Fate of chlorsulfuron in the environment. 2. Field evaluations

Abstract

:The fate and mobility of chlorsulfuron was determined in several Ðeld studies with 14C-labeled chlorsulfuron. A study comparing fall with spring applications (D100 g AI ha~1) to in-situ soil columns (35 cm depth) in neutral to alkaline soils (pH 6É9È8É2, OM 1É0È5É3) located in CO, ID and ND demonstrated that fall treatments did not persist longer into the following year than spring treatments. Mobility into the soil proÐle appeared to be initially faster following fall applications at the ID and ND sites, but di †erences between application seasons appeared to moderate with time. A Ðeld-soil metabolism study conducted at Madera, CA on a sandy loam soil (pH 6É3È6É9 and 0É3È 0É4% OM with depth) with chlorsulfuron (D158 g AI ha~1) demonstrated rapid dissipation of chlorsulfuron (pseudo-Ðrst-order half-life 18 days). No intact chlorsulfuron was found after the 120-day sampling. Major metabolites observed in this study were chlorobenzenesulfonamide (2-chlorobenzenesulfonamide) and triazine amine (4-methoxy-6-methyl-1,3,5-triazin-2-amine), products of bridge cleavage, and O-desmethylchlorsulfuron (1-(2-chlorophenylsulfonyl)-3-(4-hydroxy-6-methyl-1,3,5-triazin-2-yl)urea). No intact chlorsulfuron was detected below the 0È15 cm layer at any sampling (maximum depth 60È 90 cm), but chlorobenzenesulfonamide and ring-opened carbamoyl guanidine (1-(2-chlorophenylsulfonyl)-3-(ureido-imino)urea) were found at the 15È30 cm depth. In a similar study conducted on a silt loam soil in Moscow, ID (pH 6É1È6É9 and 2É2È1É0% OM with depth), overall dissipation was much slower than at Madera, CA due to the cooler climate (average soil temperature 8É6¡ versus 20É0¡). The initial rate of chlorsulfuron dissipation was similar (pseudo-Ðrst-order half-life 18 days), but dissipation exhibited a distinctly slower second stage (half-life 109 days) not exhibited at Madera, CA. By the 370-day sampling no intact chlorsulfuron was detected. The chlorobenzenesulfonamide and triazine amine were the major metabolites found in this study, accounting for approximately 38 and 30%, respectively, of the initial chlorsulfuron at the last sampling (571 days). Other metabolites were found in lesser amounts, including Odesmethylchlorsulfuron, ring-opened carbamoyl guanidine, hydroxy triazine amine (4-amino-6-methyl-1,3,5-triazine-2-ol), triazine urea ((4-methoxy-6-methyl-1,3,5-triazin-2-yl) urea), an undi †erentiated bound fraction and an unidentiÐed group of polar components. The presence of triazine urea indicates that soil-surface photolysis (or indirect photolysis) may have been operative. In the study in Moscow, ID, no intact chlorsulfuron was found below the 0È15 cm layer at any sampling (maximum depth 75 cm). Movement of total radioactive components was restricted to a maximum depth of 60 cm at Madera, CA and 50 cm at Moscow, ID. The overall water balance over the duration of both studies was negative, helping to explain the observed lack of leaching. The PRZM3 model was used to predict the distribution proÐle of chlorsulfuron at the Moscow, ID s...

Application of coupled liquid chromatography–mass spectrometry in hydrolysis studies of the herbicide ethametsulfuron-methyl

“…A product analogous to 7 was found in soil metabolites of chlorsulfuron under laboratory and field conditions [28,29].…”

“…Studies carried out on triasulfuron [17], thifensulfuron-methyl [37], and chlorsulfuron [28,29] (three sulfonylureas sharing a methoxy substitution in the triazine ring with chlorosulfuron) showed hydrolysis pathways similar to those of metsulfuron-methyl. For all three 86 Youbin Si et al sulfonylureas, in addition to their respective sulfonamide and aminotriazine derivatives, products both of O-demethylation and hydrolytic breakdown of the triazine ring were isolated and identified.…”

Cinosulfuron: chemical and biological degradability, adsorption and dissipation in flooded paddy field sediment

“…Although the hydrolytic pathway of cinosulfuron has not been reported in literature, the formation of the above compounds resulting from the cleavage of the sulfonylurea bridge is considered the most common primary degradation pathway of sulfonylurea in aqueous solution. In the case of sulfonylurea herbicides with a triazinic ring, such as cinosulfuron, other degradation pathways such as O ‐demethylation,12–16 and opening of the methoxytriazine ring13, 14 have also been observed. We did not observed the formation of such products in the conditions of this study.…”

Synthesis, Antibacterial and Lipoxygenase Inhibition Studies of <i>N</i>-(Alkyl/aralkyl)-<i>N</i>-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-methylbenzenesulfonamides

“…11 In addition to antiviral agents sulfonamides are also used as antitumor agents, diuretics, antileprotic, tuberculostatics and oral hypoglycemic drugs. 12,13,14 Sulfasalazine ( Figure 1); an antibiotic is used to manage the long-term inflammation of bowel diseases. 15 Aliphatic sulfonamide derivatives act as antifungal agents.…”