scholarly journals Spatial Statistical Assessment of Groundwater PCE (Tetrachloroethylene) Diffuse Contamination in Urban Areas

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1211 ◽  
Author(s):  
Licia C. Pollicino ◽  
Marco Masetti ◽  
Stefania Stevenazzi ◽  
Loris Colombo ◽  
Luca Alberti
Keyword(s):  
Urban Areas ◽  
Chlorinated Solvents ◽  
Monitoring Network ◽  
Point Sources ◽  
Shallow Aquifer ◽  
Multiple Point ◽  
Anthropogenic Contamination ◽  
Maximum Admissible Concentration ◽  
Statistical Framework ◽  
High Concentrations

Contamination by chlorinated solvents is typically associated with point sources, which are able to release high concentrations and to generate well defined plumes. Nevertheless, in urban settings (especially in functional urban areas—FUAs), multiple-point sources are frequently present, consisting of a series of unidentifiable small sources clustered within large areas, generating a diffuse, anthropogenic contamination. This situation results in the coexistence of single plumes with higher contaminant concentrations, and larger areas where the concentration is lower but still higher than the maximum admissible concentration limits. This paper proposes a methodology devised to cope with the diffuse contamination by chlorinated solvents within shallow aquifers due to multiple-point sources in FUAs. The approach is based on a Bayesian model that helps to spatially evaluate the likelihood of having active multiple-point sources, and to relate their impact on the shallow aquifer to the hydrogeological features of the area. Moreover, the approach allows testing of the efficiency of the monitoring network to properly characterize the contamination in the aquifer. The consistency of the results of the analysis was also checked for the Milan FUA (Italy) by a comparison to a previous study, performed through an inverse numerical modelling approach within a Monte Carlo statistical framework to identify the areas with the highest likelihood to host potential multiple-point sources.

scholarly journals MODELLING AND SIMULATION OF DISPERSIONS OF POWDER EMISSIONS FROM MULTIPLE SOURCES WITH THE MATHEMATICAL MODEL POL 15SM

2014 ◽  
Vol 22 (2) ◽  
pp. 151-160
Author(s):  
Mihaela Budianu ◽  
Valeriu Nagacevschi ◽  
Matei Macoveanu
Keyword(s):  
Mathematical Model ◽  
Air Pollution ◽  
Urban Areas ◽  
Point Sources ◽  
Multiple Point ◽  
Multiple Sources ◽  
Economic Agents ◽  
Sources Of Pollution ◽  
Simulation Based ◽  
The Mathematical Model

Over the last decades, air pollution has become one of the greatest challenges negatively affecting human health and the entire environment, including air, water, soil, vegetation, and urban areas. Lately, special attention has been given to mathematical modelling for diffusion of pollutants in the atmosphere as a particularly effective and efficient method that can be used to study, control and reduce air pollution. The diversity of models developed by different research groups imposed a rigorous understanding of model types in order to apply them correctly according to local or regional problems of air pollution phenomenon. Tus the authors have developed and improved two mathematical models for dispersion of air pollutants. Tis paper presents a case study of dispersion of powders in suspension originating from 14 point sources that correspond to 5 economic agents in the agroindustrial area of Vaslui city using a computer simulation based on the mathematical model Pol 15sm, for multiple point sources of pollution, designed by the authors.

scholarly journals Environmental issues due to organohalogenated compounds diffuse pollution in groundwater. Emerging issue in the Roman area?

2017 ◽  
Vol 6 (2) ◽  
Author(s):  
Isidoro Bonfà ◽  
Francesco La Vigna ◽  
Simona Martelli ◽  
Lucilla Ticconi
Keyword(s):  
Urban Areas ◽  
Industrial Development ◽  
Environmental Issues ◽  
Point Sources ◽  
Multiple Point ◽  
Industrial Activities ◽  
Clear Point ◽  
Source Contamination ◽  
The City ◽  
Very High

Most of the large urban areas, especially those with a strong industrial vocation, present important contamination of organohlaogenated compunds. Even in the City of Rome, although it has a very limited industrial development, some sites interested by this kind of contamination have been notified in recent years. The distribution of these sites is prevalent in the eastern sector of the city where the few industrial activities present are also located. Concentrations are varied and show both cases of clear point source contamination, where values are very high, and cases where a possible contamination from multiple point sources can be hypothesized. The sites reported fall into a crucial area for the hydrogeology of Rome, that is the "Paleotiber Graben" aquifer, exploited for various uses. To date, there is no proven diffuse contamination of organohalogenated compounds in Rome, nevertheless the purpose of this work is to frame this emerging issue on the basis of the available data.

scholarly journals Characterization of the subsurface urban heat island and its sources in the Milan city area, Italy

2021 ◽  
Author(s):  
Alberto Previati ◽  
Giovanni B. Crosta
Keyword(s):  
Urban Heat Island ◽  
Urban Areas ◽  
Heat Fluxes ◽  
Shallow Aquifer ◽  
Heat Island ◽  
Groundwater Temperature ◽  
City Area ◽  
Groundwater Environment ◽  
Urban Heat ◽  
The Impact

AbstractUrban areas are major contributors to the alteration of the local atmospheric and groundwater environment. The impact of such changes on the groundwater thermal regime is documented worldwide by elevated groundwater temperature in city centers with respect to the surrounding rural areas. This study investigates the subsurface urban heat island (SUHI) in the aquifers beneath the Milan city area in northern Italy, and assesses the natural and anthropogenic controls on groundwater temperatures within the urban area by analyzing groundwater head and temperature records acquired in the 2016–2020 period. This analysis demonstrates the occurrence of a SUHI with up to 3 °C intensity and reveals a correlation between the density of building/subsurface infrastructures and the mean annual groundwater temperature. Vertical heat fluxes to the aquifer are strongly related to the depth of the groundwater and the density of surface structures and infrastructures. The heat accumulation in the subsurface is reflected by a constant groundwater warming trend between +0.1 and + 0.4 °C/year that leads to a gain of 25 MJ/m2 of thermal energy per year in the shallow aquifer inside the SUHI area. Future monitoring of groundwater temperatures, combined with numerical modeling of coupled groundwater flow and heat transport, will be essential to reveal what this trend is controlled by and to make predictions on the lateral and vertical extent of the groundwater SUHI in the study area.

Night-time chemistry of biomass burning plumes in urban areas: A dual mobile chamber study

2021 ◽  
Author(s):  
Spiro Jorga ◽  
Kalliopi Florou ◽  
Christos Kaltsonoudis ◽  
John Kodros ◽  
Christina Vasilakopoulou ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Urban Areas ◽  
Mass Spectra ◽  
Prescribed Burning ◽  
Organic Aerosol ◽  
Photochemical Activity ◽  
Organic Nitrate ◽  
Night Time ◽  
Starting Point ◽  
High Concentrations

<p>Biomass burning including residential heating, agricultural fires, prescribed burning, and wildfires is a major source of gaseous and particulate pollutants in the atmosphere. Although, important changes in the size distributions and the chemical composition of the biomass burning aerosol during daytime chemistry have been observed, the corresponding changes at nighttime or in winter where photochemistry is slow, have received relatively little attention. In this study, we tested the hypothesis that nightime chemistry in biomass burning plumes can be rapid in urban areas using a dual smog chamber system.</p><p> </p><p>Ambient urban air during winter nighttime periods with high concentrations of ambient biomass burning organic aerosol is used as the starting point. Ozone was added in the perturbed chamber to simulate mixing with background air (and subsequent NO<sub>3</sub> production and aging) while the second chamber was used as a reference. Following the injection of ozone rapid organic aerosol (OA) formation was observed in all experiments leading to increases of the OA concentration by 20-70%. The oxygen to carbon ratio of the OA increased by 50% on average and the mass spectra of the produced OA was quite similar to that of the oxidized OA mass spectra reported during winter in urban areas. Good correlation was also observed with the produced mass spectra from nocturnal aging of laboratory biomass burning emissions showing the strong contribution of biomass burning emissions in the SOA formation during cold nights with high biomass burning activities. Concentrations of NO<sub>3</sub> radicals as high as 25 ppt were measured in the perturbed chamber with an accompanying production of 0.2-1.2 μg m<sup>-3</sup> of organic nitrate. These results strongly indicate that the OA in biomass burning plumes can evolve rapidly even during wintertime periods with low photochemical activity.</p>

scholarly journals Measurements in a highly polluted Asian mega city: observations of aerosol number size distribution, modal parameters and nucleation events

2005 ◽  
Vol 5 (1) ◽  
pp. 57-66 ◽  
Author(s):  
P. Mönkkönen ◽  
I. K. Koponen ◽  
K. E. J. Lehtinen ◽  
K. Hämeri ◽  
R. Uma ◽  
...  
Keyword(s):  
Size Distribution ◽  
Urban Areas ◽  
Geometric Mean ◽  
Formation Rate ◽  
Geometric Standard Deviation ◽  
Modal Parameters ◽  
Number Size Distribution ◽  
High Concentrations ◽  
Rural Sites ◽  
Aitken Mode

Abstract. Diurnal variation of number size distribution (particle size 3-800nm) and modal parameters (geometric standard deviation, geometric mean diameter and modal aerosol particle concentration) in a highly polluted urban environment was investigated during October and November 2002 in New Delhi, India. Continuous monitoring for more than two weeks with the time resolution of 10min was conducted using a Differential Mobility Particle Sizer (twin DMPS). The results indicated clear increase in Aitken mode (25-100nm) particles during traffic peak hours, but towards the evenings there were more Aitken mode particles compared to the mornings. Also high concentrations of accumulation mode particles (>100nm) were detected in the evenings only. In the evenings, biomass/refuse burning and cooking are possible sources beside the traffic. We have also shown that nucleation events are possible in this kind of atmosphere even though as clear nucleation events as observed in rural sites could not be detected. The formation rate of 3nm particles (J3) of the observed events varied from 3.3 to 13.9cm-3s-1 and the growth rate varied from 11.6 to 18.1nmh-1 showing rapid growth and high formation rate, which seems to be typical in urban areas.

scholarly journals On the point-source approximation of earthquake dynamics

2014 ◽  
Vol 57 (3) ◽  
Author(s):  
Andrea Bizzarri
Keyword(s):  
Point Source ◽  
Seismic Waves ◽  
Single Point ◽  
Seismic Source ◽  
Transition Process ◽  
Point Sources ◽  
Multiple Point ◽  
Earthquake Dynamics ◽  
Planar Fault ◽  
Source Models

<p>The focus on the present study is on the point-source approximation of a seismic source. First, we compare the synthetic motions on the free surface resulting from different analytical evolutions of the seismic source (the Gabor signal (G), the Bouchon ramp (B), the Cotton and Campillo ramp (CC), the Yoffe function (Y) and the Liu and Archuleta function (LA)). Our numerical experiments indicate that the CC and the Y functions produce synthetics with larger oscillations and correspondingly they have a higher frequency content. Moreover, the CC and the Y functions tend to produce higher peaks in the ground velocity (roughly of a factor of two). We have also found that the falloff at high frequencies is quite different: it roughly follows ω<span><sup>−2</sup></span> in the case of G and LA functions, it decays more faster than ω<span><sup>−2</sup></span> for the B function, while it is slow than ω<span><sup>−1</sup></span> for both the CC and the Y solutions. Then we perform a comparison of seismic waves resulting from 3-D extended ruptures (both supershear and subshear) obeying to different governing laws against those from a single point-source having the same features. It is shown that the point-source models tend to overestimate the ground motions and that they completely miss the Mach fronts emerging from the supershear transition process. When we compare the extended fault solutions against a multiple point-sources model the agreement becomes more significant, although relevant discrepancies still persist. Our results confirm that, and more importantly quantify how, the point-source approximation is unable to adequately describe the radiation emitted during a real world earthquake, even in the most idealized case of planar fault with homogeneous properties and embedded in a homogeneous, perfectly elastic medium.</p>

scholarly journals Super-resolution imaging of negative-refractive graded-index photonic crystal flat lens

2021 ◽  
Author(s):  
Binming Liang ◽  
Xiao Huang ◽  
Jihong Zheng
Keyword(s):  
Photonic Crystal ◽  
Imaging System ◽  
Super Resolution ◽  
Point Sources ◽  
Image Resolution ◽  
Multiple Point ◽  
Single Image ◽  
Graded Index ◽  
Resolution Imaging ◽  
Flat Lens

Abstract Photonic crystal (PC) not only breaks through the diffraction limit of traditional lenses but also can realize super-resolution imaging. Improving the resolution is the key task of PC imaging. The main work of this paper is to use a graded-index Photonic crystal (GPC) flat lens to improve the image resolution. An air-hole type two-dimensional (2D) GPC structure based on silicon medium is proposed in this paper. Numerical simulations through RSoft reveal that when the medium in the imaging area is air, the full width at half maximum (FWHM) value of a single image reaches 0.362λ. According to the Rayleigh criterion, the images of two point sources 0.57λ apart can also be distinguished. In the imaging system composed of cedar oil and GPC flat lens, the FWHM value of a single image reaches 0.34λ. In addition, the images of multiple point sources 0.49λ apart can still be distinguished.

scholarly journals Exposure of the Main Italian River Basin to Pharmaceuticals

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Federico Ferrari ◽  
Agata Gallipoli ◽  
Matteo Balderacchi ◽  
Maria M. Ulaszewska ◽  
Ettore Capri ◽  
...  
Keyword(s):  
Surface Waters ◽  
Point Sources ◽  
Preliminary Survey ◽  
Italian Economy ◽  
Sediment Samples ◽  
Pharmaceutical Contamination ◽  
Low Levels ◽  
High Concentrations ◽  
River Po ◽  
Sources Of Contamination

This study give a preliminary survey of pharmaceutical contamination and accumulation in surface waters and sediments along the river Po basin (74,000 km2, the largest in Italy), a strategic region for the Italian economy: it collects sewage from a vast industrialized area of Italy (Autorità di Baciono del fiume Po, 2006, 2009). 10 pharmaceuticals (atenolol, propanolol, metoprolol, nimesulide, furosemide, carbamazepine, ranitidine, metronidazole, paracetamol, and atorvastatin) from several therapeutic classes were searched in 54 sampling points along the river Po from the source to the delta, and at the mouth of its major effluents. In water samples were found pharmaceuticals in the range of 0.38–0.001 μg/L, except for furosemide (max conc. 0.605 μg/L), paracetamol (max conc. 3.59 μg/L), metoprolol (never detected) and for atenolol (not analysed). In sediment samples, only paracetamol was not detected, while the others were generally found in the range of 0.4–0.02 μg/kgwwwith high concentrations for atenolol (max conc. 284μg/kgww) and furosemide (max conc. 98.4μg/kgww). The findings confirm also STPs as point sources of contamination. Despite of the much evidence for the adverse effects of pharmaceuticals in the aquatic environment, the observed low levels cannot be considered to pose a serious risk to human health; further studies are necessary for a comprehensive risk assessment.

scholarly journals Legibility of Light Signals Composed of Multiple Point Sources

1995 ◽  
Vol 79 (2) ◽  
pp. 66-70
Author(s):  
Takashi Irikura ◽  
Tetsuo Taniguchi ◽  
Yoshiro Aoki
Keyword(s):  
Point Sources ◽  
Multiple Point ◽  
Light Signals
Sign in / Sign up

Export Citation Format

Share Document