Photodegradation of Chloramben on a Soil Surface:  A Laboratory-Controlled Study

Misra, Bijay; Graebing, Phillip W.; Chib, J. S.

doi:10.1021/jf960778x

Cited by 22 publications

(16 citation statements)

References 10 publications

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“…This is a reasonable penetration depth for the chemical upon application, allows for direct photolysis to be fully effective, and permits the investigation of mobility of the pesticide through the soil. Similar results have been obtained using the herbicide chloramben (17).…”

Section: Light Transmittance In Relation To Soil Depthsupporting

confidence: 86%

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Frank¹,

Graebing²,

Chib³

2002

J. Agric. Food Chem.

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The effects of soil depth and moisture on pesticide photolysis were studied. Moist soil at depths of 3, 2.5, 2, 1.5, 1, and 0.5 mm were each dosed at 2.5 microg/g with (14)C-niclosamide and photolyzed under a xenon lamp at constant temperature. Samples were removed after 20, 40, 110, and 153 h of continuous irradiation. The decrease in percent of niclosamide and the appearance of degradates were followed by analyzing the soil extracts by HPLC. A corresponding set of experiments used air-dried soil. An experiment was also performed using initially moist soil which was permitted to dry during photolysis but returned to moist conditions at each sampling. Qualitative and quantitative differences were found in the rate and route of degradation of niclosamide under these conditions. These differences have resulted from a combination of reduced photochemical activity and microbial population in dry soil. The half-lives of niclosamide in the dry soils were 2 to 5 times longer than those in the moisture-maintained soil. There was also a noticeable difference in the half-lives in soil of different depths. Moisture-maintained soil showed a uniform linear increase in half-life from 95 to 195 h as soil depth increased from 0.5 mm to 3.0 mm. With air-dried soil the half-lives were greatly dependent on soil depth, showing a much broader range of 199 h at 0.5-mm to 1064 h in 3.0-mm soil. An experimental design is described which maintains soil temperature and moisture to preset conditions.

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Section: Light Transmittance In Relation To Soil Depthsupporting

confidence: 86%

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Frank¹,

Graebing²,

Chib³

2002

J. Agric. Food Chem.

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“…After the 1-min incubation period, the assay mixtures in the S, B, R HCl-1 mM and R HCl-0 mM tubes are mixed with 10 ml 1 M Tris by brief vortexing (to adjust the assay mixture pH to [7][8], centrifuged at 12,000g for 1 min and the resulting supernatants are collected for fluorescence measurement.…”

Section: Notes: I To Verify That the Net Fu 2-oh-e þ Corresponds To mentioning

confidence: 99%

“…Studies on the photochemical oxidation of xenobiotic organic carbon (herbicides, insecticides and pesticides) in agricultural soils suggested that 1 O 2 generated by sunlight via the photosensitization of soil organics (and possibly of Ti-and Zn-oxides) to be the main oxidant 5 . The involvement of other reactive oxygen species (ROSs) such as superoxide (O 2 Á À ) and hydroxy ( Á OH) radical has been hypothesized as well [6][7][8][9][10][11] . OH is postulated to result indirectly from the reaction of water with humic substances in the excited triplet state or from degradation of H 2 O 2 by transition metal (Me tr ) cations such as Fe 3 þ via a photo-Fenton reaction 10 .…”

mentioning

confidence: 99%

Evidence for photochemical production of reactive oxygen species in desert soils

et al. 2015

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The combination of intense solar radiation and soil desiccation creates a short circuit in the biogeochemical carbon cycle, where soils release significant amounts of CO 2 and reactive nitrogen oxides by abiotic oxidation. Here we show that desert soils accumulate metal superoxides and peroxides at higher levels than non-desert soils. We also show the photogeneration of equimolar superoxide and hydroxyl radical in desiccated and aqueous soils, respectively, by a photo-induced electron transfer mechanism supported by their mineralogical composition. Reactivity of desert soils is further supported by the generation of hydroxyl radical via aqueous extracts in the dark. Our findings extend to desert soils the photogeneration of reactive oxygen species by certain mineral oxides and also explain previous studies on desert soil organic oxidant chemistry and microbiology. Similar processes driven by ultraviolet radiation may be operating in the surface soils on Mars.

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“…The chamber was connected with an air-conditioning unit to obtain the desired temperature, humidity, and flow rate of air that passes over the plants into volatile traps, and the ceiling of the chamber was made of a special glass transmittimg light from a metal-halogenide lamp to simulate exposure to natural sunlight. 10, based on the literature (Klehr et al 1983;Katagi 1990;Misra et al 1997;Kromer et al 1999;Balmer et al 2000). However, these apparati are not readily available and their maintenance is difficult; therefore, photodegradation of pesticides on plants has been mostly examined with metabolism studies.…”

Section: B Photolysis Chambersmentioning

confidence: 99%

Reviews of Environmental Contamination and Toxicology

2004

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Photodegradation of Chloramben on a Soil Surface: A Laboratory-Controlled Study

Cited by 22 publications

References 10 publications

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Effect of Soil Moisture and Sample Depth on Pesticide Photolysis

Evidence for photochemical production of reactive oxygen species in desert soils

Reviews of Environmental Contamination and Toxicology

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