Research Product

This research program was initiated to determine the chemical and biological effects of ozone in estuarine systems and to evaluate its suitability as an alternative to chlorine. Chemical studies were performed to determine oxidant decay rates and bromate formation in both natural and artificial estuarine water. Ozonation of estuarine or marine waters can produce significant amounts of bromate if the natural levels of ammonia-nitrogen and other competing compounds are low and the initial residual oxidant and bromide concentrations are high. Toxicity studies showed that the concentrations of bromate which theoretically could be formed in an ozonated discharge were not toxic to the early life stages of striped bass (Morone saxatilis) and juvenile spot (Leiostomus xanthurus). Acute toxicity studies of ozone-produced oxidants (OPO) showed that the early larval stages of the American oyster (Crassostrea virginica) and recently hatched striped bass ichthyoplankton were most sensitive to OPO; this sensitivity decreased with progressive development. Juvenile blue crabs (Callinectes sapidus), juvenile Atlantic menhaden (Brevoortia tyrannus) and adult white perch (Morone americana) were more resistant than molluscan and ichthyoplankton larval stages. Hematological and gill histopathological sublethal studies of adult white perch showed that OPO caused death by hypoxia as a result of excessive gill damage. Moderately damaged gill tissue repaired itself within a few days when fish were moved to clean waters. A comparison of the ozone data obtained in this study with similar chlorine data from the literature showed that the toxicity of ozonated and chlorinated estuarine water is similar. Thus, ozone appears to offer few, if any, advantages over chlorine in reducing toxicity to estuarine organisms.