AQUATIC TOXICOLOGY OF TRACE ELEMENTS 221 



MATERIALS AND METHODS 



Aquatic Bioassays 



Semistatic embryo— larval bioassays were performed on the 

 goldfish (Carassius auratus), the rainbow trout (Salmo gairdneri), and 

 the narrow-mouthed toad (Gastrophryne carolinensis) with rapid- 

 scan procedures previously described (Birge and Just, 1975). Eggs 

 were exposed to coal elements from fertilization through 4 days 

 posthatching, giving treatment periods of 7 days for toads and 

 goldfish and 28 days for trout. Test water and toxicant were 

 renewed at regular 12-hr intervals. Mean water hardness, with 

 standard error, was 195 ± 5.4 ppm CaCOj for goldfish and toad 

 stages and 104 ± 2.0 for trout. Test water pH averaged 7.4 ± 0.1. 

 Dissolved oxygen was maintained near saturation by continuous, 

 moderate aeration. Other chemical and physical characteristics of the 

 reconstituted test water were described by Birge and Black (1977). 

 Water temperature was 13.0 ± 0.5°C for trout eggs and 22.0 ± 1.0°C 

 for other species. 



Test organisms were examined daily to tabulate frequencies of 

 mortality and teratogenesis. Control adjusted LCj and LCjq values 

 were calculated for combined test responses by log probit analysis 

 (Daum, 1969). Anomalous survivors were counted as lethals. Control 

 eggs were cultured simultaneously with experimentals and under 

 identical conditions, except for omission of toxic coal elements. 

 Minimum sample size was set at 150 eggs per culture. 



The 22 coal elements and test compounds selected for bioassay 

 analysis are given in Table 1. Depending on the degree of anticipated 

 toxicity, exposure concentrations were initiated at 10 to 100 ppm 

 and continued at two- to tenfold dilutions until survival of 

 experimental animals equaled or approached that observed for 

 controls. Each coal element was administered at 10 to 14 exposure 

 levels. Elemental concentrations of test water were monitored by 

 atomic absorption spectrophotometry with a model 503 Perkin— 

 Elmer unit equipped vAth an HGA-2100 graphite furnace and a 

 mercury analyzer (Perkin— Elmer Corp., 1973). 



Aqueous Leaching of Fly Ash 



A bench-scale Plexiglas settling pond was designed to investigate 

 the aqueous leaching characteristics of precipitator-collected fly ash 

 obtained from a local 1000-MW coal-fired power plant. A 52-kg 

 sample of dry ash was deposited in an 88.2-liter settling chamber. A 

 Gilson Minipuls II peristaltic pump (Gilson Medical Electronics, Inc.) 

 provided a continuous flow of water over the ash bed at a rate of 1 



