Toxic Metal Bio-Monitoring: An Innovative Procedure to Get Complete Information on the Long-Term Trend of the Metal Pollution Load in Environmental Ecosystems

In recent years, rapid spread of toxic metals has occurred in all environmental matrices. The phenomenon started since many decades. Due to their bioaccumulation and toxicity, these contaminants are very dangerous pollutants for human health. The hazardousness of toxic metals is not lower than pesticides. Indeed, toxic metals are perhaps the most important reason of the pollution load in environmental ecosystems; certainly they are among the greatest. They come from almost all human activities: industries, agriculture, vehicular traffic, urban heating and so on. Pollution of an ecosystem can be caused in many ways, such as direct input through watercourses; for example, the case of aquatic ecosystems. But in general all ecosystems are subjected to pollution caused by atmospheric transport such as particulate or fumes. In order to evaluate the pollution load of ecosystems, two paths can be followed: 1) determination of pollutant concentrations by timely and repeated sampling in well-defined ecosystem sites; 2) determination of the same pollutants in species that live and are continually present in the same ecosystem (bio-monitoring). Evidently, punctual determinations cannot provide information to evaluate the long-term trend of the pollution load. This information can only be provided through bio-monitoring campaigns. Several Authors have given this suggestion, but the scientific community did not firmly support it. For each toxic-metal determination, the present work reports various species employed in bio-monitoring campaigns: mussels, oysters and clams, algae, vegetables, lichens, mosses. For each bio-monitor and for all metals or group of metals, the various analytical techniques and procedures employed are critically discussed. Particular attention is paid to the analytical performance, in terms of accuracy and detectability. A separate section is dedicated to the analytical procedure for the determination in bio-monitors of new emerging anthropic polluting traffic-related pollutants, i.e., the platinum group metals (platinum, palladium, rhodium, osmium, ruthenium and iridium)