Determination of emerging metal pollutants and toxic metals in mussels and bivalve mollusks, very important food and environmental bio-monitoring species

A quick and widespread diffusion of heavy metals as contaminants in all the environmental systems has called the attention to their determination. Indeed, heavy metals, together with pesticides, are very dangerous pollutants owing to their bioaccumulation and toxicity. It is, therefore, necessary to determine these metals at trace and ultra-trace level especially in aquatic ecosystems to establish reasonable water quality criteria. Certain marine species, in particular mussels, clams, but also oysters accumulate toxic metals, being filtering organisms. It was verified that an adult organism is able to filter several liters per hours (also up to 4-5 L h-1), depending on its weight. This prerogative involves two important facts and consequences: 1. The ability to accumulate all harmful substances for humans, toxic metals, in particular, requires particular attention and inspections before being sold on the market. 2. In addition to this important and fundamental aspect of public health, the determination of toxic metals in mussels, clams and also oysters, that are not only filtering organisms but also sessile species, can be usefully employed for bio-monitoring campaigns, that evaluate the long-term trend of the pollution load of an aquatic ecosystem, information that evidently cannot be provided by punctual determinations. For completely mapping environmental pollution, the sampling duration and cadence are very important. However, it should be emphasized that the use of bio-monitors, just proposed by several authors, but certainly not scientifically supported, is possible only in the case of a long sampling plan. In any case, the metal determination in mussels and bivalve mollusks evidently must be accurate, reproducible and especially it must show very low limits of detection. The present work reports and discusses the different analytical methodologies for the determination of emerging metals pollutants, together with all toxic metals, in mussels, clams, and oysters.