“…Heavy metals are naturally present in soils; however, anthropogenic human activities lead to increases of these elements concentrations to amounts that are harmful to microorganisms, plants and animals (Chibuike and Obiora, 2014;Gosh and Das, 2017;Hu et al, 2013;Stępniewska et al, 2009). The anthropogenic sources of metal contamination can be divided into five main groups: -metalliferous mining and smelting (arsenic, cadmium, lead and mercury); -industrial activity (arsenic, cadmium, chromium, cobalt, copper, mercury, nickel, zinc); -atmospheric deposition (arsenic, cadmium, chromium, copper, lead, mercury, uranium); -agriculture (arsenic, cadmium, copper, lead, selenium, uranium, zinc); and -waste disposal (arsenic, cadmium, chromium, copper, lead, mercury, zinc).…”