Photochemical Transformation of Dissolved Organic Matter to Carbon Dioxide in Southern England, UK.

Abstract

Dissolved inorganic carbon (DIC) is photochemically produced from coloured dissolved organic matter (CDOM). This is important since dissolved organic carbon (DOC), which in part is CDOM, has increased in UK rivers since scientists started measuring it, at least half a century ago. Therefore, a DIC increase is a possible effect of the DOC increase. This work has found significant correlation between CDOM and the DIC photoproduction rate (p-value = 4x10-5), showing that changes in DOC will conclusively affect DIC. This work has also found that changes in DIC photoproduction rate due to CDOM are 3.1 times higher in riverine water than in oceanic water. This change in the DIC photoproduction rate could be due to different elements and compounds limited in riverine water, but in higher concentrations in oceanic water, or differences in CDOM origin and composition.