Protonation Characteristics of the Dissolved Organic Matter in Seawater

Author

Douglas Lee Huizenga, University of Rhode Island

Date of Award

1977

Degree Type

Thesis

Degree Name

Master of Science in Oceanography

Department

Oceanography

First Advisor

Dana R. Kester

Abstract

The acid-base equilibria of dissolved organic matter (DOM) in seawater must be determined before a predictive model of seawater chemistry can be made. The numbers and types of sites present on the organic matter determines the chemical behavior of DOM. Acid-base titrations of organic matter isolated from various marine environments with activated charcoal were performed in 0.7m NaC10₄ medium. Only two types of sites are evident in the pH range 2 to 8. The Type 1 sites, which are probably carboxylic sites, make up about 10 μmoles of sites per milligram organic carbon (μmoles/mg OC) and are quite acidic (pK_a= 3.5). The less acidic Type 2 sites (pK_a about 6.5) were evident in only a few samples and amounted to less than 1 μmole of sites per milligram organic carbon in those samples. The Type 1 sites show a dissociation constant which varies with the degree of dissociation, similar to soil fulvic and humic acids. This variation in the dissociation constant is most likely due to both charge interaction between sites and slight chemical differences in the sites. The protonation characteristics of the Type 1 sites vary little for organic matter isolated from different marine environments.

Recommended Citation

Huizenga, Douglas Lee, "Protonation Characteristics of the Dissolved Organic Matter in Seawater" (1977). Open Access Master's Theses. Paper 2092.
https://digitalcommons.uri.edu/theses/2092