Aluminum Sulfate
Some lakes around the country are so clogged with decaying algae that local residents can no longer recreate on or near the lakeshore.
This fall, a few lakes across the Midwest will receive a one-time treatment of aluminum sulfate, or alum, in hopes of containing the excess nutrients that feed the summer algae.
A natural nutrient, phosphorus comes from a variety of sources: dead plants and animals decaying on the lake bottom, runoff from shore properties like lawns and farmland, and from stored phosphorus within the sediment itself. Each summer, shallow lakes become oxygen deficient, which causes phosphorus to leach out from the sediment and into the water.
Aluminum sulfate solves this problem by binding with phosphorus, trapping it at the lake bottom. The strategy has been used across the nation since the early 1980s with few complications. Alum treatment is often used to clarify public drinking water and swimming pools.
The primary environmental concern is the possibility that too much aluminum sulfate can poison fish or cause the water to become unhealthily acidic.
August 4, 2006 8:41 AM | Category: Chemicals