Risk Assessment of Surface Water Contamination by Herbicide Residues: Monitoring of Propanil Degradation in Irrigated Rice Field Waters using HPLC-UV and Confirmation by GC-MS

Submitted by Paula Gautério (paulaporto_g@hotmail.com) on 2014-02-26T23:23:24Z No. of bitstreams: 1 Risk Assessment of Surface Water Contamination by Herbicide Residues Monitoring of Propanil Degradation.pdf: 93502 bytes, checksum: 38e9ac0033a248bd6aa69ef123f729d4 (MD5)Approved for entry into archive by cristiane soares (krikasoares@live.com) on 2014-07-22T17:10:51Z (GMT) No. of bitstreams: 1 Risk Assessment of Surface Water Contamination by Herbicide Residues Monitoring of Propanil Degradation.pdf: 93502 bytes, checksum: 38e9ac0033a248bd6aa69ef123f729d4 (MD5)Made available in DSpace on 2014-07-22T17:10:51Z (GMT). No. of bitstreams: 1 Risk Assessment of Surface Water Contamination by Herbicide Residues Monitoring of Propanil Degradation.pdf: 93502 bytes, checksum: 38e9ac0033a248bd6aa69ef123f729d4 (MD5) Previous issue date: 2007O estudo avalia a degradação do herbicida propanil e de seu principal produto de degradação, a 3,4-dicloroanilina (3,4-DCA), em água de irrigação de lavouras de arroz irrigado no Estado do Rio Grande do Sul, Brasil. Além disso, estima, também, o risco de contaminação das águas de superfície das proximidades. Após uma etapa de extração em fase sólida, a concentração de ambos os compostos foi determinada por cromatografia líquida de alta eficiência com detecção na região do ultravioleta. A confirmação foi realizada por cromatografia gasosa-espectrometria de massas. A concentração de propanil nas amostras de água variou de 0,1 a 3600 μg L-1. O propanil degradouse rapidamente em 3,4-DCA, sendo que altas concentrações deste produto foram encontradas, variando entre 1,0 e 567,5 μg L-1. Os tempos de meia-vida para o propanil em água sob condições reais nas safras de 2001, 2002 e 2003 foram 18,2, 12,5 e 12,2 h, respectivamente.This study evaluates the degradation of the herbicide propanil and of its major degradation product, 3,4-dichloroaniline (3,4-DCA) in water from irrigated rice farming in the State of Rio Grande do Sul, Brazil. It also assesses the contamination risk of surrounding surface waters. After a solid phase extraction step, the concentration of both compounds was determined by high performance liquid chromatography with ultraviolet detection. Confirmation was conducted by gas chromatography-mass spectrometry. Concentrations of propanil in water samples varied from 0.1 to 3600 μg L-1. Propanil was degraded very rapidly to 3,4-DCA and high concentrations of this product were found, varying from 1.0 to 567.5 μg L-1 in water. The obtained half-life times for propanil in water under real conditions for the 2001, 2002 and 2003 harvests were 18.2, 12.5 and 12.2 h, respectively