Abstract
Alkalinization of natural waters by the dissolution of natural or
artificial minerals is a promising solution to sequester atmospheric
CO$_2$ and counteract acidification. Here we address the
alkalinization carbon capture efficiency (ACCE) by deriving an
analytical factor that quantifies the increase in dissolved inorganic
carbon in the water due to variations in alkalinity. We show that ACCE
strongly depends on the water pH, with a sharp transition from minimum
to maximum in a narrow interval of pH values. We also compare ACCE in
surface freshwater and seawater and discuss potential bounds for ACCE in
the soil water. Finally, we present two applications of ACCE. The first
is a local application to 156 lakes in an acid-sensitive region,
highlighting the great sensitivity of ACCE to the lake pH. The second is
a global application to the surface ocean, revealing a latitudinal
pattern of ACCE driven by differences in temperature and salinity.