The General Composition of Precipitation

General Controls on Natural Water Chemistry Chap. 8 

The maps in Fig. 8.6(a) and Fig. 8.6(b) show average concentrations of Na and Cl in rain over the contiguous United States for 1994 (NADP/NTN, 1996). The high concentrations along coastlines reflect the contribution of wind-blown salt spray, particularly within 100 to 300 km of the ocean. 

Globally, about half of all atmospheric sulfate is derived from combustion of fossil fuels and half from natural sources (Berner and Bemer 1987). It has been estimated that anthropogenic sources are responsible for 90% of the total atmospheric sulfur deposition in eastern North America, which occurs as dry deposition of SO2 gas and sulfate particles or dissolved in rain. The highest amounts of sulfate and nitrate in U.S. rain, which are found in the northeast [Fig. 8.7(a) and Fig. 8.7(b)], are 

Ion Marine input Terrestrial input Pollutive input 

K Sea salt Biogenic aerosols Soil dust Biomass burning Fertilizer 

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