Title page for etd-0625114-020807


[Back to Results | New Search]

URN etd-0625114-020807
Author Ya-ciao Yang
Author's Email Address No Public.
Statistics This thesis had been viewed 5561 times. Download 311 times.
Department Environmental Engineering
Year 2013
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Formation of Nitrosamines from Urea Herbicides during Disinfection
Date of Defense 2014-06-26
Page Count 129
Keyword
  • Emerging contaminants
  • Disinfection byproducts
  • Nitrosamines
  • Herbicides
  • Drinking water
  • Abstract Source water pollutions by the presences of urea herbicides have been widely reported. As urea herbicides in source waters have the potentials to be collected by drinking water treatment processes, these compounds may react with disinfectants/oxidants during the processes to form disinfection byproducts, which could be more potent and toxic than the parent compounds for downstream water users. In this study, six widely used urea herbicides, including diuron, fluometuron, linuron, metobromuron, propanil and isouron, were examined as model precursors to understand their potentials to form nitrosamine compounds during chlorine-employed disinfection. The nitrosamines of interest included N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), and N-nitrosopyrrolidine (NPYR). Lab-scale batch reactors containing pre-determined amounts of urea herbicides were prepared, followed by the addition of chlorine or chloramines and reactions for certain contact times to simulate disinfection in conventional drinking water treatment plants. The solutions were thus pre-treated by solid-phase extraction and analyzed by gas chromatography coupled with mass spectrometry and ultra-high pressure lquid chromatography coupled with triple quadruple mass spectrometry. Besides the investigation of nitrosamie formation from urea herbicies, these experiments were conducted under different operational and water quality circumstances to investigate the effects of different methods of adding chlorine and the presence of excess nitrogen sources on the formation of nitorsamines. In the results, it is indicated that more than one single type of nitrosamines including NPYR less reported in the early studies were produced by the reactions between urea herbicides and different disinfectants. When dichloramine was used for disinfection or ammonia is present, the formation of nitrosamine, particularly NDMA, was significantly enhanced during disinfection of urea herbiceds. Besides the types of additional nitrogen sources and disinfection mechanisms, the nitrosamine formation was also affected by the chemical structures of urea herbicides. The findings suggest the potential hazards of urea herbicides with respect to the formation of nitrosamines during disinfection and provide the information that may be of help to develop management strategies that minimize the adverse health risks of nitrosamines in drinking water by controlling their possible precursors in source waters.
    Advisory Committee
  • Chiu-Yun Chen - chair
  • Liang Ming Whang - co-chair
  • Yuan-Chung Lin - advisor
  • Wei-Hsiang Chen - advisor
  • Files
  • etd-0625114-020807.pdf
  • Indicate in-campus at 3 year and off-campus access at 3 year.
    Date of Submission 2014-07-25

    [Back to Results | New Search]


    Browse | Search All Available ETDs

    If you have more questions or technical problems, please contact eThesys