Measurements of Oxidants in Ozonized Seawater and Some Biological Reactions

Abstract

Ozonization of seawater oxidizes bromide ion to bromine (hypobromus acid and hypobromite ion) and then to bromate. If seawater is ozonized for more than 60 min, essentially all bromide is converted to bromate. Ozonization of high purity sodium chloride solution did not produce significant oxidants. However, ozonization of sodium bromide solution produced both bromine and bromate. Ozone is unstable in seawater and was undetectable several minutes after the ozonization was completed. Bromate toxicity tests on marine animals indicate the levels of bromate produced by chlorination or ozonization of power plant cooling waters are not acutely toxic. The LC50 ranged from 30 mg/L bromate for Pacific oyster, Crassostrea gigas, larva to several hundred mg/L for fish, shrimp, and clams. Key words: ozone, oxidants, bromate, bromine, seawater, toxicity