Mobility of atrazine from alginate controlled release formulations
Titel:
Mobility of atrazine from alginate controlled release formulations
Auteur:
Johnson, Richard M. Pepperman, Armand B.
Verschenen in:
Journal of environmental science and health. Part B, Pesticides, food contaminants, and agricultural wastes
Paginering:
Jaargang 30 (1995) nr. 1 pagina's 27-47
Jaar:
1995
Inhoud:
Controlled release (CR) formulations can significantly influence the fate of herbicides in the environment. The influence of alginate-encapsulated CR formulations on the mobility of atrazine (6-chloro-N-ethyl-N- (l-methylethyl)-1,3, 5-triazine-2,4-diamine) in two soil profiles was investigated. Two CR formulations were evaluated based on Na-alginate (1%), kaolin (10%) and Tween 20 (0.5%). The first formulation (CR-Oil) was prepared with linseed oil (4%) and the second formulation (CR-N) did not have oil. These formulations were compared to technical grade (TG) atrazine and to a commercial liquid (CL) formulation (Aatrex 4L). Formulations labeled with 14C were applied to packed soil columns containing a surface and a subsoil horizon. The columns were then leached with 3-cm of 0.01 M CaCl2 per day at a rate of 1.5 cm hr-1 for a period of ten days. At the termination of the experiment the columns were sectioned in 5-cm increments and extracted with MeOH. Leachate samples and extracts were analyzed by liquid scintillation (LS) techniques. The leaching potential of atrazine decreased with the CR formulations. For the CL treatment, the total amounts of 14C leached were 83 and 129% for the Ochlocknee and Evesboro soils, respectively. This is compared to 57 and 94% for the TG treatment. The CR-Oil leached 9.8 and 19% of the applied 14C, compared to 3 and 9% for the CRF-N formulation. Averaged across soils the ranking of formulations, in terms of percent 14C leached was: CL (106%) > TG (76%) > CRF-Oil (14%) > CRF-N (6%). CR formulations also increased the amount of 14C and parent atrazine retained in the soil surface horizon (58-93%), compared to TG (4.7-5.6%) and CL (2.1-3.6%) treatments.
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