抄録
Rapid and simple screening method is required for a first step of determining effects of chemicals or assessing effluent toxicity of wastewater from industry or disposal site. A screening growth inhibition test method using salt water plankton Dunaliella sp. is developed. The alga is incubated at 21 ± 0.5 °C using 50 mL Erlenmeyer flask for the test vessel with air-permeable stoppers and without shaking. Biomass is determined by cell counting with an electronic particle counter. An exponential growth of the alga was observed over 72 h, and reproducible results were obtained from 12 repetitions of growth test. The average specific growth rate for 72 h is 1.62 ± 0.03 d-1（mean ± SD）for controls. The alga was treated with eight chemicals for 72 h. Growth rates was calculated, and a 50 % inhibition of growth rate（ErC 50）is determined. The sensitivity of the algae was compared with a most popularly used alga Pseudokirchneriella subcapitata（green alga）using 72 h-ErC50. The alga was more sensitive to some chemicals than P. subcapitata and not to other chemicals. In this screening test using the algae, the 72 h-ErC50 values of chemicals tested were nearly equal to the 48 h- or the 24 h-ErC50 values. This meant a possibility of rapid testing for only 24 h exposure instead of conventional 72 h as screening testing.
