Effect of hexachlorobenzene on some growth parameters of Chlorella pyrenoidosa.

Chlorella pyrenoidosa was incubated with HCB (0.001-10.0 ppm) in a "light-thermostat" at 30 degrees C for 46 h with continuous light (4000 Lux) and aeration. HCB decreased growth as deduced from measurements of chlorophyll content, dry matter, carbohydrate content, and total nitrogen. Incubation with HCB for three months in Erlenmeyer-flasks resulted in an increase of chlorophyll over control value in cultures receiving 0.1 and 1.0 ppm HCB. After transfer of the cultures from Erlenmeyer-flasks to growth conditions of a "light-thermostat", growth of the algae was greatly enhanced by all HCB concentrations studied; a concentration of 0.1 ppm being most effective.