Solubility of BaSO₄ in Standard and Desalinated Seawater

The solubility of BaSO₄ in seawater with a salinity of 0.35–35‰ was experimentally determined. With an increase in salinity from 0.35 to 10‰, the equilibrium concentration of dissolved barium decreases from 42 to 28 μg/L, remains at the level of ~28 μg/L in the salinity range from 10 to 25‰, and increases to 30.7 μg/L at the salinity of 35‰. When the concentration of dissolved barium in the river runoff is higher than 40–45 μg/L, BaSO₄ can precipitate in the mixing zone of river and sea waters, most likely with the participation of living organisms. When the concentration of dissolved barium in the river runoff is below 40–45 μg/L, its additional source in the mixing zone of river and sea waters can be the dissolution of suspended BaSO₄, but presence of the latter in the composition of removed terrigenous material is unlikely and is not detected by direct observations.