Influence of natural events on the concentration and composition of atmospheric particulate matter

A ten-month field study aimed to determine the contribution of natural events (i.e. sea-salt and mineral dust events) to urban PM concentration was carried out at six sampling sites in Central Italy (Lazio region). Four indicators have been used to identify natural events during the period of the study. The first one is constituted by the ratio between number of particles in the coarse to the accumulation mode. It is simple, cheap, and the information are given in quasi-real time, but the nature of the event (sea-salt or mineral dust) is not detectable. The second indicator relies on the chemical analysis of the collected PM by X-ray fluorescence (XRF) and allows a robust identification of sea-salt and crustal components. The third one is based on diagnostic ratios of elemental fractions: Mg_extractable/Ti_residue for sea-salt and Ti_residue/Sb_residue for mineral dust. It requires skilled staff but it is most accurate and sensible. The last indicator, constructed on the basis of natural radioactivity data, is not diagnostic for the nature of the event but it is able to estimate the increase in PM concentration with respect to the expected concentration in the absence of natural events.The relevance of natural events and the variations in PM concentration and composition during the study are discussed. The joined use of the four indicators allowed the identification of about 20 natural PM episodes. In general, sea-salt aerosol events did not cause exceedance of the daily EU limit value for PM₁₀. Saharan dust events, instead, were in most cases responsible for the exceedance of the limit value at all stations.     

Multiparametric approach for an exemplary study of laser printer emissions

The aim of this work was the study, by a multiparametric approach, of emissions from a laser printer in an experimental box-chamber, with particular attention to nanoparticles release. The experimental design included number concentration measurements by Fast Mobility Particle Sizer (FMPS) and chemical characterizations (elements) of size segregated samples collected by Nanomoudi cascade impactor. Volatile Organic Compounds (VOCs) were also sampled by charcoal sorbent tubes by personal sampling pumps. Monitoring of ozone, total volatile organic compounds concentrations and of temperature and humidity values inside the experimental box during the printing processes were also performed by automatic analyzers. The performed monitoring allowed to evidence different ways for particles emissions by laser printers, in particular showing that nanoparticles, characterised by high concentrations of Ba, Zn, B, K, Sr and Na, are set free at the beginning of the printing process. This emission seems to be directly ascribable to the use of toner powder, as all these elements are present in it. The emission of larger particles (ca. 100-320 nm) was observed in subsequent phases of the print process, probably due to the condensation of vapours released during the progressive heating of the fuser roller. This contribution was proved by both the FMPS measurements and the cascade impactor results. Also, a low emission of particles in higher size ranges was evidenced, mainly due to paper related particles. A very high concentration of VOCs was detected inside the chamber and the chemical speciation shows that the major contribution is associated to toner components, even if some species are released from other printer components. Although the formation of secondary species by reaction of VOCs with ozone cannot be excluded, these species were present inside the chamber at concentrations lower than the detection limit.     

Improved characterisation of inorganic components in airborne particulate matter

We set up a microanalytical procedure for non-volatile ions by ion chromatography (IC) and for elements by energy-dispersive X-ray fluorescence (ED-XRF) and inductively coupled plasma optical emission spectroscopy (ICP-OES). We analysed NO₃, SO₄, NH₄, Na, Mg, Ca, Fe, S, Zn, As, Cd, Cu, Mn, Ni, Pb, Sb, Se, Ti, and V. The use of complementary techniques yields reliable data for both trace and crustal elements, overcoming the analytical restrictions characteristic of the individual techniques. Some elements determined by two or by all three techniques can be used as data quality markers. The application of the procedure to a short PM_2.5 monitoring campaign is also described, aimed to the identification of fireworks tracers.     

Inorganic constituents of urban air pollution in the Lazio region (Central Italy)

A field study was carried out at six locations in the Lazio region (Central Italy) aimed at characterising atmospheric particulate matter (PM₁₀ and PM_2.5) from the point of view of the chemical composition and grain size distribution of the particles, the mixing properties of the atmosphere, the frequency and relevance of natural events. The combination of four different analytical techniques (ion chromatography, X-ray fluorescence and ICP for inorganic components, thermo-optical analysis for carbon compounds) yielded sound results in terms of characterisation of the air masses. During the first three months of the study (October–December 2004), many pollution events of natural (sea-salt or desert dust episodes) or anthropogenic nature were identified and characterised. More than 90% of the collected mass was identified by chemical analysis. The central role played by the mixing properties of the lower atmosphere when pollution events occurred was highlighted. The results show a major impact of primary anthropogenic pollutants on traffic stations and a homogeneous distribution of secondary pollutants over the regional area. An evaluation of the sources of PM and an identification of possible reliable tracers were obtained using a chemical fractionation procedure.     

Biomonitoring of element contamination in bees and beehive products in the Rome province (Italy)

Environmental Science and Pollution Research - In this study, we determined the levels of elements (i.e. As, Be, Cd, Cr, Hg, Ni, Pb, U, and Zn) in bees and edible beehive products (honey, wax,...     

Two-stage chemical fractionation method for the analysis of elements and non-volatile inorganic ions in PM10 samples: Application to ambient samples collected in Rome (Italy)

A two-stage micro-analytical scheme for the determination of metals and ions in atmospheric particulate matter collected on only one Teflon filter was developed. In the first stage the collected particles are chemically fractionated for their solubility in a pH-buffered extracting solution; in the second stage the residue is mineralised. The major non-volatile inorganic ions (Cl⁻, NO₃⁻, SO₄²⁻, Na⁺, NH₄⁺, Ca²⁺, Mg²⁺) are determined in the first fraction by ion-chromatography (IC), while metals and metalloids (Al, As, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, S, Sb, Se, Si, Ti, V, Zn) are determined in both the acetate extractable and the mineralised residual fractions by inductively coupled plasma optical emission spectroscopy (ICP-OES).The procedure was applied to ambient 24-h PM₁₀ samples collected on Teflon filters during two field campaigns carried out at two sites in the area of Rome (Italy). The variations in the chemical composition of the collected particles during the two periods were interpreted in the light of the dilution properties of the lower atmosphere and of the back-trajectories of the air masses. The difference in the results between the two locations was interpreted in the light of their proximity to the emission sources. It was found that the acetate extractable and the mineralised residual fraction of some metals exhibit a different temporal pattern, suggesting the existence of different emission sources of the two fractions.     

Monitoring heavy metal pollution by aquatic plants

Introduction

The copper bioaccumulation by the floating Lemna minor and by the completely submerged Ranunculus tricophyllus as a function of exposure time and copper concentration was studied, with the aim of proposing these species as environmental biosensors of the water pollution.

Results

The results show that both these aquatic angiosperms are good indicators of copper pollution because the copper uptake is the only function of metal concentration (water pollution).

Conclusion

Uptake behavior is reported as a function of the time and concentration, based on the results of a 3-year study. Kinetic evaluations are proposed.     

Seasonal variations in the chemical composition of particulate matter: a case study in the Po Valley. Part II: concentration and solubility of micro- and trace-elements

Size distribution (fine and coarse fraction) and solubility distribution (extracted and residual fraction) of 20 elements (As, Ba, Be, Cd, Co, Cu, Fe, Li, Mn, Pb, Ni, Rb, S, Sb, Se, Sn, Sr, Ti, Tl, V) in atmospheric particulate matter (PM) were determined during a 5-year field study carried out in the Po Valley (peri-urban area of Ferrara, in Northern Italy). By studying the contribution of the two size fractions and the two solubility fractions to the atmospheric concentration of each element, it was possible to obtain interesting information about the variability of PM sources, to assess the role played by atmospheric stability in determining pollution episodes, and to obtain an estimate of the bio-accessible fraction. Atmospheric stability is confirmed to be one of the main causes of atmospheric pollution in this area and is to be responsible for the pronounced winter increase in both PM and elemental concentration. Long-range transport of natural and polluted air masses caused temporary increases in PM and elemental concentration, while local industrial emission seemed to play a secondary role. Regulated elements were well below their concentration limit, but many toxic elements were in the form of fine particles and soluble chemical species, more accessible to the environment, and the human body.     

Enhancement of source traceability of atmospheric PM by elemental chemical fractionation

During a 1-year study (“Fine dust” Project) funded by the Lazio regional government (Italy), about 1000 daily PM₁₀ and PM_2.5 samples collected from six sites in the region were subjected to chemical fractionation based on differences in elemental solubility. In this way, it was possible to achieve meaningful characterization of the elemental composition of individual samples. For most of the investigated elements, we found significant differences between the extracted and the mineralized residual fraction. In general, fine particulate was best characterized by the composition of the extracted fraction, while coarse particles from traffic-related sources were best characterized using residues. For several metals (Cd, Pb, Sn, Sb and V) having a critical environmental impact, this result was particularly clear.The application of Principal Component Analysis (PCA) and receptor modelling (PCR) to the data set allowed us to evidence the enhancement of selectivity towards different emission sources that is obtained when chemical fractionated data are considered instead of total element content. Chemical fractionation seems to generate very selective markers for specific emission sources and in particular for re-suspended road dusts, one of the main factors responsible for the increase of elemental concentrations in urban areas.     

Inorganic constituents of urban air pollution in the Lazio region (Central Italy)

A field study was carried out at six locations in the Lazio region (Central Italy) aimed at characterising atmospheric particulate matter (PM₁₀ and PM_2.5) from the point of view of the chemical composition and grain size distribution of the particles, the mixing properties of the atmosphere, the frequency and relevance of natural events. The combination of four different analytical techniques (ion chromatography, X-ray fluorescence and ICP for inorganic components, thermo-optical analysis for carbon compounds) yielded sound results in terms of characterisation of the air masses. During the first three months of the study (October-December 2004), many pollution events of natural (sea-salt or desert dust episodes) or anthropogenic nature were identified and characterised. More than 90% of the collected mass was identified by chemical analysis. The central role played by the mixing properties of the lower atmosphere when pollution events occurred was highlighted. The results show a major impact of primary anthropogenic pollutants on traffic stations and a homogeneous distribution of secondary pollutants over the regional area. An evaluation of the sources of PM and an identification of possible reliable tracers were obtained using a chemical fractionation procedure.