Restored wetlands as a source of disinfection byproduct precursors.
The effects of a restored wetland system in the Sacramento Valley, California on the production of dissolved organic carbon (DOC) and nitrogen (DON) and the formation potential of common disinfection byproducts (DBPs: trihalomethanes, haloacetonitriles, and chloral hydrate) were examined. Additionally, the effects of photodegradation and microbial degradation on dissolved organic matter properties and reactivitywith respect to DBP formation potential (DBP-FP) were evaluated. The wetlands increased DOC and DON concentrations by a factor of 2.2 and 1.9 times, respectively, but had little influence on the DOC and DON quality as compared to their source waters. The increase in DOC and DON concentrations increased the formation potential of all DBP species by >100%. Solar radiation and microbial degradation reduced the trihalomethane formation potential by 24 and 10%, respectively, during a 14 day incubation. In contrast, the chloral hydrate formation potential was increased by 22% after phototreatment. Results indicate that current flood-pulse management practices with a 2-3 week residence time could lead to wetlands acting as a source of DBP precursors. Enhanced DBP-FP is especially important as these wetlands contribute to a watershed that is a drinking water source for more than 23 million people.
Díaz
Francisco J
FJ
Department of Land, Air, and Water Resources, University of California, Davis, California 95616, USA. fjdiaz@ucdavis.edu
Chow
Alex T
AT
O'Geen
Anthony T
AT
Dahlgren
Randy A
RA
Wong
Po-Keung
PK