Africa Journal of Physical Sciences

Biofuel Production versus Food Security in Kenya

Evaristus M Irandu, Parita Shah — Sun, 20 Aug 2023 00:00:00 +0000

Biofuels are essential to fulfilling the United Nations Sustainable Development Goals, which place a strong emphasis on ensuring global food and energy security. It is critical to comprehend how managing natural resources, producing biofuels, and ensuring food security are related. A study of the literature suggests that food security may be impacted by the production of biofuels, but further research is needed. The development of biofuels has detrimental effects on the environment and other factors, but it benefits food security.

The purpose of the essay is to add to the existing discussion over Kenya's "biofuel or food security." This is due to the fact that more than 80% of people depend on agriculture, necessitating the need for innovation. Its primary goals are to: a) investigate how combining biofuel and food production can result in sustainable natural resource use; b) list the crops that should be grown to meet both food and energy needs; c) examine the financial incentives for pursuing biofuel energy technologies.

Using in-depth literature review and interviews with key informants, the paper adopts a qualitative research design. Ten Kenyan enterprises that produce biofuels were used as the key informants. The main finding is that food security and biofuel production are not mutually exclusive but rather complementing. It is recommended that policymakers offer appropriate incentives to increase investment in Kenya's biofuel energy generation.

Age Revision of the Mariakani Formation of the Upper Duruma Group in South Lamu Basin of Kenya Based on Preliminary Calcareous Nannofossils Biostratigraphy

Daniel Dennis Waga, Daniel Olago, Prof., Henry Nyamai, Mr., Iryna Suprun, Dr. — Wed, 30 Aug 2023 00:00:00 +0000

This paper provides new biostratigraphic evidence of the onlapping of the Jurassic and Cretaceous strata above older formations of the Duruma Series in the southern Lamu Basin. A calcareous nannofossils biostratigraphy study was undertaken on three samples consisting of sandstone and shale units outcropping in an area and mapped initially belonging to the non-marine Mariakani Formation of the Karoo-Duruma Group in the southeast coastal Kenya. This was done in an attempt to upgrade and construct a detailed Meso-Cenozoic chrono – and biostratigraphic framework for this area that will be essential for regional and global correlations, paleogeographic reconstructions and exploration for hydrocarbon, water and other mineral resources. As a result, a total of nineteen moderately-to-well-preserved taxa characterizing the Pseudoconus enigma (NJ11) Zone of the Boreal or Watznaueria barnasae (NJT11) Zone of the Tethyan zonations were identified. The assemblage of Sample №61 is dominated by such species as Watznaueria barnesiae, W. britannica, Schizosphaerella punctulata, Lotharingius cf. L. contractus, Lotharingius sigillatus, ?Discorhabdus striatus and Watznaueria manivitiae. Both nannofossil zones correlate this layer with the lowermost Bathonian Zigzag Ammonite Zone.

The overlying light grey-blue shale unit – samples №60 and 66 have an (?) Lower Cretaceous (Albian) age based on the presence of two zonal species – ?Axopodorhabdus albianus and Eiffelithus turriseiffelii that characterize the lower Eiffelithus turriseiffelii (BC27/NC10/CC9) Zone which makes them a correlative analogue of the fossiliferous Walu shales widely developed in the northern sector of the Post-Karoo Lamu Basin.

The studied sample №61 is stratigraphically younger than the upper shaly units of the Lower Member of the Kambe Formation from the Mwache River sections located some 25 km to the NE. This biostratigraphical evidence is the first recognition proving the presence of Early Bathonian strata in the Indo-Malgach Province since only Late Bajocian and Middle Bathonian ammonites have been described from this area. The examined samples, especially the Mid-Jurassic share most of the zonal species determined in the corresponding stratotypes confirming marine connections with the Tethyan and Boreal realms. Samples 60 and 66 correspond to the Eiffelithus turriseiffelii Zone (CC9/NC10), and correlate with the Walu shales developed in Northern Post-Karoo Lamu basin sections and the basal part of the Lindi Formation of Southern Tanzania. The correlations with the Bathonian and Albian stages stratotype sections and Ammonite zonations are also provided.

This study demonstrates the complex geological structure of the area with evidence of multiple transgressional-regressional episodes during the Jurassic and Cretaceous times. It also shows the need for a complete revision of the age for all mapped rock formations developed in the Karoo-Duruma and Post-Karoo Lamu basins. These results also prove that the Late Mid Jurassic and Mid-Cretaceous marine transgressions progressed much farther to the west than originally mapped. The data renew and continue the discussion of how far west did the Jurassic marine sequences overlap the Karoo-Duruma Group deposits that was first suggested by some researchers in the early 20^th century.

Temperature trends and evidence for Elevation Dependent Warming on Mount Kenya

Timothy Downing, Daniel Olago, Tobias Nyumba — Mon, 01 Jul 2024 00:00:00 +0000

Global climate models are important tools for understanding differential impacts of climate change around the world. These models depend on the existence of accurate and timely data for calibration and validation, and in some parts of the world such data is scarce. Tropical mountains are modelled to warm faster than other areas of the globe, due to a theory known as Elevation Dependent Warming (EDW). However empirical evidence for EDW is limited, particularly in tropical Africa. This study examines three types of datasets (reanalysis datasets, meteorological station data, and in-situ data loggers) to investigate temperature trends in Mount Kenya, an equatorial mountain in central Kenya. Reanalysis datasets investigated were TerraClimate (1958-2021), ERA5 (1979- 2022), and CFSR (1979- 2022), and meteorological stations examined were Munyaka Station (2070 m.a.s.l.), Naro Moru Gate Station (2420 m.a.s.l), and Naro Moru Met Station (3048 m.a.s.l), all with data from 1991-2022. Finally, six in-situ temperature loggers were placed at 200 m vertical elevation intervals from 3000 m.a.s.l to 4000 m.a.s.l, and these data were compared with historical observations at comparable elevations. The reanalysis datasets all displayed significant warming, but with widely varying magnitudes, ranging from 0.12°C to 0.48°C/decade. Meteorological station data, on the other hand, did not provide any evidence of warming. In-situ data loggers showed warming of 4-5°C for of absolute minimum temperatures since the 1950s. Despite the differences in the data sources, there was general agreement for lapse rates, which ranged from 0.5°C to 0.55°C/100 m. Each data source has its shortcomings, and a thorough knowledge of error and conditions of use and is needed before a dataset can be put to use.

Deterioration of Coating Materials Applied on Roofing Iron Sheets Under Marine Environments in Kenya

Vane Bonareri Ondiere, John Onyatta, Amir Yusuf, Vincent Madadi — Thu, 01 Aug 2024 00:00:00 +0000

Roofing iron sheets are prone to rapid corrosion when exposed to harsh environmental conditions leading to loss of mechanical strength and collapse of structures that results into huge economic loses. The aim of this study was to investigate the effect of marine environmental conditions on deterioration of the coating materials applied to protect roofing iron sheets in Kenya. We studied fading and gloss retention of green and blue coatings applied to roofing iron sheets for a period of 450 days under an outdoor setting at Diani Beach and Mariakani sites representing severe marine and industrial marine environmental conditions respectively. Prepainted roofing sheets obtained from manufacturers MR, MB and CH were cut into130 mm x 190 mm sizes, placed on racks and exposed to the atmosphere. Exposed sheets were removed at predetermined time intervals, cleaned and assessed for glossiness and fading using a Spectro guide BYK Gardner GMGH. Fourier Transform Infrared Spectroscopy was used to determine variations in functional group composition of the coatings. Meteorological data including rainfall, temperature, Ultraviolet radiation and relative humidity were collected during experimental period. Fade variations for green coating followed 0.77-5.00 and 1.33-19.60 for Diani and Mariakani respectively, while blue coating recorded 0.86-5.60 and 1.94-6.86 Hunter units per year for Diani and Mariakani respectively. Percent gloss retention for green coating varied from 30-63% and 18-63% at Diani and Mariakani respectively, while the blue coating varied from 2-77% and 10-82% at Diani and Mariakani respectively. MR coating recorded the highest percentage gloss retention between 75-77 % and the lowest fading at 0.32 - 0.86 Hunter units per year for both green and blue coatings. Mariakani site recorded higher rates of fading compared to Diani attributed to severe marine environmental conditions experienced at the site, characterized by higher levels of chloride, relative humidity- 81%, ultraviolet radiation-12 mW/cm² and temperature -27 ^oC. High ultraviolet radiation increases photo-oxidative reactions and significant degradation of the binding material in the pigments. Fourier Transform Infrared Radiation results revealed dominance of esters, polybasic acid, and phthalate O-CH2 groups and pigments, and the disappearance of some of functional groups due to photodegradation. Based on the data obtained, high chloride levels from the ocean coupled with high ultraviolet radiation and relative humidity are likely to accelerate fading and loss of gloss in marine environments which may lead to poor performance of roofing sheets under such environments. The findings of this study are of significance in improving the quality of coating materials for roofing sheets applied in marine environments.

Assessing the Effects of Deforestation on Surface Water Yields Using a Modelling Approach: The Case of Sondu River Basin

Stephen Rwigi, Alfred Opere, John Muthama — Wed, 31 Jul 2024 00:00:00 +0000

Climatic factors determine the amount and distribution of atmospheric water received at the land surface while the land cover conditions determine partitioning of this water into different hydrological components and ultimately the catchment surface water yields. This study assessed the effects of deforestation of a tropical catchment on surface water yields with a view to addressing fluctuating flows of the rivers emanating from Mau Forest, the largest water tower in Kenya. Sondu basin traverses South West Mau Forest covering an area of 3500 km². The main channel in the basin flows in a south west direction into Lake Victoria in an altitudinal range of 2900 to 1130 m above sea level over a length of 173 km. Different deforestation scenarios over the basin were integrated with climate data to form inputs to a hydrologic model, Soil and Water Assessment Tool. Using model outputs, effects of deforestation on annual and seasonal surface water yields, represented by changes in streamflow volumes under different deforestation scenarios, were evaluated. Deforestation scenarios were derived from a supervised classification scheme of time series of Satellite images to show deforestation trends. Effects of deforestation on the catchment water yielding capacity were estimated as the ratio of the difference between simulated yields under different deforestation scenarios and those simulated under the pre-deforestation scenario of 1973. Results show that forest cover declined by 18.2% and a corresponding growth in land under agriculture by 18.2% in the period between 1973 and 2010. The decline in forest coverage resulted in an increase in the annual surface water yields of about 23% over the period of study. This is possibly as a result of limited groundwater recharge due to reduced infiltration capacity leading enhanced flow fluctuations and subsequently to lower flows during the dry seasons and a higher frequency of flood incidents during the wet seasons. The study has therefore, demonstrated that deforestation has reduced the stability of Mau Forest as a water tower as evidenced by fluctuations in streamflow. Conservation of the forest will enhance the catchment’s water holding capacity thereby ensuring a stable water supply to rivers emanating from it as a way of combating floods and low flows in the basin.

Internal Compartmentalization of the Magadi Basin, Southern Kenya Rift: Insights from Aeromagnetic and Gravity Studies

Abiud Masinde, Aaron Waswa, George Muia — Wed, 31 Jul 2024 00:00:00 +0000

The southern Kenya Rift is characterized by complex faulting and internal compartmentalization. The aim of the research is to utilize aeromagnetic and gravity data to analyze compartmentalization, sediment thickness, and structural characterization. Using tilt derivatives, regional-residual separation, and Euler solutions allow for separating important structures, and lineaments. Euler solutions determine the depths and positions of causative sources. Unconstrained 3D susceptibility model reflects the compartments and surrounding geological formations. Compartmentalized structures are observed across three grabens, each with unique geological features and fault orientations. The first western graben displays tilted fault blocks and z-shaped depocenters, suggesting a strike-slip strain regime. Significant shifts in rifting style have influenced fault activity and strain concentration mechanisms. The Aswa-Nandi-Loita transfer zone greatly influences compartmentalization, fault structures, and sedimentary deposition. Analysis of sediment thickness reveals deeper signatures in the first graben that domiciles Musenke [2700m], Pakase [2600m], and Olkiramatian [1700m], depocenters. These variations are attributed to boundary fault constraints and volcanic manifestations influencing sedimentation patterns. The second graben exhibits thinner sedimentary compartments encompassing Magadi, Kordija, and Mile Forty-six. Structural characterization reveals rotated fault blocks dominating the first graben, axial zones characterized by E-W and NE-SW linear orthogonal structures in the second graben, and flexural regimes in the third graben.

Photocatalytic Activity of Semiconductor Oxide, Titanium Dioxide - Tungsten Trioxide Nanocomposite Material in Visible Light

Florence Achieng Masese, Shem Wandiga, Vincent Madadi, Damaris Mbui — Wed, 31 Jul 2024 00:00:00 +0000

A range of recalcitrant organic pollutants are introduced into environment from industrial wastewater causing global water quality risks. The study aimed to investigate the efficacy of synthesized coupled titanium (IV) oxide photocatalysts in the degradation of methylene blue, serving as a model pollutant representative of dyes and recalcitrant organic compounds in water sources. An innovative method was made use of to synthesize a semiconductor oxide, titanium dioxide coupled with tungsten trioxide nanocomposite, at room temperature in molar ratios of 1:1, 1:4, and 4:1. The synthesised nanoparticles were characterised using Brunnauer-Emmett-Teller analysis, X-ray diffraction, Ultra Violet-Visible spectroscopy and Fourier transform infrared. Photocatalytic degradation of methylene blue in aqueous solution under to visible light radiation and the performance of coupled TiO₂/WO₃ nanocomposite were evaluated. The effects of pH, catalyst loading and concentration on degradation of methylene blue was also assessed. Nanocomposite ratio of 1:1, catalystic loading of 0.25g/50 mL and 20 ppm methylene blue solution tested at pH 2 and pH 12 yielded optimal degradation results, with efficiency of 87.8% after 30 minutes exposure to visible light. The degree of mineralization of methylene blue evaluated using closed reflux colorimetric method, yielded 86% organic matter reduction in 3 hours. Reusability of titanium dioxide coupled with tungsten trioxide nanocomposite tested through 4 cycles of treatments using equimolar solutions of methylene blue yielded degradation efficiency of 93%, 90% 88% and 87% for cycles 1, 2, 3 and 4 respectively, suggesting photocatalyst stability and efficiency. Titanium dioxide coupled with tungsten trioxide was successfully synthesized. Under optimal conditions, the photocatalyst degraded 20 ppm of methylene blue. This demonstrates that coupling titanium dioxide with tungsten trioxide enhances the photo-absorption of titanium dioxide, thereby increasing its effectiveness in treating contaminated domestic water.

Titanium Dioxide Coupled with Tungsten Trioxide and Titanium Dioxide Coupled with Molybdenum Trioxide Nanocomposite-Assisted Photocatalytic Inactivation of Escherichia coli in Direct Sunlight, Solar Simulator, and Visible Light

Florence Masese, Shem Wandiga, Vincent Madadi, Damaris Mbui, Stephen Ojwach — Wed, 31 Jul 2024 00:00:00 +0000

Photocatalysis may be considered as a possible alternative method in the elimination of Escherichia coli from domestic water. It has several advantages when compared with conventional methods, as it is non-toxic, utilizes energy from the sun and offers a green route that could be used to purify water polluted with Escherichia coli. The aim of the study was to investigate the effectiveness of the synthesized modified titanium dioxide photocatalyst in disinfecting Escherichia coli in domestic water under varied light intensities. Escherichia coli concentrations between 400 and 800 colony forming units per milliliter were used to investigate photocatalytic disinfection of the water containing Escherichia coli, under three different sources of light; visible light, natural sunlight and illumination from a solar simulator.
The two linked photocatalysts, titanium dioxide coupled with tungsten trioxide and titanium dioxide coupled with molybdenum trioxide were compared in disinfection studies to examine the impact of catalyst loading on disinfection rate. The synthesised photocatalysts were also characterised using the Energy Dispersive X-ray, Transmission Electron Microscopy, and Scanning Electron Microscope. The results showed that titanium dioxide coupled with tungsten trioxide was more successful in killing Escherichia coli bacteria compared to titanium dioxide coupled with molybdenum trioxide across all tested light sources: natural sunlight, visible light, and light from a solar simulator. After 120 minutes of irradiation using 1g/L of each catalyst, the results showed significant differences in inactivation efficiencies. Under natural sunlight, titanium dioxide coupled with tungsten trioxide achieved a high disinfection rate of 96%, whereas titanium dioxide coupled with molybdenum trioxide achieved 89%. A similar trend was observed under visible light, with efficiencies of 95% and 88% for titanium dioxide coupled with tungsten trioxide and titanium dioxide coupled with molybdenum trioxide respectively. When exposed to irradiation from a solar simulator, titanium dioxide coupled with tungsten trioxide performed better, with an efficiency of 92%, compared to 83% for titanium dioxide coupled with molybdenum trioxide. Experiments carried out without catalysts, served as blanks. These experimental results confirm that coupled titanium dioxide nanoparticles are effective and may be used in treating domestic water contaminated with Escherichia coli.

Seismicity East of The Southern Kenya Rift Valley, Kenya

Gladys Karegi Kianji, Justus Obiko Barongo, Eliud Muthumbi Mathu — Sun, 17 Nov 2024 00:00:00 +0000

A new seismicity map that accounts for the seismic behavior, tectonic complexity, and potential seismic hazards in the eastern part of the southern Kenya Rift Valley is presented. The results are based on the analysis of 224 earthquakes recorded for 103 years, from 1917 to 2020, with magnitudes ranging from 2.5 to 5.6 Mw, confirming moderate to high seismicity and subsequently moderate to high-stress levels. Data from fifteen catalogs is collated and homogenized; magnitudes are unified to Mw. The seismicity is diffuse with pockets of seismic clustering, delineating seven seismic zones, namely the Simba-Mutito zone, Oloitokitok-Kimana-Chyulu zone, Mzima Springs-Mashetani Lavas zone, the Yatta-Voi zone, the Tertiary-Quaternary sediments (north) zone, the Tertiary-Quaternary sediment (south) zone, and the Mwananyamala-Davie fracture zone. Seismicity does not sorely straddle the surface faults; this is attributed to the reactivation of buried faults oriented northwest-southeast, north-south, and northeast-southwest. Further, the study infers an east-west trending shear zone running from the Mzima Springs and across the Yatta shear zones to the coastal sediments. We affirm that the seismicity is not confined to the Southern Kenya Rift but extends off the rift eastwards, re-emphasizing the need for comprehensive seismic monitoring and hazard assessment beyond the main rift zones.