Carbonate precipitation in artificial soils as a sink for atmospheric carbon dioxide

Abstract

Turnover of carbon in soils is the dominant flux in the global carbon cycle and is responsible for transporting 20 times the quantity of anthropogenic emissions each year. This paper investigates the potential for soils to be modified with calcium rich materials (e.g. demolition waste or basic slag) to capture some of the transferred carbon as geologically stable calcium carbonate. To test this principal, artificial soil known to contain calcium rich minerals (calcium silicates and portlandite) was analysed from two sites across North East England, UK. The results demonstrate an average carbon content of 30±15.3 Kg C m -2 stored as calcium carbonate, which is three times the expected organic carbon content and has accumulated at a rate of 25 ± 12.8 t C ha -1 y -1 since 1996. Isotopic analysis of the carbonates gave values between -6.4 and -27.5‰ for δ 13 C and -3.92 and -20.89‰ for  18 O respectively (against V-PDB), which suggests that a combination of carbonate formation mechanisms are operating including the hydroxylation of gaseous CO 2 in solution, the sequestration of degraded organic carbon with minor remobilisation/precipitation of lithogenic carbonates. This study implies that construction/development sites may be designed with a carbon capture function to sequester atmospheric carbon into the soil matrix with a maximum global potential of 290 Mt C y -1 .

Managing soil carbon stocks to enhance the resilience of urban ecosystems

“…Under the environmental conditions of most soils, bicarbonate and carbonate ionic forms, as well as carbonated salts in the solid phase are among the predominant stable forms of C (Macías and Arbestain, 2010). Carbon dating of SIC (i.e., pedogenic carbonates) indicates long C residence times of > 30,000 yr (Renforth et al, 2009). Similarly, radiocarbon ages of 1,000 yr to >10,000 yr have been reported for SOC, especially in sub-soil layers, and SOC turnover times increase with increase in soil depth (Rumpel and Kögel-Knabner, 2011).…”

Designing a carbon capture function into urban soils

“…Soils at both sites had an average carbon content of 30±15.3 kg C m -2 as calcium carbonate (Renforth et al, 2009) to depths of up to 3m, which is greater than the expected organic carbon content (see above). Stable isotope analysis (C, O) has confirmed the atmospheric origin of the carbon (rather than the remobilisation of rock carbonates; Renforth et al 2009).…”

“…Stable isotope analysis (C, O) has confirmed the atmospheric origin of the carbon (rather than the remobilisation of rock carbonates; Renforth et al 2009). Extrapolating the above figure to take into account the area of brownfield land within the UK, it can be speculated that brownfield land stores 12.7 Mt C as calcium carbonate (DCLG, 2007a;Scottish Executive -Statistical Bulletin, 2002).…”

Introduction of Microbial Biopolymers in Soil Treatment for Future Environmentally-Friendly and Sustainable Geotechnical Engineering

“…MICP has also been found to be applicable in various other fields, including the remediation of heavy metals [59], CO 2 sequestration [60], and the repair of concrete [61,62].…”