Bilingual Publishing Co. (BPC): E-Journals
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Correlation of Ground Penetrating Radar Data with Geotechnical Prospect Profiles: Reduto Case Study, Belém-PA, Brazil
No full textThe study presented in this manuscript aimed to relate the sedimentary strata imaged by the ground penetrating radar (GPR) method through numerical modeling with the mapping of sedimentary strata acquired through geotechnical surveys. The study aimed to expose how obtaining subsoil information through noninvasive/destructive electromagnetic waves is beneficial, as they are reliable and less costly than drilling holes beyond what is necessary to have a subsurface mapping. In this sense, physical-geological modeling was carried out. The information on the type of sediments, acquired through simple recognition surveys carried out in the city of Belém-PA, helped to create a model of a sedimentary package with its respective intrinsic physical properties. The result shows that the GPR recovered with good vertical and horizontal resolution at the beginning and end of the layers of the sedimentary package studied, proving to be very effective for locating geotechnical sounding points and safely reducing costs
Toxicity of Radon-222 in Groundwater across Keana in Nasarawa, Nigeria
No full textThe most common supply of freshwater for drinking, irrigation, and other domestic uses is groundwater; however, because of increased radon concentrations brought on by mining activities, its quality is still a severe concern. Using a liquid scintillation detector, this study investigated the radon content, its related toxicity, and its risk to human health in the groundwater of the Keana in Nasarawa, Nigeria. Ten (10) borehole samples and five (5) well samples totaling fifteen (15) groundwater samples were taken. The results showed that the average radon concentration in water samples from Keana was 2.25 Bq/L. The mean annual effective dosage (ingestion) for adults and children in Keana was 0.016 mSv/y and 0.027 mSv/y, respectively. In Keana, the additional lifetime cancer risk per adult was 5.65 × 10–5, and per child, it was 8.79 × 10–5. The study’s radon concentration was lower than the benchmark of 11.1 Bq/L established in 1991 by the Nigerian Standard Organization and the US Environmental Protection Agency. The results of this study indicate that the level of radon is safe; as a result, people can continue farming and other activities. To reduce the risk of cancer, however, more research could be done in the area. Further research should be done by looking at additional sources in the study area in order to cover the entire zone. Further investigation should be carried out both during the dry and wet seasons because radon concentrations in groundwater alter over time due to dilution by recharge from rainfall
Analytical Study on the Effect of Electric Arc Furnace Dust (EAFD) on the Rutting of Asphalt Concrete Mixtures
No full textAs a byproduct of the steelmaking process, significant amounts of hazardous electric arc furnace dust (EAFD) are produced. Utilizing the solidification/stabilization technology with asphalt mix is one way to safeguard the environment from its negative effects. Rutting was used as an indicator to assess the asphalt mixture with EAFD since it is an important factor in pavement design. This study's major goal is to ascertain how EAFD affects the rutting of asphalt-concrete mixtures. To evaluate the ideal asphalt content, the Marshall test method was applied to asphalt concrete mixtures. EAFD was added to the asphalt cement in four different volume percentages as a binder addition. Then, using the Universal Testing Machine, participants were exposed to a replica of the rutting test (UTM). Experiments were conducted at 25, 40 and 55oC, and at frequencies of 1, 4 and 8 Hz. Rutting was measured for each specimen. Tests results showed that while rut depth has negative correlation with of EAFD% and positive correlation with the temperature. The use of EAFD has dual advantages, protecting the environment from the adverse impact of EAFD and reducing the cost of asphalt mix without jeopardizing the pavement performance
Enhancing Concrete Properties Using Silica Fume: Optimized Mix Design
No full textIn the current work, concrete mixes containing (7.0-33.11) weight % silica fume as a partial replacement of cement with a water /cement ratio (0.42-0.48) were prepared according to an adopted two factorial central composite design. The samples were tested, optimized, and modeled for compressive strength and density. The estimated results confirmed that compressive strength and density increase with increasing silica fume content up to 11.9 wt.%. Response surface analysis results confirmed that silica fume concrete with developed compressive strength (53.42 MPa) could be prepared by incorporation of 11.9 wt. % silica fume as partial replacement of cement using 0.42 water/cement ratio. An increase in compressive strength and density (up to 39.3% and 2.6% ) respectively was recorded for silica fume concrete mixes compared to Portland cement concrete. Overall, the research findings revealed that silica fume concretes prepared with appropriate silica fume content and water/cement ratio exhibited superior strength and density characteristics candidate them to be used effectively in civil engineering applications
Ionospheric Currents in the Equatorial and Low Latitudes of Africa
No full textThe magnetometer data obtained for 2008 from geomagnetic stations installed across Africa by magnetic data acquisition set (MAGDAS) have been used to study the ionospheric Sq current system in the equatorial and lowlatitudes of Africa. The aim of this work is to separate the quiet-day feld variations obtained in the equatorial and low latitude regions of Africa into their external and internal feld contributions and then to use the paired external and internal coeffcients of the SHAto determine the source current and induced currents. The method used involved a spherical harmonic analysis (SHA). This was applied in the separation of the internal and external field/current contribution to the Sq variations. The result shows that the variation in the currents is seen to be a dawn-to-dusk phenomenon with the variation in the external currents different from that of the internal currents both in amplitude and in phase. Furthermore, the seasonal variation in the external current maximizes during the March equinox and minimizes during the December solstice. The maximum current observed in AAB and ILR is due to the Equatorial Electrojet Current present in the AAB and ILR stations. Seasonal variation was observed in the geomagnetic component variations as well as in the currents. This is attributed to the position of the sun with respect to the earth at different months of the year. The equinoctial maximum is observed in external current intensity which occurred mostly during the March Equinox
Indoor Air Pollution and Its Determinants in Household Settings in Jaipur, India
No full textIndividuals spend 90% of their time indoors, primarily at home or at work. Indoor environmental factors have a signifcant impact on human well-being. It was a longitudinal study that assessed the major factors that reduce indoor air quality, namely particulate matter, and bio-aerosols, using low-cost sensors and the settle plate method, respectively also to determine the effect of atmospheric parameters and land use patterns in households of commercial, industrial, residential, slum, and rural areas of the city. PM2.5 concentration levels were similar in most parts of the day across all sites. PM10.0 concentration levels increased indoors in a commercial area. PM2.5 concentration showed a negative correlation with temperature and a positive correlation with relative humidity in some areas. Very high values of PM2.5 concentration and PM10.0 concentration have been observed in this study, inside households of selected rural and urban areas. Pathogenic gram-positive cocci, gram-positive rods, Aspergillus, and Mucor species were the most common bacterial and fungal species respectively found inside households. This study examined particulate matter concentration along with bio-aerosols, as very less studies have been conducted in Jaipur the capital of Rajasthan, a state in the western part of India which assessed both of these factors together to determine the indoor air quality. Rural households surrounding the periphery of the city were found to have similar pollution levels as urban households. So, this study may form the basis for reducing pollution inside households and also for taking suitable measures for the reduction of pollution in the indoor environment
Machine Learning and Pattern Analysis Identify Distinctive Influences from Long-term Weekly Net Ecosystem Exchange at Four Deciduous Woodland Locations
No full textA methodology integrating correlation, regression (MLR), machine learning (ML), and pattern analysis of long-term weekly net ecosystem exchange (NEE) datasets are applied to four deciduous broadleaf forest (DBF) sites forming part of the AmeriFlux (FLUXNET2015) database. Such analysis effectively characterizes and distinguishes those DBF sites for which long-term NEE patterns can be accurately predicted using the recorded environmental variables, from those sites cannot be so delineated. Comparisons of twelve NEE prediction models (5 MLR; 7 ML), using multi-fold cross-validation analysis, reveal that support vector regression generates the most accurate and reliable predictions for each site considered, based on fits involving between 16 and 24 available environmental variables. SVR can accurately predict NEE for datasets for DBF sites US-MMS and US-MOz, but fail to reliably do so for sites CACbo and MX-Tes. For the latter two sites the predicted versus recorded NEE weekly data follow a Y ≠ X pattern and are characterized by rapid fluctuations between low and high NEE values across leaf-on seasonal periods. Variable influences on NEE, determined by their importance to MLR and ML model solutions, identify distinctive sets of the most and least influential variables for each site studied. Such information is valuable for monitoring and modelling the likely impacts of changing climate on the ability of these sites to serve as long-term carbon sinks. The periodically oscillating NEE weekly patterns distinguished for sites CA-Cbo and MX-Tes are not readily explained in terms of the currently recorded environmental variables. More detailed analysis of the biological processes at work in the forest understory and soil at these sites are recommended to determine additional suitable variables to measure that might better explain such fluctuations
The Influence of Induced Drought Stress on Germination of Cenchrus ciliaris L. and Cenchrus setigerus Vahl.: Implications for Rangeland Restoration in the Arid Desert Environment of Kuwait
No full textDrought impacts in arid desert ecosystems can result in decreased ecosystem productivity and biodiversity. Implementation of restoration projects in arid desert environments is largely dependent on water availability and soil moisture condition. This study investigated the influence of induced drought stress by using polyethylene glycol (PEG-6000) solution on germination viz. Cenchrus ciliaris and Cenchrus setigerus as the important rangeland species. The water stress potential treatments were 0 (control), –0.5 MPa, –1.0 MPa, –1.5 MPa, and –2.0 MPa. The extent of seed germination was severely affected by decreased water stress potential. As drought increased, the percentage of germination decreased in both Cenchrus’ species. The water deficit at –0.5 MPa showed a significant (P < 0.001) reduction in the final germination percentage in the case of C. setigerus and C. ciliaris by 65% and 42.5%, respectively. At –1.0 MPa to –1.5 MPa, changes in intermediate germination were observed in C. ciliaris (from 35% to 17.5%, respectively) and C. setigerus (from 22.5% to 11.25% respectively). Higher levels of water stress (–2.0 MPa) prevented the survival of both species. Understanding the germination strategies of native desert plant species associated with drought stress and identifying favorable conditions during the germination process can be useful for restoration practices and rangeland management actions to improve desert ecosystems and maintain biodiversity
Study on Epithermal Gold Mineralization System at Shwebontha Prospect, Monywa Copper-Gold Ore Field, Central Myanmar
No full textThe Shwebontha prospect area is situated in the Central Volcanic Belt, central Myanmar, where the well-known Sagaing Fault serves as its eastern boundary. This study aims to document key the mineralogy, host rock geochemistry and ore mineralizing fluids. The mineralization, hosted by Upper Oligocene to Middle Miocene rhyolites, displays a strong lithological control. Mineralization is characterized by gold-bearing silicified massive ore and chalcedonic quartz veins in which sulfides are clustered and disseminated not only in quartz gangue but also in rhyolite host rocks. The significant ore minerals in the mineralized veins include pyrite, sphalerite, galena, chalcopyrite, and gold. Common hydrothermal alterations such as silicic, argillic and propylitic alteration types are recognized. According to the fluid inclusion data and interpretation, ore mineralizing fluids in the research area are characterized by formation temperatures of 260-280 °C and salinity of 0.35-2.41 % wt. NaCl eq. respectively. Mixing of hydrothermal fluids was generally considered to be an effective mechanism for ore transport and deposition