Full Description

The use of oxidants in drinking water treatment is common for disinfection, oxidation ofinorganic and organic contaminants, taste and odor control, and microflocculation. Awide variety of pesticides are often observed in drinking water raw and treated waters. Itis well known that oxidation byproducts of synthetic organic compounds may have agreater, similar or lesser toxicity than the parent compound depending on the specificmodifications occurring in the chemical structure. With a few notable exceptions,relatively little is currently known about which systems of oxidants and pesticides lead tosignificant parent oxidation and removal with concurrent formation of oxidationbyproducts. In this AWWARF-funded study, the chemical reactivity of more than 70pesticides with various oxidants (free chlorine, monochloramine, ozone, permanganate,chlorine dioxide and hydrogen peroxide), plus UV radiation and hydrolysis, is beingexamined under typical drinking water treatment conditions. In this presentation, selectedsystems of the most reactive and important (as determined by potential toxicity,occurrence, use, and other parameters) pesticides will be presented in detail includingspecific oxidation byproducts and pathways. The screening study is conducted using bothGC/MS and LC/MS methods with degradate identification of byproducts conducted usingion trap LC/MS methods. Oxidation kinetic studies and parameter estimation ofbyproducts (e.g., partition coefficients, rate constants, etc.) are also determined in thisstudy. In this paper, the primary oxidation byproducts and pathways for selectedpesticides examined in detail to date will be presented including diazinon. Majorbyproducts were usually confirmed by use of standards, which also allowed detailedinvestigation of the subsequent oxidation of the byproducts themselves. Properties of thebyproducts will be presented as determined using both experimental methods andquantitative structure activity relationships (QSAR). This work will guide the direction offuture research with respect to occurrence, treatment, and toxicology of specific pesticidedegradates in drinking water. Includes reference.

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Edition: Vol. - No. Published: 11/01/2006 Number of Pages: 4 File Size: 1 file , 310 KB