Sulfate and water quality Sulfate and water quality Sulfate is second to bicarbonate as the major anion in hard water reservoirs. When naturally occurring, they are often the result of the breakdown of leaves that fall into a stream, of water passing through rock or soil containing gypsum and other common minerals, or of atmospheric deposition. Point sources include sewage treatment plants and industrial discharges such as tanneries, pulp mills, and textile mills. Runoff from fertilized agricultural lands also contributes sulfates to water bodies.
Sulfur is an essential plant nutrient.
Aquatic organisms utilize sulfur and reduced concentrations have a detrimental effect on algal growth. The most common form of sulfur in well-oxygenated waters is sulfate. On the other hand, sulfate salts can be major contaminants in natural waters. Sulfides formed as a result of acid mine runoff from coal or other mineral extraction and from industrial sources may be oxidized to form sulfates, which are less toxic. Sulfates are not considered toxic to plants or animals at normal concentrations.