Solubility of BaSO₄ in Standard and Desalinated Seawater

Abstract—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 a salinity of 35‰. When the concentration of dissolved barium in river runoff is higher than 40–45 μg/L, BaSO₄ can precipitate in the river–seawater mixing zone, most likely with the participation of living organisms. When the concentration of dissolved barium in river runoff is below 40–45 μg/L, an additional source in the river–seawater mixing zone can be dissolution of suspended BaSO₄, but the presence of the latter in the composition of eroded terrigenous material is unlikely and has not been detected by direct observations.