title: Degradation of metribuzin in two soil types of Lebanon.
abstract: The degradation of metribuzin [4-amino-6-tert-butyl-3-methylthio-1,2,4-triazin-5(4H)-one] as influenced by soil type, temperature, humidity, organic fertilizers, soil sterilization, and ultra-violet radiation was studied in two soil types of Lebanon under laboratory conditions. The two soil types were sandy loam and clay. Deamination of metribuzin in the sandy loam soil to its deaminometribuzin (DA) derivative was basically a result of biological activity. In the clay soil the first metabolite diketometribuzin (DK) was a result of oxidative desulfuration, while diketo-deaminometribuzin (DADK) was the product of reductive deamination. The two soils represented major differences in the pesticide transformation processes. Photodecomposition on the soil surface and in aqueous media was also an important process in the degradation of metribuzin. Furthermore, the increase in soil organic matter enhanced degradation.
authors.affiliation: Agricultural Department, Agronomic Research Institute, Fanar, Lebanon.
authors.forename: Randa
authors.initials: R
authors.lastname: Khoury
authors.forename: Camille M
authors.initials: CM
authors.lastname: Coste
authors.forename: Nasri S
authors.initials: NS
authors.lastname: Kawar
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates; D001673:Biodegradation, Environmental; D000077215:Clay; D004784:Environmental Monitoring / Q000379:methods; D005308:Fertilizers; D006540:Herbicides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D006813:Humidity; D007700:Kinetics; D007861:Lebanon; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D013696:Temperature; D014227:Triazines / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D014466:Ultraviolet Rays
chemical_list: D000538:Aluminum Silicates; D005308:Fertilizers; D006540:Herbicides; D016877:Oxidants; D012987:Soil; D012989:Soil Pollutants; D014227:Triazines; C009235:metribuzin; D000077215:Clay