232 BIRGE 



characterization of coal elements were not available for the first two 

 sets of effluent bioassays. Sunfish eggs, however, have the same 

 hatching time (exposure period) as goldfish and generally exhibit 

 similar sensitivity when used in aquatic bioassays (Birge, Black, 

 and Westerman, 1978). During the exposure period for sunfish eggs, 

 mean effluent metal concentrations, with standard errors, were 

 0.4 ± 0.2 ppb Ag, 1070 ± 230 ppb Al, 72.0 ± 43.0 ppb Cd, 5.5 ± 1.8 

 ppb Cu, 20.6 ± 4.8 ppb Hg, 31.5 ± 1.4 ppb Ni, and 70.0 ± 6.7 ppb 

 Zn. At the 0.1 dilution, which gave 42% survival for sunfish eggs 

 (Table 6), all analyzed metals except aluminum were well below 

 goldfish LCi values. Aluminum was present at approximately 

 two-thirds of the LC50 value. Although the effluent was not 

 analyzed for all possible toxicants, this correlation tends to support 

 application of the toxicological index given for coal elements 

 (Tables 2 and 3). Before the goldfish bioassays were initiated, 

 effluent metal concentrations had dropped to ppb Ag, 160 ± 10 

 ppb Al, 1.5 ±1.5 ppb Cd, 4.5 ± 1.8 ppb Cu, 3.8 ± 0.7 ppb Hg, 

 23.0 ± 3.0 ppb Ni, and 44.5 ± 8.0 ppb Zn. These values were all 

 below LCi 's calculated for goldfish, except aluminum, which was 

 present at about the LC50 level (Table 2). The undiluted effluent 

 gave 57% survival. 



DISCUSSION 



The embryo— larval bioassays reported in Table 2 demonstrate 

 the high toxicity of numerous inorganic coal elements to aquatic 

 biota. Depending on the animal species, LC50 values of 0.1 ppm or 

 less were observed for 15 coal elements, and calculated LCj 's 

 ranged down to 0.1 to 0.2 ppb for mercury and silver. Tungsten was 

 the least toxic element in all cases, with LC50 values ranging from 

 2.90 ppm for the toad to 120 ppm for the goldfish. When the test 

 data were averaged, the increasing order of sensitivity of animal 

 species was goldfish, trout, and toad. 



The order of toxicity of the 22 elements, as determined by LCg 

 values, varied somewhat for embryo— larval stages of the three 

 species. Only Ag, Cd, Cr, Hg, Ni, and Pb occurred among the 12 most 

 toxic elements for all three, but Al, As, Co, Cu, Ge, V, and Zn were 

 included in this group for two species (Table 2). Of particular 

 interest were the consistent extreme toxicity of mercury and silver to 

 developmental stages of all species and certain selective responses, 

 such as the high relative toxicity of aluminum to goldfish, germa- 

 nium and lanthanum to trout, and selenium and zinc to the toad. 



