The Definition of Point Sources: Point Charge, Mass Point and Heat Point Source—A Generalized Sternberg Definition of Concentrated Forces

2013 ◽  
Vol 81 (1) ◽  
Author(s):  
Haijian Chu ◽  
Minzhong Wang
Keyword(s):  
Point Source ◽  
Point Charge ◽  
Small Region ◽  
Point Sources ◽  
Mass Point ◽  
Charge Mass ◽  
Concentrated Forces ◽  
Heat Point ◽  
Definition Of ◽  
Traditional Understanding

By considering the concept of point sources, such as point charge, mass point, and heat point source, we give a unified definition of these point sources with three conditions to judge what kind of distributed source in a small region can be taken as a point source by applying Sternberg's concept on concentrated forces. Comparing it with the traditional qualitative understanding of this concept, the definition gives a new condition with a very simple form. Counter-examples demonstrate that the traditional understanding of the point source is not sufficient and the new requirement should not be omitted.

Mathematical model to assess the actual environmental risk from the point source emissions

2014 ◽  
Vol 25 (3-4) ◽  
pp. 91-98
Author(s):  
V. N. Poltoratskaya
Keyword(s):  
Mathematical Model ◽  
Air Pollution ◽  
Point Source ◽  
Density Distribution ◽  
Environmental Risk ◽  
Point Sources ◽  
Design Parameters ◽  
Worst Case ◽  
Maximum Admissible Concentration ◽  
Definition Of

A mathematical model for point source emissions, which allows to determine the ecological risk, improve the ecological situation in the region with the ability to manage risk. Environmental risk is defined as the probability of exceeding a multidimensional integral field concentrations of pollutants its Maximum Admissible Concentration (with a small number of measurements) or frequency exceeding the given measured concentrations of pollutants its Maximum Admissible Concentration (with a large number of measurements). Components of air pollution regions, cities, enterprises are individual emission sources, so primarily developing assessment and environmental risk analysis should be performed for individual sources and, above all, to prevent significant risks – for the prognostic assessment of newly constructed or reconstructed enterprises, and for existing facilities – from the measurement data. For a single point source mathematical model includes: – raw data (results undertorch measurement characteristics of pollutants, sanitary protection and residential areas, the design parameters of the source and characteristics of the external environment for the worst-case); – forecast concentrations of pollutants depending on the design parameters of the source and characteristics of an environment for a source with circular and rectangular mouth, hot and cold emissions, extremely dangerous low wind speeds; – depending on the definition of the amendments to the measured concentrations due to the difference of the worst conditions from measurements; – depending on the definition given to the worst conditions of the measured concentrations and their statistical processing in order to obtain: a) the numerical characteristics of the density distribution of the concentration of pollutants emitted (mathematical expectations, standard deviations and correlation coefficients); b) environmental risk α, defined at a relatively small number of trials as a multidimensional probability integral of the density distribution of the concentrations obtained with the numerical characteristics, and a large number of tests - the frequency of the measured concentrations exceeding; c) environmental risks from air pollution αj separate pollutants; d) depending on the definition of the numerical characteristics of the forecast distribution density is not measured (secondary) concentrations of pollutants emitted to address their risks when determining α and αj. It is shown that, in accordance with applicable regulatory requirements must consider the risk of the negative impact of air pollution to humans, the level of which is determined using the values of the maximum one-time maximum allowable concentrations pollutants. Defined by experienced stochastic patterns of distribution of contaminants in the atmosphere. Studied the random variation of concentrations. Theoretically and experimentally substantiated principles of developing a mathematical model to assess the actual risk from ecological point sources of emissions. 

Sources of Nitrogen and Phosphorus in the Catchment Area of Neusiedlersee/Fertö, Austria/Hungary

1993 ◽  
Vol 28 (3-5) ◽  
pp. 101-110 ◽  
Author(s):  
W. v. d. Emde ◽  
H. Fleckseder ◽  
N. Matsché ◽  
F. Plahl-Wabnegg ◽  
G. Spatzierer ◽  
...  
Keyword(s):  
Point Source ◽  
Catchment Area ◽  
Management Practice ◽  
Water Erosion ◽  
Nonpoint Source ◽  
Point Sources ◽  
Source Control ◽  
Nitrogen And Phosphorus ◽  
Catchment Areas ◽  
The One

Neusiedlersee (in German) / Fertö tó (in Hungarian) is a shallow lake at the Austro-Hungarian border. In the late 1970s, the question arose what to do in order to protect the lake against eutrophication. A preliminary report established the need for point-source control as well as gave first estimates for non-point source inputs. The proposed point-source control was quickly implemented, non-point sources were - among other topics - studied in detail in the period 1982 - 1986. The preliminary work had shown, based on integrated sampling and data from literature, that the aeolic input outweighed the one via water erosion (work was for totP only). In contrast to this, the 1982 - 1986 study showed that (a) water erosion by far dominates over aeolic inputs and (b) the size of nonpoint-source inputs was assessed for the largest catchment area in pronounced detail, whereas additional estimates were undertaken for smaller additional catchment areas. The methods as well as the results are presented in the following. The paper concludes with some remarks on the present management practice of nonpoint-source inputs.

Water quality modeling in the watershed-based approach for waste load allocations

1998 ◽  
Vol 38 (10) ◽  
pp. 165-172 ◽  
Author(s):  
Ruochuan Gu ◽  
Mei Dong
Keyword(s):  
Water Quality ◽  
Point Source ◽  
Water Quality Modeling ◽  
Point Sources ◽  
Low Flow ◽  
Quality Analysis ◽  
Management Approach ◽  
Water Quality Control ◽  
Quality Modeling ◽  
Waste Load

The conventional method for waste load allocations (WLA) employs spatial-differentiation, considering individual point sources, and temporal-integration, using a constant flow, typically 7Q10 low flow. This paper presents a watershed-based seasonal management approach, in which non-point source as well as point sources are incorporated, seasonal design flows are used for water quality analysis, and WLA are performend in a watershed scale. The strategy for surface water quality modeling in the watershed-based approach is described. The concept of seasonal discharge management is discussed and suggested for the watershed-based approach. A case study using the method for the Des Moines River, Iowa, USA is conducted. Modeling considerations and procedure are presented. The significance of non-point source pollutant load and its impact on water quality of the river is evaluated by analyzing field data. A water quality model is selected and validated against field measurements. The model is applied to projections of future water quality situations under different watershed management and water quality control scenarios with respect to river flow and pollutant loading rate.

scholarly journals Presence of Pathogens and Indicator Microbes at a Non-Point Source Subtropical Recreational Marine Beach

2009 ◽  
Vol 76 (3) ◽  
pp. 724-732 ◽  
Author(s):  
Amir M. Abdelzaher ◽  
Mary E. Wright ◽  
Cristina Ortega ◽  
Helena M. Solo-Gabriele ◽  
Gary Miller ◽  
...  
Keyword(s):  
Point Source ◽  
High Tide ◽  
South Florida ◽  
Point Sources ◽  
Fecal Coliforms ◽  
Health Concern ◽  
Ocean Water ◽  
Solar Insolation ◽  
Sources Of Pollution ◽  
Water Detection

ABSTRACT Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in subtropical recreational marine waters impacted by non-point source pollution.

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 Part 2: Odor-Cued Grab Sampling of Transient Environmental Odor Events; Mapping the 'Rolling Unmasking Effect' of Downwind Odor Dispersion

2020 ◽  
Author(s):  
Donald Wright ◽  
Jacek Koziel ◽  
David Parker ◽  
Anna Iwasinska
Keyword(s):  
Point Source ◽  
Sampling Strategy ◽  
Receptor Site ◽  
Final Analysis ◽  
Field Trials ◽  
Point Sources ◽  
Grab Sampling ◽  
Transient Event ◽  
Animal Feeding Operation ◽  
Straight Line

Downwind odor characteristics can be very different depending upon the size of the upwind point-source, interim topography, and wind conditions. At one extreme, the downwind odor plume from a relatively large, confined animal feeding operation (CAFO), located on a flat open plain and under stable, near-straight-line wind conditions can be rather broad, sustained and predictable relative to a fixed receptor site downwind. In contrast, the plume from a small point-source (e.g., a roof vent stack) located on irregular topography and under rapidly shifting wind conditions can be intermittent and fleeting. These transient odor events can be surprisingly intense and offensive, in spite of their fleeting occurrence and perception. This work reports on efforts to optimize an environmental odor sampling strategy, which is optimized for the challenges of (1) sampling of such transient odor 'spikes' and (2) the prioritization of odors/odorants from multiple, closely co-located point-sources, under such transient event conditions. Protocol refinement has emerged by way of 2 environmental odor assessment projects which have been undertaken on behalf of the Missouri Department of Natural Resources. The challenge of transient odor events has been mitigated utilizing rapid, odor cued whole-air grab capture sampling into metalized-FEP gas sampling bags, followed by immediate adsorption transfer onto SPME fibers or sorbent tubes for stabilization during the shipment and storage interval between collection and final analysis. Initial results demonstrated approximately 11 fold increases in target odorant yields for 900 mL sorbent tube transfers from 2-3 second 'burst' odor event bag-captures, as compared to equivalent direct collections at the same downwind receptor location but during perceived (stable) odor 'lull' periods. Results-to-date targeting refinement and field trials of this integrated environmental odor assessment strategy are presented. Preliminary application targeting general odor sampling and point-source differentiation utilizing tracer gases is also presented.

Axisymmetric outflows from binary point-source systems in the presence of an interface

2016 ◽  
Vol 790 ◽  
pp. 205-236
Author(s):  
Lawrence K. Forbes
Keyword(s):  
Binary System ◽  
Point Source ◽  
Numerical Solutions ◽  
Flow Problem ◽  
Surrounding Medium ◽  
Small Deformation ◽  
Point Sources ◽  
Fluid Mixing ◽  
Two Fluids ◽  
Narrow Region

Fluid outflow is considered, from a binary system of two point sources. The sources inject fluid of a lower density than the surrounding medium, and there is a sharp interface separating the two fluids. The overall geometry is taken to be axisymmetric around the line joining the two sources. Numerical solutions are presented for the shape of the interface in unsteady flow, and compared with a linearized solution based on small deformation of the interface from its initial spherical configuration. In addition, a novel spectral method is developed for the solution of the Boussinesq viscous flow problem, accounting exactly for the presence of the two sources and modelling the interface as a narrow region in which fluid mixing is possible. Bipolar outflow jets are seen to be possible.

scholarly journals In situ measurements of speciated atmospheric mercury and the identification of source regions in the Mexico City Metropolitan Area

2009 ◽  
Vol 9 (1) ◽  
pp. 207-220 ◽  
Author(s):  
A. P. Rutter ◽  
D. C. Snyder ◽  
E. A. Stone ◽  
J. J. Schauer ◽  
R. Gonzalez-Abraham ◽  
...  
Keyword(s):  
Point Source ◽  
Mexico City ◽  
Metropolitan Area ◽  
Atmospheric Mercury ◽  
Point Sources ◽  
Rural Site ◽  
Urban Site ◽  
Trajectory Data ◽  
Source Regions ◽  
Rural Sites

Abstract. In order to expand the currently limited understanding of atmospheric mercury source-receptor relationships in the Mexico City Metropolitan Area, real time measurements of atmospheric mercury were made at a downtown urban site, and a rural site on the outskirts of Mexico City, during March 2006. Numerous short-lived increases in particulate mercury (PHg) and reactive gaseous mercury (RGM) concentrations were observed at the urban site during the 17 day study, and less frequent increases in gaseous elemental mercury (GEM) concentrations were measured at both the urban and rural sites. The episodic increases observed were attributed to plume impacts from industrial point source emissions in and around Mexico City. Average concentrations and standard deviations measured during the study were as follows: i) urban site; PHg=187±300 pg m−3, RGM=62±64 pg m−3, GEM=7.2±4.8 ng m−3, and; ii) rural site; GEM=5.0±2.8 ng m−3. Several source regions of atmospheric mercury to the urban and rural sites were determined using Concentration Field Analysis, in which atmospheric mercury measurements were combined with back trajectory data to determine source regions. Only some source regions correlated to mercury emission sources listed in the Federal Pollutant Release and Transfer Register, leaving the rest unaccounted for. Contributions of anthropogenic mercury point sources in and around Mexico City to concentration averages measured at the urban site during the study were estimated to be: 93±3% of reactive mercury (PHg and RGM), and; 81±0.4% of GEM. Point source contributions to GEM measured at the rural site were 72±1%. GEM and reactive mercury (PHg+RGM) were not found to correlate with biomass burning at either of the measurement sites.

Microplastics from the Sources to Sinks: Assessment of Microplastics in the River Freshwater Environments and Wastewater Treatment Plants

2021 ◽  
Author(s):  
A H M Enamul Kabir ◽  
Masahiko Sekine ◽  
Tsuyoshi Imai ◽  
Koichi Yamamoto ◽  
Ariyo Kanno ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Point Source ◽  
Pollution Control ◽  
Wastewater Treatment Plants ◽  
Management Strategies ◽  
Freshwater Ecosystems ◽  
Point Sources ◽  
Source To Sink ◽  
Comprehensive Knowledge ◽  
Marine Realm

&lt;p&gt;Freshwater microplastics pollution has been a recent focus. River freshwater microplastics pollution are vital towards freshwater ecosystems as well as have been the prominent source-to-sink conduits to export MPs into the marine realm. Wastewater treatment plants (WWTPs) have been identified as one of the major point-sources. To date, sources-to-sinks comprehensive knowledge are highly limited. This study explored sources-to-sinks microplastics pollution i.e., WWTPs-to-river-to-marine comprehensively. The two rivers i.e., Koya River (KR) and Nishiki River (NR) which are flowing to the Seto Inland Sea (SIS) and the WWTPs effluent samples were collected from selected (n=37) stations in the Yamaguchi prefecture, Japan. Filtration, wet peroxidation, and density separation methods were employed to extract microplastics particles. Polymers were identified via attenuated total reflectance-Fourier transform infrared spectroscopy. The average microplastics abundances were found KR&amp;#8212;82.25&amp;#177;67.84 n/L and NR&amp;#8212;38.73&amp;#177;24.13 n/L for the river water, and KRWWTPs&amp;#8212;79.5&amp;#177;3.5 n/L and NRWWTPs&amp;#8212;72.25&amp;#177;23.64 n/L for WWTPs effluents, respectively. The KR were found to be more polluted than the NR. WWTPs effluents were found posing higher abundances than rivers. Significantly higher microplastics concentration were found in the WWTPs downstream stations than other river stations. Characterization revealed that small MPs (&lt;1000 &amp;#181;m) in size, fibers in shape, polymers&amp;#8212; polyethylene, polypropylene, polyethylene terephthalate, vinylon were major in both of the WWTPs effluents and rivers. WWTPs influenced river environments by means both of the abundances and microplastics characteristics (shapes-size-polymers). The estimated source-to-sink emission demonstrated a substantial number of MPs discharge into the rivers by the WWTPs (0.007&amp;#8212;0.086 billion/day) and rivers-to-SIS marine environments (1.15&amp;#8212;7.951 billion/day). The emission represented that the WWTPs were the prominent point-source to cause river microplastics pollution. Rivers were the initial sinks of the Japan land-sourced microplastics and prominent pathways to emit microplastics to the ultimate marine sink i.e., SIS. Large amounts of MPs are being generated on land sources before the plastics wastes degrade into MPs secondarily. The pollution characteristics (shapes-sizes-polymers) indicated ecotoxicological threats to these rivers and the downstream environments. Overall, this study provided an insight of sources-to-sinks pollution, fulfilled the preliminary knowledge gaps of pollution occurring land-sources, fate and loadings. We recommended microplastics pollution control at source. This study will aid in developing microplastics pollution control and management strategies for environmental protection and sustainability in the regional Japan as well as global context upon &amp;#8220;thinking globally and acting locally&amp;#8221;.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords: &lt;/strong&gt;Abundance, Point-source, Source-to-sink, Riverine microplastics pollution, Wastewater treatment plants&lt;/p&gt;

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