Effect of Temperature and Moisture on the Degradation and Sorption of Florasulam and 5-Hydroxyflorasulam in Soil

Effect of Temperature and Moisture on the Degradation and Sorption of Florasulam and 5-Hydroxyflorasulam in Soil

The degradation rate and sorption characteristics of the triazolopyrimidine sulfonanilide herbicide florasulam and its principal degradation product 5-hydroxyflorasulam (5-OH-florasulam) were determined as a function of temperature and moisture in three different soils. The half-life for degradation...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry Vol. 48; no. 10; pp. 4757 - 4766
Main Authors: Krieger, Mark S, Pillar, Fiona, Ostrander, Julie A
Format: Journal Article
Language:English
Published: Washington, DC American Chemical Society 01-10-2000
Subjects:
Agronomy. Soil science and plant productions
Applied sciences
Biodegradation, Environmental
Biological and medical sciences
Biological and physicochemical properties of pollutants. Interaction in the soil
Chemical control
Exact sciences and technology
Fundamental and applied biological sciences. Psychology
Herbicides - analysis
Herbicides - chemistry
Humidity
Parasitic plants. Weeds
Phytopathology. Animal pests. Plant and forest protection
Pollution
Pyrimidines - analysis
Pyrimidines - chemistry
Soil - analysis
Soil and sediments pollution
Soil and water pollution
Soil Microbiology
Soil science
Sulfonamides - analysis
Sulfonamides - chemistry
Temperature
Weeds
Degradation
Persistence
Sorption
Temperature
Soil moisture
Pesticides
Triazole derivatives
Mobility
Pyrimidine derivatives
Soil pollution
Herbicide
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Summary:The degradation rate and sorption characteristics of the triazolopyrimidine sulfonanilide herbicide florasulam and its principal degradation product 5-hydroxyflorasulam (5-OH-florasulam) were determined as a function of temperature and moisture in three different soils. The half-life for degradation of florasulam ranged from 1.0 to 8.5 days at 20−25 °C and from 6.4 to 85 days at 5 °C. The half-life for degradation of 5-OH-florasulam ranged from 8 to 36 days at 20−25 °C and from 43 to 78 days at 5 °C. The degradation rate of both compounds was strongly influenced by temperature, with activation energies ranging from 57 to 95 kJ/mol for florasulam and from 27 to 74 kJ/mol for 5-OH florasulam. Soil moisture content had negligible impact on the degradation rate. Apparent (nonequilibrium) sorption coefficients for florasulam and 5-OH-florasulam at 0 days after treatment (DAT) were 0.1−0.6 L/kg and increased linearly with time for both florasulam and 5-OH-florasulam (r 2 > 0.90) to levels as high as 12−23 L/kg. Heats of adsorption were calculated on one soil as a function of time. Heat of adsorption values for both florasulam and 5-OH-florasulam increased as incubation time increased and the amount of each compound decreased; values were near 0 kJ/mol initially and increased to a maximum of 91 and 66 kJ/mol for florasulam and 5-OH-florasulam, respectively. Keywords: Florasulam; 5-hydroxyflorasulam; 5-OH-florasulam; aerobic soil metabolism; sorption; aerobic soil degradation; apparent K d
Bibliography:istex:E73AA053E6126451BA49FF73B8C05F0D7E9360DC
ark:/67375/TPS-LV5N5KGR-9
ISSN:0021-8561
1520-5118
DOI:10.1021/jf000009k