Wang, Z.A., Bienvenu, D.J., Mann, P.J., Hoering, K.A., Poulsen, J.R., Spencer, R.G.M., Holmes, R.M., 2013. Inorganic carbon speciation and fluxes in the Congo River. Geophys. Res. Lett. 40, 511-516.
Seasonal variations in inorganic carbon chemistry and associated fluxes
from the Congo River were investigated at Brazzaville-Kinshasa. Small
seasonal variation in dissolved inorganic carbon (DIC) was found in
contrast with discharge-correlated changes in pH, total alkalinity (TA),
carbonate species, and dissolved organic carbon (DOC). DIC was almost
always greater than TA due to the importance of CO2*, the sum of dissolved CO2
and carbonic acid, as a result of low pH. Organic acids in DOC
contributed 11–61% of TA and had a strong titration effect on water pH
and carbonate speciation. The CO2* and bicarbonate fluxes accounted for ~57% and 43% of the DIC flux, respectively. Congo River surface water released CO2 at a rate of ~109 mol m−2 yr−1. The basin-wide DIC yield was ~8.84 × 104 mol km−2 yr−1. The discharge normalized DIC flux to the ocean amounted to 3.11 × 1011 mol yr−1.
The DOC titration effect on the inorganic carbon system may also be
important on a global scale for regulating carbon fluxes in rivers.