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To improve ventilation efficiency and reduce pollution concentration in urban spaces, eco-strategies, including greening, have been suggested. However, there is still very little evidence to assert the benefits of such greening options, particularly at urban street intersections. Therefore, in this work, air flow and pollutant dispersion within urban-like three-way, four-way, and roundabouts intersections are investigated with three simple and five combined greening layouts. Three-dimensional computational fluid dynamics (CFD) analysis using the Reynolds-averaged Navier–Stokes model was conducted considering multiple wind directions. The ventilation efficiency was evaluated using the ventilation indices purging flow rate (PFR) and net escape velocity (NEV). The investigation of simple greening layouts shows that shrubs alone may enhance increase ventilation (i.e., increase PFR and NEV), and trees could increase the pollutant concentration at the pedestrian level. A comparison of greening layouts combining trees and shrubs shows that the presence of greening reduces ventilation and worsens the pollution condition at street intersections, except for shrubs located in the central zone within roundabouts. Specifically, NEV decreases by 16%–43% at four-way and three-way intersections owing to the presence of greening. Greening layouts with two rows of trees located 2.2 m away from buildings show overall significant negative effects on ventilation, particularly for wind directions ϕ = 0°, 45°, and 90°. The impact of shrubs and trees on ventilation at the roundabout is less significant, with NEV varying by 4%–11%.

Forty-six ancient gold jewelry, known as ‘Ori di Taranto’ and dated in Hellenistic period (VII–VI century bc), were found in Taranto (Southern Italy) and, nowadays, are exhibited in the National Archaeological Museum. These artifacts have never been analyzed, few information are reported in the bibliography, and nothing is known about their chemical composition. The aim of our work is to determine the chemical composition of the alloy and of eventual decorations present on the objects by using non-destructive, non-invasive, and in situ analysis. In particular, the samples were studied by energy dispersive X-ray fluorescence. Most of the analyzed samples show approximately same composition of the alloy (gold, silver, and copper, respectively equal to 96.3 ± 2.0% wt, 2.8 ± 1.9% wt, and 0.9 ± 0.3% wt) except nine samples. Multivariate statistical analysis was carried out in order; to identify possible correlations and/or differences of alloy composition among the analyzed samples. Experimental results obtained could be compared with other jewelry of the same historical period, and therefore, this study can help to understand the type of processing of gold jewelry in the Hellenistic period. Copyright © 2017 John Wiley & Sons, Ltd.

Parabens and phenoxyethanol are chemical compounds widely used as preservatives and antimicrobial agents in cosmetic and personal care products. The issue of their effect on human and environmental health is a particularly topical and relevant one that many national and international agencies reported about the risk from the use of such compounds. In the present paper, iron doped TiO2 nanoparticles were synthetized and characterized by morphological and spectroscopic techniques. The proposed synthesis was designed to improve the photocatalytic activity of the nanostructures towards the two preservatives compounds when irradiated by a visible light, in order to optimize the effect of natural irradiation on the photodegradation of the two compounds. Preliminary photocatalytic tests showed that the analytes’ concentration in water solutions under illumination in presence of both iron-doped TiO2 and pure TiO2 decreased. A sensible enhancement of photocatalysis of both propylparaben and phenoxyethanol was recorded in presence of the Fe-doped nanostructures as a consequence of the physical and chemical properties of the catalyst.

Forty-six ancient gold jewelry, known as ‘Ori di Taranto’ and dated in Hellenistic period (VII–VI century bc), were found in Taranto (Southern Italy) and, nowadays, are exhibited in the National Archaeological Museum. These artifacts have never been analyzed, few information are reported in the bibliography, and nothing is known about their chemical composition. The aim of our work is to determine the chemical composition of the alloy and of eventual decorations present on the objects by using non-destructive, non-invasive, and in situ analysis. In particular, the samples were studied by energy dispersive X-ray fluorescence. Most of the analyzed samples show approximately same composition of the alloy (gold, silver, and copper, respectively equal to 96.3 ± 2.0% wt, 2.8 ± 1.9% wt, and 0.9 ± 0.3% wt) except nine samples. Multivariate statistical analysis was carried out in order to identify possible correlations and/or differences of alloy composition among the analyzed samples. Experimental results obtained could be compared with other jewelry of the same historical period, and therefore, this study can help to understand the type of processing of gold jewelry in the Hellenistic period. Copyright © 2017 John Wiley & Sons, Ltd.

This paper discusses the combined influence of building morphology and trees on air pollutant concentrations in the Marylebone neighbourhood (central London). Computational Fluid Dynamics (CFD) simulations are performed with OpenFOAM using the k - e model. Aerodynamic and deposition effects of Platanus acerifolia trees are considered. While aerodynamic effects are treated as typically done in the literature, i.e. as a porous media, for the deposition an enhanced model with an additional sink term was implemented. CFD results are compared with UK AURN (Automatic Urban and Rural Network) station concentrations. Several meteorological conditions are analysed based on London City Airport weather station data, with attention to prevailing winds. CFD simulations show that trees trap air pollution by up to about 7% at the Marylebone monitoring station in the spring, autumn and summer seasons, suggesting that the aerodynamic effects are similar over the different leaf seasons. Aerodynamic effects are more important at lower wind speeds causing little turbulent dispersion. Deposition effects are found to be 4 times less important with reductions of up to about 2%, with more deposition in summer due to a greater leaf area density. Furthermore, for winds parallel to Marylebone Road, the aerodynamic effects decrease concentrations suggesting that in such cases trees could be considered as a mitigation measures. This is different from perpendicular winds for which trees exacerbate trapping, as found in previous studies. The analysis of concentration levels obtained from CFD simulations across the whole street confirms a beneficial aerodynamic dispersive effect of trees of 0.7% in summer time for all wind directions averaged at a wind speed of 5 m/s (yearly average wind speed observed in the area). Results highlight the need to account for both aerodynamic and dispersion effects of trees in CFD modelling to achieve a comprehensive evaluation and help city planners with a sustainable design of trees in urban environments.

A novel, flexible method to derive urban morphometric parameters is presented. Through selected examples, it demonstrates its employability in a wide range of applications. This method builds upon an extension of an image-based technique for the treatment of building data to discuss objective criteria for model grid choice and related consequences. Starting from an estimation of aerodynamic parameters, and their validation by computational fluid dynamics using an existing simulation of downtown Oklahoma City in the US, the method is used to evaluate improvements in the performance of an operational dispersion model. Results are applied to flow over a neighbourhood for the determination of ventilation parameters. It is suggested that the grid used for calculation of morphometric parameters provides the best agreement with data from laboratory experiments when the selection of grid size is made upon the spatial profile of building height standard deviation and maximum building height. The implication is that when a mesoscale numerical model is employed, morphometric parameters should be calculated by positioning the computational grid based on physical boundaries, while for finer resolution (namely, smaller scale) numerical models, morphometric parameters should be calculated using the street grid as external boundary, and the maximum building height criterion performs well.

Indoor air pollution assessment in work environments remains challenging due to a combination of logistic reasons and availability of costly instrumentation for data acquisition and post-processing. Existing literature focuses on energy production environments, hospitals, and less so on food production spaces. Studies on indoor air quality in bakeries are scarce or even absent. Motivated by this, the present study investigates indoor air quality in a bakery located in Bari province in South Italy, using a combination of approaches including analytical chemistry analyses and compu- tational fluid dynamics to reconstruct the air ventilation in response to air temperature gradients within the working environment. PM2.5 indoor samplings were collected every 6 h from 7 to 19 April 2013 in the proximity of two bakery ovens powered by gas and wood, respectively. For each sampling day, 4 PM2.5 samples were collected: from 3:00 to 9:00 h (first), from 9:00 to 13:30 h (second), from 14:00 to 21:00 h (third), and from 21:00 to 3:00 h (fourth). In total, 40 samples were collected. On each sample, several polycyclic aromatic hydrocarbons (PAHs) were deter- mined such as benzo[a]anthracene (228), benzo[b]fluoranthene (252), benzo[k]fluoranthene (252), benzo[a]pyrene (252), benzo[g,h,i]perylene (276), indeno[1,2,3-cd]pyrene (276), and dibenzo[a,h]anthracene (278), the main com- pounds of 16 priority US Environmental Protection Agency (US-EPA) PAHs in particulate phase. The PAH mean concentrations showed higher values during the first (from 3:00 to 9:00 h) and fourth (from 21:00 to 3:00 h) sampling intervals than the other two with benzo[a]pyrene mean values exceeding the Italian law limit of 1 ng/m3. Taking into account benzo[a]pyrene mean concentration for the first interval and the first plus the second one, which are the hours with the largest working activity, we have estimated that the baker and co-workers are exposed to a cancer risk of 4.3 × 10-7 and 5.8 × 10-7, respectively (these values are lower than US-EPA recommended guideline of 10-6). Our study was complemented by numerical analyses using state-of-the-art computational fluid dynamics to reconstruct at high resolution air movement from the various working places, i.e., the bakery and the selling area which were connected via a door. The numerical simulations were possible given that surface temperature using infrared thermog- raphy as well as air temperature was continuously recorded throughout the sampling acquisition. The use of this approach allowed us to estimate the transport and diffusion of benzo[a]pyrene from one area to the other thus complementing the point sampling information. Computational fluid dynamic simulation results confirm the presence of benzo[a]pyrene in the laboratory as obtained from the measurements and suggests its presence in the sales' area of the bakery with concentrations similar those found in the laboratory.

The Atmosphere Special Issue “Recent Advances in Urban Ventilation Assessment and Flow Modelling” collects twenty-one original papers and one review paper published in 2017, 2018 and 2019 dealing with several aspects of ventilation in urban areas (https://www [...]

This study quantifies the influence of green spaces on microclimate and PM10 concentration in a typical residential district of Nanjing (China) by employing the CFD-based and microclimate model ENVI-met 4. Five green indices, related to quantity and structure of vegetation, are employed to investigate the impact of different types (grass, shrub and tree) and layouts of a green space located in the center of the residential district under an average Nanjing summer day. Results show that the thermal comfort (expressed by the mean radiant temperature MRT and the predicted mean vote PMV) is slightly enhanced with increasing green quantity, especially trees, even though more trees may increase the wind blocking effect with a consequent slight increase of pollutant concentration. In this regard, a single patch of trees located in the central part of the green space is preferable. The green indices are shown to be useful for studying the relationship between green space morphology, microclimate and air quality in cities.

With the objective of reducing population exposure, vegetation barriers composed by hedges and/or trees are usually located near roads to protect pedestrians from traffic-related pollutants. The main objective of this study is to quantify the effectiveness of this type of barriers. Black Carbon (BC) is used an indicator of the effectiveness of vegetation barrier and its concentration reduction behind the barrier is studied. Computational Fluid Dynamics (CFD) modelling, previously validated against BC experimental data across a vegetation barrier located in an avenue of Pamplona (Spain), is applied to simulate different barrier configurations. Additionally, the contribution of each vegetation effect (aerodynamic and deposition) on this reduction, as well as its sensitivity to different deposition velocities, are investigated. Results show barriers with hedge and trees are effective to locally reduce BC concentrations and suggest that the presence of trees is more crucial in reducing concentration rather than the hedge size or density. At 15 m from road in the presence of a row of trees and a 2 m-height and 2 m-width hedge the average concentration reduction percentage ranges between 45% and 66% (depending on deposition velocity) with respect to the case without vegetation barrier.

This paper investigates the correlation between street morphology and thermal environment of six street models representing the central morphology of Barcelona (Spain), Berlin (Germany), London (UK), New York (US), Nanjing (China) and Paris (France). The morphology is first characterized through morphological indices (i.e. opening and closing ratios, smoothness ratio, symmetry ratio) obtained from a novel “street morphology extraction” method, which allows to depict a certain feature of the geometry (the presence of openings, the shape of building envelopes and the symmetry of the street, respectively). It is found that the average Sky View Factor (SVF) is negatively correlated with the building density, the closing ratio and the symmetry ratio, and positively correlated with the opening ratio. Then, air temperature (AT), Mean Radiant Temperature (MRT) and Predicted Mean Vote (PMV) are obtained from ENVI-met simulations to assess how the thermal environment is affected by the street morphology. In particular, the average AT, MRT and PMV are positively correlated with average SVF at 12:00 and with the building density at 21:00. The presence of openings, the shape of building envelopes and the symmetry of the street differently affect the local thermal environment and comfort during the day, leading to different MRT and PMV distribution. For example, the Barcelona model, due to high building density, smoothness and symmetry, which prevent ventilation, experiences slightly warm conditions also in the night. The novel morphometric method proposed allows studying which feature mostly affects the thermal environment and can thus be employed in the early planning stage.

This paper reviews current parameterizations developed and implemented within Computational Fluid Dynamics models for the study of the effects linking vegetation, mainly trees, to urban air quality and thermal conditions. In the literature, passive mitigation via deposition is parametrized as a volumetric sink term in the transport equation of pollutants, while a volumetric source term is used for particle resuspension. The aerodynamics effects are modelled via source and sink terms of momentum, turbulent kinetic energy and turbulent dissipation rate. A volumetric cooling power is finally considered to account for the thermal (transpirational cooling) effects of vegetation. The most recent applications are also summarized with a focus on the relative importance of both aerodynamic and deposition effects, together with recent studies evaluating thermal effects. Those studies have shown that the aerodynamic effects of trees are stronger than the positive effects of deposition, however locally the pollutant concentration increases or decreases depending on the complex inter-relation between local factors such as vegetation type and density, meteorological conditions, street geometry, pollutant characteristics and emission rates. Unlike aerodynamic and deposition effects on pollutant dispersion which were also found in street far from trees, the thermal effects were in general locally restricted to the close vicinity of the vegetation and to the street canyon itself. Future requirements in CFD modelling include more in depth investigation of resuspension and thermal effects, as well as of the VOCs emissions and chemical reactions. The overall objective of this review is to provide the scientific community with a comprehensive summary on the current parameterizations of urban vegetation in CFD modelling and constitutes the starting point for the development of new parametrizations in CFD as well as in mesoscale models.

Computational fluid dynamics simulations were performed to investigate flow and pollutant dispersion in a 2D street canyon of aspect ratio H/W = 1. Different from other works, the combination of the presence of viaduct and indoor-outdoor temperature differences ΔT is investigated for different approaching wind velocities. For larger wind velocity (2 m/s, Froude number Fr~3.06–12.24) the typical clockwise vortex leads to higher concentrations of both gas and small particles at the leeward side of the street and in the leeward-side rooms; the vortex is enhanced under large ΔT (20 K) improving the dispersion of pollutants. For smaller velocity (0.5 m/s, Fr~0.19–0.77) the appearance of an anti-clockwise vortex leads to a strong accumulation of gas and particles at the windward side and in the windward-side rooms under low ΔT (5 K); increasing the ΔT raises the dispersion of pollutants with consequent lower concentrations in the rooms (up to an average of 67% with respect to the isothermal case for gaseous pollutants), but accumulation close to the ground level at both windward-side and leeward-side rooms. In the presence of viaduct, together with the main vortex above the viaduct which causes concentrations increasing from low-level to high-level leeward-side rooms, two vortices are generated below it. Still ΔT = 20 K improves the dispersion of pollutants, leading up to a maximum of about 30% lower gaseous concentrations in the rooms. In general, lower concentrations of gas and particles are found for larger velocity, indicating that the mechanical turbulence dominates over the buoyancy effects, which become crucial for smaller velocity. This study confirms previous findings that viaducts may improve pollutant dispersion under large velocity if only one viaduct-level pollutant source exists and indoor-outdoor ΔT conditions can mitigate street air pollution.

This paper is devoted to the analysis of the impact of changes in olive urban forests affected by Xylella fastidiosa on ecosystem services. The focus is on microclimate and thermal comfort evaluated by two indices: the temperature of equivalent perception (TEP) and the predicted mean vote (PMV), which take into account both microclimate parameters and personal factors (heat resistance of clothing and human activity). The work has been carried out through (i) a qualitative analysis of the potential ecosystem services changes caused by temporary transition from olive groves to uncultivated soil, (ii) a study of the potential change of land use from monumental olive groves to other types of use, and (iii) a quantitative analysis on microclimate impact due to the loss of ecosystem services in two selected neighborhoods located in the Apulia region and chosen due to their proximity to the urban context. The analysis revealed that (i) direct effects on ecosystem services are principally linked with regulation functions and cultural services, (ii) a critical loss of cultural value of monumental olive groves occurred in the two neighborhoods, (iii) such a loss may lead to an increase of TEP and PMV, indicating a decrease of thermal comfort in the whole neighborhoods. Thus, it is necessary to plan the replanting policies of the use of the areas affected by X. fastidiosa not only in terms of agricultural planning but also in terms of landscape, urban planning, and human well-being.

Superparamagnetic magnetite nanoparticles were synthetized and capped by a SiO

The impact of ship emissions on the surface concentration of nitrogen oxides (NOx) and ozone (O-3) in the Mediterranean area of the harbour of Brindisi (IT) has been investigated. Numerical simulations have been performed for a summer period of the year 2012, at different spatial scale, using the meso-scale BOLCHEM and the local-scale ADMS-Urban models. Results show that while average ground concentration of primary pollutant NOx increases in the area surrounding the port, a decrease in O-3 concentration is observed.

Wind tunnel measurements of the total drag force for aligned arrays of cubes exposed to two different boundary-layer flows at three flow velocities are discussed. The drag force for eight different building packing densities λ p (from 0.028 to 1) is measured with a standard load cell generating a novel dataset. Different λ p are reproduced by increasing the number of buildings on the same lot area; this represents a real situation that an urban planner is faced with when a lot area of a given (fixed) size is allocated to the development of new built areas. It is assumed that the surrounding terrain is uniform and there is a transition from a given roughness (smooth) to a new roughness (rough). The approaching flow will adjust itself over the new surface within a distance that in general may be larger than the horizontal length covered by the array. We investigate the region where the flow adjustment occurs. The wide range of packing densities allowed us to analyse in detail the evolution of the drag force. The drag force increases with increasing packing densities until it reaches a maximum at an intermediate packing density (λ p = 0.25 in our case) followed by a slight decrease at larger packing densities. The value of the drag force depends on the flow adjustment along the array which is evaluated by introducing the parameter “drag area” to retrieve information about the drag distribution at different λ p . Results clearly suggest a change of the distribution of the drag force, which is found to be relatively uniform at low packing densities, while most of the force acts on first rows of the arrays at large packing densities. The drag area constitutes the basis for the formulation of a new adjustment length scale defined as the ratio between the volume of the air within the array and the drag area. The proposed adjustment length scale automatically takes into account the change in drag distribution along the array for a better parameterization of urban effects in dispersion models.

Silver artefacts and particularly ancient silver artefacts present the serious problem of the black look due to ambient contamination. The black colour is the consequence of the layer forming on the surface made of acanthite and jalpaite, both compounds are sulphur composts. Recently UV laser cleaning technique has demonstrated to be very promising in processing of cultural artefacts. To operate on artefacts without to contaminate the bulk, first we determined the laser fluence threshold of the bulk, second we controlled the surface compounds and at the end we operated the laser irradiation. In this work we utilised certified silver and silver/copper samples in order to perform preliminary studies. The threshold fluence we found were 780 and 510 mJ/cm2 for the Ag pure and for the Ag/Cu alloy, respectively. The jalpaite concentration on Ag/Cu sample increased after the laser dose of 25 J/cm2, while for higher laser dose its value lowered pointing out that complex processes take part during the laser application. As a successful of our studies we applied the technique on a Carlino coin made of silver coined in 1689 under King Carlo II. The analyses were performed by two different techniques able to find the percentage of elements and the chemical compounds; the EDXRF and the XRD. We found that the sulphur concentration decreased on laser dose. Operating on the coin up to a dose of 280 J/cm2 the sulphur concentration deceases up to 20 %, while the coin look becomes clear just after a 50 J/cm2.

This paper is devoted to the application of the modelling approach, as one of the methods for the evaluation of thermal comfort, to neighborhoods located in two cities characterized by a different climate, i.e., a Mediterranean city in southern Italy (Lecce) and a northern European city in southern Finland (Lahti). The impact of the presence of vegetation in both places is evaluated and compared, further considering alternative scenarios for thermal comfort improvement. The thermal comfort condition is expressed in terms of indices (mean radiant temperature (MRT) and predicted mean vote (PMV)). Results show that at pedestrian level the presence of vegetation lead to an improvement of thermal comfort in summer of about 2 points in both neighborhoods. This improvement is also evident observing the spatial distribution of MRT with a difference of 7 &deg, C in the Lecce neighborhood and 3 &deg, C in Lahti. In winter, thermal discomfort is observed in the presence of vegetation with a difference of 1.3 &deg, C in the Lecce neighborhood and 1.5 &deg, C in Lahti in terms of MRT. However, trees and green cover have the important potential to offset climate change impact and to make urban environments less thermally stressful. This study aims to guide urban planners towards a motivated and necessary transaction towards new green infrastructure whose effect should, however, be analyzed and investigated case by case.

In recent years, several ventilation indices have been proposed and applied to assess the efficiency of “urban outdoor ventilation”, i.e. the ability of an urban area to dilute pollutants, heat and moisture by exchanging air between inside and above of the urban canopy. Here, focusing on the pollutant dispersion, the definition of 13 ventilation indices is given, which includes indoor-initially proposed and outdoor directly proposed. Then, 63 literature studies (published until 2018) applying the ventilation indices are selected, analysed and summarized in terms of the types of geometry investigated, the timeline and the frequency of employment of each index, the turbulence models employed. Based on the analysis of such studies, advantages and limitations of each index are provided, which may help the scientific community to choose the most appropriate one depending on the specific application and objective. Future perspectives are also given, suggesting the necessity to correlate ventilation indices with urban morphological parameters, to apply indices in real urban areas characterized by building height variability and complex morphology, as well as to provide threshold values useful for urban planning purposes.