Environmental Engineering Reference
In-Depth Information
• Thesoiltextureanditsadsorptionpropertiesmayinterferewiththekineticsof
theseherbicides
• Onmoistsoilsurfacesexposedtosunlight,photolysisplaysanimportantroledur-
ingtheirsttwodaysofexposurewithregardtootherfateprocessesobservedin
darkcontrols.
6.5.4.4 Dinitroaniline and Nitrile Herbicides
Photolysisoftriluralinhasbeenstudiedundersunlightconditionsanditsreactionrate
constant with HO• radicals was measured using the relative rate method (Person et al.
2007).
Thekineticsandthemechanismofthedegradationofdinitroanilineherbicidetrilura-
linandnitrileherbicidebromoxynilinaqueoussolutionsbyozonationweredescribedby
Chelme-Ayalaetal.(2010).
6.5.4.5 Pyridazinone and Nitrophenyl Ether Herbicides
Thomasetal.(2009)describedthephotodegradationinsoilsofpyridazinoneherbicidenor-
lurazonandnitrophenyletherherbicideoxyluorfen.Thomasetal.(2008)alsodescribed
thephotodegradationofnorlurazondepositedoradsorbedonsolidmaterial.
6.5.4.6 Pyridine Herbicides
Heterogenous photocatalyzed degradation of two pesticide derivatives, triclopyr (pyri-
dineherbicide)anddaminozide(growthretardant),inaqueoussuspensionsoftitanium
dioxidewasdescribedbyQamaretal.(2006).
6.5.5 Others
Photodegradationofpesticidesfromdifferentclassesandchemicalgroupswasdescribed
(Bandala et al. 2002; Guillard et al. 2003; Malato et al. 1999, 2000; Navarro et al. 2009;
SamsonovandPokrovskii2000;DevipriyaandYesodharan2005).
6.6 Conclusions
The fate of the pesticides in soils depends on chemical transformations in which living
organismsparticipate(biotic,biochemicaltransformations)andonphysical,chemical,and
photochemical processes. Photochemical transformations of pesticides are restricted to
soilandplantsurfacesandonlytocompoundssensitivetosolarradiation.Inthischapter,
thereadersmayindessentialinformationconcerningthecausesandtransformationsof
pesticidesfromvariouschemicalgroups,theirdegradationandfragmentationintheenvi-
ronment.Itishopedthatthischapterwillserveasanintegratingfactorbothinfocusing
attentionuponthosemanyresiduemattersrequiringfurtherattentionandincollating,for
variouslytrainedreaders,thepresentknowledgeinspeciicimportantareasofanalysisof
pesticidesandrelatedendeavors.
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