vertical diffusion
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MAUSAM ◽  
2022 ◽  
Vol 44 (2) ◽  
pp. 199-204
Author(s):  
BIJENDRA RAI

The present study aims at seasonal and diurnal pollution potential around Patna, the capital region of Bihar and Gaya. To assess the pollution potential, meteorological data of two stations, VIZ., Patna and the neighbouring station Gaya for five year period (1984-88) have been analysed; The analysis has been done for four representative seasonal months, viz., winter (January), pre-monsoon (April), monsoon (August) and post-monsoon (October).   The analysis shows no stable conditions in the day time and no unstable condition in the  night time in each month. April shows higher frequency and January the lowest frequencies of unstable conditions. April  has the highest mixing height and ventilation coefficient. From the results it has been concluded that day time is suitable for good dispersion in all the months. In the ca5e of existing industries, emission must be lessened during night time and particularly in the winter months. These results also suggest that pollutants are well dispersed in April and August. January and August may be regarded as the worst months for vertical diffusion of contaminants. As the predominant surface winds are easterly, any new Industrial set up should be in the west of the city in order to minimise the effects of pollutants.  


2021 ◽  
Vol 11 (24) ◽  
pp. 11765
Author(s):  
Evgeny Yakovlev ◽  
Andrey Puchkov

We present the results of field and experimental studies to assess the influence on the formation of the radon field over the kimberlite pipes of the Arkhangelsk diamondiferous province. Measurements were made in the field to establish the radon radiation in the soil air and the gas permeability of soils in the area of the Chidvinskaya pipe. Experimental work was aimed at determining the radiation and physical parameters of the rocks occurring within the kimberlite field. Based on a set of field and experimental data, a model of the diffusion transfer of radon in the area of the Chidvinskaya pipe was calculated for three profiles, represented by the rocks of the pipe, sedimentary rocks of the exocontacts of the pipe, and host sandy and clay sedimentary rocks. The results of the calculations show that the rocks of the exocontacts of the pipe have the greatest potential for increased radon radiation. The calculated values of the radon radiation produced by these rocks exceeded 9000 Bq·m−3. The diatreme kimberlites produced the lowest radon radiation. We showed that the source of the increased values of radon radiation is the rocks of the pipe’s exocontacts. This fact will make it possible to use the emanation method as an additional one for the search for kimberlite pipes.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
A. Campeau ◽  
D. Vachon ◽  
K. Bishop ◽  
M. B. Nilsson ◽  
M. B. Wallin

AbstractThe deep porewater of northern peatlands stores large amounts of carbon dioxide (CO2). This store is viewed as a stable feature in the peatland CO2 cycle. Here, we report large and rapid fluctuations in deep porewater CO2 concentration recurring every autumn over four consecutive years in a boreal peatland. Estimates of the vertical diffusion of heat indicate that CO2 diffusion occurs at the turbulent rather than molecular rate. The weakening of porewater thermal stratification in autumn likely increases turbulent diffusion, thus fostering a rapid diffusion of deeper porewater CO2 towards the surface where net losses occur. This phenomenon periodically decreases the peat porewater CO2 store by between 29 and 90 g C m−2 throughout autumn, which is comparable to the peatland’s annual C-sink. Our results establish the need to consider the role of turbulent diffusion in regularly destabilizing the CO2 store in peat porewater.


Author(s):  
Khaled S. M. Essa ◽  
Soad M. Etman ◽  
Maha S. El-Otaify ◽  
M. Embaby ◽  
Ahmed M. Mosallem ◽  
...  

AbstractIn 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.


2021 ◽  
Vol 9 ◽  
Author(s):  
Guoyin Wang ◽  
Wennan Leng ◽  
Shaojing Jiang ◽  
Bangjun Cao

Atmospheric diffusion is one of the factors affecting local air quality, dominating the evolution of air pollution episodes. Previous work has emphasized the unfavorable diffusion conditions in the Sichuan Basin resulting from its complex terrain. However, the recent spatiotemporal variation in atmospheric diffusion conditions in the basin and their effects on local air quality remain unclear. Based on the wind speed, boundary layer height, vertical potential temperature difference of ERA5 analysis, two independent metrics containing information on horizontal and vertical diffusion ability, i.e., ventilation coefficient (VE) and the air stagnant conditions (ASI), are involved to indicate wintertime atmospheric diffusion conditions in the basin. Both VE and ASI reveal a decrease tendency of atmospheric diffusion condition from the northwestern portion of the basin to the southeast. In terms of the long-term variation in diffusion conditions, VE showed a broader increasing trend from 1979 to 2019, with a distinct increase in the western region. In contrast, the occurrence of air stagnation events has declined −3∼−6%/decade in the basin, more significantly over the western basin. Both the increase in VE and the decrease in air stagnation frequency indicate the improvement of atmospheric diffusion conditions in the Sichuan Basin from 1979 to 2019, which mitigates the effects of air pollutant emissions to some extent. The enhancement of diffusion conditions is due to the improvement of vertical diffusion conditions. The lowest seasonal PM2.5 concentrations occur in the northwestern basin, where VE is highest and ASI is lowest. Atmospheric diffusion conditions can explain approximately 25–50% of the interannual variation in PM2.5 concentrations in Chengdu.


2021 ◽  
Vol 2083 (3) ◽  
pp. 032074
Author(s):  
Tiantian Jin ◽  
Yang Li ◽  
Jianshuang Du ◽  
Lei Wang ◽  
Zhizheng Mao

Abstract Based on the data of environmental monitoring stations and meteorological stations in typical city in the Bohai Rim region in June 2021 and June 2020. The air quality in June 2021 was better than that in the same period in 2020. Ozone (O3) was the primary pollutant in June 2021 and June 2020. The overall meteorological conditions in May 2021 were relatively favorable. In June 2021, the number of light wind days and wind speed had no significant impact on air quality compared with the same period last year. The dominant wind direction in June 2021 was southeast wind, which was not conducive to the increase of ozone concentration compared with the southwest wind frequency in the same period in 2020; the relative humidity in June 2021 was slightly higher year-on-year, which was slightly conducive to the hygroscopic growth of pollution; the static stability index in June 2021 was lower year-on-year, and the weather conditions for comprehensive pollution diffusion were preferred year-on-year; the height of the mixed layer in June 2021 was lower year-on-year, the vertical diffusion weather conditions were deviated year-on-year; the average temperature, sunshine hours and total radiation in June 2021 were all low, which was not conducive to the generation of ozone.


2021 ◽  
Vol 921 (2) ◽  
pp. 173
Author(s):  
Ryo Tazaki ◽  
Koji Murakawa ◽  
Takayuki Muto ◽  
Mitsuhiko Honda ◽  
Akio K. Inoue

Abstract We study the 3 μm scattering feature of water ice detected in the outer disk of HD 142527 by performing radiative transfer simulations. We show that an ice mass abundance at the outer disk surface of HD 142527 is much lower than estimated in a previous study. It is even lower than inferred from far-infrared ice observations, implying ice disruption at the disk surface. Next, we demonstrate that a polarization fraction of disk-scattered light varies across the ice-band wavelengths depending on ice grain properties; hence, polarimetric spectra would be another tool for characterizing water-ice properties. Finally, we argue that the observed reddish disk-scattered light is due to grains a few microns in size. To explain the presence of such grains at the disk surface, we need a mechanism that can efficiently oppose dust settling. If we assume turbulent mixing, our estimate requires α ≳ 2 × 10−3, where α is a nondimensional parameter describing the vertical diffusion coefficient of grains. Future observations probing gas kinematics would be helpful to elucidate vertical grain dynamics in the outer disk of HD 142527.


Molecules ◽  
2021 ◽  
Vol 26 (21) ◽  
pp. 6611
Author(s):  
Ritamaria di Lorenzo ◽  
Antonietta Bernardi ◽  
Lucia Grumetto ◽  
Antonia Sacchi ◽  
Carmen Avagliano ◽  
...  

Human skin is colonized by diverse commensal microbes, making up the skin microbiota (SM), contributing to skin integrity and homeostasis. Many of the beneficial effects aroused by the SM are exerted by microbial metabolites such as short-chain fatty acids (SCFAs), including butyric acid. The SCFAs can be used in cosmetic formulations against skin diseases to protect SM by preserving and/or restoring their natural balance. Unpleasant sensorial properties and unfavorable physico-chemical properties of butyrate strongly limit its cosmetic use. In contrast, some butyrate derivatives, including phenylalanine butyramide (C13H18N2O2, FBA), a solid form of butyric acid, are odorless while retaining the pharmacokinetic properties and safety profile of butyric acid. This study assessed the FBA’s permeation across the skin and its soothing and anti-reddening potential to estimate its cosmetic application. The dosage method used to estimate FBA’s levels was validated to be sure of analytical results. The FBA diffusion tests were estimated in vitro using a Franz-type vertical diffusion cell. The soothing action was evaluated in vivo by Colorimeter CL400, measuring the erythema index. The results suggest that the FBA represents an innovative way to exploit the benefits of butyric acid in the cosmetic fields since it cannot reach the bloodstream, is odorless, and has a significative soothing action (decrease the erythema index −15.7% after 30′, and −17.8% after 60′).


2021 ◽  
Vol 13 (20) ◽  
pp. 4052
Author(s):  
Xitong Xu ◽  
Shengbo Chen ◽  
Yan Yu ◽  
Sen Zhang

The attention towards links of atmospheric parameter variation and earthquakes has increased exponentially by utilizing new methods and more accurate observations. Persistent research makes it possible to gain insight into the precursor mechanism of earthquakes. In this paper, we studied the universality of detecting atmospheric anomalies associated with earthquakes based on tidal force fluctuation in China for earthquakes of Ms > 6.0, and explored the influence of tidal force on tectonic stress. The data of air temperature, geopotential height, ozone mixing ratio, and relative humidity from the National Center for Environmental Prediction (NCEP) were analyzed to reveal the spatiotemporal variation of atmospheric anomalies at multiple isobaric surfaces. Furthermore, the coupling of atmospheric parameters was investigated. The results showed that continuous solicitation exerted by tidal forces could change the strength of tectonic stress that causes earthquakes. The evolution pattern of air temperature, geopotential height, and relative humidity could be supported by atmospheric thermal vertical diffusion, while the anomalies of ozone mixing ratio was not evident. This verified the feasibility of detecting multi-parameter atmospheric anomalies associated with earthquakes based on tidal force fluctuation. Our results provide more evidence for understanding the atmospheric precursor characteristics of earthquakes.


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