Levels of Gaseous Mercury in Italian Cities
Mercury is an element naturally present in biosphere: it can be of both natural (e.g. volcanic eruption, etc.) and anthropogenic (e.g., pig iron production, power plants or heat production, sanitary waste incinerators, etc.) origins. It is redistributed in atmosphere, in water and in soil doing so a very complex cycle of which only some passages are known while many other attend to be clarified. The interest for a greater knowledge of the mercury cycle in biosphere is connected to its level: in fact, because it represents a real hazard for the human health it should be necessary to keep low its levels.
From the chemical point of view mercury is present in atmosphere in gaseous form as elementary mercury (Hg0) and Reactive Gaseous Mercury, RGM(e.g., HgCl2), and adsorbed onto particulate matter (Total Particulate Mercury, TPM) over that in other forms in ultra-trace (e.g., methilated form). From the toxicological point of view mercury is extremely toxic, reaches all the organs (particularly, the kidneys) and besides it is quickly absorbed by the lungs. For this reasons the World Health Organization (WHO) has more times affirmed the necessity to keep an high level of attention to the mercury exposure recommending also to monitor such pollutant.
In this study seasonal study campaigns have been performed during 2005-2006 in urban areas of different Italian cities, Campobasso, Rome, Taranto and Venice, to investigate the levels and the behavior of gaseous-phase mercury.
The cities have been chosen on the basis of the urbanization in their perimeter: high anthropogenic activities (autovehicular traffic, domestic heating), presence of industrial port and large industrial areas, urban installation not situated close to natural mercury sources. This context can be considered as example of specific anthropogenic pollution, allowing so to collect data that can contribute to a best knowledge of the mercury presence in biosphere.
For the sampling and analysis a portable instrument was used based on the atomic absorption methodology with the background correction through the Zeeman effect. The daily trends obtained by such measures are discussed in the present paper and, at the same time, the determined levels are compared with how reported in literature (very few data) and in the guidelines of the European Union document. No relevant situations for the human health were found (the levels range between 1 and 15 ng/m3 according the areas). Finally, the mercury levels and behavior have been discussed to the atmospheric stability conditions and some other important pollutants such as particulate matter and benzene. It should be noted that these data represent the first systematic investigation of this pollutant in Italian urban cities.