Environmental Engineering Reference
In-Depth Information
TABLE 6.1
Classiications of Pesticides
By Target
By Mode or Time of Action
Type
Target
Type
Action
By Chemical Structure
Bactericide
(sanitizersor
disinfected)
Bacteria
Contact
Killsbycontactwith
pest
Pesticidescanbeeither
organicorinorganic
chemicals.Mostof
today'spesticidesare
organic
Commonlyused
inorganicpesticides
includecopper-based
fungicides.Lime-
sulfurusedtocontrol
fungiandmites,boric
acidusedfor
cockroachcontrol,and
ammoniumsulfamate
herbicides
Organicinsecticidescan
eitherbenatural
(usuallyextracted
fromplantsor
bacteria)orsynthetic.
Mostpesticidesused
todayaresynthetic
organicchemicals.
Theycanbegrouped
intochemicalfamilies
basedontheir
structure
Defoliant
Cropfoliage
Eradicant
Effectiveafterinfection
bypathogen
Desiccant
Cropfoliage
Fumigants
Enterspestasagas
Fungicide
Fungi
Nonselective
Toxictobothcropand
weed
Herbicide
Weeds
Postemergence
Effectivewhenapplied
aftercroporweed
emergence
Insecticide
Insects
Preemergence
Effectivewhenapplied
afterplantingand
beforecroporweed
emergence
Miticide(acaricide)
Mitesandticks
Preplant
Effectivewhenapplied
priortoplanting
Molluscicide
Slugsand
snails
Protectants
Effectivewhenapplied
beforepathogen
infectstheplant
Nematicide
Nematodes
Selective
Toxiconlytoweed
Plantgrowth
regulator
Cropgrowth
processes
Soilsterilant
Toxictoallvegetation
Rodenticide
Rodents
Stomachpoison
Killsanimalpestsafter
ingestion
Woodpreservative
Systemic Transportedthrough
croporpestfollowing
absorption
Source: Reprintedfrom Agric. Ecosyst. Environ. ,123,Arias-Estévez,M.,López-Periago,E.,Martínez-Carballo,E.,
Simal-Gándara,J.,Mejuto,J.-C.,andGarcía-Río,L.,Themobilityanddegradationofpesticidesinsoils
andthepollutionofgroundwaterresources,247-260,(2008),withpermissionfromElsevier.
Wood-
destroying
organisms
6.4 Degradation of Pesticides by Microorganisms and Soil
Pesticidescanbeclassiiedaccordingtotheirtargets,modesorperiodsofactionasshown
inTable6.1(Arias-Estévezetal.2008),andtheirchemistryasshownin Table6.2 .
Thebehaviorofpesticidesinsoilsisgovernedbyavarietyofcomplexdynamicphysical,
chemical,andbiologicalprocesses,includingsorption-desorption,volatilization,chemi-
calandbiologicaldegradation,uptakebyplants,runoff,andleachingasshownin Table6.3
(Arias-Estévez et al. 2008). How long the pesticide remains in the soil depends on how
strongly it is bound by soil components and how readily it is degraded. Degradation is
fundamentalforattenuatingpesticideresiduelevelsinsoil(Arias-Estévezetal.2008;Guo
etal.2000).Itisgovernedbybothabioticandbioticfactors(thelatterincludingenzymatic
catalysis by microorganisms). These factors can follow complex pathways involving a
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