Downtown Rome Research Articles

GPR application to the structural control of historical buildings: two case studies in Rome, Italy

ABSTRACTPreservation of historical buildings requires particular care, as any intervention must not alter or damage the style, structure or contents of the edifice. In order to properly plan the restoration of a building, non‐destructive techniques can be used extensively to detect structural elements and weaknesses. Ground‐penetrating radar (GPR) is particularly well adapted to this type of work, as the method is non‐invasive, rapid and provides high‐resolution images of contrasting subsurface materials.In the present work we show the successful application of the GPR technique to the investigation of two historical buildings that differ in age, structure and geometry.The first case is the GPR detection of fractures and internal lesions in the architrave of the Porticus Octaviae, a partially restored Roman building. The second case uses GPR in the important Zuccari Palace to determine the internal structure above vaulted ceilings that host a series of 16th century frescos. Both buildings are located in downtown Rome, Italy.These examples show that GPR can give detailed, non‐invasive data that describe the state of conservation of historical buildings. In particular, this technique can produce fundamental information for the restorers (e.g., location, dimension and geometry of the structural lesions) that will help them develop the best possible protection plan, retrieving quantitative information about the location and the dimension of the lesions as well as the thickness of the different layers.

Particulate organic acids in the atmosphere of Italian cities: Are they environmentally relevant?

Mono- and dicarboxylic n-alkyl acids were extensively investigated in downtown Rome, Italy, and in Montelibretti, ∼30 km NE of the city, during 2005–2007. Congeners ranging from lauric to mellisic, and from succinic to α,ω-docosanedioic acids were evaluated as well as phthalic, palmitoleic and oleic acids, by solvent extraction of airborne particulates followed by derivatization with propanol in the presence of boron trifluoride, and gas chromatographic-mass spectrometric analysis. Shorter measurements were made in Milan, in Taranto, at suburban and rural sites of Italy, and in the polar regions, from 1996 to 2005. The predominance of palmitic and stearic acids observed elsewhere was confirmed, and the behaviour of azelaic and phthalic acids resulted strongly dependent upon the year season. In the urban sites, among the long-chain compounds, the lignoceric acid was usually the most abundant, while the cerotic, montanic and mellisic homologues cumulatively never exceeded 8% of the total. Unlike other contaminants, the concentrations of organic acids remained fairly invariant over the last decade, suggesting that more attention must be paid to them in the future.

Assessing the applicability of fractional order statistics for computing confidence intervals for extreme quantiles

The main aim of frequency analysis of hydrological data is the definition of the quantiles with a given return period, also known as return levels, namely, the values x T of a hydrological variable X exceeded on average once in T time intervals. To make the analysis effective, these values have to be complemented with information about their uncertainty, which is usually quantified by confidence intervals (CIs). The paper discusses and compares some parametric, non-parametric, and simulation techniques to build CIs for quantiles with emphasis on the extreme ones. In particular, the work focuses on the usefulness of fractional order statistics to compute CIs for quantiles. This approach appears attractive as it involves simple analytical formulas and allows computing fully non-parametric CIs without requiring information about the parent distribution of the data. Since CIs for order statistics can be used to approximate CIs for quantiles based on order statistics, the relation between them is explored as well. The applicability of methods based on order statistics is assessed by studying the actual coverage probability through simulations, and applying these approaches to annual maximum peak discharge records from 22 streamgage stations in the continental United States and a streamgage station downtown Rome, Italy. For extreme quantiles, results show that these techniques are generally outperformed in term of coverage probability by other methods, such as Monte Carlo approach, when the parent distribution is well-specified or mis-specification involves distributions with tail behavior similar to the one used to generate the sample. On the other hand, the application to real world data indicates that the values of confidence limits based on order statistics are close to those obtained by Monte Carlo approach. In particular, the upper limits from non-parametric setups often result in cautionary values.

Atmospheric VOC composition in downtown Rome in the last fifteen years

Atmospheric VOC composition in downtown Rome in the last fifteen years

Heavy metal determination in atmospheric particulate matter by Instrumental Neutron Activation Analysis

Instrumental Neutron Activation Analysis (INAA) is employed for its important analytical properties. Fundamentally, INAA is a multi-elemental technique allowing the determination of about 40 elements with a good Limit of Detection. In this paper we applied this nuclear technique to study the element composition in PM10 determining about 30 elements. 25 filters were collected in downtown Rome from October 1999 to April 2000 and irradiated at the nuclear reactor Triga Mark II (ENEA-Casaccia Laboratories). The γ-ray measurements have allowed the quali- and quantitative analysis. The element levels in PM10 with the relative correlations have been determined: basically, the concentrations are very low. Furthermore, the enrichment factors of all elements will be reported in order to understand the natural or anthropogenic origins of the particulate matter: some elements may be attributed to long-range transport phenomena from other natural and/or anthropogenic sources.

Characterization and distribution of mineral content in fine and coarse airborne particle fractions by neutron activation analysis*

Nowadays, much attention is devoted to the study of toxic elements at trace and sub-trace levels in the investigation of particulate matter composition, especially in PM10 and PM2.5. Furthermore, it should be considered that the behavior knowledge is an other important task for understanding such species. Finally, the determination of particular elements with a few data in literature can assume relevant importance in industrial processes (Pd, Rh, Ir, etc. for catalytic pot, Sm, Ce, Eu, etc. for optical fibers and electronic process). In this article, we apply a nuclear technique, i.e. Instrumental Neutron Activation Analysis, for the study of metal composition in fine and coarse fractions. This nuclear technique allows the determination of about 25 elements: for some of them, this is the first determination in the ambient air of Rome. The investigation was performed in a reserved area in downtown Rome during a 15-day intensive campaign. The sampled filters were irradiated at the nuclear reactor Triga Mark II (ENEA-Casaccia Laboratories) at neutron flux of 2.6 × 1012 n cm−2 s−1 for 32.55 h. The measurements of the γ-ray allow the qualitative and quantitative analysis. The element levels in fine and coarse fractions will be shown with the correlations among some elements being more interesting in the toxicological field: basically, the concentrations are very low. * Presented at the 10th EuCheMS-DCE International Conference on Chemistry and the Environment in Rimini on 4–7 September 2005.

PHYSICO-CHEMICAL ARTEFACTS IN ATMOSPHERIC PAH DENUDER SAMPLING

Two annular diffusion denuder-filter samplers were operated concurrently to assess sampling artefacts arising from possible breakthrough of gas-phase PAH, blow-off of particle-bound PAH and degradation due to atmospheric ozone. The results of a field investigation held at Montelibretti (Rome, Italy) indicate that such artefacts are minimized or avoided when 6 h air samples are collected at 6 L min−1 and an ozone scrubbing denuder is placed at the beginning of the sampling train. The partitioning of semi-volatile PAH followed closely that previously observed in downtown Rome but their absolute concentrations were up to an order of magnitude lower.

Sediment transport time series in the Tiber River

The hydrologic regime of the Tiber River basin in central Italy has been impacted considerably in the last decades by intensive anthropic activities, and hydraulic works in particular (e.g. hydropower reservoirs, land use modification). In the Tiber River the wash load, in particular, plays an important role in sediment transport, and the knowledge of this hydrological variable is very important for the evaluation of medium–long-term dynamic of shoreline, and the evaluation of reservoir landfill. The Ripetta flow gauge, located in downtown Rome, has been continuously monitoring the daily discharge for decades, while daily sediment load measurements are available only for short terms. In this research, the yearly sediment rate is simulated using a simple stochastic model based on the evaluation of sediment rating curves. The sediment rating curve, i.e. the average relation between discharge and suspended sediment concentration for a specific location, is estimated using a power law model. The fitting curve, obtained by regression analysis, lacks the physical characterization of the phenomenon, often represented by the empirical evidences of erosion severity and the erosional power of river. Model results provide useful insights on the impact of recent hydraulic works on the sediment transport regime.

Measurement of phase-distributed nitrophenols in Rome ambient air

Atmospheric nitrophenols (NPs) were determined both in the gas and particle phases by combining the annular denuder sampling technique with GC–MS analysis. The phase distribution of six mono-NPs identified in air sampled in downtown Rome was assessed. 4-NP, 3-methyl-4-NP and 2,6-dimethyl-4-NP were found for more than 75% in the particle phase, whilst 2-NP, 4-methyl-2-NP and 5-methyl-2-NP predominated in the gas phase. Concentration levels lower than 20 ng m −3 were observed for all NPs, among which 4-NP (17.8 ± 5.6 ng m −3) and 2-NP (10.4 ± 4.2 ng m −3) were the most abundant congeners in the two phases, respectively.

Carbonaceous Aerosol in the Breathable Particulate Matter (PM10) in Urban Area

Carbonaceous material is a large fraction of urban aerosol and it is classified into Elemental Carbon (EC) and Organic Carbon (OC). EC particles are emitted from combustion sources. Because most combustion sources are anthropogenic and generally EC does not undergo chemical transformations, EC is a good indicator of primary anthropogenic primary pollution. OC particles species are emitted from primary emission sources either anthropogenic or biogenic sources. In this paper we have measured the ground concentration of Particulate Matter (PM), Total Carbon (TC), EC and OC in two Monitoring Stations in Rome. The first station is situated downtown Rome (near S.M. Maggiore Cathedral) where the traffic emission flux is strong. The second station is located in the inner a green park (Villa Ada Park): this site is not directly influenced by anthropogenic emissions. The results show that in Rome the TC contribution is about 30% of PM and the OC/EC vary between 0.5 and 1.5 according to the site we are considering. About the chemical particle composition the long-chain carboxylic have been identified as major constituent of organic aerosol and a range values are reported for two important compound class, the Polyciclic Aromatic Hydrocarbons and the nitro-PAHs wich are at very low levels.

Determination of phase-distributed PAH in Rome ambient air by denuder/GC-MS method

Abstract An annular denuder—filter sampler has been tested for determination of both gaseous and particulate polycyclic aromatic hydrocarbons (PAH) in air. Collection efficiency and capacity over 6-h sampling at an air flow rate of 6 l min −1 were assessed. Concentrations were measured and phase distributions of the most important 2–6 ring PAH in air samples collected in downtown Rome during November 2002 to April 2003 were determined. The 2- and 3-ring PAH were found for more than 90% in the gas phase, whilst congeners with more than 4 rings were present almost entirely in the particle phase. Comparison with a high-volume filter—PUF sampler showed that similar results for total PAH contents (gas + particle) were observed only for congeners with molecular mass higher than 178 (phenanthrene and anthracene).

Sources and photodecomposition of formaldehyde and acetaldehyde in Rome ambient air

Atmospheric levels of formaldehyde and acetaldehyde as well as their diurnal and seasonal variations were investigated from 1994 to 1997 in downtown Rome during sunny and wind calm days. Hourly concentrations of formaldehyde ranged from 8 to 28 ppbV in summer and 7 to 17 ppbv in winter; acetaldehyde concentrations varied correspondingly within the 3–18 and 2–7 ppbv intervals. Percentages of both aldehydes photochemically produced were estimated through a simple relationship based upon the comparison of individual ratios of formaldehyde and acetaldehyde to toluene in ambient air and automobile emission. Photochemical production was found to weigh upon atmospheric levels for 80–90% in summer days. It dropped below 35% in the winter period, when direct emission from traffic largely predominated. Photochemical summer source was more efficient for acetaldehyde than for formaldehyde, especially in the early morning. The importance of formaldehyde as the major source of hydroxyl radicals in Rome was also assessed.

OBSERVATION OF ORGANIC ACIDS IN ATMOSPHERIC AEROSOLS IN THE ROME PROVINCE TERRITORY

Congener distribution and seasonal variation of organic acids in aerosols colleted in downtown Rome and its outskirts have been investigated.Acetic and palmitic acids were the most abundant among short- and long-chain aliphatic acids, respectively. A different behaviour of the two groups has been observed, indicating that photochemical and vegetative sources were predominant in different periods of the year. In the outskirts of Rome the total content of n-alkanoic acids was equal or higher than in the city centre.

Size distribution of organic components in aerosol in downtown Rome

Size distribution of organic components in aerosol in downtown Rome

Distribution of n-alkanes, polynuclear aromatic hydrocarbons and nitrated polynuclear aromatic hydrocarbons between the fine and coarse fractions of inhalable atmospheric particulates

The distribution ratios of n-alkanes, polynuclear aromatic hydrocarbons (PAHs) and nitrated PAH components between fine and coarse fractions of soot has been investigated in downtown Rome through three field campaigns carried out at different times of the year. The preferential accumulation of almost all species investigated onto fine particles has been observed in all field experiments performed. Moreover, nitrated PAHs had varied distributions, according to the origin of their occurrence in the atmosphere; in fact, congeners of photochemical origin accumulated more in fine particles than those released by primary sources.

Seismic response in archaeological areas: the case-histories of Rome

Rome is affected by earthquakes associated to three different seismogenic districts: the Central Apennines area, the Colli Albani volcanic area and the Roman area. The major effects were exclusively due to Apennine seismicity and reached in some cases felt intensities up to VII–VIII degree (MCS scale). The predominant role in the damage distribution seems to be played by the local geological conditions. The historical centre of the city is characterized by the presence of two geomorphologic domains: the alluvial plain of Tiber river and the topographic relieves of Roman Hills, where tradition indicates the first site of the city foundation. In particular, the right river side is characterized by the outcropping of the regional bedrock along the Monte Mario–Gianicolo ridge, while the eastern relieves are the remnants of the Sabatini and Albani volcanic plateau, deeply eroded by the Tiber river and its tributaries during the last glacial low-stand (Würm). These domains are characterized by a large difference in seismic response, due to the high impedance contrast between Holocene coarse deposits filling the Tiber Valley and sedimentary and volcanic Plio–Pleistocene units. Seismic damage observed in 150 monuments of downtown Rome was indicating a significant concentration on alluvial recent deposits. This result was confirmed by the geographical distribution of conservation and retrofitting activities subsequent to main earthquakes, mostly related to local geological conditions. The cases of Marcus Aurelius' Column and Colosseum confirmed the influence of the Holocene alluvial network in local seismic response. During 2500 years of history, the monuments of Rome have `memorized' the seismic effects of historical earthquakes. In some cases, the integration of historical and geological research and macroseismic observations may provide original and useful indications to seismologists to define the seismic response of the city. Local site effects represent a serious threat for historical buildings in Rome and in other historical towns with similar cultural heritage and geological characteristics, as in the Mediterranean region, even in areas that are not affected by a local seismic activity.

Distribution of effects in the urban area of Rome During the October 14, 1997 Umbria Marche earthquake

In the last years many studies were carried out in order to assess the correlation between nearsurface geology and seismic response of downtown Rome during local and regional earthquakes. Nevertheless, only historical macroseismic data and theoretical modelling could be used so far to estimate the ground motion in the historical part of the city. The occurrence of the October 14, 1997 Umbria Marche event (Mw = 5.7), located about 115 km far from Rome but largely felt in the city, allowed us to verify our knowledge of the seismic response on the basis of the present urban setting of Rome.A prompt macroseismic survey in the urban area within the ring-road (G.R.A.) was performed. 949 questionnaires were compiled by means of 1842 interviews: such a large amount of macroseismic information, for the first time available in Rome, was related to 669 observation points providing a picture of local intensity variations. The areal distribution of collected intensity points is quite homogeneous.The data analysis points out a preferential distribution of larger effects (65%) in correspondence of Holocene alluvium outcrops. Furthermore, a tight correspondence between remarkable intensities and alluvial sediments is pointed out in suburban areas characterized by the minor hydrographic network of the Tiber River. Macroseismic anomalies were outlined in sectors of the urban area where local hydrogeological conditions can be responsible for a significant deterioration of geomechanical properties.