Case Study of a Marine Discharge: Comparison of Effluent and Receiving Water Toxicity

An on-site investigation was conducted in northeast Florida to evaluate the toxicity ofa pulp and paper mill discharge and to determine whether there was any receiving water toxicity associated with that discharge. The species tested included the macroalga Champia parvula, the mysid Mysidopsis bahia, and two fish species, Cyprinodon variegatus and Menidia beryllina. All methods evaluated the critical, sensitive life stages and estimated chronic toxicity. Test results indicated that effluent effect concentrations were approximately 1% for the two most sensitive species (mysids and the macroalga) and 32% for the least sensitive (C. variegatus). Receiving waters adjacent to the discharge were sampled and tested daily over a seven-day period. Water samples collected at stations closest to the discharge were toxic to the macroalga, and the effect concentrations (estimated by a previous dye study) were consistent with those determined in the effluent tests. In addition, the Environmental Protection Agency's (EPA's) Duluth Laboratory conducted on-site chemical fractionation studies using the freshwater crustacean, Ceriodaphnia reticulata. Results of these studies indicated that unionized ammonia was the primary toxic component of the effluent. Data in this case study, from the suite of methods developed (or modified) at EPA's Narragansett Laboratory, appear suitable for the derivation of toxicity-based National Pollutant Discharge Elimination System permits for the marine environment.