Cai, W.J., Y. Wang and R.E. Hodson. 1998. Acid-base properties of dissolved organic matter in the estuarine waters of Georgia, U.S.A. Geochemica Acta. 62:473-483.
         The contribution of dissolved organic matter (DOM) to alkalinity in
    estuarine waters and its relationship to CO2 chemistry has not
    received much previous attention. In this paper, we present some of the
    first organic alkalinity measurements in the context of estuarine mixing,
    focusing on three rivers in the Southeastern US. The simple model presented
    here demonstrates that the organic contribution to alkalinity in estuarine
    waters is largely controlled by the dramatic pH change in the early stage of
    the mixing. As mixing continues, organic alkalinity becomes nearly
    conservative with respect to salinity change. Although we did not detect any
    DOM removal during estuarine mixing, this work provides an alternative
    approach to evaluate the issues of colloids and small particles formation
    and coagulation during mixing. This paper demonstrates that a large part of
    the chargeable sites of humic substances are either completely protonated or
    deprotonated during the estuarine mixing processes and therefore do not
    contribute to alkalinity nor proton transfer reactions. One class of
    chargeable sites may be adequate to describe the changing acid-base
    properties of humic substances during the mixing process. Furthermore,
    dependence of acidty on ionic strength is of second order importance. The
    data shall be valuable for evaluating the more elaborate models of humic
    substances, which either have multiple sites or continues site distribution
    and take ionic strength into consideration.