title: Rapid Removal of Atmospheric CO2 by Urban Soils.
abstract: The measured calcium carbonate content of soils to a depth of 100 mm at a large urban development site has increased over 18 months at a rate that corresponds to the sequestration of 85 t of CO2/ha (8.5 kg of CO2 m(-2)) annually. This is a consequence of rapid weathering of calcium silicate and hydroxide minerals derived from the demolition of concrete structures, which releases Ca that combines with CO2 ultimately derived from the atmosphere, precipitating as calcite. Stable isotope data confirm an atmospheric origin for carbonate carbon, and 14C dating indicates the predominance of modern carbon in the pedogenic calcite. Trial pits show that carbonation extends to depths of ≥1 m. Work at other sites shows that the occurrence of pedogenic carbonates is widespread in artificially created urban soils containing Ca and Mg silicate minerals. Appropriate management of fewer than 12000 ha of urban land to maximize calcite precipitation has the potential to remove 1 million t of CO2 from the atmosphere annually. The maximal global potential is estimated to be approximately 700-1200 Mt of CO2 per year (representing 2.0-3.7% of total emissions from fossil fuel combustion) based on current rates of production of industry-derived Ca- and Mg-bearing materials.
authors.affiliation: †School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
authors.forename: Carla-Leanne
authors.initials: CL
authors.lastname: Washbourne
authors.affiliation: †School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
authors.forename: Elisa
authors.initials: E
authors.lastname: Lopez-Capel
authors.forename: Phil
authors.initials: P
authors.lastname: Renforth
authors.affiliation: §Scottish Universities Environmental Research Centre, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride G75 0QF, U.K.
authors.forename: Philippa L
authors.initials: PL
authors.lastname: Ascough
authors.affiliation: †School of Civil Engineering and Geosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, U.K.
authors.forename: David A C
authors.initials: DA
authors.lastname: Manning
mesh_terms: D001272:Atmosphere; D002119:Calcium Carbonate / Q000032:analysis* / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D002245:Carbon Dioxide / Q000737:chemistry; D002250:Carbon Radioisotopes / Q000032:analysis; D057965:Carbon Sequestration; D002947:Cities; D004739:England; D005579:Fossil Fuels; D008903:Minerals / Q000737:chemistry; D017640:Silicates / Q000737:chemistry; D012987:Soil / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D002250:Carbon Radioisotopes; D005579:Fossil Fuels; D008903:Minerals; D017640:Silicates; D012987:Soil; D002245:Carbon Dioxide; D002119:Calcium Carbonate; C031293:calcium silicate