[Show abstract][Hide abstract] ABSTRACT: The objectives of the project were to assess the critical relationships between environmental factors and damage of the artifacts and other cultural property exposed inside museums, by studying: (a) the outdoor/indoor pollutant concentration and their transfer inside the museum; (b) the distribution and circulation of pollutants inside the museum influenced by various factors; (c) chemical interactions between pollutants in the gas phase leading to removal and/or formation of secondary pollutants; (d) the final deposition of the indoor pollutants on surfaces of artistic interest and the damage on them, governed by strictly defined physicochemical parameters. All the above information, together with the main factors influencing each stage, were obtained by applying the methodology developed and described in detail here. Measurements of rate constants of reactions in the gas phase, of physicochemical deposition parameters on artefacts, and the synergistic effects of pollutants on the deposition parameters, were conducted. Seven PC programmes for analysing the experimental data were written and used. The pollutants, the solid materials and the museums chosen in this programme are only examples needed to develop the necessary methodology. The numerical results obtained serve the purpose of exemplifying the procedures and not enriching the world's bibliography with useless empirical information. Two commercially available protectives for marble were investigated from the point of view of their reactivity towards SO2 by using a diffusional technique. From measurements of SO2 concentration carried out on three types of marble, the deposition velocities have been calculated. Indoor monitoring of the church of San Luigi dei Francesi and of the Museo della Civiltá Romana in Rome has shown that indoor production of nitrous acid most likely results from heterogeneous reactions indoors, on the walls and the exposed surfaces.
[Show abstract][Hide abstract] ABSTRACT: Since conventional badge-type samplers depend entirely on an empirical calibration against gas mixtures and use of the constant determined for calculations, a system based on the use of two badge-type passive samplers of different lengths has been studied for the determination of NO2 or SO2. The samplers make use of a filter membrane barrier to damp out eddy motions and promote molecular diffusion from the ambient air to the trapping medium. The badges have a large ratio of crosssectional area to length of diffusion in order to increase sensitivity. Diffusion theory applied to this configuration shows that the concentration results are independent of wind-flow velocity. The samplers have been evaluated at different levels of relative humidity ranging from 0% to 90%. Batches of samplers were exposed for 48 h side-by-side with samplers exposed for consecutive periods of 24 h over the same interval. The results, expressed as a ratio (R) between the 48 h and the consecutive 24 h periods showed that the analytes collected (nitrite and sulphate) are stable (R = 0.98 ± 0.05 for nitrite and R = 1.08 ± 0.09 for sulphate). The detection limit attained (5 ppb of NO2 and 10 ppb of SO2 for a 24 h sampling) is adequate for the determination in urban and rural areas. The accuracy of the proposed method, expressed as percent relative error, when compared to a standard denuder technique for NO2 and SO2, was found to be better than about ±10% with coefficient of variation of 5.5% and 6.5%, respectively.
[Show abstract][Hide abstract] ABSTRACT: Simultaneous indoor and outdoor samples collected in the Church of San Luigi dei Francesi were analyzed for nitrous acid, sulphur dioxide, nitrogen oxides and ammonia in the gas phase and for ammonium, sulphate, and nitrate ions in the particulate matter. Indoor levels of nitrogen oxide, nitrous acid and ammonia were found to largely exceed those outdoors. For NO1, and SO2 lower indoor levels were always measured, while for nitrate and sulphate, the indoor/outdoor ratios ranged from 0.5 to 3.5. These results show that indoor production of nitrous acid could result from heterogeneous reactions indoors, on the walls and exposed surfaces. Furthermore, they demonstrate that non-reactive species such as nitrogen oxide and particles penetrate indoors, where they remain segregated and are very slowly depleted, due to their small deposition velocities.
International Journal of Environmental Analytical Chemistry 09/1996; 64(1):71-81. DOI:10.1080/03067319608028336 · 1.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A diffusion denuder for simultaneous collection of ambient nitrogen dioxide and peroxyacetyl nitrate (PAN), based on quantitative collection on an alkaline active carbon surface, has been developed. Nitrogen dioxide yields nitrite anion whereas PAN yields nitrate which are extracted after sampling with water and analysed by ion chromatography. Laboratory and field tests concerning sorption efficiency, effect of humidity and capacity were carried out. The pre-exponential and exponent for the first term of the Gormley-Kennedy equation applied to annular geometry were estimated. It was found that for PAN the agreement between the experimental and calculated values is quite good and compatible with a “perfect sink” behaviour of carbon, whereas, in the case of NO2, the experimental collection efficiency is lower than theory but still suitable for ambient sampling.Nitrogen oxide and ozone do not interfere in the determination. SO2, HONO and HNO3 which could interfere can be removed by using two diffusion denuders placed in line before the carbon denuder: one coated with tetrachloromercurate (TCM), for the removal of SO2 and HNO3, and the second, coated with carbonate, for the removal of HONO. The detection limit for 24 h sampling is better than 0.05 and 0.06 ppb for NO2 and PAN, respectively. The response for NO2 was compared during a field campaign in Milan with the corresponding integrated response of a chemiluminescence analyser, while data for PAN were compared with the integrated response of a GC-ECD technique. The results obtained are reported and discussed.