Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Relative roles of biogenic emissions and Saharan dust as ice nuclei in the Amazon basin

Abstract

Some aerosol particles, known as ice nuclei, can initiate ice formation in clouds, thereby influencing precipitation, cloud dynamics and the amount of incoming and outgoing solar radiation. In the absence of biomass burning, aerosol mass concentrations in the Amazon basin are low1. Tropical forests emit primary biological particles directly into the atmosphere; secondary organic aerosols form from the emission and oxidation of biogenic gases2. In addition, particles derived from biomass burning in central Africa, marine aerosols, and wind-blown dust from North Africa3,4,5 often reach the central part of the Amazon basin during the wet season. The contribution of these aerosol sources to ice nucleation in the region is uncertain. Here we present observations of the concentration and elemental composition of ice nuclei in the Amazon basin during the wet season. Using transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, we show that ice nuclei are primarily composed of carbonaceous material and dust. We show that biological particles dominate the carbonaceous fraction, whereas import of Saharan dust explains the intermittent appearance of dust-containing nuclei. We conclude that ice-nucleus concentration and abundance can be explained almost entirely by local emissions of biological particles supplemented by import of Saharan dust. Using a simple model, we tentatively suggest that the contribution of local biological particles to ice nucleation is increased at higher atmospheric temperatures, whereas the contribution of dust particles is increased at lower temperatures.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Ice-nucleus number concentrations.
Figure 2: Dust relation to ice-nucleus measurements.
Figure 3: Predicted ice-nucleus number concentrations.

References

  1. Graham, B. et al. Composition and diurnal variability of the natural Amazonian aerosol. J. Geophys. Res. 108, 4765 (2003).

    Google Scholar 

  2. Artaxo, P., Gerab, F., Yamasoe, M. A. & Martins, J. V. Fine mode aerosol composition at three long-term atmospheric monitoring sites in the Amazon basin. J. Geophys. Res. 99, 22857–22868 (1994).

    Article  Google Scholar 

  3. Artaxo, P. & Hansson, H.-C. Size distribution of biogenic aerosol particles from the Amazon Basin. Atmos. Environ. 29, 393–402 (1995).

    Article  Google Scholar 

  4. Formenti, P. et al. Saharan dust in Brazil and Suriname during the large-scale biosphere–atmosphere experiment in Amazonia (LBA)—cooperative LBA regional experiment (CLAIRE) in March 1998. J. Geophys. Res. 106, 14919–14934 (2001).

    Article  Google Scholar 

  5. Swap, R. et al. Saharan dust in the Amazon basin. Tellus B 44, 133–149 (1992).

    Article  Google Scholar 

  6. Chahine, M. T. The hydrological cycle and its influence on climate. Nature 359, 373–380 (1992).

    Article  Google Scholar 

  7. Tomasella, J. et al. The water balance of an Amazonian micro-catchment: The effect of interannual variability of rainfall on hydrological behaviour. Hydrol. Process. 22, 2133–2147 (2008).

    Article  Google Scholar 

  8. Silva Dias, M. A. F. et al. Cloud and rain processes in a biosphere–atmosphere interaction context in the Amazon Region. J. Geophys. Res. 107, 8072 (2002).

    Article  Google Scholar 

  9. Garstang, M. et al. The Amazon boundary-layer experiment (ABLE-2b)—A meteorological perspective. Am. Meteorol. Soc. B 71, 19–32 (1990).

    Article  Google Scholar 

  10. Roberts, G. C. et al. Sensitivity of CCN spectra on chemical and physical properties of aerosol: A case study from the Amazon basin. J. Geophys. Res. 107, 8070 (2002).

    Article  Google Scholar 

  11. Rissler, J. et al. Physical properties of the sub-micrometer aerosol over the Amazon rain forest during the wet-to-dry season transition—comparison of modeled and measured CCN concentrations. Atmos. Chem. Phys. 4, 2119–2143 (2004).

    Article  Google Scholar 

  12. Andreae, M. O. et al. Smoking rain clouds over the Amazon. Science 303, 1337–1342 (2004).

    Article  Google Scholar 

  13. Williams, E. et al. Contrasting convective regimes over the Amazon: Implications for cloud electrification. J. Geophys. Res. 107, 8082 (2002).

    Article  Google Scholar 

  14. Petersen, W. A. & Rutledge, S. A. Regional variability in tropical convection: Observations from TRMM. J. Clim. 14, 3566–3586 (2001).

    Article  Google Scholar 

  15. Zuidema, P. et al. An Arctic springtime mixed-phase cloudy boundary layer observed during SHEBA. J. Atmos. Sci. 62, 160–176 (2005).

    Article  Google Scholar 

  16. Harrington, J. Y. & Olsson, P. Q. On the potential influence of ice nuclei on surface-forced marine stratocumulus cloud dynamics. J. Geophys. Res. 106, 27473–27484 (2001).

    Article  Google Scholar 

  17. Rogers, D. C., DeMott, P. J., Kreidenweis, S. M. & Chen, Y. A continuous-flow diffusion chamber for airborne measurements of ice nuclei. J. Atmos. Ocean. Technol. 18, 725–741 (2001).

    Article  Google Scholar 

  18. DeMott, P. J. et al. Measurements of the concentration and composition of nuclei for cirrus formation. Proc. Natl Acad. Sci. 100, 14655–14660 (2003).

    Article  Google Scholar 

  19. Fletcher, N. H. Physics of Rain Clouds (Cambridge Univ. Press, 1962).

    Google Scholar 

  20. Richardson, M. S. et al. Measurements of heterogeneous ice nuclei in the western United States in springtime and their relation to aerosol characteristics. J. Geophys. Res. 112, D02209 (2007).

    Google Scholar 

  21. Möhler, O. et al. The effect of organic coating on the heterogeneous ice nucleation efficiency of mineral dust aerosols. Environ. Res. Lett. 3, 025007 (2008).

    Article  Google Scholar 

  22. Möhler, O., DeMott, P. J., Vali, G. & Levin, Z. Microbiology and atmospheric processes: The role of biological particles in cloud physics. Biogeosciences 4, 1059–1071 (2007).

    Article  Google Scholar 

  23. Szyrmer, W. & Zawadzki, I. Biogenic and anthropogenic sources of ice-forming nuclei: A review. Am. Meteorol. Soc. B 78, 209–228 (1997).

    Article  Google Scholar 

  24. Bauer, H. et al. The contribution of bacteria and fungal spores to the organic carbon content of cloud water, precipitation and aerosols. Atmos. Res. 64, 109–119 (2002).

    Article  Google Scholar 

  25. Christner, B. C. et al. Ubiquity of biological ice nucleators in snowfall. Science 319, 1214–1214 (2008).

    Article  Google Scholar 

  26. Hairston, P. P., Ho, J. & Quant, F. R. Design of an instrument for real-time detection of bioaerosols using simultaneous measurement of particle aerodynamic size and intrinsic fluorescence. J. Aerosol. Sci. 28, 471–482 (1997).

    Article  Google Scholar 

  27. Ward, P. J. & DeMott, P. J. Preliminary experimental evaluation of SnomaxTM, Pseudomonas syringae, as an artificial ice nucleus for weather modification. J. Weath. Mod. 21, 9–13 (1989).

    Google Scholar 

  28. Zimmermann, F. et al. Ice nucleation properties of the most abundant mineral dust phases. J. Geophys. Res. 113, D23204 (2008).

    Article  Google Scholar 

  29. Ho, J. Future of biological aerosol detection. Anal. Chim. Acta 457, 125–148 (2002).

    Article  Google Scholar 

  30. Fairlie, T. D., Jacob, D. J. & Park, R. J. The impact of transpacific transport of mineral dust in the United States. Atmos. Environ. 41, 1251–1266 (2007).

    Article  Google Scholar 

Download references

Acknowledgements

This work was financially supported by the NASA New Investigator Program, grant NNG04GR44G. S.T.M. acknowledges support received from the US National Science Foundation (ATM-0723582). P.A. acknowledges financial support from the Millennium Institute Program from CNPq. The authors wish to acknowledge R. J. Lee Group for TEM-EDX analysis. The authors also wish to acknowledge the entire AMAZE-08 team, and specifically J. Jimenez, D. Farmer and Q. Chen for their contributions to the AMS data collection and analysis.

Author information

Authors and Affiliations

Authors

Contributions

A.J.P. and M.D.P. carried out ice-nucleus measurements, processed ice-nucleus data and analysed ice-nucleus data in the context of the aerosol measurements. S.M.K. aided in the ice-nucleus analysis and in writing the manuscript. C.L.H. did simulations with GEOS-Chem. S.T.M. served as one of the project organizers of AMAZE-08 and helped with interpretation of AMS data. P.A. served as one of the project organizers of AMAZE-08, made the PIXE measurements and helped with interpretation of PIXE data. R.M.G. carried out the ultraviolet-APS measurements and helped process ultraviolet-APS data. A.G.W. helped process ultraviolet-APS data and helped with interpretation of ultraviolet-APS data. U.P. served as PI for ultraviolet-APS measurements and helped with interpretation of ultraviolet-APS data.

Corresponding author

Correspondence to Anthony J. Prenni.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Prenni, A., Petters, M., Kreidenweis, S. et al. Relative roles of biogenic emissions and Saharan dust as ice nuclei in the Amazon basin. Nature Geosci 2, 402–405 (2009). https://doi.org/10.1038/ngeo517

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/ngeo517

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing