||Effects of Hardness, Alkalinity and pH on the Toxicity of Pentachlorophenol to 'Selenastrum Capricornutum' (Printz).
Smith, P. D. ;
Brockway, D. L. ;
Stanch, F. E. ;
||Environmental Research Lab., Athens, GA.
Culture media ;
Selenastrum capricornutum ;
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The toxicity of pentachlorophenol (PCP) to Selenastrum capricornutum was examined in three different culture media: a hard and a soft form of Freeman's reference water and the algal assay bottle test (AABT) medium (a soft water). The 96-h growth potentials of the media were equal (28-29 mg/L dry wt.) but 96-h EC50s ranged sevenfold: 0.11 mg/L (AABT), 0.15 mg/L (Freeman's soft water) and 0.76 mg/L (Freeman's hard water). Culture media equilibrium pH and 96-h EC50s were strongly correlated (r=1.00). Evidence is presented that supports the hypothesis that the toxicity of PCP, a weak acid, is due primarily to the concentration of the undissociated species.