Some characteristic parameters of Gaussian plume model

The Gaussian solution of the diffusion equation for line source is used to have the first four moments of the vertical concentration distribution (centroid, variance, skewness, and kurtosis). The magnitude and position of maximum concentration level were evaluated. Also the plume advection wind speed is estimated. Equations for the ground level concentration were compared with wind tunnel measurements.

Maximum ground level concentration Of air pollutant

The emission of an air pollutant from an elevated point source according to Gaussian plume model has been presented. Au. elementary theoretical treatment for both the highest possible ground-level concentration and the downwind distance at which this maximum occurs for different stability classes has been constructed. The effective height release modification was taken into consideration. An illustrative case study, namely, the emission from the research reactor in Inchas, has been studied. The results of these analytical treatments and of the derived semi-empirical formulae are discussed and presented in few illustrative diagrams.

Maximum crosswind integrated ground level concentration in two stability classes

bl 'kks/k i= esa fu"izHkkoh vkSj vfLFkj fLFkfr;ksa esa ØkWliou lekdfyr lkanz.k ysus ds fy, nks fn’kkvksa esa vfHkogu folj.k lehdj.k ¼ADE½ dks gy fd;k x;k gSA ykIykl :ikarj.k rduhd dk mi;ksx rFkk m/okZ/kj Å¡pkbZ ij vk/kkfjr iou xfr vkSj Hkaoj folj.k’khyrk dh leh{kk djrs gq, ;g gy fudkyk x;k gSA blds lkFk gh Hkw&Lrj vkSj vf/kdre lkanz.kksa dk Hkh vkdyu fd;k x;k gSA geus bl ekWMy esa iwokZuqekfur vkSj izsf{kr lkanz.k vk¡dM+ksa ds e/; rqyuk djus ds fy, dksiugsxu ¼MsuekdZ½ ls fy, x, vkuqHkfod vk¡dM+ksa dk mi;ksx fd;k gSA The advection diffusion equation (ADE) is solved in two directions to obtain the crosswind integrated concentration in neutral and unstable conditions. The solution is solved using Laplace transformation technique and considering the wind speed and eddy diffusivity depending on the vertical height. Also the ground level and maximum concentrations are estimated. We use in this model empirical data from Copenhagen (Denmark) to compare between predicted and observed concentration data.

Using dispersion modeling for ground level concentration

A short range model calculating ground-level concentration from elevated sources is estimated, which realized a Fickian-type formula. Taking the source and mixing height are functions of the wind velocity and eddy diffusivity profiles. The model estimated with an exact solution of the advection diffusion equation is compared with experimental ground level concentrations using meteorological data collected near the ground.

Different solutions of the diffusion equation and its applications

In this report, we solved the advection–diffusion equation under pollutants deposition on the ground surface, taking wind speed and vertical diffusion depend on the vertical height. Also, we estimated a simple diffusion model from point source in an urban atmosphere and the conservative material with downwind was evaluated. Then, we calculated the extreme ground-level concentration as a function of stack height and plume rise in two cases. Comparison between the proposed models and the emission from the Egyptian Atomic Research Reactor at Inshas had been done. Lastly, we discussed the results in this report.

Is Exposure to PM2.5 and PM10, a Factor of Surge of 2nd Wave of COVID-19- A Case Study of Delhi, India?

Exposure to air pollutants cause severe health issues. Restriction onmajor activities induced by government improves the air quality during the lockdown due to Covid-19 pandemic. Investigation of correlation of high level of Severe Acute Respiratory Syndrome Coronavirus2 and its mortality rate with ground level particulate matter concentration was carried out in this study during the second wave of covid-19 in the megacity Delhi, India. Daily average concentration of major two fractions of particulate matter PM2.5 and PM10 were analyzed for the period of 22 March 2021 to 15 May 2021 that grouped into two categories before lockdown and during lockdown. Results revealed that overall reduction of 1.6% in PM2.5 concentration and 15% in PM10 concentration was observed on imposing the lockdown and significant reduction in Particulate Matter concentration was observed for most of the locations for the lockdown period as compared to before lockdown period. Furthermore daily new Covid-19 cases and its death rate was found negatively associated (very weak correlation) with the ground level concentration of PM2.5 and PM10 i.e. before lockdown period while positive association (moderately correlated) was noticed among the daily new Covid-19 cases, its death rate, ground level concentration of PM2.5 and PM10 in time period of lockdown. This Study revealed that the high degree of atmospheric contamination in Northern India can be deemed an external co-factor in the area's high mortality and high positivity rate during the second wave Covid19 pandemic.

Particulate Matter Pollution around a Cement Industry and its Potential Effect

Analysis of particulate matter (PM) PM2.5 and PM10 was done around a cement company in Rivers State, Nigeria. Measurements were taken for the concentration of PM2.5 and PM10 and other atmospheric parameters at intervals of 100 m up to 1000 m and field observation was carried out for two days. The temperature of the area varied between 26.6 degrees and 33.3 degrees, relative humidity was between 70.2 and 98.2% and the wind speed ranged from 0.2 to 3.6 m/s. The minimum PM10 and PM2.5 values were 38 and 18 µg/m3 respectively and the maximum PM10 and PM2.5 values were 616 and 298 µg/m3 respectively. A two way analysis of variance was done at 5 % level of significance to determine the influence the time the measurement was taken and the distance from the stack have on the particulate matter concentration. P values were lower than P = .05 therefore, the null hypothesis was rejected. The pollution index for PM10 was determined and about 86% of the pollution index are above 100, 80% are above 150 and about 21% is above 400. About 96% of the pollution index for PM2.5 is above 100, 87% are above 150 and about 21% are above 300. As shown on Air quality index charts, values between 100 and 150 are unhealthy for sensitive groups, values above 150 are unhealthy, and values above 300 are hazardous while values above 400 are very hazardous. It is concluded that the ground level concentration of PM10 and PM2.5 up to 1200 m from the stack is generally unhealthy for the receptors.

Mapping Ground Exposure Rate and External Hazard Index in Part of Basement Complex Rock of North Central Nigeria

In this work, a preprocessed aero radiometric survey data of geologic survey map series of Nigeria basement complex sheet 145 was used to map the spatial distribution of ground level concentration of the three radioelements that contribute significantly to the emission of gamma rays, notably potassium (40K), thorium (232Th) and uranium (238U) and estimating the external hazard associated with human exposure due to the elements. The elemental average concentrations of 40K, 232Th and 238U obtained from the survey data are 1.37485%, 24.5297ppm and 5.5491ppm respectively. The relative concentrations of the three elements are in line with the global trend where Th records the highest mean concentration, followed by U with then K recording the least. Except for K, the values of the other elements were found to be above the global crustal abundance ranges of 2 - 2.5% for 40K, 8 – 12 ppm for 232Th and 2 – 3 ppm for 238U. The mean ground level external dose rate was found to be 213.2 ±21.2 nGyh-1. This is about four times higher than the global average terrestrial dose rate of 55 nGyh-1. The computed external hazard index however gives an average value of 0.329, which is within the acceptable limit (<1). External hazard index above this limit were however recorded at three points, spanning a small area of about 0.096 km2. In situ and ground geophysical measurements are therefore

NUMERICAL MODELLING OF DUST DISTRIBUTION IN THE ATMOSPHERE OF A CITY WITH COMPLEX RELIEF

Microscale processes of dust distribution in the city of Tbilisi with a very complex topography are modeled using a 3D regional model of atmospheric processes and numerical integration of the transport-diffusion equation of the impurity. The Terrain-following coordinate system is used to take into account the influence of a very complex relief on the process of atmospheric pollution. Modeling is carried out using horizontal grid steps of 300 m and 400 m along latitude and longitude, respectively. The cases of the stationary background eastern and western weak winds are considered. In the model, motor transport is considered as a nonstationary source of pollution from which dust is emitted into the atmosphere. Modelling of dust micro-scale diffusion process showed that the city air pollution depends on spatial distribution of the main sources of city pollution, i.e. on vehicle traffic intensity, as well as on spatial distribution of highways, and micro-orography of city and surrounding territories. It is shown that the dust pollution level in the surface layer of the atmosphere is minimal at 6 a.m. Ground-level concentration rapidly grows with increase of vehicle traffic intensity and by 12 a.m. reaches maximum allowable concentration (MAC = 0.5 mg/m3) in the vicinity of central city mains. From 12 a.m. to 9 p.m. maximum dust concentration values are within the limits of 0.9-1.2 MAC. In the mentioned time interval formation of the highly dusty zones, and slow growth of their areas and value of ground-level concentrations take place. These zones are located in both central and peripheral parts of the city. Their disposition and area sizes depend on spatial distribution of local wind generated under action of complex terrain, as well as on the processes of turbulent and advective dust transfer. From 9 to 12 p.m. reduction of dust pollution and ground-level concentration takes place. After the midnight city dust pollution process continues quasi-periodically. As result of the analysis of vertical distribution of dust concentration is obtained that a basic dust mass emitted into the atmosphere is located in the 100 m surface layer. Concentration value in the upper part of this layer reaches 0.8 MAC and rapidly decreases with altitude increase.