Factors controlling the acidity of natural rainwater

  title={Factors controlling the acidity of natural rainwater},
  author={Robert J. Charlson and Henning Rodhe},
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… 
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Bulk measurements of particulate NO3−, SO3−−, Cl−, and NH4+ were made over continental and marine areas, at altitudes from 0.17 to 7 km, as a part of project Gametag. Above the boundary layer, little