Inorganic Carbon Speciation and Fluxes in the Congo River

Zhaohui Wang, Dinga Bienvenu, Paul Mann, Katherine Hoering, John Poulsen, Robert Spencer, Robert Holmes

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)

Abstract

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.
Original languageEnglish
Pages (from-to)511-516
JournalGeophysical Research Letters
Volume40
Issue number3
DOIs
Publication statusPublished - Feb 2013

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