Pesticide Fate in The Environment. Pesticide Fate. Volatilization vs. Drift? Overview. Troy Bauder Soil and Crop Sciences

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1 Overview Pesticide Fate in The Environment Pesticide properties Site interactions Pesticides in Colorado ground and surface water Application considerations Troy Bauder Soil and Crop Sciences Pesticide Fate Environmental Fate Site Characteristics Pesticide Characteristics Management What are the Pesticide Characteristics Influencing Movement and Degradation? Volatilization vs. Drift? Volatility moving with air Solubility moving with water Adsorptivity attached to soil Persistence and degradation (half-life) Change of state vs. physical movement Potential depends upon chemical properties and conditions 1

2 Volatility of Common Pesticides Trade Name Common Name Vapor Pressure (mm Hg) Pesticides in Soil System Aatrex atrazine 2.89 x 1-7 Banvel dicamba Tordon picloram 6.2 x 1-7 Roundup glyphosate Weedone 2,4-D Acid.2 Weedar 2,4-D Amine 7.5 x 1-7 Adsorption - Partitioning of a compound between solid matter and water (Koc or Kd) Sorption Soil Adsorption of Common Pesticides Trade Name Common Name Sorption index (K oc ) Aatrex atrazine 1 Banvel dicamba 2 Tordon picloram 16 Physio-chemical process, Largely electrostatic bonds ph induced charges Roundup glyphosate 24, Weedone 2,4-D Acid 1 Comite Propargite 4, Soil factors affecting pesticide adsorption Degradation Pathways Soil Properties Organic Matter Low OM High OM Clay content ph moisture 2

3 Soil conditions Temperature Moisture Organic matter Aeration ph Persistence Half Life 1 Half life = amount of time it takes for 5% of the 9 pesticide 8to degrade. 7 Does that mean the pesticide is 1% degraded (no 6 longer 5 present) after two half-lives? % Pesticide Remaining Number of Half-Lives Degradation Rate Persistence (Half Life) Optimum Above Optimum Affected by: Temperature Soil moisture Half-life (days) Soil Moisture and Half-life % 1% 18% Days From: Guenzi and Beard, 1976 Simazine Velpar From: Varcia-Valcarcel and Tadeo, 1999 Persistence of Common Pesticides Trade Name Common Name Soil Half Life (days) Aatrex atrazine 6 Banvel dicamba 14 Tordon Picloram 9 Gramaxone paraquat 5 Pesticide Environmental Fate Properties and Ratings Treflan trifluralin 6 3

4 Pesticides with Groundwater Advisories Trade name Common name Trade name Common name Weed B Gone 2,4-D, salt Plateau Imazapic Lasso Alachlor Kilprop MCPP, DMA salt Temik Aldicarb Dual Metolachlor Sencor Metribuzin Aatrex Atrazine Solicam Norflurazon Abound Azoxystrobin VydateC-LV Oxamyl Hyvar Bromacil Tordon Picloram Furadan Carbofuran Princep Simazine Dacthal DCPA Confirm 2F Tebufenozide Casoron Dichlobenil Sinbar Terbacil Imidacloprid 4F Imidacloprid Platinum Thiamethoxam Balance Isoxaflutole Bayleton 5 Triadimefon Where Do You Find The Ground or Surface Water Advisory? Web information: Pesticide Fate Environmental Fate Site Characteristics Pesticide Characteristics Management waterquality.colostate.edu Site Characteristics? Leaching Potential Factors Leaching Overlying soil type Permeability Organic matter Depth to water table Geology Recharge rate (precipitation and irrigation) Runoff Soil type Slope Soil conditions Irrigation Vegetation characteristics Other ground cover Soil characteristics sandy soil low organic matter numerous macropores Pesticide properties long half-life Numeric guidelines* less then 1% OM greater then 21 days low adsorptivity K OC less then 3-5 high solubility greater than 3 ppm 4

5 Permeability Depth to Groundwater Texture Sand, silt, clay Time Slope Structure / Opportunity for adsorption and degradation Dilution Geologic Conditions Potential for Recharge Ground Water Sensitivity to Pesticide Contamination in Colorado Groundwater Monitoring N E W S 1 km (62 miles) Low Sensitivity Moderate Sensitivity High Sensitivity Aquifer present Depth to groundwater Soil Permeability & Slope Irrigation Ag Chemicals and Groundwater Protection Program 3,359 samples from 1281 wells Since 1992 Analyze: Nitrate Other inorganic ~1 pesticide ai s Non-irrigated BUT Shallow Water Table Non-irrigated and No Shallow Water Table 5

6 Pesticide Detections % of Wells > Std 1% > Std. <1% % Samples Detects 26% Detects 36% BDL 73% BDL 64% Pesticides Detected in Groundwater (61) 2,4-D Dicamba Malathion Acetochlor Dichlorvos MCPA Acetochlor ESA Diflufenzopyr MCPP Alachlor Dimethenamid ESA Metalaxyl Alachlor ESA Dimethenamid OA Metolachlor Alachlor OA Dimethoate Metolachlor ESA Aldicarb sulfone Diuron Metolachlor OA Atrazine Ethoprop Metribuzin Azoxystrobin Fenamiphos Nicosulfuron Bentazon Fenamiphos sulfone Oxydemeton methyl Bromacil Hexazinone Phosphamidon Chlorantraniliprole Hydroxy Atrazine Picloram Chlorpyrifos Imazamethabenz acid Prometon Chlorsulfuron Imazamox Propazine Clopyralid Imazapic Quinclorac Cyromazine Imazapyr Simazine DCPA Imazethapyr Tebuthiuron Desethyl Atrazine Imidacloprid Tetraconazole Desisopropyl Atrazine Lindane Thiamethoxam Diazinon OA Linuron Triazine(ELISA) Long List a Concern? 27 compounds detected above 1. µg / L (ppb) 3 compounds detected fewer than five times Detection limits for some compounds as low as.3 µg / L (ppb) Most detections <.1 µg / L (ppb) i.e. dose makes the poison Above Drinking Water Standard West Slope Detections Unusual in Colorado Only 2 active ingredients have defined standard or health advisory level Often suggest possible spill in area All products with leaching characteristics ug /L # of Hits Alachlor ESA Imazapyr Metolachlor ESA Chlorsulfuron Hexazinone Desethyl Atrazine Alachlor OA Malathion Imidacloprid Imazethapyr Prometon Acetochlor ESA ppb Imazapyr Malathion Chlorsulfuron Alachlor ESA Hexazinone Imidacloprid Metolachlor ESA Imazethapyr Prometon Acetochlor ESA Desethyl Atrazine Alachlor OA 6

7 Surface Water Sampling Number of pesticide detections by basin South Platte North Fork Gunnison Arkansas Detected pesticide concentration by basin.6 Concentration (ppb=µg/l) Number of detections Less frequent and coordinated as groundwater Typically CDPHE, USGS Generally focused on basins with use Surface Water Pesticides.5.4 South Platte North Fork Gunnison Monitoring Summary Pesticide detection varies widely depending upon area of state. Application Considerations Awareness: Pesticide choice Site Characteristics Setback from water sources (Wells) Chemicals with leaching properties and higher rates are most frequently detected compounds. Detections above drinking water standard are rare. Application Considerations Awareness Location: Nearby surface water Topography Low lying areas Slopes toward water Extremely sandy soils Avoid overspray onto impermeable surfaces!! Timing incoming weather, irrigation Application Label setbacks Mixing and loading Application timing pending irrigation or rain See newly revised BMPs for Pesticide and Fertilizer Storage and Handling: Most pesticide detections at higher levels (in Colorado) are likely due to point sources Poor mixing and loading Uncontained spills Mixing near wellhead Improper storage and disposal 7

8 Agricultural Chemicals and Groundwater Protection Program Requires secondary containment and mixing and loading pads if you.. Store pesticide in bulk containers > 55 gal. (non-dot approved or >66 gal) Mix more than 5 gal product at 1 site annually Field mixing and loading is exempt Other Resources RUP Recordkeeping Updated Excel Program estrecordbook.shtml Colorado RUP Recordkeeping App (CRURA) Available on App Store soon Certain Colorado waters are vulnerable to pesticide impacts, however Site characteristics Chemical selection Application/ management practices Determine actual impacts. Summary Contact Information Troy Bauder Department of Soil and Crop Sciences Colorado State University Fort Collins, CO (97) troy.bauder@colostate.edu 8