This graphic shows the average bicarbonate concentrations, in milligrams per litre, at major river mouths for the time periods 1976 to 1990 and 1991 to 2000. The graphic also shows the changes in average bicarbonate levels between these two time periods. Bicarbonate is an indication of the alkalinity in the rivers which reflects the geology (rock, minerals, sand) and increases the buffering capacity, but can also increase the risk of eutrophication (excess nutrients).
From collection: Vital Water Graphics
Philippe Rekacewicz, Delphine Digout, UNEP/GRID-Arendal