Measuring Total Reactive N and its Composition Bret A. Schichtel 1, Katie Benedict 2, Christian M. Carrico 2, Anthony Prenni 2, Jr. 2, Ezra Levin 2, Derek Day 3, Doris Chen 2, John Ray 1, William C. Malm 3, Jeffrey L. Collett 2, Sonia M. Kreidenweis 2 1 National Park Service, CSU/CIRA, Fort Collins, Colorado 80523 2 Department of Atmospheric Science, Colorado State University 3 Cooperative Institute for Research in the Atmosphere (CIRA), CSU
Measuring Total Chemically Reactive N TCRN = NOy + NHx (Oxidized) (Reduced) NOy NO + NO 2 + NO 3 + 2xN 2 O 5 + HNO 3 + HONO + HO 2 NO 2 + R-ONO 2 (organic nitrates such as PAN and alkyl nitrates) + R-ONO (organic nitrites) + NO 3 - (particulate nitrate). NHx = NH 3 + NH 4 + amines (R-NHx) other reduced organic molecules Everything but N 2 O and N 2
Reactive N Measurement Needs Ecosystem health Total reactive N deposition at weekly-monthly scales Assess critical loads (target loads?) Track status and trends of Nr inputs to ecosystems Reactive N Management Speciated organic and inorganic Nr deposition with 24-h or less duration Attribution of each species to its emission source (control measures) Assessment of other effects: SOx/NOx NAAQS, ozone, visibility, human health,
Current Monitoring Networks Issues Important species are not measured Accuracy with which some species are measured Time scale of measurement (weekly is long for source attribution, models) Spatial representation of CASTNET is poor network distribution is uneven deposition data can t be spatially interpolated Deposition is not measured but estimated and only at one location
Species of interest Measured Dry: HNO 3, particle NO 3 and NH 4 Wet: NO 3-, NH 4 + Missing Dry Species NH 3 NO x (NO and NO 2 ) Reduced organic gases (Aliphatic amines..) Oxidized organic gases (PAN - alkyl nitrates ) Reduced and oxidized organic nitrogen containing particulates Wet Species Oxidized and reduced organic compounds All occult deposition
Why the Missing Components Matter Dry Deposition (Spring) ON (estimated) 10% NOx NH3 4% Total Deposition Budget (Spring) Dry 9% 1% 3%? Wet Wet ON 20% Measured NO3 4% NH4 12% NH3 37% NH3 NOx ON Gas/particles NO3 NH4 HNO3 7% Wet NH4 Wet NO3 20% ON Gas/particles (estimated) 34% Missing 26% NOx 13% ROMANS data
Total Water Soluble Particulate Organic nitrogen WSON = TN (NO 2 + NO 3 + NH 4+ ) Total water soluble N Shimadzu TOC V CSH total organic carbon analyzer with a total nitrogen module NO 2, NO 3, NH 4 + ion chromatography Individual organic nitrogen compounds Liquid Chromatography with Time of Flight Mass Spectrometry using electrospray ionization PM2.5 Hivol samplers Benedict et al., 2011
Total Water Soluble Particulate Organic N and Biomass Burning Markers at ROMO Benedict et al., 2011
Teledyne NH3 Chemiluminescent Analyzer NH3 = TNx Nox: TNx contains reduced organic and other compounds
Teledyne Instrument Sensitivity to Non-NH3 Gas Species (Permeation Tube Lab Tests) Acetaldehyde Acetonitrile 1 Acetonitrile 2 Alpha-Pinene Isoprene Methylamine 1 Methylamine 2 Methylamine 3 Fractional Sensitivity of Instrument* Importance Chemiluminescence Ion Mobility Cavity Ring Down Biogenic Chemiluminescent Compound [Marley and Biomass Burning Emissions [Yokelson et al., 2009] Biogenic Emissions (Coniferous) Biogenic Emissions (Deciduous) Primary Amine Ammonia-like, Particle and Gas phase [Ge et al., 2011] 0.4% 0.1% -0.1% 77.6% 0.2% 1.1% 63.1% 0.0% -0.2% 0.9% 0.0% -0.1% 3.5% 0.2% 0.9% 69.2% 77.0% 5.5% 74.2% 84.8% 3.2% 86.8% 84.9% 5.6% *using a 67 ppb input concentration generated with a permeation tube Sensitivity: Negligible Slight High
Ambient Urban Air with NH 3 Denuder In-line 8 7 6 Chemiluminescence Cavity Ring Down Ion Mobility NH 3 Concentration (ppb) 5 4 3 2 Zero Air TNx NOy NH 3 1 0 0:00 6:00 12:00 18:00 0:00-1 Chemiluminescence clearly has some non-nh 3 interferences
Boulder, CO Smoke Impacts Smoke Impact Total gaseous reduced N + Artifacts Estimate of Reduced Organic N Gas
Reduced N at Targhee, WY (Grand Teton) - 1 hr avg Smoke event NH 3 Reduced organic N
Ammonia + CO (1 hr avg)
Modified IMPROVE Samplers to Collect Reduced Nitrogen Phosphoric acid impregnated cellulose backup filter to collect NH 3 and volatilized NH 3 from nylasorb filters Acid impregnated cellulose front filter to collect NH 3 + NH + 4 and other gases e.g. methylamine IMPROVE samplers collects 24-h samples Filters analyzed for NH + 4 and methylamine by ion chromatography
Measurement Quality Good agreement vs. URG denuder + filterpack Good precision
IMPROVE NHx and Methylamine Monitoring Sites June 2011-June 2012 Using IMPROVE infrastructure: Site operators, RTI performing IC analysis CSU (Collett et al.,) is coordinating monitoring, QA/QC, data reduction, filter prep
A first look: monthly average NHx (1-in-3 day sampling) Pilot IMPROVE NH x network 2011 Obs Seasonal cycle apparent at all sites Highest concentrations at eastern and southern sites NH 4+ from IMPROVE Module B filter will help constrain gas/particle split
Missing Nr Components Measurements Routine or semi-routine methods to measure Total wet organic N Dry NH 3 Soluble particulate organic N NO / NO2 / gaseous oxidized organic N Research Oxidized and reduced wet organic N Reduced gas and particle organic N ON marker species useable in receptor models
Some Possible Next Steps Determine which of the non-measured N species contribute significantly to Nr deposition Develop the tools to measure these compounds suitable for routine monitoring in remote locations Assess where these N species come from and if appropriate develop emission control strategies