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SALT LAKE CITY — For those who have seen piles of white, pillowed foam along the shores of the Great Salt Lake and wondered what caused it, the Utah Geological Survey has an answer.
The foam often appears during and after windstorms along the shoreline. Utah Geological Survey biologist J. Wallace Gwynn said the deep foam piles don't appear at fresh-water lakes, leading many to believe that the foam is caused by the salt in the Great Salt Lake.
However, Gwynn said the formation of the foam is caused by surfactants, organic compounds similar to soap, that lower the surface tension of the water.
"Fresh water has a high-surface tension, somewhat like a strong, thin, invisible film on its surface," Gwynn said. "It is this property that allows insects like water skaters to walk on the water or for a needle to be supported if it is carefully placed flat on the water's surface."
Crashing waves also form bubbles in fresh-water lakes, but because the high-surface tension of fresh water prevents the bubble from stretching once it reaches the surface of the water, the bubble immediately pops. Experiments have shown that salt typically causes a higher surface tension than that of fresh water, but the naturally-occurring surfactants in the Great Salt Lake lower the surface tension, Gwynn said.
The surfactants are produced by the abundant phytoplankton algae that live in the Great Salt Lake. The algae produce the organic compounds during their natural metabolic process and when they die. Because the surfactants are part of natural processes that occur in the lake, they aren't considered pollutants, Gwynn said.
