**7. Conclusions**

Heavy metals and metalloids are critical environmental contaminants for both marine and terrestrial environments and ecosystem. The danger of an environmental chemical is a function of its persistence, toxicity and bioaccumulative ability in the environment. Due to these three characteristics: persistence, bioaccumulation, and toxicity; HMs are considered as harmful. The most dangerous heavy metals and metalloids that are environmentally important include Cr, As, Cd, Pb, Hg, Ni, Cu and Zn. In aquatic and terrestrial food chains, the trophic transition of these elements has major consequences for different lives of ecosystem and human health. So contamination of environment of heavy metals is of great concern, and its treatment from the soil and water around industrial areas is needed urgently in every place. The assessment and monitoring of the concentrations of potentially toxic heavy metals and metalloids in the various environmental segments and in the resident biota is very significant. A detailed environmental chemistry and ecotoxicology analysis of dangerous heavy metals and metalloids demonstrates that steps should be taken to mitigate the effects on human health and the environment of these elements.
