Assessment of atmosheric heavy metal deposition in the Taranto urban area using the moss biomonitoring techimique and ICP-MS analysis.

Biomonitoring using mosses is a well-developed technique employed in many parts of the world to assess the concentrations of trace elements in the atmosphere and their potential sources. The stability of metal organic complexes and chelates and the great cation exchange capacity of the tissues are primarily conditions for the sorption of heavy metals by mosses. The use of mosses as passive biomonitors for analysis of atmospheric deposition has been reported in a large number of studies in different parts of the world. The moss technique is particularly favourable for estimation of long-term temporal and spatial changes in metal deposition. Bioaccumulation monitoring methods can be divided into two groups: active and passive. Active monitoring includes the exposure of well-defined species under controlled conditions, whereas passive monitoring refers to the observation or chemical analysis of indigenous bryophytes. Mosses are well suited to this purpose because they receive metals directly from the atmosphere and efficiently retain a number of elements. In this study, a biomonitoring of heavy metal (Cd, Cr, Ni, Cu, Mn, Pd, Hg, V, As, Fe, Al, Mn) in the urban Taranto area has been conducted through mosses belonging to the autochthonous species, Pleurochaete squarrosa and Hypnum cupressiforme. Active and passive monitoring methods were used to evaluate air quality and metal contamination in the atmospheric depositions. Samples of epigeouses mosses were taken in areas exposed to different human impacts. Surveys were conducted in different seasons in order to correlate metal contamination levels with climatologic factors. The analyzed metals were those originated both from industrial area (ILVA-Iron and Steel factory, ENIRefinery) and from vehicular traffic. The results of air monitoring, according to air quality indexes determined by automatic stations, confirmed that Pleurochaete squarrosa and Hypnum cupressiforme, are very good bioindicators for analysis of atmospheric metals contamination.