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

Bicarbonate ( ), 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 to the oceans and subsequent reactions affect atmospheric CO 2 , global climate and ocean pH. This review summarizes controls on the production of 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 production, and water throughput controls transport into rivers. Human influences on 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 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 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.