Sulphate in water
Sodium, potassium, and magnesium sulphates are all readily soluble in water. Calcium sulphates are relatively less soluble than sodium, potassium, and magnesium sulphates, and are slightly more soluble in cold water than warm water, while barium and some other heavy metal sulphates are not (CRC Handbook of Chemistry and Physics, 50th Ed). Dissolved sulphate may be reduced to sulphide, volatilized to the air as hydrogen sulphide, precipitated as insoluble salt or incorporated into living organisms.
Analytical Techniques
Sulphate in aqueous solutions may be determined by ion chromatography using a conductivity detector; the detection limit for this method is about 0.05 mg/L (APHA, 1985).