Effects of Climatic Change to the Radionuclide Levels in Tanzania | Chapter 4 | X-Ray and Gamma Ray Spectrometers for Environmental Studies in Tanzania

 

The activity concentrations data of radionuclides 7Be and 212Pb from CTBTO radionuclides monitoring station located in Dar es Salaam were for the first time measured and analyzed. In Tanzania, the data were used together with the meteorological one to investigate the mechanism that governs radionuclides concentration level in the atmosphere. The two radionuclides of different origin showed different periodic pattern of atmospheric concentration for the past 11 years (2008 – 2018). No correlation was found between 7Be and 212Pb activity concentration. This suggests that the surface air concentration between 212Pb (was a terrestrial radionuclide) and 7Be (was cosmogenic radionuclide), was affected differently by local conditions of atmospheric processes. The mean values of both 7Be and 212Pb were higher in dry seasons and lower in rain seasons due to vertical mixing and greater deposition of radionuclides. It was also observed that, both 7Be and 212Pb decrease with the increase in rainfall and humidity. The mean activity concentrations of 7Be and 212Pb were found to be within the range of 1.29 – 5.71 mBq/m3 and 10.85 – 50.06 mBq/m3, respectively. The annual mean activity concentrations of 7Be and 212Pb were 4.72 ± 1.18 mBq/m3 and 29.76 ± 13.63 mBq/m3, respectively. Distinct annual trends were depicted on 7Be and 212Pb, suggesting that the two radionuclides were affected differently with atmospheric conditions. Monthly atmospheric concentrations of 7Be showed a strong seasonal variation trend with the highest in January and February and lowest in April. 212Pb depicted the highest concentration during June and July and lowest in January and December. The regression analysis for 7Be and 212Pb activity concentrations together with number of meteorological parameters revealed that the relative humidity, rainfall, air temperature, absolute humidity and wind speed are the most significant parameters affecting radionuclides activity concentrations in the atmosphere. The sunspot numbers show 66.7% of its variability with 7Be activity concentration which further suggesting that other parameters may influence its variation. 212Pb, on the other hand, shows only 27.3% of its variability which clearly indicates that the existence of cosmic rays does not affect its activity concentration in the atmosphere. Based on the findings of this study it is evident that effect meteorological parameters on radionuclides concentrations vary from one location to another. This is due to different climatic conditions, altitude and latitude position and even the source location.

 

 

Author(s) Details

 

Yusuf Ismail Ally Koleleni

Department of Physics, University of Dar es Salaam, P. O. Box 35063, Dar es Salaam, Tanzania and Department of Physics, Muslim University of Morogoro, P. O. Box 1031, Morogoro, Tanzania.

D. R. Seif

Department of Physics, University of Dar es Salaam, P. O. Box 35063, Dar es Salaam, Tanzania.

 

Please see the book here:- https://doi.org/10.9734/bpi/mono/978-81-974388-4-4/CH4

Analysis of Ground Ozone and Its Correlation with Meteorological Parameters over Kigali, Rwanda | New Visions in Science and Technology Vol. 5

 When the air temperature is less than or equal to 19oC, the ground ozone concentration over Kigali is directly proportional to solar radiation; however, when the air temperature exceeds this range, the ozone concentration begins to decrease, but R2 is very low, implying that this is a very unlikely scenario. For wind speeds between 2 and 2.81 m/s, ambient ozone concentration is inversely related to solar radiation, but for wind speeds above 2.81 m/s, ambient ozone increases as solar radiation increases. The ambient ozone concentration rises as atmospheric relative humidity rises when the wind speed is between 2 and 2.81 m/s, but when the wind speed is larger than 2.81 m/s, the ambient ozone concentration declines as atmospheric relative humidity rises. The average wind speed reported was 3.7402 m/s with a quiet status of 0%. With maximum wind speeds of 6–7.62 m/s, the major wind direction was west-south with a frequency of 31%, followed by southeast and southwest with a frequency of 22%. As a result, if a pollutant source exists in the west, southwest, southeast, south, or east, it may be primarily disseminated in the north, northwest, or northeast from July to September 2020. Wind speed was 4.3217 m/s at the lower lever of 10.3ppb to 20.2ppb, with a prominent direction of westerly, westsouth, southeast, and a frequency of around 18%, 30%. Ambient ozone was delivered from a number of directions for values more than 20.2 ppb, including west, southwest, south, southeast, and east, with maximum wind speeds ranging from 6 to 7.62 m/s.

Author (S) Details

J. D. Ndayisenga

Department of Physics, College of Science and Technology, University of Rwanda, Kigali, Rwanda.

View Book :- https://stm.bookpi.org/NVST-V5/article/view/4098

An Illustrative Study of Surface Radio Refractivity in Awka, South Eastern Nigeria | Chapter 2 | International Research in Environment, Geography and Earth Science Vol. 7

This work uses meteorological parameters of surface air temperature, pressure and relative humidity obtained from 2013-2014, respectively, to investigate the radio refractivity over Awka, South Eastern Nigeria, using Davis weather station vantage pro 2 (with Integrated Sensor Suite, ISS) located near to the ground surface. Data were collected at an interval of 30 minutes continuously for each day during the period. From the data collected, hourly, daily and monthly averages of radio refractivity during dry and wet seasons were determined. The result showed that during the wet season, radio refractivity is greater than during the dry season. This is due to variations in meteorological parameters such as relative humidity and temperature that cause the radio refractivity to vary at different times of the day, while the difference in pressure tends to be negligible. Results of the refractivity gradient, however, show that the propagation conditions have varying degrees of occurrence, with conditions of super-refractivity found to be prevalent during the two-year span. The month of January has the highest refractivity gradient value, while in July there were at least around -63 N-units per km and propagation implications, taking into account that the lower the gradient (that is, the more negative), the more super refractive the troposphere is, and the better the conditions of propagation. For radio engineers, the findings obtained from this work are useful for enhancing VHF/UHF terrestrial connections based on clear-air considerations. The study of this work showed that the surface refractivity over Awka for the two-year cycle showed seasonal fluctuations with high rainy season values and low dry season values. Unlike the wet season refractivity, which had limited variability, the dry season was extremely variable. The propagation situation will often be super-refractive for radio wave propagation in Awka and nearby areas. But the month of January had the highest refractivity gradient value, while July had the least.

Author(s) Details

Ikeh U. Chinelo
Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.

Okeke C. Chukwunike
Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.

View Book :- https://bp.bookpi.org/index.php/bpi/catalog/book/358