14 Permethrin Degradation in Soil and Microbial Cultures DONALD D. KAUFMAN and S. CLARK HAYNES Agricultural Environment Quality Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Md. 20705 EDWARD G. JORDAN and ANTHONY J. KAYSER Downloaded by CORNELL UNIV on May 13, 2017 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0042.ch014
Department of Botany, University of Maryland, College Park, Md. 20742
Pyrethroids are one of the oldest classes of organic i n s e c t i cides known. Although natural and synthetic pyrethroids are excel lent insecticides, their i n s t a b i l i t y in light and a i r has limited their use in protecting agricultural crops. Recent work (1) has demonstrated, however, that the most labile groups in pyrethroids can be replaced by others which provide greater s t a b i l i t y and equal or increased insecticidal a c t i v i t y . Knowledge of the pathways by which natural and synthetic pyre throids are metabolized i n mammals (2-11), or photochemically de graded (1, 12-14), has developed rapidly i n the last several years. A literature survey indicated that despite their long history of use, essentially nothing is known about the degradation or persis tence of pyrethroids in soil. This paper describes the results of a cursory investigation of the degradation and persistence of permethrin [m-phenoxybenzyl c i s , trans-(+)-3-(2,2-dichlorovinyl)2,2-dimethylcyclopropanecarboxylate] (FMC 33297, Ν DC 143) in s o i l (15). A more detailed report w i l l be published elseshere. Degradation in Aerobic Soil Aerobic s o i l metabolism studies were performed with soils placed in a simple flow-through system which permits simultaneous measurement of loss by volatilization and metabolic CO evolution from s o i l (16). Chemical and physical characteristics of the soils used are l i s t e d in Table 1. C-Carbonyl (acid) and Cmethylene (alcohol) permethrin (Fig. 1) were used i n these inves tigations. Material applications were made i n 0.1 ml benzene to a final concentration of 0.2 lb/A of the cis/trans mixture after which each sample was thoroughly mixed, watered to 75% moisture content at 1/3 bar moisture, and incubated at 25°C. Sodium azide was used as a microbial inhibitor i n soils to assess the contribu tion of s o i l microbial activity to permethrin degradation. At the conclusion of the incubation period, the soils were extracted and processed as shown in F i g . 2. 2
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Elliott; Synthetic Pyrethroids ACS Symposium Series; American Chemical Society: Washington, DC, 1977.
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SYNTHETIC
Downloaded by CORNELL UNIV on May 13, 2017 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0042.ch014
Figure 1.
PYRETHROIDS
C-labeling pattern of C-permethrin indicating carbonyl and methylene hbeling positions 14
14
Treated S o i l Incubation
t i c , glc etc.
Bound residues
^
Soluble \^
Fulvic acid
Memphis s i l t
characteristics of s o i l s .
O.M.
% Mois. content pH 1/3 b a r
0..7
5. 8
37.6
CEC Sand (meq/lOOgm)
Silt
% Clay
16.3
20.8
54.0
25.2
8.5
48.8
44.0
7.2
1..0
5. 9
23.7
33.6
20.8
32.0
47.2
6..1
5. 9
45.5
8.8
17.0
50.6
32.4
2. .3
7. 5
32.6
48.0
42.0
9.7
1..2
7. 2
22.4
loam
Dubbs loam Sharkey C l a y Hagerstown s i l . c l a y loam San Joaquin sandy loam
• r e s i d u a l (humin) combustion
Soil extraction procedure
Chemical and p h y s i c a l
S o i l type
Alkaline extraction
Humic acid
Figure 2.
Table I.
