Readme file for the final hydrocarbon datasets, Blodgett Forest 1999, ponderosa pine plantation by Gunnar Schade and Allen Goldstein University of California at Berkeley Department of Environmental Science, Policy and Management Ecosystem Science Division 250 Hilgard Hall Berkeley, CA 94720-3110 ph.: 1-510-643-2451 Fax: 1-510-643-5098 e-mail: ahg@nature.Berkeley.edu These data sets and measurement methods are fully described in the following publications: Goldstein, A.H., G.W. Schade, G. Dreyfus, Whole Ecosystem Measurements of Biogenic Hydrocarbon Emissions, Final Report, State of California Air Resources Board Award No. 98-328, 85 pages, 2001. (available at: http://www.cnr.berkeley.edu/~ahg) Schade, G.W. and A.H. Goldstein, Fluxes of oxygenated volatile organic compounds from a ponderosa pine plantation, J. Geophys. Res., Vol. 106, No. D3, 3111, 2001. Schade, G.W. and A.H. Goldstein, Plant physiological influences on the fluxes of oxygenated volatile organic compounds from ponderosa pine trees, J. Geophys. Research, Vol. 107, No. D10, 2002. Dreyfus, G.B., G.W. Schade, and A.H. Goldstein, Observational constraints on the contribution of isoprene oxidation to ozone production on the western slope of the Sierra Nevada, CA, J. Geophys. Research, 107, D19, 4365, 10.1029/2001JD001490, 2002. Goldstein, A.H., and G.W. Schade, Quantifying biogenic and anthropogenic contributions to acetone mixing ratios in a rural environment, Atmospheric Environment, 34, 29-30, 4997-5006, 2000. --------------------- I. Data set hc99_v1: General: This data set contains mixing ratios of biogenic and anthropogenic volatile organic compounds measured between July 6 and September 8, 1999. All values are reported in ppb. All compounds have been identified by retention time compared to addition of standards to real air samples. It is still possible that co-elutions of other unidentified compounds could affect the reported mixing ratios or fluxes. Calibration was carried out against one or more diluted ppm-Standards as described in the text and below. All mixing ratio data are from “up-drafts”. Some very high and very low mixing ratios that were identified as outliers have been set "NA". All samples that contain standard additions have been set “NA”. The microtraps were changed once during the measurement period. Chromatographic columns (Rtx-Wax columns, 60 m, wide-bore: 0.53 mm ID) were cut when necessary to remove degraded parts. Note: All chromatograms have been integrated manually for proper identification and quantification. A small amount of human error, however, is of course unavoidable. Zero mixing ratios were not set "NA". Compound description (numbering refers to column number): (Calibration Standard(s) used for identification and quantification is(are) given in parentheses behind compound name) 0. "time": Day of year + decimal day fraction. Note that the time line is NOT based on local summer time (PDT), but on local standard time (Pacific Standard Time = PST); value is centered on the full hour. 1. "hour": Hour of measurement during that day in decimals; value is centered at 15 min after the full hour, the middle of the actual sampling interval. Isoprene and its oxidation products: 2. "isoprene" (S1, OVOC): C5H8, biogenic VOC; among the most precisely measured compounds; stable response throughout the whole data set. 3. "MVK": Methyl-vinyl-ketone, C4H6O, major isoprene oxidation product; a small blank interference was removed from the MVK data throughout the data set, however, comparing the nighttime mixing ratios to 1998 data, we have to assume that this minor interference was not stable but may have introduced a positive bias into the nighttime MVK data, which we were unable to identify; the compound is not calibrated with an external standard, but its FID- response is assumed to equal that of MACR (see next). 4. "MACR" (S1, OVOC, BPIN): Methacrolein, C4H6O, major isoprene oxidation product; among the most precisely measured compounds throughout the data set. Note: The theoretical response factor based on the relative FID response of MACR versus isoprene was used for calibration rather than the actually measured response factors according to our standard (would have been 20% higher). 5. separation vector. Oxygenated VOCs: 6. "methanol" (OVOC): CH3OH, most abundant VOC; has both biogenic and anthropogenic sources and long atmospheric lifetime; mixing ratios should be viewed with some caution, as they are empirically corrected for the coeluting compounds methyl-ethyl-ketone, and 3-methyl-furan; varying occurrence in blank samples. 7. "ethanol" (OVOC): C2H5OH, partially coeluting with benzene; mixing ratios may slightly overestimate actual abundance; sources are dominantly biogenic; small and varying occurrence in blank samples. 8. "acetaldehyde" (OVOC): CH3CHO, most abundant alkanal measured; has anthropogenic and biogenic sources; mixing ratios might be overestimating actual abundance due to a minor coelution with an unknown compound; small and varying occurrence in blank samples. 9. "acetone" (S1, OVOC): (CH3)2CO, most abundant ketone measured; among the most precisely measured compounds; very long atmospheric lifetime; major MBO oxidation product; no known chromatographic interferences. 10. "MBO" (MBO, BPIN): Methylbutenol, C5H9OH, dominant local emission compound from ponderosa pine; most abundant reactive hydrocarbon. 11. separation vector. Monoterpenes: 12. "a-pinene" (S1, S2): ?-pinene, C10H16, monoterpene; emitted from ponderosa pine and other trees in the area; no known chromatographic interferences. 13. "b-pinene" (BPIN): ?-pinene, C10H16, monoterpene; emitted mostly from ponderosa pine in the area; no known chromatographic interferences; ?-pinene shows issues of instability and conversion (often into another monoterpene) presumably during desorption from the microtraps, wherefore the given mixing ratios may partially be underestimates. 14. "3-carene" (S2): ?-3-carene, C10H16, monoterpene; emitted mostly from ponderosa pine in the area; no known chromatographic interferences; ?-3-carene shows issues of breakthrough at higher mixing ratios, wherefore the given mixing ratios may partially be underestimates, and obvious outliers have been removed from the data set. 15. separation vector Anthropogenic VOCs: 16. "MTBE": Methyl-tertiary-butyl-ether, C5H12O; only quantified VOC of unequivocally solely anthropogenic origin; retention time identified with authentic standard; its FID response was estimated theoretically from comparison with isoprene; mixing ratios should be viewed with some caution due to incomplete separation from another, smaller anthropogenic compound, and acetaldehyde. 17. "toluene" (BPIN): anthropogenic, aromatic hydrocarbon, C7H8; occasional, very small blank sample; no known chromatographic interferences; no indication of biogenic sources as suggested by other authors. Standards (manufacturer's accuracy in parenthesis): S1 (Scott-Marrin): acetaldehyde (?5%), MACR (?10%), heptane (?2%), ?-pinene (?2%), acetone (?2%), isoprene (?2%) balance: nitrogen S2 (Scott-Marrin): heptane, ?-3-carene, ?-pinene, d-limonene (unanalyzed Standard; ?-pinene and heptane are consistent with S1). balance: nitrogen MBO (Scott-Marrin): 2-methyl-3-buten-2-ol (?2%) balance: nitrogen OVOC (Scott-Marrin; mixing ratios assigned by NCAR and highly uncertain for the aldehydes and alcohols): butane, isoprene, acetaldehyde, acetone, butanal, MACR, MEK, methanol, benzene, ethanol, pentanal, 2-pentanone, hexanal, n-butanol balance: nitrogen BPIN (Scott Marrin): ?-pinene (?2%), MACR (?2%), MBO (?2%), toluene (?2%), 3-methyl-furan(?2%) balance: nitrogen II. Data set f_hc99_v1: General: This data set contains the fluxes of biogenic volatile organic compounds as calculated from equation 3, for the time period between July 6 and September 8, 1999. All flux values are reported in mg C m-2 hr-1 (carbon mass units). See text for details on calculation and error estimates. All fluxes have been scrutinized for outliers. Negative fluxes were not removed from the data set. Fluxes for MACR are not defined due to its use as channel intercomparison compound. Fluxes of isoprene and MVK were clearly within the error limits of detection, and the data suggest that, if MVK were deposited, its average deposition velocity would most probably be smaller than 0.5 cm s-1, and likely smaller than 0.3 cm s-1. Compound description: 0. "time": same as described under I. 1. "hour": same as described under I. Oxygenated VOCs: 2. "methanol": CH3OH, data should be viewed with some caution due to the corrections applied to the mixing ratios; emissions seem to be temperature and light-driven. 3. "ethanol": C2H5OH; emissions appear to be mostly temperature-driven. 4. "acetaldehyde": CH3CHO; emissions appear to be mostly temperature-driven. 5. "acetone": (CH3)2CO; emissions appear to be mostly temperature-driven. 6. "MBO": Methylbutenol, C5H9OH; emissions are temperature- and light-driven. 7. separation vector. Monoterpenes: 8. "a-pinene": ?-pinene, C10H16; emissions are mostly temperature-driven. 9. "b-pinene": ?-pinene, C10H16; emissions are mostly temperature-driven; data after day 214 have been removed due to possible losses on one chromatographic channel that lead to an offset which could not be corrected for; mean flux data reported in Table 1 refer to a shorter and warmer time period and can therefore not directly be compared to the ?-pinene and ?-3-pinene data without restricting these to the same time period. 10. "3-carene": ?-3-carene, C10H16; emissions are mostly temperature-driven; data between days 217 and day 233 have been removed due to losses in the chromatographic channels; mean flux data reported in Table 1 refer to shorter and warmer time periods and can therefore not directly be compared to the ?-pinene or ?-pinene data without restricting ?-3-carene to the data availability of ?-pinene. III. Data set met_hc99_v1: General: This data set contains meteorological data useful to interpret the VOC data sets. Compound description: 0. time: as described under I. 1. hour: as described under I. 2. wind speed: reported in m s-1, measured at ~6 m above the average tree height. 3. wind direction: reported in degrees, measured at ~6 m above the average tree height. 4. PAR: photosynthetically active radiation in µmol m-2 s-1; measured at approximately 6 m above the average tree height. 5. rH: relative humidity in percent: measured at the average tree height. 6. Tair: air temperature in degrees Celsius: measured at the average tree height. 7. pressure: ambient pressure in mbar measured at the average tree height. 8. ozone: ambient mixing ratio in ppb, measured ~6 m above the average tree height. New Version of 1999 data sets. Berkeley, CA, July 19, 2001 Notes on version 2 of the hydrocarbon data set and acompanying meteorology data set for Blodgett Forest hc99.2 met.hc99.2 The following changes have been made to the first version, hc99.1 : 1. Data from June 1999 from a DB-624 column were attached to the data set. 2. Data from the first days in July 1999 from a Rtx-WAX column were also attached. 3. Version 2 now contains the correct mixing ratio vector for MTBE. Due to a processing error version 1 contained a slightly different vector. 4. A varying Blank (0-20 ppt) has been substracted from the toluene data. If any toluene mixing ratio decreased below 0 ppb due to this procedure, the respective value was set "NA". The following changes have been made to the first version of the meteorology data set, met.hc99.1 : 1. Data from June 1999 were attached to the data set. 2. Data from the first days in July 1999 were also attached. signed, Gunnar Schade