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Pesticides in Nursery Runoff: Sources and Transport Processes Jay Gan Dept. Environmental Sciences UC Riverside, CA 92521 jgan@mail.ucr.edu 909-787-2712 Outline Nursery and pesticides Current issues How does it happen? Governing Processes Nursery in CA (2001) Production sales:

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pesticides in nursery runoff sources and transport processes

Pesticides in Nursery Runoff:Sources and Transport Processes

Jay Gan

Dept. Environmental Sciences

UC Riverside, CA 92521

jgan@mail.ucr.edu

909-787-2712

outline
Outline
  • Nursery and pesticides
  • Current issues
  • How does it happen?
  • Governing Processes
nursery in ca 2001
Nursery in CA(2001)
  • Production sales:
    • $3.17 billion
    • 10.6% of CA agricultural output
    • 2nd among all CA agricultural products
    • 21.3% of the U.S. nursery/floriculture total (11.9% for FL)
  • Retail sales
    • $10.1 billion
    • 1st in the U.S.
  • CA horticulture industry jobs
    • 81,011 jobs in production
    • 87,856 jobs in retailing
ca nursery industry
CA Nursery Industry

Total CA Nursery/Floral Production: $3.2 billion

(2001)

Floral

12%

Misc.

8%

Woody, decidous

Evergreen

26%

Potted plants

Flowering foliage

20%

Bedding plants

15%

Non-

Ornamentals

19%

ca nursery industry5
CA Nursery Industry

Total CA Retail Sales: $10.1 billion

(2001)

Florists

$988 mil

Hardware

Home centers

$3,576 mil

Chain stores

Warehouses

$2,757 mil

Garden centers

Farms

Nurseries

$2,859 mil

ca nursery industry6
CA Nursery Industry

Total Sales Composition (2001)

Lawn furniture

Accessories

Tree trim

20.8%

EquipmentTools

28.4%

Chemicals

Fertilizers

24.8%

Green goods

26.0%

nurseries pesticides
Nurseries & Pesticides
  • Pesticide Uses
    • Agricultural crops
    • Home lawns/gardens
    • Structural/indoor pest control
    • Nurseries
    • Roadside
    • Parks
trend of pesticide use total
Trend of Pesticide Use Total

Active Ingredients (mil lbs)

surface water risk pesticides

Midge Chironomus

Mayfly Procloeon

Surface water-Risk Pesticides
  • Not human safety concern !
  • Aquatic toxicity:
    • Organophosphate insecticides

(e.g., Dusban, diazinon)

    • Carbamate insecticides

(e.g., carbaryl)

    • Synthetic pyrethroids

(e.g., cyfluthrin, permethrin, …)

slide21

Most Used Nursery Pesticides

(San Diego County, 2002)

Greenhouse Containers

Source: CDPR

slide22

Most Used Nursery Pesticides

(San Diego County, 2002)

Outdoor Containers

Source: CDPR

slide23

Aquatic Toxic Insecticides

(San Diego County, 2002)

Greenhouse Containers

Source: CDPR

slide24

Aquatic Toxic Insecticides

(San Diego County, 2002)

Outdoor Containers

Source: CDPR

water quality issues
Water Quality Issues
  • Ground water issues
  • Surface water issues
    • TMDLs
    • TMDL examples
groundwater issues
Groundwater Issues
  • TheCA Picture (CDPR, CWRCB)
    • 324 of 3,165 wells in year 2000
    • 84 verified detections
    • From previous use (fumigants)
      • DBCP, EDB, 1,2-D
    • From existing use (herbicides):
      • Simazine, ACET (from simazine or atrazine), DACT, norflurazon, bromacil, diuron, atrazine, deethyl atrazine
surface water quality issues
Surface Water Quality Issues
  • Urban surface water quality issues
    • Pesticide detections in most streams
      • 99% streams with 1 pesticide
      • 70% streams with  5 pesticides
    • Sustained insecticide levels
    • Harmful to aquatic organisms
      • Beneficial use
    • TMDLs for many streams
      • The new rule!
slide29
What is TMDL?
    • CWA 303(d)
    • States to make list of “impaired” waters
    • Develop TMDLs for the listed waters
    • TMDLs to account for all pollutants and all sources,
    • TMDL includes non-point sources, e.g., urban and agricultural runoffs
    • Develop implementation plans (Basin Plans or Water Quality Control Plans in CA)
slide30
California:
    • RWQCBs
    • 800 TMDLs in total
    • 120 TMDLs in progress
    • Amend the Basin Plan by incorporating TMDLs
  • TMDL Elements:
    • Problem statement
    • Numeric targets
    • Source analysis
    • Allocations
    • Implementation plan
    • Linkage analysis
    • Monitoring/Re-evaluation
    • Margin of safety
san diego creek pesticide tmdls34
San Diego Creek Pesticide TMDLs
  • Diazinon:
    • 200-455 ppt  50 ppt
    • 300-900% reduction!
  • Chlorpyrifos:
    • 87-111 ppt  14 ppt
    • 600-800% reduction!
  • Legacy pesticides:
    • DDT, chlordane,…
  • Urban use is the No.1 source!
slide35

Table 1. Proposed Water-Quality Criteria

for Diazinon and Chlorpyrifos

how does it happen
How Does It Happen?
  • Storm water runoff
  • Irrigation runoff
    • Leaching through containers?
    • Planting media spills?
    • Runoff + planting media

= pesticide runoff?

slide40

Runoff Driven:

Storm runoff

 Over-irrigation

slide42

Step 1: Scrap off surface soil

Step 2: Estimate potting mix

content

Step 3: Analyze pesticides

Step 4: Correlation

governing processes
Governing Processes
  • Degradation
    • Chemical
    • Microbial
  • Adsorption
  • Leaching Potential
  • Runoff Potential
degradation in soil
Degradation in Soil
  • What is “degradation”?
    • Structural changes caused by chemical and/or microbial reactions
    • Desirable environmentally
    • Pesticide-dependent
    • Vary in different soil types
    • Measured by persistence or “half-life” T1/2
    • Long “half-life” = problems
      • T1/2 = leaching potential 
      • T1/2  = runoff potential 
what causes degradation
What Causes Degradation?
  • Chemical reactions
    • Hydrolysis (OPs, carbamates, etc.) – pH sensitive
    • Photolysis – by UV, near the surface
    • Oxidation – reduction by soil chemical species
    • Nucleophilic attacks by soil nucleophiles
    • Pesticide dependent
    • Soil dependent
what causes degradation51
What Causes Degradation?
  • Microbial transformations
    • Biodegradation – bacteria use pesticides as “food”
    • Cometabolism –degradation by “accident”
    • Enzyme-based transformations
    • Pesticide dependent
    • Soil dependent
      • Microbial ecology
      • Organic matter plays a big role
adsorption in soil
Adsorption in Soil
  • What is “adsorption”?
    • Retention of pesticides by soil
    • Pesticide dependent
    • Soil dependent
      • Organic matter content , adsorption 
    • Weak adsorption + long persistence  worst for ground water
    • Adsorption  = runoff in water
    • Adsorption  = runoff with soil
adsorption coefficient
Adsorption Coefficient
  • Kd
    • Adsorbed concentration / dissolved concentration

Kd = Cs / Cw

    • Kd = strong adsorption
  • Koc
    • Koc = Kd / OC (%)
    • Adsorption is proportional to soil OC%
    • Koc < 100, weakly adsorbing
    • Koc > 1000, strongly adsorbing
leaching potential
Leaching Potential
  • What is leaching?
    • Ability of pesticides to move through soil to reach groundwater
  • High leaching potential
    • Weak adsorption
    • Long persistence
    • Shallow groundwater table
    • Active water movement
    • Sandy texture
leaching and adsorption
Leaching and Adsorption
  • Retardation factor:
    • Reflect difficulty in moving with water
    • As R increases, rate of movement decreases
    • As Kd increases, rate of movement quickly decreases
gus index
GUS Index
  • “GUS”
    • Groundwater Ubiquity Score

GUS = log(T1/2) * (4 – log(Koc))

  • Leaching risk
    • Gus > 2.8: high leaching risk
    • Gus < 1.8: low leaching risk
    • 1.8 < GUS < 2.8: intermediate leaching risk
runoff potential
Runoff Potential
  • Move in water
    • Diazinon, chlorpyrifos, many herbicides
  • Move with loose soil particles
    • synthetic pyrethroids

Water flow

DOC-

DOC-

runoff
Runoff
  • Long persistence + weak adsorption

 high runoff potential

  • Long persistence + strong adsorption

 intermediate runoff potential

  • Short persistence + weak adsorption

 Transient

  • Short persistence + strong adsorption

 Harmless

contact info

Contact Info:

Jay Gan

Dept. Environmental Sciences

UC Riverside, CA 92521

jgan@mail.ucr.edu

(909) 787-2712

slide67

Acknowledgement

California Department of Food & Agriculture

California Department of Pesticide Regulation

California SWRCB

Santa Ana RWQCB

El Modeno Gardens Nursery

FMC Inc.