The phototoxicity of benzo[a]pyrene in the green alga Selenastrum capricornutum.

The effects of selected polycyclic aromatic hydrocarbons (PAHs) on the growth of the green alga Selenastrum capricornutum in three light regimens were examined. In gold fluorescent light, benzo[a]pyrene (BaP) at 12 mg/liter (48 mumole/liter), benz[a]anthracene (BaA) at 40 mg/liter (175 mumole/liter), anthracene (A) at 40 mg/liter (224 mumole/liter), and 13 metabolites of BaP each at 40 micrograms/liter had no effect on algal growth. In cool-white fluorescent light, 30% inhibition of algal growth occurred with 0.1 mumole/liter BaP, 8.0 mumole/liter BaA, and 40 mumole/liter A. BaP at 0.16 mg/liter (0.64 mumole/liter) totally inhibited growth. BaP concentrations an order of magnitude lower inhibited algal growth in fluorescent blacklight. In cool-white light, 5 of 13 metabolites of BaP (each 40 micrograms/liter) inhibited algal growth: 3,6-quinone; 6-hydroxy; 9-hydroxy; 3-hydroxy; and 1,6-quinone. Based on these results, PAHs and metabolites of BaP are selectively phototoxic to S. capricornutum due to the incident light intensity below 550 nm.