Algae may be used in a number of industrial applications to lower the cost of co-producing biofuels. The effects of heavy metal contamination on the environment and public health have prompted interest in creating environmental biotechnology methods. The majority of studies have been on aquatic environments, however there is little information on using algae to bioremediate soil. However, the present work was conducted to evaluate the soil bioremediation potential and biochemical response of algae to some heavy metals. In the present study, algae samples were obtained from Kashgaran Nature Pak Laboratory and cultivated in Zaruk culture medium under suitable conditions. Finally, after the growth of algae samples, heavy metal treatments were prepared and the algae were treated with heavy metals. The experiment was designed in a factorial with algae types at three types (Cladophora sp, Anabaena sp, and Scenedesmus sp.) and five types of heavy metals (control, Cd, Cr, Cu, Hg) in three replicates. For this purpose, heavy metal accumulation in algae, chlorophyll (Chl.) content, the activity of antioxidant enzymes, and malondialdehyde (MDA) were measured. The results showed that the algae had different responses to heavy metals, Scenedesmus accumulated the most Cr and Hg, whereas and Cladophora accumulated the most Cu. The Chl significantly decreased as a result of heavy metals, with Anabaena obtaining the highest quantity. The activity of superoxide dismutase (SOD) and catalase (CAT) enzymes increased under heavy meals, particularly under Cd toxicity. The maximum amount of SOD and CAT have been reported under Cr stress and Scenedesmus. Heavy metals, in particular Cd, increased MDA, with Anabaena exhibiting the least change and Scenedesmus exhibiting the most change. According to agglomerative hierarchical clustering (AHC), three algae have paced in three special clusters. According to the obtained results, it was found that algae have a high potential in the accumulation of heavy metals and can be used to purify polluted environments, however, heavy metals can cause the destruction of photosynthetic systems and by increasing the amount of radicals increase the free activity of antioxidant enzymes. However, different species of algae have different potentials in the accumulation of heavy metals, and the potential of different species for different heavy metals can be identified with further research.
