Judy Worthington, age 11, of Trumbull, Conn., for her question:

How much salt is in the ocean?

We cannot measure the salt in the entire ocean. But scientists can estimate the total contents from small samples of sea water. They can, for example, estimate the amount of dissolved salts in a cubic mile of average sea water. This is enough water to fill a square tank with walls one mile wide and one mile high one mile high. In this amount of sea water, the staggering amount of dissolved salts is estimated to be about 166 million tons.

Most of the salt dissolved in the sea is sodium chloride, alias ordinary table salt. Through the ages, this and other minerals have been stolen from the land and dumped by rivers into the ocean. The total amount of dissolved salts in the worldwide ocean is estimated to be around 50 quadrillion tons. This is a figure 5 plus a tail of 16 zeros. If all this material were spread on the land, it could cover the continents with a layer of salty chemicals about 500 feet thick. So let's just leave it there in the sea.