Environmental Engineering Reference
In-Depth Information
Degradation is faster in soil (t
1/2
= 1.54 day) than in water (t
1/2
= 8.2 days) (Washburn
2003).
Monocrotophos
, Dimethyl (E)-1-methyl-2 (methylcarbamoyl) vinyl (phosphate), a foliar
insecticide, on photochemical degradation forms dimethylphosphate, and its degradation
in soil depends on soil moisture.
Monocrotophos (MCP)
Esterase
O
CH
3
O
H
CH
3
NH
2
P
C
CH
3
O
C
Phosphatase
COOH
H
3
C
O
CH
3
O
P
OH
CH
3
O
Valeric acid / Acetic acid
CH
3
(CH
2
)
3
COOH / CH
3
COOH
Dimethyl phosphate
PO
-3
CO
2
NH
3
3.3.3  Carbamate Pesticides
Carbamate pesticides, which include insecticides, molluscicides, and nematicides, show a
high biological activity and have medium to high polarity.
Carbamate pesticides possess the following general structure:
O
CH
3
Carboxylic group
or Heterocyclic group
or Amine derivative
C
C
O
H
3
C or H
The three subgroups of carbamate pesticides include the following: (i) N-methylcarbamates
and esters of phenols, for example, carbaryl, methiocarb, and propoxur; (ii) N-methyl
and N-dimethyl carbamate esters of heterocyclic phenols, for example, carbofuran or
pirimicarb; and (iii) oxime derivatives of aldehydes, for example, aldicarb, methomyl,
oxamyl, etc.
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