Understanding Sulfate: Impacts on Water & Health
Sulfate: Understanding Its Presence and Effects
The sulfate ion (SO42-) is one of the major anions found in natural waters. Most sulfates are soluble in water, except for lead sulfate, barium sulfate, and strontium sulfate. Sulfate has various commercial applications, including in metallurgical industries as a reagent, and in the manufacturing of products like copper sulfate, which is used as a fungicide and algaecide. Sulfate also occurs naturally in soil, sediments, and rocks. Sulfates are discharged into surface waters via dust from coal and metallurgical processes.
Sulfate’s Role in the Environment
Characteristics: Sulfates are present in natural waters at varying concentrations. Monitoring sulfate levels in drinking water is crucial for maintaining a pleasant taste. It is also important in beer production for organoleptic quality. However, sulfate ions can contribute to the corrosion of high-pressure boilers, electrical pipes, and heat exchangers. Therefore, the concentration of these ions is usually controlled below a certain level in water used for electricity production.
Health Effects of Sulfate
How does sulfate affect health? The primary health effect observed after ingesting sulfate is a laxative action. The associated cation influences this effect; the sulfate anion seems to have some impact on the salt’s laxative potency. For instance, calcium sulfate is much less potent than magnesium sulfate or sodium sulfate, due to the nature of the cations themselves.
The mechanism by which sulfate ions induce laxative effects is complex and not fully understood.
Can sulfate harm animals? Animals are also sensitive to high sulfate levels. In young animals, high levels may be associated with chronic, severe diarrhea, and in some cases, death. Like humans, animals tend to become accustomed to sulfate over time. Diluting water with high sulfate concentrations with water containing lower concentrations can help avoid diarrhea and dehydration in young animals and those unaccustomed to high-sulfate water.
Sulfate in Groundwater
How does sulfate get into groundwater? As water moves through rock formations and soils containing sulfide minerals, some of the sulfate dissolves into the groundwater. Sulfate-containing minerals include magnesium sulfate (Epsom salt), sodium sulfate (Glauber’s salt), and calcium sulfate (gypsum).
Other Potential Problems Caused by Sulfate
Can sulfate cause other issues? If the sulfate concentration in water exceeds 250 mg/L, a bitter or medicinal taste can make the water unpleasant to drink.
High sulfate levels can also corrode plumbing, particularly copper pipes. In areas with high sulfate levels, corrosion-resistant materials, such as plastic pipes, are commonly used.
Health Risks for Humans
Are there health risks for humans drinking water containing sulfates? People unaccustomed to drinking water with high sulfate levels may experience diarrhea and dehydration. Children are often more sensitive to sulfate than adults. As a precaution, water with a sulfate level exceeding 400 mg/L should not be used to prepare food for children. Older children and adults typically become accustomed to high sulfate levels after a few days.
Sulfate Removal from Water
How can sulfate be removed from water? Three types of treatment systems are effective in removing sulfate from drinking water: reverse osmosis, distillation, and ion exchange. Water softeners, carbon filters, and sediment filters do not remove sulfate. Water softeners merely convert calcium sulfate or magnesium sulfate to sodium sulfate, which has a stronger laxative effect.