise, and cost-effective. Here, we outline a mass-balance-based method in which analysis of the chemical composition of soil samples is used to track in situ silicate rock weathering. We show that signal-to-noise issues of in situ soil analysis can be mitigated by using isotope-dilution mass spectrometry to reduce analytical error. We implement a proofof-concept experiment demonstrating the method in controlled mesocosms. In our experiment, a basalt rock feedstock is added to soil columns containing the cereal crop Sorghum bicolor at a rate equivalent to 50 t ha −1 . Using our approach, we calculate rock weathering corresponding to an average initial CDR value of 1.44 ± 0.27 tCO 2 eq ha −1 from our experiments after 235 days, within error of an independent estimate calculated using conventional elemental budgeting of reaction products. Our method provides a robust time-integrated estimate of initial CDR, to feed into models that track and validate large-scale carbon removal through ERW.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Initial Validation of a Soil-Based Mass-Balance Approach for Empirical Monitoring of Enhanced Rock Weathering Rates

Reershemius,

Kelland,

Jordan

et al. 2023

Environ. Sci. Technol.

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“…Kelland et al, 2020). It has furthermore been suggested that silica saturation may limit feedstock dissolution and the CDR potential of EW (Köhler et al, 2010;Hartmann et al, 2013;Harrington et al, 2023), however the role of silica saturation in limiting enhanced weathering is debated (Schuiling et al, 2011).…”

Section: Base Cations and Dissolved Siliconmentioning

confidence: 99%

“…Downstream losses are more difficult to monitor directly compared to capture processes. As such, Earth system models and national riverine monitoring networks may show promise for addressing open system losses (Calabrese et al, 2022;Kanzaki et al, 2022Kanzaki et al, , 2023Knapp and Tipper, 2022;Zhang et al, 2022;Harrington et al, 2023) but there is currently little industry guidance on how to handle them in CDR claims. Upstream losses (i.e.…”

Section: Introductionmentioning

confidence: 99%

A Review of Measurement for Quantification of Carbon Dioxide Removal by Enhanced Weathering in Soil

Clarkson,

Larkin,

Swoboda

et al. 2023

Preprint

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All pathways which limit global temperature rise to <2oC above pre-industrial temperatures now require carbon dioxide removal (CDR) in addition to rapid greenhouse gas emissions reductions. Novel and durable CDR strategies need to rapidly scale over the next few decades in order to reach Paris Agreement Targets. Terrestrial enhanced weathering (EW) involves the acceleration of natural weathering processes via the deployment of crushed rock feedstocks, typically Ca- and Mg-rich silicates, in soils. While models predict this has the potential to remove multiple gigatonnes of CO2 annually, as an open-system pathway, the measurement (monitoring), reporting, and verification (MRV) of carbon removal and storage is challenging. Here we provide a review of the current literature showing the state-of-play of different methods for monitoring EW. We focus on geochemical characterization of weathering processes at the weathering site itself, acknowledging that the final storage of carbon is largely in the oceans, with potential losses occurring during transfer. There are two main approaches for measuring EW, one focused on solid phase measurements, including exchangeable phases, and the other on the aqueous phase. Additionally, gas phase measurements have been employed to understand CO2 fluxes, but can be dominated by short-term organic carbon cycling. We stress that, although there is complexity in tracing EW CDR in the natural field environment, established literature validates existing approaches, and each approach has strengths and limitations. The complexity inherent in open-system CDR pathways is navigable through surplus measurement strategies and well designed experiments, which we highlight are critical in the early stage of the EW CDR industry.

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Question-Led Innovation: Public priorities for enhanced weathering research in Malaysia

Cox,

Lim,

Spence

et al. 2025

Environmental Science & Policy

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Implications of the Riverine Response to Enhanced Weathering for CO2 removal in the UK

Cited by 9 publications

References 33 publications

Initial Validation of a Soil-Based Mass-Balance Approach for Empirical Monitoring of Enhanced Rock Weathering Rates

Initial Validation of a Soil-Based Mass-Balance Approach for Empirical Monitoring of Enhanced Rock Weathering Rates

A Review of Measurement for Quantification of Carbon Dioxide Removal by Enhanced Weathering in Soil

Question-Led Innovation: Public priorities for enhanced weathering research in Malaysia

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