236 BIRGE 



to 1435 hr. On the basis of the Environmental Protection Agency's 

 (EPA) application factor (0.01) and the trout, toad, and goldfish 

 embryo— larval LCg o values, nickel and zinc concentrations exceeded 

 recommended levels for all test species through 1775 hr, and silver 

 was above acceptable limits for 1050 to 1266 hr. Copper, with an 

 application factor of 0.1, exceeded calculated concentrations for 

 trout and toad through 1000 to 1500 hr but was over the goldfish 

 limit for only 22 hr. Using embryo— larval rather than adult LCj o 

 values resulted in more stringent limits for Ag, Cu, Ni, and Zn. 

 However, freshwater standards should permit adequate protection 

 for sensitive life-cycle stages. Except for copper, the suggested EPA 

 application factors appeared acceptable for embryo— larval stages. On 

 the basis of data in Table 2, 0.01 to 0.05 of LC50 determinations 

 gave values that generally fell within or near 95% confidence limits 

 for LCi 's. In comparison with the EPA value of 0.1, a more suitable 

 application factor for copper was found to be 0.05 for goldfish and 

 trout and 0.01 for the toad. 



Since combined toxicological effects of complex suites of trace 

 metals are difficult to quantify by existing hazard-assessment criteria, 

 direct bioassay monitoring was used to provide further characteriza- 

 tion of ash effluent. As noted, after 1033 hr of continuous elution, 

 undiluted ash effluent produced 100% mortality of sunfish eggs, and 

 survival of goldfish eggs was reduced to 57% when exposure was 

 initiated at 1775 hr. A 0.1 dilution produced an approximate LC50 

 for sunfish, and 0.01 gave essentially control-level survival for both 

 species. When median survival was obtained, concentrations of all 

 monitored metals except aluminum were at or below goldfish LCi 

 values, and aluminum was present at about the LC50 level (Table 2). 

 Effluent dilutions that gave control-level survival did not contain any 

 monitored metals at concentrations exceeding goldfish LCj values. 

 Although ash effluent was not analyzed for all possible toxicants, 

 results obtained by direct effluent monitoring were in good 

 agreement with the independent embryo— larval bioassays for coal 

 elements. Also, trace metals present at or below the probit LCj 's did 

 not exert any overt synergistic effects. In addition, results indicate 

 that continuous-flow embryo— larval test systems are highly suitable 

 for in situ toxicological monitoring of complex coal effluents. 



Although not intended to serve in lieu of actual field studies, 

 simulated ash ponds can be used to characterize aqueous leaching 

 processes and to evaluate ash effluents for potential environmental 

 hazards. Test parameters can be manipulated individually to deter- 

 mine effects on metal elution rates, and such model systems can be 

 particularly useful in comparing ash residues of coal from different 



