Natural dust and acid rain

Atmospheric dust originates from three sources: terrestrial airborne matter, volcanic, and cosmic. Terrestrial natural dust makes up the main bulk reflecting the soil composition to 150 mi away. Soil erosion from flood plains, plowed fields and construction sites is the main source. Quartz, feldspar, the carbonates calcite and dolomite, and clay minerals are the components in decreasing order of frequency. Natural dust in the atmosphere interacts with rainwater converting the carbonates to benign gypsum (CaSO₄.2H₂0). Naturally leached soils produce less calcite than unweathered sediments on flood plains and construction sites, and in granitic and crystalline rocks less than in limestone areas. Heavy industrialization associated with high emission of C0₂ and S0₂ on the one hand, and excess production of dust on the other appears to counteract man's interference with natural ecosystems in the opposite direction.