You are here:
ATRAZOME CHLORINATION TRANSFORMATION PRODUCTS UNDER DRINKING WATER DISTRIBUTION SYSTEM CONDITIONS
Citation:
Ybarra*, M, M L. Magnuson*, K Kleier*, AND S K. Brown*. ATRAZOME CHLORINATION TRANSFORMATION PRODUCTS UNDER DRINKING WATER DISTRIBUTION SYSTEM CONDITIONS. Presented at AWWA WQTC, San Antonio, TX, November 14 - 18, 2004.
Impact/Purpose:
To inform the public.
Description:
Chlorination is a commonly-used disinfectant step in drinking water treatment. Should free chlorine be added to water used as a drinking water source, it is widely understood that many biological species in the water, along with dissolved organic and inorganic chemicals, will react with the chlorine. Reaction with biological species can result in beneficial disinfection of the water while reaction with the chemicals can produce detrimental by-products. If pesticides are present, whether from agricultural runoff or an accidental spill, they might undergo reactions with chlorine. This investigation focuses on atrazine, a widely applied herbicide (76 million pounds annually) which is currently regulated at 3 ppb, although the entire triazine family has recently been included in the U.S. EPA Candidate Contaminant List. It has been reported that atrazine entering a drinking water treatment plant is not transformed by chlorination. However, more recent concerns about pesticides, driven by the Food Quality Protection Act, focus not on what comes out of the plant, as required by the amended Safe Drinking Water Act, but on what reaches the consumer's tap.
Residence times in distribution systems can be days as opposed to minutes inside plants, and this may allow sufficient time for the atrazine to be transformed by chlorination into unknown species with unknown toxicities. Hence, there is a need to more completely study atrazine chlorination for residence times typical of distribution systems. This study aims to address three important issues in this regard. First, the chemical conditions under which atrazine transforms need to be determined. Second, any potential transformation products need to be identified. Third, the mechanistic pathways for these transformation products will have to be elucidated.