M. Caselli

Assessment of the impact of the vehicular traffic on BTEX concentration in ring roads in urban areas of Bari (Italy).

A BTEX monitoring campaign, consisting of two weekly periods, was carried out in Bari, south-eastern Italy, in order to evaluate the impact of the vehicular traffic on the air quality at the main access roads of the city. Twenty-one sampling sites were selected: the pollution produced by the traffic in the vicinity of all exits from the ring road and some access roads to the city, those with higher traffic density, were monitored. Contemporarily the main meteorological parameters (ambient temperature, wind, atmospheric pressure and natural radioactivity) were investigated. It was found that in the same traffic conditions, barriers, buildings and local meteorological conditions can have important effects on the atmospheric dispersion of pollutants. This situation is more critical in downtown where narrow roads and high buildings avoid an efficient dispersion producing higher levels of BTEX. High spatial resolution monitoring allowed both detecting the most critical areas of the city with high precision and obtaining information on the mean level of pollution, meaning air quality standard of the city. The same concentration pattern and the correlation among BTEX levels in all sites confirmed the presence of a single source, the vehicular traffic, having a strong impact on air quality.

Particulate PAHs in two urban areas of Southern Italy: Impact of the sources, meteorological and background conditions on air quality.

The present work studied how much the meteorological parameters and the emission sources can influence the particulate polycyclic aromatic hydrocarbons (Invalid Journal Information PAHs) concentrations in two areas located in Southern Italy (Bari and Taranto). It was found that when the vehicular traffic is the main source of PAHs, there is a negative correlation between ambient temperature, wind speed and PAHs concentration (Bari). This is because these parameters are generally correlated with the dispersion capacity of the atmosphere. In the presence of a large industrial area, the wind direction becomes an important parameter able to determinate large changes in PAHs concentrations. This happened in Taranto where PAHs concentrations are exceptionally high. During the study the seasonal trend of particulate PAHs and PM10 was compared. PM10 did not show a significant seasonal cycle during the year because it is conditioned from a high regional aerosol background, especially during the summertime. On the contrary, particulate PAHs exerted distinct seasonal variation with higher concentrations in the winter and lower concentration during other months of the year. This evidence suggested that PAHs concentrations can be considered a more reliable index for air-quality assessment. In order to identify an index that considers the contributions of other particulate PAHs, it is necessary to calculate the carcinogenic potency of total PAHs (i.e., total BaPeq) obtained by the sum of the benzo[a]pyrene equivalent concentration (BaPeq) for each PAH.

Monitoring of volatile organic compounds in non‐residential indoor environments

UNLABELLED A weekly monitoring campaign of volatile organic compounds (VOC), with single sampling of 24 h, was carried out in non-residential indoor environments such as libraries, pharmacies, offices, gymnasiums, etc., in order to evaluate the VOC concentrations to which people are exposed. Moreover, an outdoor sample was coupled to each indoor site to point out the influence of indoor sources. They were sampled with Radiello diffusive samplers for thermal desorption and analyzed by GC-MS. As already described in other papers, the VOC levels of most of the indoor sites were higher than that observed in the corresponding outdoor sites. For example, some sites showed a level of pollution that is ten times higher than their corresponding outdoor site. The monitored environments that had higher concentrations of the investigated VOC were the pharmacies, a newspaper stand, a copy center, and the coffee shops. Analysis of the weekly average concentrations of each pollutant and the use of literature allowed pointing out some site-specific characteristics that singled out possible sources of VOC. These results were verified analyzing the indoor-outdoor ratio (I/O) too. Newspaper stands were characterized by very high concentrations of toluene and pharmacies were characterized by high concentrations of aromatic compounds. PRACTICAL IMPLICATIONS Indoor air pollution caused by volatile organic compounds (VOC) might affect human health at home as well as in public and commercial buildings. The main VOC sources in indoor environments are human activities, personal care products, smoking, house cleaning products, building products, and outside pollution. To preserve human health it is necessary to evaluate the average concentrations of VOC to which people are exposed and to identify the main sources of indoor pollution by means of suitable indoor monitoring campaigns in several environments. These investigations allow pointing out the characteristic critical situations of some indoor environments or some other types of environments.

Determination of nutrients in the presence of high chloride concentrations by column-switching ion chromatography

Determination of inorganic anions in waters of high salinity is one of the most difficult task in analytical chemistry. A simple column-switching method, based on an original chromatographic set-up, for the determination of nutrients (nitrate, nitrite and phosphate) in chloride rich aqueous matrices is presented. A pre-separation system (made of two in line pre-columns, Dionex AG9-HC 4 mm) connected to an analytical column (Dionex AS9-HC 4 mm) by a four way pneumatic valve, allows chloride to be eluted off into the waste and nutrients to be separated and detected by a conductimeter and/or a UV spectrophotometer. Neither chemical pre-treatment nor sample dilution are required; sample matrices presenting a large range of chloride concentrations can be investigated. Moreover by using this technology, automation for routine analysis, low analysis time and low costs can be achieved. LODs of 100, 300, 1000 microg/l for nitrate, nitrite and phosphate, respectively, have been obtained by spiking a synthetic sea water sample containing 20,000 mg/l of chloride and 3000 mg/l of sulphate. Analyte calibration curves of analytes are linear (r>0.99) in the range between the LODs and 60 mg/l. This method was applied to nutrients determination in sea water samples collected near a river outlet.

Determination of polycyclic aromatic hydrocarbons (PAHs) in particulate matter collected with low volume samplers.

The determination of polycyclic aromatic hydrocarbons (PAHs) contained in samples of particulate matter (PM), collected with low volume pumps, were carried out with an high sensitivity method that comes from several revisions of a previous method. The present work describes how, by using programmable temperature vaporization (PTV) and a mass selective detector with inert ionic source for the GC-MS analysis and the modifications of microwave-assisted extraction (MAE), the sensitivity of the method can be increased. The PAHs chosen for testing the method are: benzo[a]anthracene (BaA), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (Ip) and dibenzo[a,h]anthracene (DbA). They, in fact, belong to that group of substances that are the most harmful for human health for their carcinogenicity. PAHs recoveries for spiked standard solutions at different concentrations were between 95 and 100% with relative standard deviation ranging from 1 to 3%. The revised method was validated using a 1649a urban dust standard reference material (SRM). The results obtained were in good agreement with certified values. The high sensitivity of the method allows to carry out analyses using only a half of the sampled filter (usually 47mm diameter membranes). In this way, the other half can be used for the characterization of the other components of PM (heavy metals, organic carbon, ions, etc). The last step has been constituted by application of the optimized method on real samples collected in two cities located in Southern Italy (Bari and Taranto).

Indoor contaminants from newspapers: VOCs emissions in newspaper stands

Mean volatile organic compound (VOC) concentrations in 16 newspaper stands and in two printing shops were monitored for the purpose of quantifying the various VOCs in these areas and to relate the results. In each site halogenated, oxygenated, aliphatic, and aromatic compounds were monitored during one workweek. They were sampled with diffusive samplers for thermal desorption and analysed by GC-MS. The results showed that in all newspaper stands the indoor levels of toluene were much higher than the outdoor levels; some sites had toluene indoor concentrations 100 times higher than their correspondent outdoor levels. The investigations in two printing shops confirmed that newspapers, in particular the inks, are the main sources of toluene in the newspaper stands.

Adsorption of lead(II) chloride by chronoamperometric measurements

Summary Chronoamperometry with linear potential scanning has been used to measure the adsorption of lead (II) on a mercury electrode surface as a function of the concentration of chloride, nitrate and perchlorate in the lead solution. It has been found that the experimental β o values cannot be interpreted only as a function of the distribution of lead(II) among the different complexes with Cl − and NO 3 − ions. If the competitive adsorption of these ions is considered, two different mechanisms may explain all the experimental data: the adsorption of the particle PbCl 3 − via one adsorbed Cl − according to: PbCl 4 2− +Cl ads − ⇄PbCl 4 ads 2− , or the adsorption of PbCl 4 2− according to: PbCl 4 2− ⇄PbCl 4 ads 2− . The second mechanism seems to be more likely. In the latter case, assuming for Γ PbCl 4 2− s -a value for 1/4 Γ Cl − s =10 −10 mol cm −2 , an equilibrium constant for a Langmuir linear isotherm of 8.3×10 −8 mol cm −3 was obtained. From the dependence of K PbCl 4 2− on the temperature, values of Δ H =12 kcal mol −1 and Δ S =7.9 cal deg −1 mol −1 were calculated. Chronoamperometry presents the same order of precision, accuracy and sensitivity as the other methods and is a good technique for gaining rapid information about the adsorption mechanism of any system that is able ro react on the electrode surface.

Simultaneous determination of SO2, NO and NO2 in air by differential pulse polarography

Abstract The method of Garber and Wilson for SO 2 determination has been tested on real samples of air. The results demonstrate the possibility of simultaneous determination of SO 2 , NO and NO 2 in the sample. Detection limits as low as 7 μl/m 3 for SO 2 and about 50 μl/m 3 for nitric oxides can be reached.

Analysis of heavy metals in atmospheric particulate by ion chromatography

Cu, Ni, Zn, Co, Fe+2, Mn, Cd, Fe+3 and Pb are easily separated and detected in isocratic mode by ion chromatography with post-column derivatization using a bifunctional ion-exchange column and an eluent formed by oxalic acid (28 mM) and sodium nitrate (250 mM). The separation is optimised by using a suggested sample solution containing a given concentration of chloride. Detection limits were 10-15 ppb for all the metals except for cadmium and lead, for which detection limits of 30 and 60 ppb were found, respectively. The method was tested on an atmospheric particulate certified sample. The measured values were in good agreement with certified values. Real samples of atmospheric particulate from industrial and urban sites were analysed and the results are discussed.

A polarographic investigation on the equilibrium constants of crown complexes in alcoholic solutions

Abstract The complexation constants of sodium, potassium, and cesium salts with crown compounds have been measured polarographically in methanol, ethanol, and n-propanol. For each ion the equilibrium constant increases with the decreasing polarity of the solvent. In all solvents the constant relative to K+ ion presents the greatest value. The results are discussed taking into account the solvation energy of the ions in different solvents; the ratio between the ionic radius and the radius of the cavity of the complexing agent; and the interaction between the ion and the dipole groups of the ligand.