Methane Source and Turnover in the Shallow Sediments to the West of Haima Cold Seeps on the Northwestern Slope of the South China Sea

Table 2

Rate expressions of the reactions considered in the model.

Rate	Kinetic rate law
Total POC degradation (wt.% C yr^-1)
POM degradation via sulfate reduction (mmol cm^-3 yr^-1 of SO4^2-)
Methanogenesis (mmol cm^-3 yr^-1 of CH4)
Anaerobic oxidation of methane (mmol cm^-3 yr^-1 of CH4)
Authigenic Ca-carbonate precipitation (mmol cm^-3 yr^-1 of Ca^2+)
Authigenic Mg-carbonate precipitation (mmol cm^-3 yr^-1 of Mg^2+)
Gas bubble irrigation (mmol cm^-3 yr^-1)
Gas bubble dissolution (mmol cm^-3 yr^-1 of CH4)

f_POC converts between POC (dry wt.%) and DIC (mmol cm^-3 of porewater): , where is the molecular weight of carbon (12 g mol^-1), is the density of dry sediments, and is the porosity.