October 2011Antimicrobial Copper TransportCopper Transport and Fate fromAlgae-Resistant Shingles and Treated WoodMark Velleux, Paul Paquin,Aaron Redman, and Robert Santore2Antimicrobial Copper PesticideszCopper-containing biocides used to preserveroofing shingles and woodzDiffers from agricultural pesticides:“[D]etermining human and ecological risks fromexposure to antimicrobial pesticides requiresdifferent types of measurements and models thanthose needed for pesticides largely applied to cropsand other plants.” (http://www.epa.gov/oppad001/)zExposure scenario designed for these uses3Exposure Scenario DesignzThree factors control scenario design:zChemical useszPhysical settingzLandscape specific to setting and useszAntimicrobial copper uses evaluated:zAlgae-resistant (AR) shingleszTreated woodzThese products are building materials:zRoofszWood decks, fences, and utility poles4Uses Control Setting and LandscapezUses evaluated are building materialszGreatest density of use expected in urbanized areas(constructed environments)zMarket share information identifies southeast U.S. asregion where product use is greatestzCopper releases depend on rainfallzSoutheast U.S. climate has above average rainfall(Average: 50 inches/year, WY83-92: 62 inches/year)zAn urban landscape in a Southeast U.S. settingprovides expected upper bound for assessment5Physical Setting: Goodwin Creek, MSzWell-know watershed in southeast U.S.zExtensively studiedzHigh runoff/erosion vulnerability (Yazoo, MS area)zDetailed database to assist model set-upzLoess soils characteristic of many parts of U.S.zIn a climate with high rainfall (50-62 inches/year)zDatabase allows model representation of majorprocesses to reflect realistic conditionszFurther described as part of model set-up...6Landscape: Urbanized AreazDesigned to reflect a range of developmentz1, 4, and 8 house(s) per acrezIncludes impervious area for roofs, sidewalks,driveways and roadwayszOverall set-up includes other development types withopen space, commercial areas with parking lots, etc.zBased on Census Bureau and housing marketstatistics, antimicrobial market share data, etc.zReasonable maximum for copper usezFurther described as part of landscape design...7Setting: Homogeneous vs. HeterogeneouszWhy not PRZM?zAgricultural Use:zFarm fieldszUniform applicationzBuilding Products:zUrbanized areaszSpatially variable!zBiocide mass released notequal to mass installedzAddress variability withwatershed approach8TERRA: Two-DimensionalExposure and Rainfall-Runoff Analysis(Velleux et al. 2008)Major Inputs:zTopography (DEM)zSoil characteristicszLand coverzStream and sedimentcharacteristicszRainfallzChemical applicationand release rateszChemical partitioningand fate parametershttp://www.engr.colostate.edu/~pierre/ce_old/Projects/TREX%20Web%20Pages/TREX-Home.html9Watershed ModelSet-up and Calibration10Physical Setting is a Real WatershedLocation:Goodwin Creek, MSBasin Size:21.4 km2(5,104 acres)Land Cover:Grassland, pasture, etc.Land cover was modified torepresent an urban setting...Database:14 stream gages, GIS dataModel Resolution:90 m x 90 m (2,558 grid cells)R. Rojas, 2002Panola County, MSYazoo County, MSModel Set-upzSet-up based on standard data sourceszUsed 90-m grid scale (2,558 cells)zWatershed topography and basic landcover from USGSzSoil properties from USDA NRCSzRainfall from USDA ARSzCalibration to three storm events:z17-October-1981, 28-August-1982, and 20-September-1983zBased on previous publicationszSimulate solids as 5 particle types:zclay, silt, sand, fine gravel, coarse gravel11Digital Elevation Model and Stream NetworkTopographyDigital ElevationModel (DEM)12Stream NetworkDelineation18 links in networkshown by colored linesSoilsSpatial Distributionof SoilsDetermines grain size distribution,infiltration properties, erodibility...13Land Cover (Not Urbanized)Spatial Distributionof Land CoverDetermines interception, surfaceroughness, land use management14Hydrology and Sediment TransportResponse to StormsGaging StationCompare simulated streamflow and solids concentrationto measurements at differentgages across watershed...0.00.51.01.52.02.53.03.54.00 50 100 150 200 250 300 350Time (min)

Intensity (in/h)125671012143435414252616465Rain Gage15Results: October 17, 19811617

Results: August 28, 1982Results: September 20, 19831819Copper Release Rates20Copper Release Rate AnalysiszAR shingles:zShort-term (3-4 months) and long-term (2-15+ years) studieszReleases were directly proportional to exposed area and rainfallzAverage release rate: 0.16 mg copper per m2per mmzTreated Wood (decks, fences, utility poles):zShort-term and long-term studieszReleases were proportional to exposed area and rainfallzAverage CCA release rate: 0.26 mg copper per m2per mmzAverage non-CCA release rate: 3.2 mg copper per m2per mmzAssumed wood mix: 20% CCA, 80% non-CCA for upper boundzExpected to represent reasonable maximum copper use21Copper Release Rate: AR Shingles0.11101001000100001 10 100 1,000 10,000 100,000

Cumulative Copper Release (mg m

-2 )Cumulative Rainfall (mm)Palo AltoHoustonHomesteadHagerstownMeanU95%L5%Short-Term (Palo Alto) Study1 test panel, 3 monthsMean = 0.52 mg m-2mm-1All Long-Term StudiesMean = 0.16 mg m-2mm-1Houston Study11 test panels, 8-15 yearsMean = 0.09 mg m-2mm-1Hagerstown Study6 test panels, ~13 yearsMean = 0.28 mg m-2mm-1Homestead Study18 test panels, ~4-14 years22Copper Sources: Treated WoodMean Release RatesCCA = 0.26 mg m-2mm-1Non-CCA = 3.2 mg m-2mm-10.1110AR Shingles CCA Wood Non-CCA Wood

Copper Rel ease Rate (mg m

-2 mm -1 )23Summary of Copper Release Rates0.16 mg/m2/mm0.26 mg/m2/mmAssumed Mix of Wood Preservatives: 20% CCA, 80% non-CCA3.2 mg/m2/mmOverall: 2.6 mg/m2/mm24Rainfall Data AnalysisRainfall AnalysiszFocused on southeast US:zArea of expected greatest use ofAR shingles and treated woodzHigher than average rainfall compared to other (non-coastal)regions of US (Long-term average: 50 inches/year)zExamined more than 100 years of regional rainfall data:zRainfall distributions at four stations (up to 113 years of data)zConsidered daily, hourly, and 15-minute recordszWater Years 1983-1992Æ62 inches/yearzPeriod with highest 10-year average rainfall on recordzIncludes biggest storms on recordzUsing 15-minute rainfall data, 772 storm events occur25Distributions Rainfall Measurements•University gageused for analysis•Representative ofregional conditions•113 years of dailyand hourly records•Longest record of15-minute data•Time series fromgage defines stormrecord...26WY 1983-1992 Used for Model Simulations0123456789 10/01/81 10/01/82 10/01/83 09/30/84 10/01/85 10/01/86 10/01/87 09/30/88 10/01/89 10/01/90 10/01/91 09/30/92 10/01/93

Rainfall (inches)27Annual Rainfall for WY 1983-1992: 62 inches/year28Urban Landscape Development29Urban Landscape DevelopmentzSimulated urban land cover: looks like suburbiazReflects spatial variations in development:zHousing densities: 1, 4, & 8 house(s)/acrezHouses with AR shingle roofs determined frommarket share datazHouses with decks and fences determined fromCensus Bureau statistics and market share datazUtility pole placement and treatment type based onstudy for Toledo, Ohio urban areazRepresents reasonable maximum copper use30Copper Sources: Shingles, Decks, FencesAR Shingle Roofs,Treated Wood Decksand Fences...Copper Source Detail31Copper Sources: Utility PolesCCA treatedUtility PolesLandscape Includes Impervious AreaLandUseTotalArea(acres)ImperviousArea(acres)PerviousArea(acres)CreekSet‐Back59059ResidentialUse(total)4520921.53598.51House/Acre(subtotal)4Houses/Acre(subtotal)8Houses/Acre(subtotal)15071507150678.4313.5529.61428.61193.5976.4OpenSpace45245407CommercialUse2015.84.2GovernmentUse30921Education2313.99.2Elementary/MiddleSchools117.53.6HighSchool126.45.6EntireWatershed51041005.24098.932Density of Antimicrobial Copper Uses33All HousesDevelopmentHousingUnitsRooftopArea (m2)DeckArea (m2)FenceArea (m2)Utility PoleArea (m2)1 house/acre1,507350,00010,800145,50014,3204 house/acre6,0281,400,10043,000291,10014,3208 house/acre12,0482,126,70053,700415,60014,310Houses With Antimicrobial Copper Building Material Construction1 house/acre613140,0004,50027,8002,1504 house/acre2,411560,00018,10055,6002,1508 house/acre4,819850,70022,60079,3002,150Note: Surface area values rounded to simplify display.Accounting for Urban Landscape FeatureszMany urban landscape features occur at spatial scalessmaller than the 90-m model grid scale:zIndividual buildings, sidewalks, roads, individual lawns, etc.zImpervious area is handled as sub-grid scale featurezHydraulic conductivity, flow resistance, and soil erodibilityare scaled by impervious cover for each land use class34()()imperviousimperviousnaturalhurbanhffKK01,,+−=()()...11+−+−=concreteconcretelawnlawnurbanfnfnn()()imperviousimperviousnaturalUSLEurbanUSLEffKK01,,+−=35Environmental Quality Benchmarks36Environmental Benchmarks for CopperzSurface water:zBiotic Ligand Model (BLM)zWater quality for regional siteszVary by month: 11.7 to 33.7μg/LzSediment:zEquilibrium sediment guidelines(ESG) (USEPA, 2000)zCopper as excess metalzAssumed 5% organic carbonz320 mg/kgzSoil:zEmpirical relationships, 10% effectslevel (Rooney et al. 2006)zUsed local soil chemistry dataz36 mg/kg37Copper Transport Simulation ResultszTERRA was used to perform simulations for 770+ individualstorm events over a 10 year periodzDaily average EECs calculated for surface water, soil, andsedimentzEECs compared to benchmarks38Copper from AR Shingles Over 10 Years: WaterzOver 10 years:zMean = 0.25 μg/LzSt Dev = 0.79 μg/LzMin = 0 μg/LzMax = 7.1 μg/LzCu releases driven by rainfallz10% of Cu release goes tostream, 1% exportedzEECs at watershed outletzWater benchmark: 11.7–33.7μg/L39Copper from AR Shingles After 10 Years: SoilzSpatially variabledistribution of homeswith AR shingle roofszCu releases drivenby rainfallz90% of Cu infiltrateszAfter 10 years:zMean = 1.7 mg/kgzSt Dev = 1.5 mg/kgzMin = 0 mg/kgzMax = 8.8 mg/kgzSoil benchmark:z36 mg/kg40Copper from AR Shingles After 10 Years: SedimentzSpatially variabledistribution of homeswith AR shingle roofszCu transport drivenby runoff from rainfallz9% of Cu depositszAfter 10 years:zMean = 6.7 mg/kgzSt Dev = 4.9 mg/kgzMin = 1.0 mg/kgzMax = 34.5 mg/kgzSediment benchmark:z320 mg/kg41EECs and Benchmarks: AR ShinglesMediaConcentrationUnitsMeanSt DevMinMaxBenchmarkWater0.250.7907.111.7 – 33.7μg/LSediment6.74.91.034.5320mg/kgSoil1.71.508.836mg/kgNotes: Benchmarks for surface water are time variable to reflect water chemistrydifferences over time. Values shown represent an average condition determinedfrom data from six regional sites in the USGS NAWQA database42Copper from Treated Wood Over 10 Years: WaterzOver 10 years:zMean = 0.58 μg/LzSt Dev = 1.7 μg/LzMin = 0 μg/LzMax = 16.7 μg/LzCu releases driven by rainfallz10% of Cu release goes tostream, 1% exportedzEECs at watershed outletzWater benchmark: 11.7–33.7μg/L43Copper from Treated Wood After 10 Years: SoilzSpatially variabledistribution of homeswith decks, fences...zCu releases drivenby rainfallz90% of Cu infiltrateszAfter 10 years:zMean = 3.8 mg/kgzSt Dev = 4.9 mg/kgzMin = 0 mg/kgzMax = 31.8 mg/kgzSoil benchmark:z36 mg/kg44Copper from Treated Wood After 10 Years: Sed.zSpatially variabledistribution of homeswith decks, fences...zCu releases driven byrainfallz90% of Cu infiltrateszAfter 10 years:zMean = 14.1 mg/kgzSt Dev = 9.4 mg/kgzMin = 2.1 mg/kgzMax = 66.8 mg/kgzSediment benchmark:z320 mg/kg45EECs and Benchmarks: Treated WoodMediaConcentrationUnitsMeanSt DevMinMaxBenchmarkWater0.581.7016.711.7 – 33.7μg/LSediment14.19.42.166.8320mg/kgSoil3.84.9031.836mg/kgNotes: Benchmarks for surface water are time variable to reflect water chemistrydifferences over time. Values shown represent an average condition determinedfrom data from six regional sites in the USGS NAWQA database46Simulated Copper Mass Fate: Urban SettingzOver 10 years:z90% infiltrates to soilz10% runs off to streamz9% deposits to sedimentz1% leaves watershedzMost copper infiltratesbecause nearly all is inthe dissolved phase...zOnce in surface soil,copper sorbs to particlesurfaces and does notsignificantly leach...Algae-Resistant ShinglesTreated Wood (Decks, Fences, Poles)47Benchmark ExceedancesNote: For surface water, three benchmarks were evaluated: (1) upper (lesssensitive); (2) average; and (3) lower (more sensitive). Exceedances reflect thenumber of days in 10 years when dissolved copper concentrations are greater thanthe benchmark for that day. An exceedance rate of 1 day in 3 years (3-4 days in 10years) or less is typically considered acceptable (Stephan et al. 1985)MediaAR ShinglesTreated WoodSurface WaterUpperAverageLowerZeroZeroZeroZero2 days in 10 years64 days in 10 yearsSedimentZeroZeroSoilZeroZero48OutcomeszResults are expected to be conservative:zSettings include high-end estimates for density of copper useon land surface and in streamzLow TSS and low Kpmaximize dissolved copper EECszGenerally low EECs consistent with low releases:zVery low effective application rates compared to agriculturaluses: 0.15–0.32 lbs/acre/year vs. 1–16 lbs/acre/yearzSimulated EECs similar to measurements in urban water(Boulanger and Nikolaidis, 2003)zSimulated EECs much lower than measured at agricultural siteswith high application rates (Fernández-Calviño et al. 2008)49Copper Application Rate Comparison50Antimicrobial Case Study Summary51Antimicrobial Case Study SummaryzExamined two separate antimicrobial copper uses:zAlgae-resistant (AR) shingles (e.g. Cu2O)zTreated wood (e.g. CCA, CA, ACQ, etc.)zUses and setting differ from agricultural case:zUrban setting with spatially-variable landscape conditionszRainfall-driven releases from roofs, decks, fences, and poles...zSimulated copper transport and fate to calculateestimated environmental concentrations (EECs):zExcess copper in surface water, sediment, and soil52Exposure Simulation OutcomeszGenerally low EECs consistent with low releases:zVery low effective application rates compared to agriculturaluses: 0.15–0.32 lbs/acre/year vs. 1–16 lbs/acre/yearzResults consistent with measurements for other caseszSimulated EECs similar to measurements in urban water(Boulanger and Nikolaidis, 2003)zSimulated EECs much lower than measured at agricultural siteswith high application rates (Fernández-Calviño et al. 2008)zFew surface water exceedances occur, none occur forsoil or sediment53Scenario Designed To Be RepresentativezPhysical setting and landscape design constrained by:zUses (driven by market share data and Census statistics)zMaterial types (building products)zRelease mechanism (rainfall-driven, so we want higher rainfall)ÆUrbanized area, southeast U.S., high rainfall, dense product usezGoodwin Creek used for physical setting because itmeets location and climate needs and has database soKhand other parameters can be definedzScenario accounts for impervious area (but not sewers)zKhand other parameters scaled to account for urban land cover54Why this Scenario Design?zWhy Goodwin Creek? Why not Seattle or elsewhere?zAny site could be used, but southeast U.S. is the region ofgreatest product use paired with highest rainfall for this case...zAnnual rainfall: Seattle = 36 in/yr, Goodwin Creek = 50-62 in/yr...zAnother advantage of Goodwin Creek site is that extensive dataexist so we can show that basic model mechanics are rightzHigh runoff/erosion vulnerability (near Yazoo, MS area)zOver time, more scenarios can be developed the wayUSEPA developed scenarios for agriculture pesticideszScenarios can be designed to include more featuresover time (more chemical processes, stormsewers, etc.)55Parameterization and CalibrationzValues are specified for each model parameterzTrue for PRZM/EXAMS, true for TERRA, true for all models...zInitial parameter values may be selected fromwide ranges (notjust one value)presented in publications and other sourceszUnless demonstrated by comparison to measurements, modelparameterization may not agree with field measurementszCalibration is a refinement of an initial parameterizationzParameter values adjusted so model results agree with datazEnsures a proper balance exists between transport processeszMost important calibrated parameter used in urban scenario isKhbecause values scaled to account for impervious area...October 2011Any Questions?57Extra Slides if Time PermitsSample Hot Spot Analysis58Location of Sites...59Copper EECs: Watershed Outlet60Copper EECs: Gage 461Copper EECs: Gage 662Copper EECs: Gage 763Copper EECs: Gage 864Copper EECs: Gage 1465Copper EEC Probability Distributions66Copper Toxic Unit Probability DistributionsNote: Toxic Unit (TU) = Copper Concentration÷Benchmark