Pesticide Residues in the Environment - Pesticides: Evaluation of Environmental Pollution - page 176

extractionandHPLCanalysisandwereshowntoconsistofunchangedisoproturon,solu-
blemetabolites(monodemethyl-isoproturon,didemethyl-isoproturon,1-OH-isoproturon,
2-OH-isoproturon, 2-OH-didemethyl-isoproturon,

ispropenyl-isoproturon and unidentiied metabolites), and nonextractable residues
(von Wirén-Lehr et al. 2002). von Wirén-Lehr and Dörler found that biomineralization
of plant-incorporated 14 C-isoproturon residues and soil microbial biomass and activity
parameterswererelatedinthreesoils,whereassoilsamplesfromaformerhopsgarden
didnotshowtheserelationships.Thisindicatesthattheoverallsoilmicrobialparameters
inmanycasesareinsuficienttodescribetheinluenceofbioticfactorsonthefateofpesti-
cidesinsoils(vonWirén-Lehretal.2002).Thebiotransformationofphenylureaherbicides
andsomeoftheirmostprominentdegradationsbydifferentsoilmicroorganismswere
alsoinvestigated(Berger1998).Insomecasesdescribedbytheauthors(Berger1998),the
differentbiotransformationratescorrelatedwithhighoctanol-waterpartitioncoeficients
andweretransformedfasterthancompoundswithahighwatersolubility.Degradation
ofphenylureaherbicides(diuronandisoproturon)andotherherbicides(diclofop-methyl,
bentazon,andpendimethalin)insoilswasalsodescribed(Piuttietal.2002).Theresults
oftheprincipalcomponentanalysis(PCA)basedonkineticparametersobtainedbyit-
tingthemodiiedGompertzmodeltomineralizationkineticsaftertwocroppingcycles
inthegreenhousearepresentedinFigure6.8a(Piuttietal.2002).Thisigureshowedthe
positioningofthedifferentsoils(plantedornot,treatedornot)intheirstprincipalplane

2-OH-monodemethyl-isoproturon,

t O

a

b

20 50 30

25
20

Nontreated soil

40

15

30
20
10

15
10
5
0

10

1.5

5 a

1 b

W53

1.0

0 0

S53

(b)

TB51 T836

0.5

T854

t O

T852

a

b

TOM52

OR81 S53 T855

TCR50

TCR54

10
8
8
4
2
0

70 20

Treated soil

0.0

S54
S24 60

50
40
30
20
10
0

S51 S51

W34

OR53

W55

15

W52

CR52

TA52 TCR53

-0.5

10

B82

a
10
b

S51

5

-1.0

0

-3 -2 -1 0 1 2 3

(c) (a) Axis 1 (94%)

FIGURE 6.8
(a-c)PCAondiclofop-methylmineralizationkineticsparametersobtainedinsoilsamplesaftertwocropping
cycles in the greenhouse: BS, bulk soil; WS, wheat-planted soil; ORS, oilseed rape-planted soil; SS, soybean-
planted soil. TBS, TWS, TORS, and TSS, the same but treated with diclofop-methyl in the greenhouse. 1-5,
treatment replicate in the greenhouse experiment. (From Piutti, S., Marchand, A.-L., Lagacherie, B., Martin-
Laurent,F.,andSoulas,G.Effectofcroppingcyclesandrepeatedherbicideapplicationsonthedegradationof
diclofop-methyl,bentazon,diuron,isoproturonandpendimethalininsoil. Pest Manag. Sci. ,2002,58,303-312.
CopyrightWiley-VCHVerlagGmbH&Co.KGaA.Reproducedwithpermission.)