Pesticides in Nursery Runoff: Sources and Transport Processes

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Pesticides in Nursery Runoff Sources and
Transport Processes

• Jay Gan
• Dept. Environmental Sciences
• UC Riverside, CA 92521
• jgan_at_mail.ucr.edu
• 909-787-2712

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Outline

• Nursery and pesticides
• Current issues
• How does it happen?
• Governing Processes

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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

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CA Nursery Industry
Total CA Nursery/Floral Production 3.2
billion (2001)
Floral 12
Woody, decidous Evergreen 26
Misc. 8
Potted plants Flowering foliage 20
Bedding plants 15
Non- Ornamentals 19
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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
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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
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CAs Top 10 Nursery, Flower and Foliage
Producing Counties
County Production (mil) Share of state
San Diego 855 27
Ventura 223 7.4
Orange 219 6.9
Monterey 179 5.6
Los Angeles 172 5.4
Santa Clara 150 4.7
Riverside 138 4.4
San Mateo 137 4.3
Santa Barbara 131 4.1
Kern 114 3.6
Total 2,319 73.45
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Nurseries Pesticides

• Pesticide Uses
• Agricultural crops
• Home lawns/gardens
• Structural/indoor pest control
• Nurseries
• Roadside
• Parks

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Pesticide Use in California by Sectors (million
lbs)
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Trend of Pesticide Use Total
Active Ingredients (mil lbs)
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Top Ten in California
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Use Trend of Reproductive Toxic Pesticides in CA
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Reproductive Toxic Products
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Use Trend of Carcinogenic Pesticides in CA
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Carcinogenic Pesticides
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Use Trend of Cholinesterase Inhibiting Pesticides
in CA
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Cholinesterase-Inhibiting Pesticides
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Use Trend of Groundwater-Risk Pesticides in CA
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Groundwater-risk Pesticides
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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, )

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Most Used Nursery Pesticides (San Diego County,
2002) Greenhouse Containers
Chemical Amount (lb)
Acephate 759
Chlorpyrifos 252
Daminozide 864
Diazinon 402
Fosetyl-Al 634
Glyphosate 964
Iprodione 468
Malathion 361
Mancozeb 562
Methyl bromide 1476
Potash soap 1425
Petroleum products 1449
Thiophanate-methyl 2202
Source CDPR
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Most Used Nursery Pesticides (San Diego County,
2002) Outdoor Containers
Chemical Amount (lb)
Acephate 1405
Chlorothalonil 1539
Chlorpyrifos 379
Daminozide 1240
Diazinon 226
Fosetyl-Al 1202
Glyphosate 9730
Iprodione 676
Malathion 1361
Mancozeb 1459
Methyl bromide 1546
Potash soap 1298
Petroleum products 6724
Thiophanate-methyl 2163
Source CDPR
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Aquatic Toxic Insecticides (San Diego County,
2002) Greenhouse Containers
Chemical Amount (lb)
Bifenthrin 18
Chlorpyrifos 252
Cyfluthrin 12
Diazinon 402
Fenpropathrin 23
Malathion 361
Methiocarb 112
Permethrin 119
Source CDPR
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Aquatic Toxic Insecticides (San Diego County,
2002) Outdoor Containers
Chemical Amount (lb)
Bifenthrin 60
Carbaryl 199
Chlorpyrifos 380
Cyfluthrin 35
Deltamethrin 12
Diazinon 226
Fenpropathrin 87
Malathion 1365
Methiocarb 22
Permethrin 217
Source CDPR
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Water Quality Issues

• Ground water issues
• Surface water issues
• TMDLs
• TMDL examples

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Groundwater Issues

• The CA 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

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Distribution of Verified Detections
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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!

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• 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)

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• 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

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High priority TMDLs in CA
Pollutant Total
Pesticides 125 18
Metals/trace elements 118 17
Sediment 114 16.4
Other organics 95 13.7
Nutrients 67 9.6
Caliform/pathogens 45 6.5
Ammonia 22 3.2
Other 108 13.6
Total 694 100
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High priority pesticide TMDLs in CA
Pesticide Total
DDT 76
Chlordane 15
Diazinon 9
Chlorpyrifos 6
Endosulfan 9
Unspecified 10
Total 125
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San Diego Creek Pesticide TMDLs
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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!

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Table 1. Proposed Water-Quality Criteria for
Diazinon and Chlorpyrifos
  Acute (ppt) Chronic (ppt) Ceriodaphnia LC50
Diazinon 80 50 450
Chlorpyrifos 20 14 80
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How Does It Happen?

• Storm water runoff
• Irrigation runoff
• Leaching through containers?
• Planting media spills?
• Runoff planting media
• pesticide runoff?

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Irrigation
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Nursery Runoff
Runoff!
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Runoff Driven ? Storm runoff ? Over-irrigation
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Planting Media
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Step 1 Scrap off surface soil Step 2 Estimate
potting mix content Step 3 Analyze
pesticides Step 4 Correlation
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 Sample Concentration (µg/kg) Concentration (µg/kg) Concentration (µg/kg) Potting mix
 Sample Bifenthrin cis-Permethrin trans-Permethrin Potting mix
1 3,971 ? 373 4,625 ? 1,194 53 ? 13 80
2 306 ? 4 658 ? 240 70 ? 2 20
3 344 ? 17 1,556 ? 322 178 ? 94 5
4 109 ? 13 471 ? 396 18 ? 5 1
5 163 ? 18 521 ? 96 58 ? 6 lt1
6 275 ? 81 5,948 ? 651 1,478 ? 43 50
7 307 ? 55 71 ? 124 243 ? 28 10
8 17,440 ? 436 631 ? 831 642 ? 1,085 100
9 163 ? 123 290 ? 138 17 ? 9 5
10 125 ? 6 113 ? 101 23 ? 9 1
11 2,470 ? 451 1,697 ? 369 0 ? 0 100
12 389 ? 17 387 ? 137 24 ? 2 1
13 1,309 ? 24 753 ? 201 21 ? 9 20
14 852 ? 19 1,535 ? 506 16 ? 2 15
15 430 ? 33 455 ? 89 18 ? 3 1
16 3,055 ? 211 5,115 ? 1,669 80 ? 139 50
17 353 ? 26 1,613 ? 765 163 ? 12 80
18 95 ? 7 238 ? 21 27 ? 3 1
19 303 ? 10 587 ? 184 48 ? 5 20
20 305 ? 25 178 ? 39 35 ? 1 1
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Pesticides in Spilled Potting Mix
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Loose Potting Mix
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Governing Processes

• Degradation
• Chemical
• Microbial
• Adsorption
• Leaching Potential
• Runoff Potential

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Transport after application
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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 ?

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Pesticide degradation in soil
T1/2
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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

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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

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Persistence ? Risk ?
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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

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Adsorption Coefficient

• Kd
• Adsorbed concentration / dissolved concentration
• Kd Cs / Cw
• Kd ? strong adsorption
• Koc
• Koc Kd / OC ()
• Adsorption is proportional to soil OC
• Koc lt 100, weakly adsorbing
• Koc gt 1000, strongly adsorbing

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PesticideWise Searchable Webpages
www.pw.ucr.edu
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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

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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

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GUS Index

• GUS
• Groundwater Ubiquity Score
• GUS log(T1/2) (4 log(Koc))
• Leaching risk
• Gus gt 2.8 high leaching risk
• Gus lt 1.8 low leaching risk
• 1.8 lt GUS lt 2.8 intermediate leaching risk

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Groundwater-risk Pesticides
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Runoff Potential

• Move in water
• Diazinon, chlorpyrifos, many herbicides
• Move with loose soil particles
• synthetic pyrethroids

Water flow
DOC-
DOC-
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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

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Contact Info

• Jay Gan
• Dept. Environmental Sciences
• UC Riverside, CA 92521
• jgan_at_mail.ucr.edu
• [phone]

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Acknowledgement
California Department of Food
Agriculture California Department of Pesticide
Regulation California SWRCB Santa Ana RWQCB El
Modeno Gardens Nursery FMC Inc.