Sulfates
Sulfates
There are a variety of diverse sources for sulfates in waterbodies. Sulfate concentrations in a waterbody are influenced primarily by natural deposits of minerals and organic matter in its watershed. Sulfate is also widely used in industry and agriculture, and many wastewaters contain high concentrations of sulfate. Acidic rainfall (containing sulfuric acid) is a major source of sulfate in some waterbodies.
The primary source of sulfate in rain in industrialized areas is through atmospheric discharges from power plants that burn sulfur-containing fuels and from certain industries.
The primary source of sulfate in rain in non-industrialized areas is through atmospherically oxidized hydrogen sulfide (the chemical symbol for hydrogen sulfide is H2S) which is produced along coastal regions by anaerobic bacteria. Volcanic emissions also contribute sulfur to the atmosphere.
The Role of Sulfur in Waterbodies
Sulfate is used by all aquatic organisms for building proteins. Sulfur changes from one form to
another (known as cycling) in quite complex ways. Sulfur cycling can influence the cycles
of other nutrients like iron and phosphorus and can also affect the biological productivity and the
distribution of organisms in a waterbody.
Bacteria can significantly influence the sulfur cycle in water. For example, under conditions where dissolved oxygen is lacking, certain bacteria can convert sulfate to hydrogen sulfide gas (H2S). Hydrogen sulfide gas has a distinctive rotten egg smell, and in high concentrations can be toxic to aquatic animals and fish.
In Florida
Waterbodies in the Florida LAKEWATCH database have sulfate
concentrations which range from 0 to about 500 mg/L. Over 75% of
these waterbodies had concentrations of sulfates less than 20mg/L.
Health Concerns
Sulfates pose no known direct threat to human health. In some Florida lakes, the decomposition
of large deposits of organic matter along the shorelines will cause the formation of pockets of
hydrogen sulfide gas in the bottom sediments. On the rare occasion when people step into these
pockets, they can experience a burning sensation on their skin. Florida natives may refer to these
sediments as "hot mud".
The information on this page was derived in part from the following
publication of
Florida Lakewatch of the University of Florida Department of
Fisheries and Aquatic Sciences.
This booklet may be downloaded in its entirety as a PDF file
by clicking here.
Scroll down till you see the Circular 101 icon.
A collaboration of the Center for Aquatic and Invasive Plants, University of Florida, and the Invasive Plant Management Section of the Florida Fish and Wildlife Conservation Commission.
