Calculating carbon mass balance from unsaturated soil columns treated with CaSO4-minerals: Test of soil carbon sequestration

摘要: Abstract Renewed interest in managing C balance soils is motivated by increasing atmospheric concentrations of CO2 and consequent climate change. Here, experiments were conducted soil columns to determine mass balances with without addition CaSO4-minerals (anhydrite gypsum), which hypothesized promote organic carbon (SOC) retention inorganic (SIC) precipitation as calcite under slightly alkaline conditions. Changes contents three phases (gas, liquid solid) measured unsaturated tested for one year comprehensive determined. The had no inputs, only utilization microbial activity transformations assumed the chemistry. measurements showed that changes inventories occurred through two processes, SOC loss SIC gain. However, losses treated lower than their corresponding control columns, indicating amendments promoted retention. resulted mostly from respiration atmosphere rather chemical leaching. Microbial oxidation appears have been suppressed increased Ca2+ SO42− dissolution CaSO4 minerals. For conditions tested, accumulation per m2 area CaSO4-treatment ranged 130 260 g C m−1 infiltrated water (20–120 g C m−1 net benefit). These results demonstrate potential sequestration via CaSO4-treatment.