Effects of Natural Processes on Sea Level Change along the West African Coastline

Coastal hazards induced by meteo-marine forcing are exacerbated by sea level change along the West African coastline. Changes in sea level are induced by ocean processes such as ocean heat content and river discharge. However, although these processes control largely change in sea level, they remain poorly understood. This study analyzes changes in ocean heat content, river discharge, and sea level and establishes an interconnection between these parameters using several statistical methods over the 1993-2021 period. Results showed a significant correlation between sea level and ocean heat content at 2000 m depth. The yearly minimum value appears in July from Cote d’Ivoire to Benin, whilst this value appears in June in Nigeria. The temporal variability of ocean heat content, river discharge and sea level along the West African coastline exhibits three or four periods interrupted by some breakpoints with unequal duration. The results indicate that the 1993-2000 period was dominated by an increasing ocean heat content along the coastline, while the period after the 2000s exhibits mostly a decreasing trend. Positive and negative trends characterized river discharge and sea level along this coastline. The result of multiple linear regression between sea level, river discharge and ocean heat content is a good approximation of sea level trend along the West African coastline. The results of this study could be used to predict future sea level trends along the coast.

Flood Risk Assessment in the Lower Valley of Ouémé, Benin

In response to the increased frequency of flood events in recent years, it has become crucial to enhance preparedness and anticipation through precise flood risk assessments. To this end, this study aims to produce updated and precise flood risk maps for the Lower Valley of Ouémé River Basin, located in the South of Benin. The methodology used consisted of a combination of geographical information systems (GIS) and multi-criteria analysis, including Analytical Hierarchy Process (AHP) methods to define and quantify criteria for flood risk assessment. Seven hydro-geomorphological indicators (elevation, rainfall, slope, distance from rivers, flow accumulation, soil type, and drainage density), four socio-economic vulnerability indicators (female population density, literacy rate, poverty index, and road network density), and two exposure indicators (population density and land use) were integrated to generate risk maps. The results indicate that approximately 21.5% of the Lower Valley is under high and very high flood risk, mainly in the south between Dangbo, So-Ava, and Aguégués. The study findings align with the historical flood pattern in the region, which confirms the suitability of the used method. The novelty of this work lies in its comprehensive approach, the incorporation of AHP for weighting factors, and the use of remote sensing data, GIS technology, and spatial analysis techniques which adds precision to the mapping process. This work advances the scientific understanding of flood risk assessment and offers practical insights and solutions for flood-prone regions. The detailed flood risk indicator maps obtained stand out from previous studies and provide valuable information for effective flood risk management and mitigation efforts in the Lower Valley of Ouémé.

Possible Synergistic Toxicity of Oxygen Scavenger and Defoamer on the Niger Delta Freshwater <i>Tilapia guineensis</i>

Globally, the generation of produced water keeps increasing due to depleting wells and about 40% of this wastewater is disposed of into the environment. Produced water is made up of several components that are toxic in nature, like production chemicals that are used for oil and gas production activities. Oxygen scavenger and defoamer are commonly used for corrosion prevention as both are applied at different stages of corrosion prevention. Evaluation of the possible synergistic toxicity contribution of oxygen scavenger and defoamer formed the basis of this research and was conducted using the Tilapia guineensis as bio-indicator. The toxicity test was carried out using the ELIMINOX (oxygen scavenger) and EC9017A (defoamer) individually and both chemicals were combined together. The choice of these chemicals was premised on previous researches that have confirmed that they are toxic individually, without further research on how they interact when they are combined. These chemicals and freshwater were used to generate produced water samples in the laboratory. The experiment was set up by adding ten fishes into each of the glass containers, containing the produced water samples at different concentrations and a control sample without the chemicals. The rate of mortality of the fish for the individual chemicals ranged from 100% to 10% for the different percentage concentrations. While on the other hand, a combination of the two chemicals had more survival than mortality, the percentage survival rate ranged from 100% to 90% across all the percentage concentrations. The lethal concentration also showed that the oxygen scavenger was more toxic than the defoamer, however, when they were combined;they showed an antagonistic relationship as the toxicity of the oxygen scavenger drastically reduced. The research findings intend to create awareness of the possible interaction of production chemicals when they are used for oil and gas activities and their combined toxicity contribution to produced water. This will in turn aid government regulators in their decision-making for disposal of produced water.

Estimating Volume of Shale in a Clastic Niger Delta Reservoir from Well Logs: A Comparative Study

The volume of shale (Vsh) is a critical parameter in petrophysical analysis that enables the accurate estimation of other petrophysical parameters like effective porosity, saturation and Net-to-Gross. This is an important step in characterization of reservoirs as well as valuation of hydrocarbon potentials. GR (Gamma Ray), Neutron and Density as well as Potassium, Uranium and Thorium logs were adopted to estimate and analyze Vsh for sand 4 reservoir interval across five wells using the empirical (GR-linear and non-linear) and Neutron-Density methods. Results show that Vsh estimated by the different methods varied from 0.24 - 0.39 for the GR linear method (highest), 0.12 - 0.24 for the Larionov method (intermediate), and 0.04 - 0.28 for the Neutron-Density method (lowest). Although the Neutron-Density method gives the lowest values of volume of shale, this does not translate to the most accurate and reliable results. This may be attributed to the non-singularity in measurements and varying sensitivities of the well logs used in this method as well as the complexities of the wellbore condition. The GR non-linear (Larionov) method provides consistent and comparable volume of shale estimations with the neutron-density method than the linear GR method and consequently, the non-linear GR method is recommended for estimation of Vsh in the studied field.

Clausena anisata(Willd.)Hook.f.ex Benth.(Rutaceae):ethnomedicinal uses,phytochemistry,pharmacological activities,toxicity,and clinical application

Clausena anisata(Willd.)Hook.f.ex Benth.is a plant extensively used in traditional medicine.Here,a synopsis of the research on various aspects of Clausena anisata(Willd.)Hook.f.ex Benth.is presented.An electronic literature review revealed that formulations containing Clausena anisata(Willd.)Hook.f.ex Benth.are used to manage and treat diabetes,eye problems,malaria,snake envenomation,malignancies,as well as venereal,gastrointestinal,reproductive,respiratory,dermatological,and odonatological ailments.To date,90 compounds have been isolated and characterized from extracts of Clausena anisata(Willd.)Hook.f.ex Benth.Crude extracts and isolated compounds from Clausena anisata(Willd.)Hook.f.ex Benth.possess anti-inflammatory,antimicrobial,antioxidant,antiplasmodial,antiproliferative,anti-human immunodeficiency virus-1,antimycobacterial,antihypertensive,and antidiabetic activities.These bioactivities can be attributed to alkaloids,coumarins,limonoids,and phenylpropanoids present in different parts of the plant.Although some studies have indicated moderate toxicity of the extracts,some of the dominant compounds in this species,such as estragole and carbazole alkaloids,are mutagenic or cytotoxic.A clinical trial utilizing a Ghanaian herbal formulation containing Clausena anisata(Willd.)Hook.f.ex Benth.was found to be effective in reducing pain associated with osteoarthritis.Research progress to date supports the traditional use of this species in herbal medicine.However,these studies do not explain the relationships between traditional uses,pharmacological activities,and mechanisms of action.Thus,further studies should be designed to understand the biochemical properties and physiological effects of Clausena anisata(Willd.)Hook.f.ex Benth.extracts,facilitating the development and utilization of this medicinal resource.

Drop Factor and Infusion Dose Calculation Discrepancies among Nurses in Southern Nigeria: A Cross-Sectional Study

Nurses must deliver infusions as prescribed since too slow or fast a dose could be deleterious to patients. Nurses experience challenges with infusion dose calculations, making them vulnerable to errors. The research team examined drop factor and infusion dose calculation discrepancies among nurses in southern Nigeria. Five university teaching hospitals were involved in this cross-sectional study conducted in 2019. To establish the drop factor of commonly available macro drip sets, the team randomly sourced 25 macro drip sets from the hospitals’ pharmacies. A sample of 291 nurses was selected using a proportionate random sampling technique. The team collected data using the Adult Infusion Dose Calculation Quiz and analyzed it at a 5% significance level. Twenty (80%) of the sampled macro drip sets displayed a drop factor value of 20 drops per milliliter (gtt/ml) on their packaging. When measured experimentally, 25 (100%) of the macro drip sets delivered exactly 20 gtt/ml. Only 36 (12.4%) respondents calculated macro drip infusion doses using the correct drop factor of 20 gtt/ml. Non-attendance of infusion administration training updates significantly increased the risk of error by 38% (p ≤ 0.001). In conclusion, the drop factor of macro drip sets used in southern Nigeria is 20 gtt/ml;nurses were prone to infusing patients at a lower dose than prescribed. Special training in infusion therapy might remedy this concern.

Aboveground carbon stock is related to land cover and woody species diversity in tropical ecosystems of Eastern Ethiopia

Background:Current theories on biodiversity-carbon sequestration relationship describe biodiversity as an important factor influencing carbon storage,either through complementarity effect or by mass ratio effect.So far,the expected form of biodiversity-carbon relationships in tropical ecosystems has not been known with certainty.Therefore,we explored the relationship between aboveground carbon stock and different biodiversity measurement indices(i.e.,species richness,species diversity,species evenness,and functional diversity)in different land cover types of Eastern Ethiopia.A total of 48 plots were established using stratified random sampling.Vegetation parameters such as diameter at breast height,diameter at stump height,tree height,and species type were recorded.Results:We found that the average aboveground carbon stock of the study area is 147.6±17.2 t ha^(−1)(mean,SE)across land cover types.Species richness,Shannon index,and functional diversity together explained 73.5%,61.4%,58.9%,and 52.0%of the variation in aboveground carbon storage in woodland,riparian forest,bushland,and farmland,respectively.Functional diversity was a significant predictor explaining the total aboveground carbon stocks(26.7%)across the land cover types.The effects of biodiversity on aboveground carbon storage were mediated by functional diversity and presence and dominance of species.This shows that both the selection effects and the niche complementarity are important for carbon storage.However,the impact of functional diversity effects(niche complementarity)was higher than that of functional dominance effects(selection effects).Conclusions:Implementation of protected area-based ecosystem conservation practices in the country seems feasible to mitigate climate change and Reducing Emissions from Deforestation and Forest Degradation(REDD+)programme should emphasize on biodiversity conservation.

Inhibition of sulfate-reducing bacteria influenced corrosion on hydrophobic poly(dimethylsiloxane)coatings

Sulfate-reducing bacteria(SRB)has been pointed out as one of the causative agents of microbial induced corrosion in the marine environment.To address this problem,novel strategies are being experimented as against the earlier methods which have been banned due to their toxic effects on useful aquatic lives.Thus,the aim of this study was to investigate the effect of non-toxic perfluorodecyltrichlorosilane(PFDTS)on resistance of hydrophobic poly(dimethylsiloxane)/phosphoric acid-treated zinc oxide(PDMS/PA-treated ZnO)coatings to SRB-induced biofouling and corrosion.The surface features of the coatings before and after exposure to SRB/NaCl solution were analyzed by scanning electron microscopy(SEM).Wettability of the coatings before and after exposure was also measured.The interaction of SRB with the coatings was investigated by FTIR spectroscopy.The resistance performance of the modified coatings against SRB-induced corrosion was monitored by electrochemical impedance spectroscopy(EIS).The EIS measurements revealed that 0.20 g PFDTS-based coating displayed highest corrosion resistance with impedance modulus of 6.301×10^10 after 15 d of exposure to SRB/NaCl medium.The results were corroborated by surface and chemical interaction analyses,and thus,indicate that 0.20 g PFDTSmodified PDMS/PA-treated ZnO coating has potentials for excellent SRB-induced corrosion resistance and anti-biofouling performance.

Multifunctional superhydrophobic coatings fabricated from basalt scales on a fluorocarbon coating base

Superhydrophobic coatings are increasingly being evaluated as anticorrosion interventions in exceedingly hydrated environments.However,concerns about their long-term durability and amenability to large-area applications in marine environments are still hindering commercial-scale deployment.This study is focused on development of easy-to-apply superhydrophobic coatings,with multifunctional capabilities,in order to extend the integrity and durability of the coatings in harsh marine environments.Here,a set of facile methods involving selective chemical etching using concentrated Na OH,as well as fluorination with perfluoropolyether methyl ester were adopted to fabricate a superhydrophobic surface on basalt scales,having the required rough hierarchical micro-nanotextured and low surface energy.The superhydrophobic basalt scales were subsequently aligned atop a fluorocarbon resin,pre-deposited on a metal substrate,to yield a multifunctional superhydrophobic coating(3μL water droplet;contact angle=165.1°,rolling angle=0.7°),easily amenable to large surface area application and having excellent wear resistance,UV-aging resistance,salt spray resistance,corrosion resistance and antibacterial capabilities.