Passive CO2 removal in urban soils: evidence from brownfield sites

M. Ehsan Jorat*, Mark A. Goddard, Peter Manning, Hiu Kwan Lau, Samuel Ngeow, Saran P. Sohi, David A. C. Manning

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Management of urban brownfield land can contribute to significant removal of atmospheric CO2 through the development of soil carbonate minerals. However, the potential magnitude and stability of this carbon sink is poorly quantified as previous studies address a limited range of conditions and short durations. Furthermore, the suitability of carbonate-sequestering soils for construction has not been investigated. To address these issues we measured total inorganic carbon, permeability and ground strength in the top 20 cm of soil at 20 brownfield sites in northern England, between 2015 and 2017. Across all sites accumulation occurred at a rate of 1–16 t C ha−1 yr−1, as calcite (CaCO3), corresponding to removal of approximately 4–59 t CO2 ha−1 yr−1, with the highest rate in the first 15 years after demolition. C and O stable isotope analysis of calcite confirms the atmospheric origin of the measured inorganic carbon. Statistical modelling found that pH and the content of fine materials (combined silt and clay content) were the best predictors of the total inorganic carbon content of the samples. Measurement of permeability shows that sites with carbonated soils possess a similar risk of run-off or flooding to sandy soils. Soil strength, measured as in-situ bearing capacity, increased with carbonation. These results demonstrate that the management of urban brownfield land to retain fine material derived from concrete crushing on site following demolition will promote calcite precipitation in soils, and so offers an additional CO2 removal mechanism, with no detrimental effect on drainage and possible improvements in strength. Given the large area of brownfield land that is available for development, the contribution of this process to CO2 removal by urban soils needs to be recognised in CO2 mitigation policies.
Original languageEnglish
Article number135573
Number of pages9
JournalScience of the Total Environment
Early online date18 Nov 2019
DOIs
Publication statusE-pub ahead of print - 18 Nov 2019

Fingerprint

brownfield site
Soils
inorganic carbon
Calcium Carbonate
Calcite
Carbon
calcite
soil
demolition
Demolition
permeability
carbonate
carbon sink
soil strength
Carbonate minerals
crushing
bearing capacity
sandy soil
Carbonation
removal

Cite this

Jorat, M. E., Goddard, M. A., Manning, P., Lau, H. K., Ngeow, S., Sohi, S. P., & Manning, D. A. C. (2019). Passive CO2 removal in urban soils: evidence from brownfield sites. Science of the Total Environment, [135573]. https://doi.org/10.1016/j.scitotenv.2019.135573
Jorat, M. Ehsan ; Goddard, Mark A. ; Manning, Peter ; Lau, Hiu Kwan ; Ngeow, Samuel ; Sohi, Saran P. ; Manning, David A. C. / Passive CO2 removal in urban soils : evidence from brownfield sites. In: Science of the Total Environment. 2019.
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Passive CO2 removal in urban soils : evidence from brownfield sites. / Jorat, M. Ehsan; Goddard, Mark A.; Manning, Peter; Lau, Hiu Kwan; Ngeow, Samuel; Sohi, Saran P.; Manning, David A. C.

In: Science of the Total Environment, 18.11.2019.

Research output: Contribution to journalArticle

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T1 - Passive CO2 removal in urban soils

T2 - evidence from brownfield sites

AU - Jorat, M. Ehsan

AU - Goddard, Mark A.

AU - Manning, Peter

AU - Lau, Hiu Kwan

AU - Ngeow, Samuel

AU - Sohi, Saran P.

AU - Manning, David A. C.

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N2 - Management of urban brownfield land can contribute to significant removal of atmospheric CO2 through the development of soil carbonate minerals. However, the potential magnitude and stability of this carbon sink is poorly quantified as previous studies address a limited range of conditions and short durations. Furthermore, the suitability of carbonate-sequestering soils for construction has not been investigated. To address these issues we measured total inorganic carbon, permeability and ground strength in the top 20 cm of soil at 20 brownfield sites in northern England, between 2015 and 2017. Across all sites accumulation occurred at a rate of 1–16 t C ha−1 yr−1, as calcite (CaCO3), corresponding to removal of approximately 4–59 t CO2 ha−1 yr−1, with the highest rate in the first 15 years after demolition. C and O stable isotope analysis of calcite confirms the atmospheric origin of the measured inorganic carbon. Statistical modelling found that pH and the content of fine materials (combined silt and clay content) were the best predictors of the total inorganic carbon content of the samples. Measurement of permeability shows that sites with carbonated soils possess a similar risk of run-off or flooding to sandy soils. Soil strength, measured as in-situ bearing capacity, increased with carbonation. These results demonstrate that the management of urban brownfield land to retain fine material derived from concrete crushing on site following demolition will promote calcite precipitation in soils, and so offers an additional CO2 removal mechanism, with no detrimental effect on drainage and possible improvements in strength. Given the large area of brownfield land that is available for development, the contribution of this process to CO2 removal by urban soils needs to be recognised in CO2 mitigation policies.

AB - Management of urban brownfield land can contribute to significant removal of atmospheric CO2 through the development of soil carbonate minerals. However, the potential magnitude and stability of this carbon sink is poorly quantified as previous studies address a limited range of conditions and short durations. Furthermore, the suitability of carbonate-sequestering soils for construction has not been investigated. To address these issues we measured total inorganic carbon, permeability and ground strength in the top 20 cm of soil at 20 brownfield sites in northern England, between 2015 and 2017. Across all sites accumulation occurred at a rate of 1–16 t C ha−1 yr−1, as calcite (CaCO3), corresponding to removal of approximately 4–59 t CO2 ha−1 yr−1, with the highest rate in the first 15 years after demolition. C and O stable isotope analysis of calcite confirms the atmospheric origin of the measured inorganic carbon. Statistical modelling found that pH and the content of fine materials (combined silt and clay content) were the best predictors of the total inorganic carbon content of the samples. Measurement of permeability shows that sites with carbonated soils possess a similar risk of run-off or flooding to sandy soils. Soil strength, measured as in-situ bearing capacity, increased with carbonation. These results demonstrate that the management of urban brownfield land to retain fine material derived from concrete crushing on site following demolition will promote calcite precipitation in soils, and so offers an additional CO2 removal mechanism, with no detrimental effect on drainage and possible improvements in strength. Given the large area of brownfield land that is available for development, the contribution of this process to CO2 removal by urban soils needs to be recognised in CO2 mitigation policies.

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JF - Science of the Total Environment

SN - 0048-9697

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