Effect of heavy metals (Cu and Zn) on the content of photosynthetic pigments in the cells of algae Chlorella vulgaris

Abstract

The purpose of this paper is to determine the effect of heavy metals on the photosynthetic pigments of chlorophyll a, b and the carotenoids found in the cells of algae Chlorella vulgaris. In order to analyze the influence of heavy metals on Chlorella vulgaris algae, two heavy metals were chosen, i.e. copper and zinc. The samples for analysis were collected daily for 7 days. Copper(II) sulphate, which is widely regarded as an algicide, was used in the study. Chlorella vulgaris grows at the highest concentration tested, amounting to 0.15 mg CuSO4/dm3. In the trial with a concentration of 0.15 mg CuSO4/dm3, a decrease in the content of chlorophyll was observed, which was lower by 63% in comparison to the control sample, 7 days after incubation was observed. In the second study using zinc(II) sulphate at a concentration of 100 mg ZnSO4/dm3, the death of Chlorella vulgaris was observed after 5 days of incubation. In subsequent tests with lower concentrations of zinc(II) sulphate, Chlorella vulgaris is growing, but with lesser dynamics than in the case of the control sample. The increase in the content of photosynthetic pigments, along with the incubation time, indicates the development of algae breeding. The conducted research shows that the Chlorella vulgaris algae has a specific resistance to the presence of the elevated content of tested heavy metals in the breeding medium.