Adsorption and degradation rates of chlorsulfuron and metsulfuron-methyl were measured in soil taken from depths of 0-20, 20-40 and 40-60 cm at eight sites. Adsorption of both herbicides was negatively correlated with soil pH, and positively correlated with soil organic matter content. When two soils with very high organic matter were excluded from the calculations, the correlations with organic matter content were no longer statistically significant but those with soil pH were affected only .slightly. Degradation rates of both herbicides generally decreased with increasing depth in the soil and were positively correlated with microbial biomass and negatively correlated with soil pH. The possible significance of the results to persistence of the herbicides in the field is discussed.
Adsorption et degradation du chlorsulfuron methyl dans des sols issus de profondeurs differentesLes niveaux d'adsorption et de degradation du chlorsulfuron ct du metsulfuron-methyl ont ete mesures dans des sols preleves a des profondeurs de 0-20; 20-40 et 40-60 cm dans huit sites.L'adsorption des deux herbicides exprimait une correlation negative avec le pH du sol, et positive avec la teneur en matieres organiques. Quand les deux sols a haute teneur en matieres organiques etaient exclus des calculs, la correlation avec la teneur en matiere organique n'etait plus statistiquement significative, tandis que celle avec le pH etait seulement peu afFectee. Les taux de degradation des deux herbicides baissent en general avec I'augmentation de la profondeur du sol, et exprimaient une correlation positive avec la biomasse microbienne et negative avec le pH du sol. La transposition possible de ces resultats a la persistance des herbicides au champ est discutee.
Adsoption und Abbau von Chlorsulfuron und Metsulfuron in verschiedenen BodentiefenDie Adsorptions-und Abbauraten von Chlorsulfuron und Metsulfuron in Bodenproben von 8 verschiedenen Orten aus 0-20, 20-40 und 40-60 cm Tiefe wurden gemessen. Die Adsorption der beiden Herbizide war mit dem pH-Wert negativ und mit der organischen Substanz positiv korreliert. Bei Herausnahme der Werte von 2 Boden mit besonders hohem Gehalt an organischer Substanz lieB sich die Korrelation zur organischen Substanz nicht mehr statistisch sichern, wahrend die Berechnung fCir den pH-Wert nur wenig beeinfluBt wurde. Die Abbaurate der beiden Herbizide nahm allgemein mit zunehmender Bodentiefe ab; sie war mit der mikrobiellen Biomasse positiv und mit dem pH-Wert negativ korrelierl. Die Bedeutung der Ergebnisse fur die Persistenz der Herbizide im Freiland wird diskutiert.
IutroductionChlorsulfuron and metsulfuron-methyl are members of the sulphonylurea group of herbi-
The measurement of the sulfonyl urea herbicides, chlorsulfuron and metsulfuron‐methyl as pentafluorobenzyl derivatives has been investigated and the kinetics of reaction optimised. The reaction product was identified by mass spectroscopy as N,N‐bis(pentafluorobenzyl)‐2‐chlorobenzenesulfonamide. Amounts of herbicide derivative as low as 0·1 pg per injection can be detected. Suitable conditions for both packed and capillary chromatography are given. Application of the method to residue determination is discussed and the method is shown to be suitable for residues in soil and water but less so for plant material.
Methanol was more efficient than solvent systems based on acetonitrile or chloroform for the extraction of a number of weathered herbicide residues from soil. The presence of water in the soil improved recovery. Methanolic extracts, on examination by gas‐liquid chromatography, also gave lower background levels than the extracts with other solvents.
The herbicides are extracted from soil with saturatcd calcium hydroxide solution. After clean-up the residues are ethylated using iodoethane and tetrabutylammonium hydrogen sulphate as counter ion. Liquidliquid partition and the use of a macroreticular resin column were compared as clean-up steps and the reaction conditions for optimum yield of ethyl ester or ether were evaluated. Recoveries in excess of 80% were achieved for 2,4-D, dicamba, 3,6-dichloropicolinic acid, dichlorprop, picloram, 2,4,5-T, fenoprop, 2,3,6-TBA, bromoxynil and ioxynil.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.