Practicum Project | 2010

Evaluating the Characteristics of Dissolved Organic Matter and its Interactions with Hydrophobic Organic Contaminants in Natural and Treated Waters

Students: Christina Cheng

Independent Project

Advisor: Dr. I.H. (Mel) Suffet

Dissolved organic matter (DOM) is a complex mixture of compounds found ubiquitously in natural waters. Sources of DOM include degraded biological materials in soil that is carried to water, as well as agricultural and urban runoffs. Previous research has shown that DOM can associate with hydrophobic organic compounds (HOCs) to lower the hazards of HOCs in the environment. Polycyclic aromatic hydrocarbons (PAHs) are a class of HOCs that can enter aquatic systems through industrial discharges and non-point source runoff. Due to its hydrophobicity, free PAHs can cross the non-polar gill membranes of fish and accumulate in the fatty tissues of aquatic organisms. However, when a free PAH binds to DOM, it forms a complex that is too large to be absorbed by aquatic organisms. This PAH-DOM interaction (PAHfree + DOM ↔ PAHbound-DOM) can be defined by a DOM-water partition coefficient, KDOM. The KDOM depends upon the nature of the DOM, as certain properties of DOM may favor PAH-DOM interaction. Using perylene as a non-toxic marker of HOC, this study will evaluate the composition, polarity, size, and other characteristics of DOM that may influence its association with HOCs in natural waters and during water treatment. By understanding the changes in DOM characteristics at different stages of water treatment, we can also provide information that is essential for optimizing the treatment process for the removal of DOM and hazardous, free PAHs.