Research ArticleATMOSPHERIC SCIENCE

Multicomponent new particle formation from sulfuric acid, ammonia, and biogenic vapors

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Science Advances  12 Dec 2018:
Vol. 4, no. 12, eaau5363
DOI: 10.1126/sciadv.aau5363
  • Fig. 1 The effect of adding different vapors on biogenic nucleation rates (J1.7).

    All points have similar MT (530 to 590 pptv) and ozone (40 ppbv) mixing ratios. The leftmost points were measured with only MTs added to the chamber, and each step to the right represents addition of one more component to the system. Solid arrows describe the addition of ca. 1 ppbv of SO2 (resulting in an H2SO4 concentration of 1 × 107 to 2 × 107 cm−3), dashed arrows describe the addition of ca. 0.7 ppbv of NOx, and dotted arrows describe the addition of ca. 180 pptv of NH3. Circles are experiments at neutral conditions (N), and diamonds are experiments at GCR conditions. Colors of the symbols indicate the measured MT mixing ratio. The error bars describe the uncertainty in the nucleation rates, which was calculated similar to earlier CLOUD publications, taking into account both the systematic and statistical errors and run-to-run repeatability (see Supplementary Materials and Methods). See fig. S1 for the formation rate of 2.5-nm particles.

  • Fig. 2 Relation of nucleation rates to different HOM categories.

    Nucleation rates (J1.7) as a function of the (A) total concentration of HOMs [regardless whether the molecule has nitrate group(s) or not], (B) non-nitrate HOMs, (C) nitrate HOMs (ONs), and (D) non-nitrate HOM dimers. Open circles refer to neutral experiments, closed diamonds refer to GCR experiments, and the color refers to the H2SO4 concentration (blue points were measured without added SO2). All points were measured at 278 K and 38% RH, with varying MT concentrations (100 to 1500 pptv) and NOx levels (0 to 5 ppbv; NO/NO2, about 0.6%) without added NH3.

  • Fig. 3 Nucleation and GRs at CLOUD compared to atmospheric observations in Hyytiälä.

    Here, we chose a series of experiments with constant MT/NOx ratio (ca. 0.6, NO/NO2 = 7%), while H2SO4 and NH3 concentrations were varied across the range relevant for boreal forest. (A) Nucleation rates (J1.7) at CLOUD (colored points) and ambient observations in Hyytiälä (5, 8) (gray circles). The blue and cyan lines represent binary (H2SO4-H2O) and ternary (H2SO4-H2O-NH3, 7 < [NH3] < 40 pptv) nucleation, respectively, based on earlier CLOUD data (21), while the pure biogenic nucleation rate at similar MT/NOx ratio would be <1 cm−3 s−1 (fig. S3). (B) GRs of 1.8- to 3.2-nm-sized and 3.2- to 8-nm-sized particles in the same experiments compared to observations of initial GR in Hyytiälä (40).

  • Fig. 4 Nucleation rates (J1.7) as a function of the product of the concentrations of H2SO4, NH3, and non-nitrate HOM dimers.

    Circles refer to neutral experiments, diamonds refer to GCR experiments, and the color refers to the NH3 concentration. All points here were measured at 278 K and 38% RH. The MT mixing ratio was varied between 100 and 1200 pptv, H2SO4 concentration between 5 × 106 and 6 × 107 cm−3, NH3 between 2 and 3000 pptv, and NOx between 0.7 and 2.1 ppbv (NO/NO2 = 0.6%). The dashed line gives the maximum rate from ion-induced nucleation based on the ion pair production rate in CLOUD under GCR conditions (15). The solid line is the multicomponent parametrization for neutral experiments based on Eq. 1 with k = 7.4 × 10−23 s−1 pptv−1 cm6.

  • Fig. 5 Negative ions and ion clusters detected during multicomponent NPF in the CLOUD chamber and in Hyytiälä.

    The mass defect shows the difference between nominal and exact mass of the ions detected with the negative atmospheric pressure interface–time-of-flight mass spectrometer. (A). Data from the CLOUD chamber, averaged over several experiments (the orange and red points in Fig. 3) with H2SO4 (1 × 106 to 1 × 107 cm−3), NOx (1 ppb), and NH3 (200 to 500 pptv). (B) Data from Hyytiälä during an NPF event on 5 April 2012. The colored symbols indicate the identified ions: pure sulfuric acid and S-O–based clusters (red), sulfuric acid–ammonia clusters (cyan), HOMs clustered with NO3 (dark green), ONs clustered with NO3 (light green), HOMs clustered with HSO4 (light brown), and ON clustered with HSO4 (dark brown). The symbol size corresponds to the relative signal intensity on a logarithmic scale. The pie charts give the fraction of all identified peaks, excluding the pure S-O–based peaks.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/12/eaau5363/DC1

    Supplementary Materials and Methods

    Fig. S1. The effect of different additional vapors on the NPF rates (J2.5).

    Fig. S2. The effect of different additional vapors on the biogenic nucleation rate (J1.7) at different NOx concentrations.

    Fig. S3. Nucleation rates (J1.7) as a function of the MT to NOx ratio (MT/NOx).

    Fig. S4. Nucleation rates (J1.7) as a function of NH3 mixing ratio.

    Fig. S5. Modeled versus measured nucleation rates.

    Fig. S6. Modeled versus measured GRs.

    Fig. S7. Positive ions and ion clusters detected during multicomponent NPF in the CLOUD chamber.

    Fig. S8. Global annual mean concentrations of vapors involved in NPF.

    Table S1. Pearson’s correlation coefficient (R) between J1.7 and the concentration of different precursors in the chamber.

    References (4156)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Materials and Methods
    • Fig. S1. The effect of different additional vapors on the NPF rates (J2.5).
    • Fig. S2. The effect of different additional vapors on the biogenic nucleation rate (J1.7) at different NOx concentrations.
    • Fig. S3. Nucleation rates (J1.7) as a function of the MT to NOx ratio (MT/NOx).
    • Fig. S4. Nucleation rates (J1.7) as a function of NH3 mixing ratio.
    • Fig. S5. Modeled versus measured nucleation rates.
    • Fig. S6. Modeled versus measured GRs.
    • Fig. S7. Positive ions and ion clusters detected during multicomponent NPF in the CLOUD chamber.
    • Fig. S8. Global annual mean concentrations of vapors involved in NPF.
    • Table S1. Pearson’s correlation coefficient (R) between J1.7 and the concentration of different precursors in the chamber.
    • References (4156)

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