Alkalinization Types

Table 5 Controlled vocabularies for source materials for OAE (based on Renforth and Henderson, 2017; Caserini et al., 2022).

No.	Source materials	Chemical formula	OAE mechanism
1	Lime	CaO	CaO + H2O → Ca(OH)2; Ca(OH)2 + 2CO2 → Ca2+ + 2HCO3-
2	Portlandite	Ca(OH)2	Ca(OH)2 + 2CO2 + H2O → Ca2+ + 2HCO3-
3	Calcium Carbonate (e.g., calcite/aragonite)	CaCO3	CaCO3 + CO2 + H2O → Ca2+ + 2HCO3-
4	Anorthite	CaAl2Si2O8	CaAl2Si2O8 + 2CO2 + 3H2O → Ca2+ + 2HCO3- + Al2Si2O5(OH)4
5	Dolomite	CaMg(CO3)2	CaMg(CO3)2 + 2CO2 + 2H2O → Ca2+ + Mg2+ + 4HCO3-
6	Periclase	MgO	MgO + 2CO2 + H2O → Mg2+ + 2HCO3-
7	Brucite	Mg(OH)2	Mg(OH)2 + 2CO2 + H2O → Mg2+ + 2HCO3-
8	Magnesite	MgCO3	MgCO3 + CO2 + H2O → Mg2+ + 2HCO3-
9	Forsterite	Mg2SiO4	Mg2SiO4 + 4CO2 + 4H2O → 2Mg2+ + 4HCO3- + H4SiO4
10	Mg-rich Olivine (Fe-Forsterite)	(Mg, Fe)2SiO4	(Mg, Fe)2SiO4 + 4CO2 + 4H2O → 2(Mg, Fe)2+ + 4HCO3- + H4SiO4
11	Sodium hydroxide	NaOH	NaOH + CO2 → Na+ + HCO3- (electrochemical weathering)
12	Natrite	Na2CO3	Na2CO3 + CO2 + H2O → 2Na+ + 2HCO3-
13	Nahcolite	NaHCO3	NaHCO3 → Na+ + HCO3-

Citation:
Jiang, L.-Q., Subhas, A., Basso, D., Fennel, K., and Gattuso, J.-P. (2023). Data reporting and sharing for ocean alkalinity enhancement research, in: Guide to Best Practices in Ocean Alkalinity Enhancement Research (OAE Guide 23), edited by: Oschlies, A., Stevenson, A., Bach, L., Fennel, K., Rickaby, R., Satterfield, T., Webb, R., and Gattuso, J.-P., Copernicus Publications, State Planet, https://doi.org/10.5194/sp-2-oae2023-13-2023.