Influence of organic solvents on the growth of marine microalgae

Ninety-six-hour toxicity tests of five organic solvents (methanol, ethanol, acetone, N,N-dimethylformamide [DMF], and dimethyl sulfoxide [DMSO]) on ni ne species of marine microalgae (Bacillariophyceae; Skeletonema costatum, a nd Chaetoceros calcitrans, Prasinophyceae; Tetraselmis tetrathele, Haptophy ceae; Isochrysis galbana and Pavlova lutheri, Dinophyceae; Prorocentrum min imum, Raphidophyceae; Heterosigma akashiwo, Euglenophyceae; Eutreptiella sp ., Chlorophyceae; Dunaliella tertiolecta) were conducted. For D. tertiolect a, T. tetrathele, I. galbana, and P. lutheri, methanol was the least toxic solvent. For S. costatum, C. calcitrans and Eutreptiella sp., DMSO was the least toxic solvent. For Heterosigma akashiwo, DMF was the least toxic solv ent. In general, solvent toxicity was ethanol > methanol or acetone > DMF > DMSO. In relation to sensitivity of the microalgae to solvents, D. tertiol ecta and T. tetrathele were lower in sensitivity, and Eutreptiella sp. and H. akashiwo were higher in sensitivity than the other species. The no obser ved effect concentration (NOEC) of acetone, DMF, and DMSO were higher than for ethanol and methanol. Acetone, DMF, and DMSO were suitable for carrier solvents used in toxicity test of water-insoluble chemicals. Excellent regr ession between logEC(50) and logNOEC was obtained (logNOEC = 1.09 x logEC(5 0) - 0.84, R-2 = 0.91). This equation indicated that higher toxicity was hi gher application factor (EC50/NOEC) than lower toxicity. All application fa ctors were higher than 0.1.