3 Sources of Dissolved Organic Carbon to Groundwater Systems

There are three principal sources of DOC to groundwater. The first are allochthonous sources derived from plant material at land surface and transported to aquifers by infiltrating recharge water (Cronan and Aiken, 1985). Allochthonous DOC is typically the major source of DOC to shallow water table aquifers. The second major source is autochthonous DOC derived from particulate organic carbon that was buried with aquifer sediments at the time of deposition. Autochthonous DOC is typically a more important source of DOC to deeper confined aquifers (McMahon and Chapelle, 1991a). Finally, there are anthropogenic sources (carbon derived from human activities) of DOC as well. These anthropogenic sources include chemical contaminants such as petroleum hydrocarbons or chlorinated solvents (Wiedemeier et al., 1999) and DOC derived from agricultural activities (Thayalakumaran et al., 2015) and animal husbandry practices (Coote and Hore, 1979).