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.

  • Letter
  • Published:

Factors controlling the acidity of natural rainwater

Abstract

It is often assumed1–4 that the pH of natural rainwater is controlled by the dissociation of dissolved CO2, has a value of 5.6, and that decreases below this are due to the addition of acidic components by human activity. However, decreases could be due to the removal by rainwater of naturally occurring acids from the air (notably H2SO4 in the natural portion of the sulphur cycle). Consideration of the cycling of water and sulphate through the atmosphere and the amount and composition of sulphate aerosol expected to be scavenged by a given amount of cloud water in remote locations indicates that, in the absence of basic materials (such as NH3 and CaCO3), average pH values of 5 are expected to occur in pristine locations. This value must vary considerably due to variability in scavenging efficiencies as well as geographical patchiness of the sulphur, nitrogen and water cycles. Thus, pH values might range from 4.5 to 5.6 due to variability of the sulphur cycle alone. Because of widespread concern regarding the acidification of rain, it is important to understand the factors controlling the pH and composition of natural rainwater. We suggest here that there are integral constraints imposed by (1) the requirement for mass continuity in each elemental cycle and (2) the relative concentrations of soluble species and liquid water in cloudy air; these factors must be mutually consistent.

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

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Similar content being viewed by others

References

  1. Garrels, R. M. & MacKenzie, F. T. Evolution of Sedimentary Rocks (Norton, New York, 1971).

    Google Scholar 

  2. Galloway, J. N. Likens, G. E. & Edgerton, E. S. Science 194, 722–724 (1976).

    Article  ADS  CAS  Google Scholar 

  3. Likens, G. E. & Bormann, F. H. Science 184, 1176–1179 (1974).

    Article  ADS  CAS  Google Scholar 

  4. Likens, G. E. Bormann, F. H. & Johnson, N. M. in Some Perspectives of the Major Biogeochemical Cycles SCOPE Rep. 17 (ed. Likens, G. E.) (Wiley, Chichester, 1981).

    Google Scholar 

  5. Hallberg, R. O. in Nitrogen, Phosphorus and Sulphur–Global Cycles SCOPE Rep. 7, (eds Svensson, B. H. & Söderlund, R.) 93–101 (Swedish Natural Science Research Council, 1976).

    Google Scholar 

  6. Granat, L. in Nitrogen, Phosphorus and Sulphur—Global Cycles SCOPE Rep. 7 (eds Svensson, B. H. and Söderlund, R.) 102–122 (1976).

    Google Scholar 

  7. Nguyen, B. C. Gaudry, A. Bonsang, B. & Lambert, G. Nature 275, 637–639 (1978).

    Article  ADS  Google Scholar 

  8. Hansen, M. H., Ingvorsen, K. & Jørgensen, B. B. Limnol. Oceanogr. 23, 68–76 (1978).

    Article  ADS  CAS  Google Scholar 

  9. Cadle, R. D. J. geophys. Res. 80, 1650–1652 (1975).

    Article  ADS  CAS  Google Scholar 

  10. Friend, J. P. in Chemistry of the Lower Atmosphere (ed. Rasool, S. I.) 177–201 (Plenum, New York, 1973).

    Book  Google Scholar 

  11. Cullis, C. F. & Hirschler, M. M. Atmos. Envir. 14, 1263–1278 (1980).

    Article  CAS  Google Scholar 

  12. Rodhe, H. & Isaksen, I. J. geophys. Res. 85, 7401–7409 (1980).

    Article  ADS  CAS  Google Scholar 

  13. Eriksson, E. Tellus 12, 63–109 (1960).

    Article  ADS  Google Scholar 

  14. Rodhe, H. Atmos. Envir. 12, 671–680 (1978).

    Article  CAS  Google Scholar 

  15. Rodhe, H. in Nitrogen, Phosphorus and Sulphur—Global Cycles SCOPE Rep. 7 (eds Svensson, B. H. & Söderlund, R.) 123–128 (Swedish Natural Science Research Council, 1976).

    Google Scholar 

  16. Galloway, J. N. & Whelpdale, D. M. Atmos. Envir. 14, 409–418 (1980).

    Article  CAS  Google Scholar 

  17. Taylor, G. S. Baker, M. B. & Charlson, R. J. in Interaction of the Biogeochemical Cycles (eds Bolin, B. & Cook, R.) (Wiley, London, 1982).

    Google Scholar 

  18. Duce, R. A. Biogeochemical Cycles and the Air/Sea Exchange of Aerosols (Wiley, London, 1982).

    Google Scholar 

  19. Sillén, L. G. in Equilibrium Concepts in Natural Water Systems Adv. Chem. Ser. no. 67, 45–56 (American Chemical Society, Washington DC, 1967).

    Book  Google Scholar 

  20. Junge, C. E. Air Chemistry and Radioactivity (Academic, New York, 1963).

    Google Scholar 

  21. OECD. The OECD Programme on Long Range Transport of Air Pollutants, Measurements and Findings (Organization for Economic Cooperation and Development, Paris, 1977).

  22. Fletcher, N. H. The Physics of Rain Clouds (Cambridge University Press, 1962).

    Google Scholar 

  23. Slinn, W. G. N. et al. Atmos. Envir. 12, 2055–2087 (1978).

    Article  CAS  Google Scholar 

  24. Scott, B. C. J. appl. Met. 20, 619–625 (1981).

    Article  ADS  CAS  Google Scholar 

  25. Maroulis, P. J. Torres, A. L. Goldberg, A. B. & Bandy, A. R. J. geophys. Res. 85, 7345–7349 (1980).

    Article  ADS  CAS  Google Scholar 

  26. Garland, J. A. Q. J. R. met. Soc. 97, 483 (1971).

    Article  ADS  Google Scholar 

  27. Lawson, D. R. & Winchester, J. W. Science 205, 1267–1269 (1979).

    Article  ADS  CAS  Google Scholar 

  28. Huebert, B. J. & Lazrus, A. L. J. geophys. Res. 85, 7337–7344 (1980).

    Article  ADS  CAS  Google Scholar 

  29. Bonsang, B. Nguyen, B. C. Gaudry, A. & Lambert, G. J. geophys. Res. 85, 7410–7416 (1980).

    Article  ADS  CAS  Google Scholar 

  30. Bolin, B. et al. Air Pollution Across National Boundaries ; The Impact on the Environment of Sulfur in Air and Precipitation (Royal Ministry for Foreign Affiairs, Stockholm, 1971).

    Google Scholar 

  31. Drabløs, D. & Tollan, A. Ecological Impact of Acid Precipitation; Proceedings of an International Conference (SNSF, Ås, Norway, 1980).

    Google Scholar 

  32. Granat, L. Atmos. Envir. 12, 413–424 (1978).

    Article  CAS  Google Scholar 

  33. NOAA. Geophysical Monitoring for Climatic Change No. 7 (National Oceanic and Atmospheric Administration, Boulder, Colorado, 1979).

  34. Kerr, R. A. Science 212, 1014 (1981).

    Article  ADS  CAS  Google Scholar 

  35. Larsen, T. V. & Harrison, H. Atmos. Envir. 11, 1133–1141 (1977).

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

About this article

Cite this article

Charlson, R., Rodhe, H. Factors controlling the acidity of natural rainwater. Nature 295, 683–685 (1982). https://doi.org/10.1038/295683a0

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/295683a0

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

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