RESUMEN
Short-term (24-h) experiments were performed to examine the effect of phenanthrene (PHE) and anthracene (ANT) on algae grown in a batch culture system at irradiances of 12, 33, 48, and 64 W m(-2) of the PAR range. Cultures were aerated (0.1 or 2% CO(2)) or nonaerated. As a result of aeration the concentration of ANT dropped from 0.45 mg L(-1) at the beginning of the experiment (t(0)) to an undetectable value after 10 h. The PHE concentration dropped from 9.36 mg L(-1) at t0 to 0.17 mg L(-1) after 24 h. ANT at nominal concentrations exceeding 0.05 mg L(-1) inhibited the growth of the algae in a concentration- and irradiance-dependent manner. The algistatic effect of ANT observed at 64 and 48 W m(-2) was independent of the CO(2) level, whereas the growth inhibition at 33 and 12 W m(-2) was much greater in cultures aerated with 2% than with 0.1% CO(2). PHE inhibited the growth only at a concentration of 10 mg L(-1) (about 50% of the control) regardless of the irradiance or the CO(2) concentration. The toxicity of both PHE and ANT was similar in aerated (0.1% CO(2)) and nonaerated cultures. ANT and PHE had a distinct effect on the photosynthesis. At 0.1% CO(2), the irradiance-dependent inhibition (ANT) and stimulation (PHE) of the photosynthesis was observed. The inhibitory effect of ANT was enhanced when algae were grown at 2% CO(2), but at the same CO(2) concentration PHE did not affect the photosynthesis. ANT stimulated the total superoxide dismutase (SOD) activity in the cells, this effect being generally more pronounced at elevated CO(2) levels and increasing with the irradiance. The total SOD activity was 250-300% higher in cells treated with PHE aerated with 0.1% CO(2). At 2% CO(2) no effect of PHE on the enzyme's activity was noted. The results obtained indicate that ANT acts as a photosensitizer causing an oxidative damage of cells, while PHE seems to affect the macromolecular synthesis.
Asunto(s)
Antracenos/toxicidad , Depuradores de Radicales Libres/farmacología , Fenantrenos/toxicidad , Fotosíntesis/efectos de los fármacos , Scenedesmus/crecimiento & desarrollo , Superóxido Dismutasa/farmacología , Dióxido de Carbono/análisis , Scenedesmus/fisiología , Luz Solar , Contaminantes del Agua/toxicidadRESUMEN
The growth of Scenedesmus quadricauda algae in a batch culture was examined in the presence of crude oil and fuel oil, added to the cultivation medium in the form of a water-soluble fraction (WSF), water extract (WE) and oil-water dispersion (OWD). On applying various concentrations of oils, a decrease in the number of cells, dry matter and chlorophyll 'a' production, with respect to the cell population, was observed. The extent of this decrease depended on the kind and concentration of the soluble and dispersed hydrocarbon fractions and on the proportions in which these occurred in the culture medium. On the other hand, the water extracts of both oils stimulated dry mass and chlorophyll 'a' content with respect to a single cell. This effect was accompanied by increased size of the algal cells. The WSF, WE and OWD of fuel oil, prepared from 200, 50 and 1 cm(3) of oil per dm(3) of BBM medium, respectively, had a similar inhibitory effect, which points to the dominant role of oil dispersion in the reduction of algal growth. Chemical analysis of the water extracts of fuel oil revealed the presence of 35 hydrocarbons of various kinds, mainly n-alkanes and polycyclic aromatic hydrocarbons.