Tropical surface water quality studies: Implications for the aquatic fate of N-methyl carbamate pesticides

Simple item page
dc.contributor.authorHa, Bao
dc.contributor.authorZamini, Leili
dc.contributor.authorMonn, Jeremy
dc.contributor.authorNjoroge, Samuel
dc.contributor.authorThimo, Laban
dc.contributor.authorOndeti, Maria
dc.contributor.authorMurungi, Jane I.
dc.contributor.authorMuhoro, Clare N.
dc.date.accessioned2018-01-09T09:38:30Z
dc.date.available2018-01-09T09:38:30Z
dc.date.issued2017
dc.descriptionResearch Articleen_US
dc.description.abstractWater quality assessment was conducted on the Ruiru River, a tributary of an important tropical river system in Kenya, to determine baseline river conditions for studies on the aquatic fate of N-methyl carbamate (NMC) pesticides. Measurements were taken at the end of the long rainy season in early June 2013. Concentrations of copper (0.21–1.51 ppm), nitrates (2.28–4.89 ppm) and phosphates (0.01– 0.50 ppm) were detected at higher values than in uncontaminated waters, and attributed to surface runoff from agricultural activity in the surrounding area. Concentrations of dissolved oxygen (8–10 ppm), ammonia (0.02–0.22 ppm) and phenols (0.19–0.83 ppm) were found to lie within normal ranges. The Ruiru River was found to be slightly basic (pH 7.08–7.70) with a temperature of 17.8–21.2 C. The half-life values for hydrolysis of three NMC pesticides (carbofuran, carbaryl and propoxur) used in the area were measured under laboratory conditions, revealing that rates of decay were influenced by the electronic nature of the NMCs. The hydrolysis half-lives at pH 9 and 18 C decreased in the order carbofuran (57.8 h) > propoxur (38.5 h) > carbaryl (19.3 h). In general, a decrease in the electron density of the NMC aromatic ring increases the acidity of the N-bound proton removed in the rate-limiting step of the hydrolysis mechanism. Our results are consistent with this prediction, and the most electron-poor NMC (carbaryl) hydrolyzed fastest, while the most electron-rich NMC (carbofuran) hydrolyzed slowest. Results from this study should provide baseline data for future studies on NMC pesticide chemical fate in the Ruiru River and similar tropical water systems.en_US
dc.identifier.citationBao Ha, Leili Zamini, Jeremy Monn, Samuel Njoroge, Laban Thimo, Maria Ondeti, Jane I. Murungi & Clare N. Muhoro (2017): Tropical surface water quality studies: Implications for the aquatic fate of N-methyl carbamate pesticides, Journal of Environmental Science and Health, Part B, DOI: 10.1080/03601234.2017.1399768en_US
dc.identifier.issn0360-1234
dc.identifier.urihttps://doi.org/10.1080/03601234.2017.1399768
dc.identifier.urihttp://ir-library.ku.ac.ke/handle/123456789/18097
dc.language.isoenen_US
dc.publisherTaylor & Francisen_US
dc.subjectN-methylcarbamatesen_US
dc.subjectCarbofuranen_US
dc.subjectCarbarylen_US
dc.subjectPropoxuren_US
dc.subjectTropical river water qualityen_US
dc.subjectRuiruen_US
dc.subjectKenyaen_US
dc.subjectCarbamate hydrolysis ratesen_US
dc.titleTropical surface water quality studies: Implications for the aquatic fate of N-methyl carbamate pesticidesen_US
dc.typeArticleen_US
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Tropical surface water quality studies Implications for the aquatic fate of N methyl carbamate pesticides.pdf
Size:
1.02 MB
Format:
Adobe Portable Document Format
Description:
Full Text Article
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
RP-Department of Chemistry