The release of metals into the environment by anthropogenic
activities has deleterious effects on ecosystems and on human
health, as these metals tend to persist indefinitely, circulating
between the several compartments of the biosphere and
accumulating throughout the food chain [8,7]. Human concern
about metals has been focused on the highly toxic and nonessential
metals, like mercury and cadmium [28]. Due to their hazard,
mercury and cadmium were classified as “priority hazardous
substances” by Water Framework Directive [10], and occupied in
2013 the 3rd and 7th position on the list of priority substances
provided by the Agency for Substances and Toxic Diseases Registry
[2]. The presence of these metals in aquatic systems is of great
concern and it became strictly important to implement actions
aiming their progressive reduction, and ceasing or phasing out
their discharges, emissions and losses, within an appropriate
timetable