Why evaluate nitrate losses from Why evaluate nitrate losses from watersheds?watersheds?

Potential health risks to public and private water supplies

Eutrophication

Hypoxia - Deficiency in the amount of oxygen reaching body tissues.

TMDLs

Why atrazine?Why atrazine?

Risk to human and aquatic life forms

Interim Reregistration Decision (IRED) Memorandum of agreement USEPA standard

maximum annual average of 2.6 ppb 90-day average of 37.5 ppb

of atrazine and all triazine compounds

Probability potential of atrazineProbability potential of atrazine

Average Yearly Atrazine Concentrations

0

1

2

3

4

5

6

1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49

Year

Co

ncen

trati

on

(p

pb

)

AtrazineAtrazine Herbicide widely used to control numerous broad-leaved Herbicide widely used to control numerous broad-leaved

weeds and is primarily applied to cornweeds and is primarily applied to corn

Atrazine is one of the most widely used herbicides in the Atrazine is one of the most widely used herbicides in the United States with 62% of corn acreage nation wide United States with 62% of corn acreage nation wide being treated and 78% of the corn acreage in Indiana being treated and 78% of the corn acreage in Indiana

The extensive use of atrazine as a pre-emergence The extensive use of atrazine as a pre-emergence herbicide to control broad-leaf weeds has the potential to herbicide to control broad-leaf weeds has the potential to impact aquatic life and human health impact aquatic life and human health

AtrazineAtrazine Atrazine has the potential of causing effects within an

ecosystem, disrupting the normal processes of some species.

According to Wiegand et al. (2001), atrazine at concentration levels between 10 and 20 mg/L can cause retardations in organogenesis, a slow down of movements, and functional disturbances of the heart

Atrazine has also been known to induce hermaphroditism at 0.1 ppb in American Leopard Frogs (Hayes et al., 2003

Atrazine StudiesAtrazine Studies

One study on human health in Minnesota measured children’s exposure to pesticides through urine samples, where 102 children between the ages of three and thirteen years were studied. Atrazine metabolites were detected 4% of the time (Adgate et al., 2001).

USEPA standard of a maximum annual average of 3.0 ppb or a 90-day average of 37.5 ppb of atrazine and all triazine compounds

Atrazine MobilityAtrazine Mobility

Transport mechanisms of atrazine are primarily in Transport mechanisms of atrazine are primarily in solution with water; there is little adsorption on solution with water; there is little adsorption on sediment and observed adsorption seems sediment and observed adsorption seems reversiblereversible

The high mobility of atrazine and its persistence The high mobility of atrazine and its persistence leads to the concern for human health leads to the concern for human health

NAPRANAPRA National Agricultural Pesticide Risk National Agricultural Pesticide Risk

Analysis (NAPRA) Analysis (NAPRA) Developed by USDA NRCSDeveloped by USDA NRCS Extended by ABE PurdueExtended by ABE Purdue Designed to assess risk of pesticide Designed to assess risk of pesticide

loss to ground or surface water as a loss to ground or surface water as a result of various crop-tillage result of various crop-tillage management practicesmanagement practices

The NAPRA ProcessThe NAPRA ProcessThe NAPRA ProcessThe NAPRA Process

Analysis of the environmental risk Analysis of the environmental risk associated with pesticide management associated with pesticide management decisionsdecisions

Quantify environmental benefits of Quantify environmental benefits of alternative management strategiesalternative management strategies

Assist farmers in striking a balance Assist farmers in striking a balance (economic vs. environment) in their pest (economic vs. environment) in their pest management decisionsmanagement decisions

Key GLEAMS/NAPRA FeaturesKey GLEAMS/NAPRA Features GLEAMS modelGLEAMS model Weather databaseWeather database Soil DatabasesSoil Databases Risk componentRisk component WWW interfaceWWW interface

Seepage/Percolation

Runoff

Rainfall

• Soil – Type or Geographic Location

• Climate– Weather Station

• Crop– Type– Planting/Harvesting Date

INPUT INTERFACE

• Pesticide and nutrients– Type– Application Rate

• Management Practices

• Website: http://danpatch.ecn.purdue.edu/~napra/TCT/mainFrame.html

INPUT INTERFACE

• Source

– Percolation, Runoff or Sediments

• Time

– 90-Day Maximum or Annual

• Units

– Loading (g/ha) or Concentration (ppb)

OUTPUT TYPES

OUTPUT INTERFACE

Pes

ticid

e in

Run

off (

ppb)

Time

3 ppb

OUTPUT INTERFACE

Probability of ExceedancePes

ticid

e in

Run

off (

ppb)

3 ppb

80%

SummarySummary GLEAMS/NAPRA approach potentially GLEAMS/NAPRA approach potentially

spans scales from regional to localspans scales from regional to local GLEAMS/NAPRA approach allows GLEAMS/NAPRA approach allows

accounting for managementaccounting for management WWW and databases make NAPRA WWW and databases make NAPRA

easy to useeasy to use