Newsletter - Spring 2009

Current Research - Environmental Quality

Understanding the sources and qualities of dissolved organic carbon

Dissolved organic carbon (DOC) from natural landscapes doesn’t seem like it should be a water quality concern, it’s just made up of plant material and isn’t a whole lot different than tea.  In its natural state, it really isn’t a problem, and in fact, is vital for supporting microbial foodwebs.  However, when water is disinfected by chlorination or ozonation for drinking water purposes, that natural dissolved organic carbon becomes unnatural, forming halogenated carcinogenic compounds that are regulated by the EPA.

For Professor Peter Hernes and his research group, understanding the sources and quality of DOC is the key to developing management strategies for improving drinking water quality.  Hernes uses molecular biomarkers such as lignin, carbohydrates, fatty acids, and amino acids to investigate differences in DOC composition and reactivity from different landscapes and water sources in California, including the Sacramento/San Joaquin River Delta, the California State Water Project, shallow ground water beneath dairy farms, the Sierra Foothill Research & Extension Center, and an agricultural watershed local to Davis, Willow Slough.

Findings demonstrate that DOC concentrations, compositions, reactivities, and sources can vary significantly throughout the year, and are not in synch between the different land uses.  Thus, management strategies will have to be equally sophisticated in order to effectively improve our water quality.

At low flow, the DOC was 2 mg/L.

The storm flow value was 6.5 mg/L.

Picture taken by Brian Pellerin