Pesticide Residues in the Environment - Pesticides: Evaluation of Environmental Pollution - page 179

applied[ 14 C]bromoxyniland44%ofthe[ 14 C]bromoxyniloctanoateformednonextract-
able residues in the soil. Plant cell-wall-bound [ 14 C]bromoxynil residues were also
mineralized to an extent of about 21% within 70 days; the main portion of 76% per-
sisted as nonextractable residues in soil. In bacterial enrichment cultures, two polar
metaboliteswereobservedbytheseauthors(Rosenbrocketal.2004):oneofthemcould
beidentiiedas3,5-dibromo-4-hydroxybenzoateandtheothercouldbedescribedten-
tativelyas3,5-dibromo-4-hydroxybenzamide.
6.4.4.8 Quaternary Ammonium Herbicides
Theeffectsofparaquatdichlorideonthelaccaseactivityandsomebiochemicalparameters
of Trametes versicolor and Abortiporus biennis strainsbelongingtowhite-rot Basidiomycetes
fungiwereexaminedbyJaszeketal.(2006).Exposureof Trametes versicolor and Abortiporus
biennis toparaquatdichlorideenhancedtheirnaturalligninolyticmetabolismasaconse-
quenceofadaptationtooxidativestressconditionsofthisgroupoffungi.Resultsobtained
byJaszeketal.(2006)areinterestingbecausealthoughoxidativestressdefenseshavebeen
veryoftendescribedintherecentliterature,veryfewstudiesestimatethepossibleadap-
tiveoxidativestressresponseinthewhite-rotfungi.Theincreasedactivityoflaccasein
thepresenceofparaquatdichloridemayalsosuggestthatithasanimportantroleinfun-
gal oxidative stress defense mechanism (Jaszek et al. 2006). The results obtained by Jóri
etal.(2007)indicatethatparaquatisabletoenterthechloroplastsintheresistantbiotype,
causing transitional inhibition that can be clearly detected on the basis of luorescence
quenching.Investigationsprovedthatparaquatenteredthecellsofbothresistantandsus-
ceptible biotypes, approached the maximum within the irst hour in chloroplasts, and
thendeclinedinallorganellefractions.Intheresistantbiotype,paraquatwaslocatedin
thevacuolesadayaftertreatment.Selectivetransporterinhibitorsblockedthesequestra-
tionofparaquat,suggestingtheparticipationoftransportersnotdirectlyenergized(Jóri
etal.2007).
6.4.5 Others
Among modern pesticides, several different classes of fungicides are very persistent,
thoughnodeleteriouseffectsonsoilmicrobialprocesseshavebeenreported.Thebehav-
iors of ive such fungicides (lutriafol, epoxiconazole, propiconazole, triadimefon, and
triadimenol)havebeenexaminedbyBromilowetal.(1999)intwoieldtrialsutilizingdif-
ferentagronomictreatments.Microbialdegradationofchlorothalonilinagriculturalsoil
wasdescribedbyvanEdenetal.(2000).Interactionbetweenthefollowingfactorscould
haveinluencedtherateofbiodegradation(vanEdenetal.2000).
• Soilconditionsthatdeterminedthedegreetowhichsoilbacteriawereconditioned
bypreexposureforinvitroaerobicutilizationofchlorothalonil.
• Thenumberofviablebacteriaininoculums,aswellastheirinvitroculturability.
• Thecompositionofindigenoussoilpopulations.
• Soilcharacteristicsthatinluencedthebioavailabilityofchlorothalonil.
Structuralandfunctionalapproachtostudyingpesticide(quininefungicidedithianon)
sideeffectsonspeciicsoilfunctionswasproposedbyLiebichetal.(2003).Aerobicbiodeg-
radationof[ 14 C]3-chloro-p-toluidinehydrochlorideinloamsoilwasdescribed(Spanggord