Anthropogenic influences on riverine fluxes of dissolved inorganic carbon to the oceans

• Published in: Limnology and oceanography letters 2018-06, Vol.3 (3), p.143-155
• Main Authors: Raymond, Peter A., Hamilton, Stephen K.
• Format: Article
• Language: English
• Subjects: Acidification; Acids; Alkalinity; Anthropogenic factors; Aquatic ecosystems; Biogeochemistry; Calcification; Carbon cycle; Carbon dioxide; Chemistry; Climate change; Dissolved inorganic carbon; Global warming; Hydrologic cycle; Liming; Minerals; Mining; Natural waters; Oceans; Precipitation; River systems; Rivers; Seawater; Sediments; Water treatment; Watersheds; Weathering; Weathering zone
• ISSN: 2378-2242; 2378-2242
• DOI: 10.1002/lol2.10069

Bicarbonate (HCO3−), the predominant form of dissolved inorganic carbon in natural waters, originates mostly from watershed mineral weathering. On time scales of decades to centuries, riverine fluxes of HCO3− to the oceans and subsequent reactions affect atmospheric CO2, global climate and ocean pH. This review summarizes controls on the production of HCO3− from chemical weathering and its transport into river systems. The availability of minerals and weathering agents (carbonic, sulfuric, and nitric acids) in the weathering zone interact to control HCO3− production, and water throughput controls HCO3− transport into rivers. Human influences on HCO3− fluxes include climate warming, acid precipitation, mining, concrete use, and agricultural fertilization and liming. We currently cannot evaluate the net result of human influences on a global scale but HCO3− fluxes are clearly increasing in some major rivers as shown here for much of the United States. This increase could be partly a return to pre‐industrial HCO3− fluxes as anthropogenic acidification has been mitigated in the United States, but elsewhere around the world anthropogenic acidification could be leading to decreased concentrations and fluxes.