Toxicity, sources and biogeochemical cycle of mercury

Among the heavy metals, mercury is one of the most studied environmental pollutants. This is largely due to its toxicity and its high mobility in the environment. Due to the ability to travel over long distances in the atmosphere as gaseous elemental species, far front the point emission source, mercury is regarded as a 'global pollutant'. The maximum toxicity of mercury is given by its methylated form, methylmercury. The main pathway of contamination of the humans with mercury is the food chain, where the most toxic species, methylmercury, bioaccumulates. This species is widely recognized as a neurotoxin affecting humans. Since it is recognized that not only the total concentration of mercury in an environmental compartment but its chemical forms determine the toxicity/essentiality and bioavailability, there is growing need in developing analytical methods able to distinguish among its species.