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1 1 1 1 ~I 1 CYANIDE 17 Table 2. Continued. Environmental Concentration• compartment (mg/kg or mg/L,) lleferenceb Wastewater treatment plants, Chicago Treated effluent Total cyanide 0.005--0.03 15 Dissociable cyanide 0.003-0.007 15 Complex cyanide 0.002-0.02 15 Thiocyanate 0.006-0.03 15 Untreated wastewater Total cyanide 0.02-0.06 15 Dissociable cyanide 0.004-0.05 15 Complex cyanide 0.02-0.08 15 Thiocyanate 0.03-0.27 15 Sludge Total cyanide 0.49-3.79 15 Dissociable cyanide 0.06-0.44 15 Complex cyanide 0.43-5.4 15 Thiocyanate 0.2-0.9 15 • Concentrations arc shown as means, range (in parentheses), and maximum (Mex.). t 1. Towill eta). 1978:2. Shaw 1986; 3. Gomez et al. 1983; 4. Casadei et el. ]984; 5. Ukhun and Dibic 1989; 6. DMfour 1968; 7.Okolie and Ugochukwu 1989; 8. Duffey 1981; 9. Berningeret al. 1989; 10. Epekeze and Oehme 1980; 11. Leduc 1981;12. Leduc 1984;13. EPA 1980;14. Leduc et al. 1982; 15. Kclada 1989;16. Nonomura and Hobo 1989; 17. Vennesland et al. 1981x; 18. Beyer 1990; 19. Clark end Hothem 1991. • Concentration is in milligrams per kilogram dry weight. Northwest Territories of Canada (Table 2). C}•a- nides are ubiquitous in industrial effluents, and their increasing generation from power plants and from the combustion of solid wastes is expected to result in elevated cyanide levels in air and water (Leduc 1984). However, data are scarce on back- ground concentrations of cyanides in various non- biologica] materials. In soils, for example, high concentrations are unusual and are nearly always the result of improper waste disposal (Towil] et al. 1978). Cyanides in soils are not absorbed or re- tained; under aerobic conditions, microbial me- tabolism rapidly degrades cyanides to carbon dioxide and ammonia; under anaerobic conditions, cyanides are converted by bacteria to gaseous ni- trogen compounds that escape to the atmosphere (Tow•ill et al. 1978). Heat treatment wastes from metal processing operations may contain up to 200 g CN/kg, mostly as NaCN, and are frequently hauled to landfills for disposal (Lagos et al. 1982). The presence of cyanide in landfill waste is poten- tially hazardous because of the possibility that cyanide may leach to soil and groundwater, release HCN, and disturb natural microbiological degra- dation of organic materials. Measurements at landfills in England and the Netherlands showed total cyanide levels up to 560 g/kg in soil and 12 µg2 in groundwater (Lagos et al. 1982). How- ever, 7-month-long experimental studies of cya- nide inheat treatment wastes in landfills showed that between 72 and 82°0 of the cyanide was con- verted, mostly to ammonium and prganic nitrogen compounds; between 4 and 22°'0 of the cyanide leached as free or complex cyanide; and up to l lci0 remained in the landfill (Lagos et al. 1982). Hydrogen cyanide (HCN) is a common indus- trial pollutant and frequently occurs in water at concentrations between 0.1 and several milli- grams per liter of free HCN (Leduc 1978; Leduc et al. 1982). Total cyanides is the rllost often cited measurement in aqueous solutions, owing to limi- tations in analytical methodologies (Leduc et al. 1982). Cyanides have been identit~ed in fresh tva- ters of rural and wilderness areas in Canada and Germany. Concentrations rangingbetween 30 and 60 µg total cyanides per liter seem related to runoff, with cyanide peaks more frequent in fall and winter during periods of minimal runoff (Leduc et al. 1982). In larger rivers, cyanide was