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Background: Particulate Matter pollution in urban areas is due to different sources and varies in composition, where the carbonaceous fraction is of particularly importance due to its effects on human health and the climate., Objectives: to study the contribution of the carbonaceous fraction in PM10 pollution in the urban area of Rome and identify the composition of its organic fraction., Methods: Separation of Elemental Carbon (EC) from Organic Carbon (OC) was carried out by means of a 5400 Ambient Carbon Particulate Monitor 5400 based on a two-step combustion procedure., Results: The carbonaceous fraction in central Rome accounted for 30-40% of PM10 at ground level and consisted of 60-70% Elemental Carbon and 30-40% Organic Carbon. Polycyclic Aromatic Hydrocarbons, n-Alkanes and n-Alkanoic acids were identified among the constituents of the OC fraction, sulphates, nitrate and ammonia in the hydrosoluble inorganic fraction and heavy metals (Cd, Cr, Fe, Ni, Pb, V, Zn) in the non-hydrosoluble inorganic fraction. PM10 temporal trends were interpreted using measurement of the natural radioactivity (radon and its short-lived decay products) as tracer of the dynamic properties of the atmospheric boundary layer., Conclusions: Carbonaceous particulate matter is a fundamental parameter to evaluate atmospheric pollution due to combustion processes and can be considered as a specific index of motor vehicle traffic pollution. Its separation into elemental carbon, of primary origin, and organic carbon, of both primary and secondary origin, is toxicologically signficant and in order to study the formation mechanisms of photochemical pollution.

Background: Among the atmospheric pollutants detectable in the environment, the inhalable airborne particulate (PM10) is regarded with increasing concern. Indeed a number of epidemiological studies support the correlation between both acute and chronic adverse health effects and the presence of PM10 levels even lower than the WHO guide lines. Despite these epidemiological findings, it is yet unclear and still widely debated which characteristics of particulate matter are responsible for the observed health effects. The identification of one or more components of PM10 related to the health effects observed in the urban population is a research subject of primary importance for the coming years., Objectives: The aim of the present study was to characterise from a physical-chemical point of view the "coarse" (PM10-2.1) and the "fine" (PM2.1) fractions of the airborne particulate matter (PM10) sampled in three different sites dissimilar with regard to the weather conditions, the residential density and industrial activities., Methods: The particles were collected by an eight-stage cascade impactor (Andersen particle fractionating sampler) with a pre-separator stage able to remove particles with aerodynamic diameter > 10 microns. Analysis of the particle samples was performed by a scanning electron microscopy (SEM) equipped with a thin-window system for X-ray microanalysis by energy dispersion spectrometry., Results: The Hierarchical Cluster Analysis (HCA) of the analytical data revealed the presence of seven different particulate types (particle clusters) in the sampling sites: C-rich particles (cluster 1); Ca and Mg carbonates (cluster 2); Ca sulphates (cluster 3); silica particles (cluster 4); silicates (cluster 5); Fe-rich particles (cluster 6); metal compounds (cluster 7)., Conclusions: Data obtained in this study demonstrated a significant correlation between the "coarse" fraction (PM10-2.1) composition and the characteristics of the sampling site. On the contrary the "fine" fraction (PM2.1) composition showed an unexpected uniformity in all the environments.

The carbonaceous material, present especially in the respirable atmospheric particulate, is emitted directly from the combustion processes and it is composed of an organic fraction, organic carbon (OC) and of a fraction which is resistant to oxidation at temperatures below approximately 400 degrees C, elemental carbon (EC). In this paper OC and EC concentrations are reported measured in downtown Rome and in a park, Villa Ada, by means of an analyzer which utilizes the thermal properties of the particles. The temporal trends of EC and OC in Rome are in good agreement during the entire period investigated (correlation coefficient between 0.86-0.90). On the other hand the comparison with Villa Ada shows a different contribution from secondary origin pollutants. The carbonaceous fraction in the total particulate mass, measured by means of a TEOM analyzer, varies between 30-40% in downtown and 20-25% in the park, respectively.

The antibacterical activity of prodigiosin varies according to the C/N ratio in the cultural media for S. marcescens. In organic media, as nutrient agar, peptone or soytone, the optimal ratio lies between 4 and 5, and higher values are required for "mineral media" where the nitrogen source is essentially an ammonium salt. The separate C source would be probably used as "acetate source" for the synthesis of the terminal alkylpyrrole.