Pesticides in Nursery Runoff: Sources and Transport Processes Jay Gan Dept. Environmental Sciences UC Riverside, CA

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

Nursery in CA (2001)   Production sales: $3.17 billion 10.6% of CA agricultural output 2 nd among all CA agricultural products 21.3% of the U.S. nursery/floriculture total (11.9% for FL)   Retail sales $10.1 billion 1 st in the U.S.   CA horticulture industry jobs 81,011 jobs in production 87,856 jobs in retailing

CA Nursery Industry Total CA Nursery/Floral Production: $3.2 billion (2001) Woody, decidous Evergreen 26% Bedding plants 15% Non- Ornamentals 19% Potted plants Flowering foliage 20% Misc. 8% Floral 12%

CA Nursery Industry Total CA Retail Sales: $10.1 billion (2001) Hardware Home centers $3,576 mil Garden centers Farms Nurseries $2,859 mil Chain stores Warehouses $2,757 mil Florists $988 mil

CA Nursery Industry Total Sales Composition (2001) Lawn furniture Accessories Tree trim 20.8% Chemicals Fertilizers 24.8% Green goods 26.0% Equipment Tools 28.4%

CA’s Top 10 Nursery, Flower and Foliage Producing Counties CountyProduction (mil)Share of state San Diego85527 Ventura Orange Monterey Los Angeles Santa Clara Riverside San Mateo Santa Barbara Kern Total2, %

Nurseries & Pesticides  Pesticide Uses Agricultural crops Agricultural crops Home lawns/gardens Home lawns/gardens Structural/indoor pest control Structural/indoor pest control Nurseries Nurseries Roadside Roadside Parks Parks

Pesticide Use in California by Sectors (million lbs)

Trend of Pesticide Use Total Active Ingredients (mil lbs)

Top Ten in California

Use Trend of “Reproductive Toxic” Pesticides in CA

Reproductive Toxic Products

Use Trend of Carcinogenic Pesticides in CA

Carcinogenic Pesticides

Use Trend of Cholinesterase Inhibiting Pesticides in CA

Cholinesterase-Inhibiting Pesticides

Use Trend of Groundwater-Risk Pesticides in CA

Groundwater-risk Pesticides

Surface water-Risk Pesticides  Not human safety concern !  Aquatic toxicity: Organophosphate insecticides Organophosphate insecticides (e.g., Dusban, diazinon) Carbamate insecticides Carbamate insecticides (e.g., carbaryl) Synthetic pyrethroids Synthetic pyrethroids (e.g., cyfluthrin, permethrin, …) Mayfly Procloeon Midge Chironomus

Most Used Nursery Pesticides (San Diego County, 2002) Greenhouse Containers ChemicalAmount (lb) Acephate759 Chlorpyrifos252 Daminozide864 Diazinon402 Fosetyl-Al634 Glyphosate964 Iprodione468 Malathion361 Mancozeb562 Methyl bromide1476 Potash soap1425 Petroleum products1449 Thiophanate-methyl2202 Source: CDPR

Most Used Nursery Pesticides (San Diego County, 2002) Outdoor Containers ChemicalAmount (lb) Acephate1405 Chlorothalonil1539 Chlorpyrifos379 Daminozide1240 Diazinon226 Fosetyl-Al1202 Glyphosate9730 Iprodione676 Malathion1361 Mancozeb1459 Methyl bromide1546 Potash soap1298 Petroleum products6724 Thiophanate-methyl2163 Source: CDPR

Aquatic Toxic Insecticides (San Diego County, 2002) Greenhouse Containers ChemicalAmount (lb) Bifenthrin18 Chlorpyrifos252 Cyfluthrin12 Diazinon402 Fenpropathrin23 Malathion361 Methiocarb112 Permethrin119 Source: CDPR

Aquatic Toxic Insecticides (San Diego County, 2002) Outdoor Containers ChemicalAmount (lb) Bifenthrin60 Carbaryl199 Chlorpyrifos380 Cyfluthrin35 Deltamethrin12 Diazinon226 Fenpropathrin87 Malathion1365 Methiocarb22 Permethrin217 Source: CDPR

Water Quality Issues  Ground water issues  Surface water issues TMDLs TMDLs TMDL examples TMDL examples

Groundwater Issues  The CA Picture (CDPR, CWRCB) 324 of 3,165 wells in year of 3,165 wells in year verified detections 84 verified detections From previous use (fumigants) From previous use (fumigants) DBCP, EDB, 1,2-D DBCP, EDB, 1,2-D From existing use (herbicides): From existing use (herbicides): Simazine, ACET (from simazine or atrazine), DACT, norflurazon, bromacil, diuron, atrazine, deethyl atrazineSimazine, ACET (from simazine or atrazine), DACT, norflurazon, bromacil, diuron, atrazine, deethyl atrazine

Distribution of Verified Detections

Surface Water Quality Issues  Urban surface water quality issues Pesticide detections in most streams Pesticide detections in most streams 99% streams with 1 pesticide99% streams with 1 pesticide 70% streams with  5 pesticides70% streams with  5 pesticides Sustained insecticide levels Sustained insecticide levels Harmful to aquatic organisms Harmful to aquatic organisms Beneficial useBeneficial use TMDLs for many streams TMDLs for many streams The new rule!The new rule!

 What is TMDL? CWA 303(d) CWA 303(d) States to make list of “impaired” waters States to make list of “impaired” waters Develop TMDLs for the listed waters Develop TMDLs for the listed waters TMDLs to account for all pollutants and all sources, TMDLs to account for all pollutants and all sources, TMDL includes non-point sources, e.g., urban and agricultural runoffs TMDL includes non-point sources, e.g., urban and agricultural runoffs Develop implementation plans (Basin Plans or Water Quality Control Plans in CA) Develop implementation plans (Basin Plans or Water Quality Control Plans in CA)

 California: RWQCBs RWQCBs 800 TMDLs in total 800 TMDLs in total 120 TMDLs in progress 120 TMDLs in progress Amend the Basin Plan by incorporating TMDLs Amend the Basin Plan by incorporating TMDLs  TMDL Elements: Problem statement Problem statement Numeric targets Numeric targets Source analysis Source analysis Allocations Allocations Implementation plan Implementation plan Linkage analysis Linkage analysis Monitoring/Re-evaluation Monitoring/Re-evaluation Margin of safety Margin of safety

High priority TMDLs in CA PollutantTotal% Pesticides12518 Metals/trace elements11817 Sediment Other organics Nutrients679.6 Caliform/pathogens456.5 Ammonia223.2 Other Total694100

High priority pesticide TMDLs in CA PesticideTotal DDT76 Chlordane15 Diazinon9 Chlorpyrifos6 Endosulfan9 Unspecified10 Total125

San Diego Creek Pesticide TMDLs

 Diazinon: ppt  50 ppt ppt  50 ppt % reduction! % reduction!  Chlorpyrifos : ppt  14 ppt ppt  14 ppt % reduction! % reduction!  Legacy pesticides: DDT, chlordane,… DDT, chlordane,…  Urban use is the No.1 source! San Diego Creek Pesticide TMDLs

Table 1. Proposed Water-Quality Criteria for Diazinon and Chlorpyrifos Acute (ppt) Chronic (ppt) Ceriodaphnia LC 50 Diazinon Chlorpyrifos201480

How Does It Happen?  Storm water runoff  Irrigation runoff Leaching through containers? Leaching through containers? Planting media spills? Planting media spills? Runoff + planting media Runoff + planting media = pesticide runoff?

Irrigation

Nursery Runoff Runoff!

Runoff Driven:  Storm runoff  Over-irrigation

Planting Media

Step 1: Scrap off surface soil Step 2: Estimate potting mix content Step 3: Analyze pesticides Step 4: Correlation

Sample Concentration (µg/kg) Potting mix † Bifenthrincis-Permethrintrans-Permethrin 1 3,971  373 4,625  1,  13 80%    2 20%  17 1,556   94 5%    5 1%    6 <1%  81 5,948  6511,478  43 50%    28 10% 8 17,440    1, %    9 5%    9 1% 11 2,470  451 1,697   0 100%    2 1% 13 1,309    9 20%  19 1,535   2 15%    3 1% 16 3,055  211 5,115  1,  %  26 1,613   12 80%    3 1%    5 20%    1 1%

Pesticides in Spilled Potting Mix

Loose Potting Mix

Governing Processes  Degradation Chemical Chemical Microbial Microbial  Adsorption  Leaching Potential  Runoff Potential

Transport after application

Degradation in Soil  What is “degradation”? Structural changes caused by chemical and/or microbial reactions Structural changes caused by chemical and/or microbial reactions Desirable environmentally Desirable environmentally Pesticide-dependent Pesticide-dependent Vary in different soil types Vary in different soil types Measured by persistence or “half-life” T 1/2 Measured by persistence or “half-life” T 1/2 Long “half-life” = problems Long “half-life” = problems T 1/2  = leaching potential T 1/2  = leaching potential  T 1/2  = runoff potential T 1/2  = runoff potential 

Pesticide degradation in soil T 1/2

What Causes Degradation?  Chemical reactions Hydrolysis (OPs, carbamates, etc.) – pH sensitive Hydrolysis (OPs, carbamates, etc.) – pH sensitive Photolysis – by UV, near the surface Photolysis – by UV, near the surface Oxidation – reduction by soil chemical species Oxidation – reduction by soil chemical species Nucleophilic attacks by soil nucleophiles Nucleophilic attacks by soil nucleophiles Pesticide dependent Pesticide dependent Soil dependent Soil dependent

What Causes Degradation?  Microbial transformations Biodegradation – bacteria use pesticides as “food” Biodegradation – bacteria use pesticides as “food” Cometabolism –degradation by “accident” Cometabolism –degradation by “accident” Enzyme-based transformations Enzyme-based transformations Pesticide dependent Pesticide dependent Soil dependent Soil dependent Microbial ecologyMicrobial ecology Organic matter plays a big roleOrganic matter plays a big role

Persistence  Risk 

Adsorption in Soil  What is “adsorption”? Retention of pesticides by soil Retention of pesticides by soil Pesticide dependent Pesticide dependent Soil dependent Soil dependent Organic matter content , adsorption Organic matter content , adsorption  Weak adsorption + long persistence  worst for ground water Weak adsorption + long persistence  worst for ground water Adsorption  = runoff in water Adsorption  = runoff in water Adsorption  = runoff with soil Adsorption  = runoff with soil

Adsorption Coefficient  K d Adsorbed concentration / dissolved concentration Adsorbed concentration / dissolved concentration K d = C s / C w K d  = strong adsorption K d  = strong adsorption  K oc K oc = K d / OC (%) K oc = K d / OC (%) Adsorption is proportional to soil OC% Adsorption is proportional to soil OC% K oc < 100, weakly adsorbing K oc < 100, weakly adsorbing K oc > 1000, strongly adsorbing K oc > 1000, strongly adsorbing

PesticideWise Searchable Webpages

Leaching Potential  What is leaching? Ability of pesticides to move through soil to reach groundwater Ability of pesticides to move through soil to reach groundwater  High leaching potential Weak adsorption Weak adsorption Long persistence Long persistence Shallow groundwater table Shallow groundwater table Active water movement Active water movement Sandy texture Sandy texture

Leaching and Adsorption  Retardation factor: Reflect difficulty in moving with water Reflect difficulty in moving with water As R increases, rate of movement decreases As R increases, rate of movement decreases As K d increases, rate of movement quickly decreases As K d increases, rate of movement quickly decreases

GUS Index  “GUS” Groundwater Ubiquity Score Groundwater Ubiquity Score GUS = log(T 1/2 ) * (4 – log(K oc ))  Leaching risk Gus > 2.8: high leaching risk Gus > 2.8: high leaching risk Gus < 1.8: low leaching risk Gus < 1.8: low leaching risk 1.8 < GUS < 2.8: intermediate leaching risk 1.8 < GUS < 2.8: intermediate leaching risk

Groundwater-risk Pesticides

Runoff Potential  Move in water Diazinon, chlorpyrifos, many herbicides Diazinon, chlorpyrifos, many herbicides  Move with loose soil particles synthetic pyrethroids synthetic pyrethroids Water flow DOC-

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: Jay Gan Dept. Environmental Sciences UC Riverside, CA (909)

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