30 



plus 3 ppm tetrachlorocatechol (rJLVJ+3TCC) was still toxic to 

 sockeye fry at UO per cent concentration (TAbLE 9) . Follouing 

 five days of biological treatment, I©W+3TCC was non-toxic at 

 65 per cent concentration, the highest concentration bioassayed, 

 indicating that biological treatment was apparently able to oxidize 

 the tetrachlorocatechol molecule. 



TABLE 9 - Toxicity of neutralized bleach waste (NBW) and ilBW plus 

 3 ppm tetrachlorocatechol (iiBW+3TCC), before and after biological 

 treatment. Per cent mortality recorded during 96-hr bioassays of 

 Pitt Lake sockeye fry (mean length 42 mm) held at 4.7°F. 



The toxicity of NBV/ alone was reduced more quickly than that of 

 NBW+3TCC. Before treatment, all test fish died at 30 per cent 

 concentration of i\lBW and 20 per cent died at 20 per cent concentration 

 (Table 9). Following 24 hr of treatment the waste was non-toxic at 65 

 per cent concentration, while 40 per cent of the fry died at 90 per cent 

 concentration of treated i\!BW, After five days of treatment no 

 mortalities occurred at 90 per cent concentration, the highest 

 bioassayed. Sufficient NBU+3TGG was not available after five days to 

 use a 90 per cent bioassay concentration, as used with iffiW. However, 

 since biological treatment apparently oxidized tetrachlorocatechol it 

 is likely that 90 per cent concentration of NBW+3TCC would not have been 

 toxic. 



DISCUSSION 

 Acute Toxicity 



Ninety-six Hour Exposure 



The 96-hr TL of young sockeye salmon ranged between 0.7 and 1.3 

 ppm tetrachlorocatechol. Specifically, the 96-hr TL^^ for natural 

 smolts, frestily hatched natural and hatchery alevins, hatchery fry 

 and incubation channel fry averaged about 0.8 ppm tetrachlorocatechol^ 



