Salted_ A Manifesto on the World's Most Essential Mineral, With Recipes - Mark Bitterman [22]
Solar salt fields in the United States made up about 8 percent of the total U.S. salt production in 2007, but this number doesn’t take into account several of the largest solar salt farms in the world, located just outside the country. Mega salt farms, like Morton’s Inagua salt fields in the Bahamas, produce upward of 2 million tons of solar evaporated salt each year. There are even bigger farms in Mexico, like Exportadora de Sal in Baja California, which can yield up to 7 million tons a year. Still more industrial sea salt is imported from overseas.
To keep production up and costs down, industrial solar evaporation relies on two key processes—pure sodium chloride crystallization and mechanized harvesting. The nutritional potential of the natural salt is disregarded. Industrially produced solar salt is made by evaporating water until the calcium carbonate and other unwanted salts crystallize and precipitate out. The remaining water is transferred to ponds where the sodium chloride is crystallized. Then, at about 75 percent salinity, before any of the magnesium or potassium salts begin to crystallize, all of the remaining dissolved salts are pumped out. The salt crystals are often rinsed in brine to remove any lingering magnesium salts. The resulting salt is about 99.7 percent sodium chloride. For example, California sea salt, manufactured by Cargill in the San Francisco Bay, is 99.83 percent sodium chloride.
Sea salt is harvested by bulldozers that scrape it from the pond beds in 350-ton loads. Thousands of tons are produced in a single day. Industrially produced solar salt sells for about $60 a ton, or about 3 cents a pound. The culinary or dietary benefits that might be gained from capturing calcium, magnesium, and potassium salts and the host of other minerals in the natural source water are not a consideration, because the majority of the product is not meant for the table. Most solar evaporated sodium chloride is used industrially, where chemical purity trumps flavor, crystal structure, and mineral content. However, some of this salt is washed to remove the residue of industrial handling and other environmental pollutants and purified so that it can be marketed as “sea salt.”
Traditional salt makers shift their brine from evaporating ponds to crystallization pans when the concentration reaches about 170 grams of salts per liter of water, and allow it to remain there until some or all potassium and magnesium salt crystallization is complete, thus capturing a much broader swath of the sea’s natural mineral spectrum. It is true, however, that industrialized crystallization and harvesting techniques do not, in theory, have to be used solely to optimize sodium chloride yield. They could also be employed to create salts with a more diverse mineral content.
Industrial salt production can be damaging to the environment. Industrial solar evaporated salt is commonly produced in salt marshes and lakes that are sensitive ecosystems: they are often essential locations on the migratory paths of birds and are the habitat of flora and fauna that are extremely sensitive to changes in the salinity of the water. Coastal salt marshes can play an important role as a storm buffer. Industrial operations generate significant waste, such as highly salinated bittern, which, if released into the surrounding ecosystem, can prove lethal to aquatic life not adapted to high salinity.
Not that industrial salt makers are indifferent to the ecological imbalances created by improperly managed salt making. Scientists believe that not only does a healthy salt pond ecology support native wildlife, it also contributes to the productivity of the crystallizing pans. Bad salt pan ecology can be disastrous. For example, Ghana’s 12,500-acre