Pesticides and their DegradationProducts in Surface Water and Ground

Water of the Mid-Atlantic Region

Jeffrey M Fischer

US Geological SurveyTrenton NJ

Why study PesticideDegradation Products?

• When measured, degradation productsare often detected more frequently thanparent compounds.

• Concentrations of pesticide degradatesoften exceed concentrations of parentcompounds.

Sources of Data

• Primarily NationalWater QualityAssessmentProgram (NAWQA)

• State Programs• Cooperative studies

What analyze for?• Widely used pesticides and their degradation

products.• 2-3 lab schedules, >150 compounds

Delaware River Basin Agricultural Pesticide Use, 1992(usage greater than 25,000 pounds per year shown)

0

100,000

200,000

300,000

400,000

500,000

600,000

SULFUR

METOLACHLO

RATRAZIN

E

OILALA

CHLOR

CAPTAN

PENDIMETH

ALINGLY

PHOSATE

CHLOROTHALO

NILMANCOZEBCYANAZIN

E

2_4_

DCHLO

RPYRIFOS

LINURON

CRYOLITE

SIMAZIN

EMETHOMYL

MANEB

METHYL_BROMID

E

Poun

ds A

pplie

d

Frequently Detected Pesticides

Primarilydiscussingdegradationproducts of:

• TriazineHerbicides

• AcetalinideHerbicides

• Few OtherPesticides

Detection frequenciesvary seasonally

Detections greater instreams than wells

Herbicide Degradates in StreamsMetolachlor degradates in the Schuylkill River

GeologicDifferences

0%10%20%30%40%50%60%70%

ATRAZINE

DEETHYL ATRAZINE

DEETHYLDEISOPROPYL ATRAZINE

Perc

ent D

etec

tion Piedmont

Valley & RidgeGlacial Fill

0%5%

10%15%20%25%30%35%40%45%50%

METOLACHLOR

METOLACHLOR ESA

METOLACHLOR OA

Perc

ent D

etec

tion

PiedmontValley & RidgeGlacial Fill

• Time since applied• Age of water• Thickness of

Unsaturated Zone?• Permeability?• Soil Properties?

Not

de

tect

ed

Not

de

tect

ed

Not

de

tect

ed

Long Island

Long Island

Pesticide Concentrations inStreams and Domestic Wells

• Degradateconcentrationstypically are equalto or greater thanparents

• Degradates haveno drinking waterstandards, butsometimesapproach MCL forparents.

Concentration (ug/L)

Toxicity of Degradates

• In surface water:• Sampled Raritan and Delaware Rivers• 32 of 83 pesticides detected, including• 9 degradates

• In ground water:• Sampled 34 monitoring wells in Coastal

Plain• 135 of 137 pesticides detected, including• 34 degradates

Frequently Detected Pesticides in Ground Water

0% 10% 20% 30% 40% 50% 60%

Simazine,

CEAT

CIAT

Caffeine,

Atrazine,

Prometon,

Imidacloprid,

Dieldrin,

Fenuron,

Metolachlor,

3-Ketocarbofuran,

3,5-Dichloroaniline,

OIET

Acifluorfen,

Imazethapyr,

Metsulfuron,

Fipronil sulfone

Metalaxyl,

Carbaryl,

Percent Detection

Other Recent Pesticide Sampling

Other Pesticide Degradates

0% 10% 20% 30% 40% 50% 60%

Fipronil

Desulfinyl fipronil

Desulfinylfipronilamide

Fipronil sulfide

Fipronil sulfone

Streamswells

• Fipronil Maximum Parent concentrations• SW=0.020 ug/L; GW=0.100 ug/L

• Maximum Degradate concentrations• SW=0.013 ug/L; GW=0.194 ug/L

Summary• Pesticide degradation products are often

detected more frequently than parentcompounds.

• Concentrations of pesticide degradates oftenexceed concentrations of parent compounds,especially in ground water.

• Formation of degradation products iscontrolled by geologic and hydrologicconditions as well as chemical properties.

• Degradation products have no standards forprotection of humans or wildlife.