AQUATIC TOXICOLOGY OF TRACE ELEMENTS 

 OF COAL AND FLY ASH 



WESLEY J. BIRGE 



T. H. Morgan School of Biological Sciences, University of Kentucky, 



Lexington, Kentucky 



ABSTRACT 



Aquatic bioassays were performed on 22 coal elements, with developmental and 

 juvenile stages of fish and amphibians used as test organisms. For more sensitive 

 test species, LC50 values of 0.1 ppm or less were observed for 15 trace elements, 

 and LCi values ranged down to 0.1 to 0.2 ppb for mercury and silver. Studies 

 also were performed on the aqueous leaching characteristics and toxicological 

 properties of coal-produced fly ash. A 52-kg sample of precipitator-collected fly 

 ash was subjected to continuous flow-through washing for 2000 consecutive 

 hours in a bench-scale ash-settling pond. Chemical characteristics of the 

 simulated effluent compared closely with those recorded for actual ash-settling 

 ponds. During the first 500 hr of operation, conductivity averaged 690 

 /Umhos/cm, and a mean of 0.56 g/liter was observed for total dissolved solids. 

 Gradual decreases were observed thereafter. Effluent pH averaged 4.3 during the 

 first 500 hr but approached the level of influent water (7.1 to 7.9) by 2000 hr. 

 Maximum effluent concentrations detected for seven selected metals were 126 

 ppm Al, 766 ppb Zn, 518 ppb Cu, 500 ppb Cd, 370 ppb Ni, 87 ppb Hg, and 8 

 ppb Ag. Mean concentrations for the first 500 hr of elution were 32.6 ppm Al, 

 350 ppb Zn, 156 ppb Cd, 155 ppb Ni, 110 ppb Cu, 2.1 ppb Ag, and 1.8 ppb Hg. 

 All metals except mercui-y reached maximum levels within 500 hr, and 

 concentrations declined thereafter. Mean mercury levels increased to 27 and 15 

 ppb for the second and third 500-hr elution intervals. After 522 and 1033 hr of 

 elution time, continuous-flow treatment with undiluted ash effluent produced 

 100% mortality of frog and sunfish eggs. A 0.1 dilution at 1033 hr resulted in 

 42% hatchability of sunfish eggs. After 1775 hr of continuous leaching, 

 undiluted ash effluent and 0.1 and 0.01 dilutions gave survival frequencies of 57, 

 76, and 88% for goldfish eggs, compared with 92% for controls. Metals analyzed 

 for undiluted effluent administered to goldfish were well below LCj determina- 

 tions, except aluminum, which was present at the LC50 level. 



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