The 3.9 × 109 tons carried annually in solution to the oceans are but a small fraction of the total amount of material in solution in the oceans. Nevertheless, when integrated over the whole of geological time, more than 4 × 109 years, it greatly exceeds the present material in solution. Some of the material, especially sodium chloride, is of course cyclical, being circulated from the oceans to the land as aerosols and incorporated in marine sedimentary rocks and ultimately in large part being returned to the oceans in runoff.
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