ABSTRACT
The term “heavy metal” is generally applied to the chemical elements having atomic weight between 63.5 and 200.6 and an atomic density greater than 6 g/cm3. While a large number of atomic species fall into this category, the ones that are relevant in environmental context due to their highly toxic effect are cadmium, lead, mercury, arsenic, chromium, copper, nickel, and zinc, with the rst three being considered harmful even at trace levels (O’Connell et al. 2008, Barakat 2011). Their presence in groundwater and soil places both humans and ecosystems in danger because heavy metals are not biodegradable and tend to accumulate in soft tissues producing long-term damage, as described in detail in numerous toxicology studies (Iarc 1990, Nordberg et al. 2007, Thompson and Bannigan 2008).
