Effects of different concentrations of lead on growth, photosynthetic pigmentation and Protein Micro alga Isochrysis galbana

 Pollution of the environment by heavy metals is one of the main environmental problems. Heavy metals are of special importance due to their toxic effects on the environment and bioaccumulation in various aquatic species and the creation of bio magnification in food chains. In water resources, microalgae are considered as important and valuable reserves in terms of production of organic matter and being at the base of the pyramid and energy production, and other organisms are directly or indirectly dependent on microalgae in the food chain. The aim of this study was to compare the toxicity of lead metal in different concentrations on the growth of I.galbana algae. 

 After reaching the desired volume, the prepared microalgae were tested to evaluate the effect of different concentrations (lead chloride) on the growth rate, chlorophyll and protein over a period of 15 days. For algae culture, F2 medium with 25 salinity was used. Lead metal treatments were selected at five concentrations (control, 5, 50, 100, 250 and 500 μg/l).

Analysis of statistical data was presented in the form of tables and graphs with the help of Excel and SPSS software for final conclusions and comparative understanding. . Observations showed that a concentration of 500 μg/l of lead metal reduced the growth of I.galbana algae. The highest growth rates were obtained at concentrations of 50 and 100 μg/l. In this experiment, the highest chlorophyll a content was related to the concentration of 5 μg/l and the lowest content was related to the concentration of 500 μg/l. Also, by studying the effect of tested metals on the amount of microalgae protein, it was found that in low concentrations it increased the amount of protein and in high concentrations it decreased the amount of microalgae protein. 

 The present studies showed that the species of microalgae I. galbana is not able to grow in low pests but was observed with increasing the concentration of lead metal and with increasing time inhibiting the growth of microalgae.