Interagency Monitoring of Protected Visual Environments (IMPROVE) Data Precision Nicole P. Hyslop and Warren H. White

IMPROVE Collocated (Duplicate) Measurements Established for the first time in Established for the first time in Seven collocated modules of each type. Seven collocated modules of each type. Two objectives Two objectives –Evaluate precision of measurements and –Determine if uncertainty estimates are accurate. Captures uncertainty resulting from sample collection, sample analysis, and data processing. Captures uncertainty resulting from sample collection, sample analysis, and data processing. Does not capture uncertainty resulting from temperature uncertainty or calibration uncertainty. Does not capture uncertainty resulting from temperature uncertainty or calibration uncertainty.

Module Type Site Code Site Name Stat e Start Date A PM 2.5 mass & elements MEVEMesa Verde NPCO8/13/03 PMRF Proctor Maple Research Facility VT9/3/03 OLYMOlympic NPWA11/8/03 PHOEPhoenixAZ3/30/04 SAFOSac and Fox NationKS 11/20/0 3 TRCRTrapper CreekAK6/22/04 SAMASaint MarksFL 11/18/0 4 B PM 2.5 anions LAVOLassen Volcanic NPCA4/18/03 MACAMammoth Cave NPKY5/12/03 BIBEBig Bend NPTX8/30/03 GAMO Gates of the Mountains WA MT9/23/03 FRREFrostburg ReservoirMD4/15/04 BLMO Blue Mounds State Park MN9/16/04 PHOEPhoenixAZ3/30/04 Module Type Site Code Site Name Stat e Start Date C PM 2.5 organic & elemental carbon EVEREverglades NPFL7/11/03 SENESeney NWRMI8/10/03 HOOVHoover WACA8/13/03 MELAMedicine Lake NWRMT9/25/03 PHOEPhoenixAZ3/30/04 SAWESaguaro NP WestAZ3/25/04 HEGLHercules-Glade WAMO9/15/04 D PM 10 mass JOSHJoshua Tree NPCA8/7/03 QUREQuabbin ReservoirMA9/4/03 HOUSHoustonTX4/4/03 JARBJarbridge WANV6/30/04 PHOEPhoenixAZ3/30/04 WICAWind Cave NPSD9/17/04 SWANSwanquarter WANC11/9/04

Uncertainty and Precision in this Presentation Uncertainty refers to the expected variance in outcomes of measurements repeated under the same conditions. Uncertainty refers to the expected variance in outcomes of measurements repeated under the same conditions. Collocated precision refers to the variance of relative differences between the duplicate measurements. Collocated precision refers to the variance of relative differences between the duplicate measurements.

Collocated Sulfur Data

Collocated Selenium Data

Collocated Precision Calculations U.S. EPA designated method (FRM, 1997) U.S. EPA designated method (FRM, 1997) Only use pairs where the average concentration is greater than 3 * MDL. Only use pairs where the average concentration is greater than 3 * MDL.

Estimated Uncertainty for each Concentration An uncertainty estimate is reported with every species concentration. An uncertainty estimate is reported with every species concentration. –Estimates are based on individual sources of measurement uncertainty and propagation of errors.

Why don’t the collocated precisions meet the expectations? Analytical issues Analytical issues –Analysis area –Minimum detectable limits (mdl’s) –Concentrations always close to mdl Sampling discrepancies Sampling discrepancies –Cyclone cutpoint differences –Non-uniform deposits –Deposit area

Copper-anode XRF Element Metrics Species Count > 3*MDL † Estimated Uncertainty Collocated Precision Collocated/ Estimated Na1525%50%2.0 Mg9n < 10 - Al25714%69%5.0 Si53311%41%3.7 P2118%131%7.3 S5775%8%1.6 Cl10512%68%5.6 K5776%13%2.3 Ca5776%19%3.0 Ti52811%30%2.6 V45718%21%1.2 Cr10828%56%2.0 Mn52912%24%2.0 Fe5775%18%3.3 † 577 valid pairs

Sulfur by XRF and Sulfate by IC Species Count > 3*MDL Estimated Uncertainty Collocated Precision Collocated/ Estimated Sulfur577/5775.3%8.2%1.56 Sulfate801/8234.8%4.1%0.86

Soil-derived Elements Species Count > 3*MDL Estimated Uncertainty Collocated Precision Collocated/ Estimated Ca577/5776.2%18.8%3.0 Fe577/5775.5%17.9%3.3

Minimum Detectable Limits (mdl) Species Count > 3*MDL Estimated Uncertainty Collocated Precision Collocated/ Estimated Si533/ %40.5%3.7 Cl105/ %68.4%5.7

Entire networkJanuary - April

Original CriteriaBoth Detected Species No. Pairs Collo / Estimated No. Pairs Collo / Estimated Na Mg Al Si P S Cl K Ca Ti V Cr Mn Fe Original CriteriaBoth Detected Species No. Pairs Collo / Estimated No. Pairs Collo / Estimated PM H Ni Cu Zn As Se Br Rb Sr Zr Pb

Molybdenum-anode XRF Element Metrics Species Count > 3*MDL † Estimated Uncertainty Collocated Precision Collocated/ Estimated Ni22212%32%2.8 Cu49912%30%2.5 Zn5756%25%4.0 As6014%15%1.1 Pb54112%22%1.8 Se40614%15%1.1 Br5767%8%1.2 Rb6424%28%1.2 Sr26611%23%2.1 Zr5n < 10 - † 577 valid pairs

Thermal Optical Carbon Metrics Species Count > 3*MDL † Estimated Uncertainty Collocated Precision Collocated/ Estimated O17233%44%1.3 O230322%18%0.8 O325517%24%1.4 O445617%26%1.5 OP21229%45%1.5 E161416%24%1.5 E221530%37%1.2 E312952%115%2.2 OC39912%17%1.5 LAC24412%22%1.8 TC42411%17%1.5 † 775 valid pairs

Carbon Fraction Analytical Uncertainty, u analytic 2004 Replicate Precision Precision/ Uncertainty OC127%41%1.5 OC216%17%1.1 OC311%19%1.7 OC413%20%1.5 OP27%50%1.9 EC113%24%1.9 EC226%31%1.2 EC340%66%1.7 OC-11%- EC-21%-

Mass, PESA, and Ion Metrics SpeciesCount > 3*MDL Estimated Uncertainty Collocated Precision Collocated/ Estimated PM out of %6.2%0.95 PM out of %8.0%1.63 H577 out of %8.4%1.31 Chloride183 out of %32.5%2.96 Nitrate685 out of %10.4%1.34 Sulfate801 out of %4.1%0.86

Conclusions and Future Work Estimated uncertainties are not accurate for most species Estimated uncertainties are not accurate for most species –Additional sampling-related sources of uncertainty must be considered –Sample deposit uniformity must be measured –Cyclone collection efficiency must be modeled Minimum detectable limits (mdl’s) are too low for several species Minimum detectable limits (mdl’s) are too low for several species –Collocated data will be used to evaluate mdl’s

Species with Decent Agreement between Precision and Uncertainty Species Estimated Uncertainty Collocated Precision Collocated/ Estimated PM 2.5 7%6%1.0 PM 10 5%8%1.6 Na25%50%2.0 S5%8%1.6 V18%21%1.2 Mn12%24%2.0 As14%15%1.1 Pb12%22%1.8 Se14%15%1.1 Br7%9%1.2 Rb24%28%1.2 H6%8%1.3 Nitrate8%10%1.3 Sulfate5%4%0.9 OC133%44%1.3 OC222%18%0.8 OC317%24%1.5 OC417%26%1.5 OP29%45%1.5 EC116%24%1.5 EC231%37%1.2 OC12%17%1.5 EC12%22%1.8 TC11%17%1.5