African Journal of Environmental Science and Technology最新文献

{"title":"A comparative analysis of MODIS-derived drought indices for Northern and Central Namibia","authors":"D. Wyss, K. Negussie, Antonia Staacke, Amadé Karnagel, Malin Engelhardt, M. Kappas","doi":"10.5897/ajest2022.3096","DOIUrl":"https://doi.org/10.5897/ajest2022.3096","url":null,"abstract":"Namibia is a semi-arid country with erratic and unpredictable rainfall. Extreme weather patterns, such as floods and extensive droughts, have become more common in recent years, with strong impact on surface and ground water availability, rangeland and agricultural productivity, food security, and further land degradation, such as bush encroachment or soil erosion. The previous 10 years were characterized by a perennial drought that lasted from 2013 to 2016 and an extreme drought that occurred during the rainy season of 2018/2019, which was the driest in 90 years. In January 2021, however, rainfall totals doubled to tripled the norm. The paper compares five drought indices in order to identify, visualize, monitor, and better understand the nature, characteristics, and spatial-temporal patterns of drought in northern and central Namibia. Based on their sensitivity to vegetation greenness, land surface temperature, evapotranspiration, and precipitation, the indices allow for calculation, time series analysis, and cross-comparison. Droughts occur every year, but the intensity of the drought varies depending on the index type. It is concluded that a comparative analysis of multiple indices provides a better interpretation of drought than single parameter systems. Future research should include biophysical properties such as soil characteristics, soil moisture, and hydrology, as well as socioeconomic studies, in order to develop an integrated drought index for northern Namibia.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"104 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79163562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of water level on plant characteristics in a restored wetland and referenced natural wetland in Wakiso, Uganda","authors":"K. B. Vesselly, A. Opio, M. Mwanjalolo, F. Kansiime","doi":"10.5897/ajest2018.2637","DOIUrl":"https://doi.org/10.5897/ajest2018.2637","url":null,"abstract":"Wetland restoration success is dependent on the likeness of both structure and function of the restored wetland systems comparable to reference sites. Assessing the success of restoration is reliant on the monitoring and evaluation of the restored system overtime as was done with Nakyesanja, a restored wetland, and Kiryagonja, a referenced natural wetland in Wakiso District, Uganda. The objectives of this study were to determine plant characteristics (species abundance, diversity, height and phytomass) in the wetlands and evaluate the effect of water level on plants establishment and phytomass accumulation. Two transects were established in each wetland with five plots measuring 1×1 m 2 on each transect. Plant species were identified in the plots while papyrus was measured and harvested. The water level was also measured in each plot. No significant difference was detected in the above ground phytomass of Cyperus papyrus L. in the restored and the natural wetlands (p = 0.202). The restoration process has caused papyrus plants to accumulate productivity similar to the natural level. No significant difference was also observed in the heights of papyrus (p = 0.232). This indicated that the restoration methodology was effective on plants growth; making plants acquiring heights as their counterparts in the natural wetland. Uneven water distribution affected the growth and distribution of plants in the restored wetland. Areas of high water level got colonized with typical wetland species while areas with low water level got colonized by opportunistic plants. However, the water level was positively correlated (R 2 = 0.485, p = 0.042) with species diversity in the natural wetland making waterlogging the key determinant of macrophytic plants establishment in a natural environment. Periodic study is therefore recommended to monitor the success of the wetland restoration overtime.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81811891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effectiveness of Moringa Oleifera seed coagulant in reducing the turbidity and modifying the physico-chemical characteristics of water","authors":"U. K. Johnson, N. Imelda, M. M. Geoffrey, W. H. Caro, Mutiso Festus, Kioko D., Kimatu Josphert","doi":"10.5897/ajest2022.3093","DOIUrl":"https://doi.org/10.5897/ajest2022.3093","url":null,"abstract":"Moringa oleifera plant is unique due to its coagulation effect on turbid water. However, the extent to which the seed’s powder coagulant changes the physico-chemical characteristics of treated water has not been discussed in previous studies. In addition, there are limited data and information on the optimum concentration of M. oleifera seed powder coagulant and the nature of the sludge that forms after the treatment of water. The aim of this study is to examine the extent to which M. oleifera seed powder can be used as a coagulant in treating different types of turbid waters and how it changes the physico-chemical characteristics of treated water. Samples of turbid water were subjected to various dosages of dry M. oleifera seed powder concentrations to determine the degree of clarification, changes in physico-chemical characteristics of water and the proportion of sludge formed after coagulation process. The results showed that M. oleifera seed powder leads to reduction of water turbidity from 461 NTU to about 15 NTU within 45 min. Significant clarification of turbid water occurred at the mean optimum concentration of M. oleifera seed powder coagulant (0.20 g/l) and maximum optimum concentration of 0.50 g/l. The mean water turbidity reduction efficiency was 64% with the maximum efficiency of 95%. Increasing coagulant concentration above 0.50 g/l led to an increase in water turbidity, electrical conductivity, salinity and total dissolved solids (TDS). The sludge formed after water treatment was found to be equivalent to 10% of the total volume of treated water. There are also significant differences in the effectiveness of coagulant derived from various provenances of M. oleifera found in Eastern and Coastal regions of Kenya in terms of turbidity reduction. turbidity determined in the field using Hanna Instruments Microprocessor turbidity measuring turbidity in the range of 0 to 1000FTU. Conductivity, TDS, salinity and temperature were also determined in the field using portable Martini Instruments EC/TDS/NaCl/Temperature meter (APHA/AWWA/WEF, 2012). The methods of data analysis that were applied in this study include regression analysis, correlation analysis, analysis of variance, and use of measures of central tendency.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"71 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91402596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Potential of biochar for clean-up of heavy metal contaminated soil and water","authors":"Adaobi Onmonya Yvonne, Galadima Adamu Sadiq, Sadi Maryam","doi":"10.5897/ajest2021.3038","DOIUrl":"https://doi.org/10.5897/ajest2021.3038","url":null,"abstract":"Heavy metals exist in the environment naturally aside those due to anthropogenic impact. These metals are removed from effluents and water using different techniques like adsorption, oxidation/reduction, chemical precipitation, membrane separation, filtration and ion exchange. Biosorption is very effective because it is highly renewed naturally, is cheap, and can remove metals greatly because the pollutant can be recovered either by desorbing or incinerating the biomass. Therefore, this work aims to identify some biochars utilized as adsorbents to remove lead, chromium, mercury and copper in soil and water, according to different researchers. In conclusion adsorption is a very effective method to remove or recover heavy metals from the environment. These biochars can be used in place of commercial activated charcoal because, besides being cheap, they are very effective treatment in removing metal ions based on wastewater discharge standards.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87518532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adoption of climate change friendly New Rice for Africa (NERICA) varieties among farmers in Mwea West Sub-county, Kenya","authors":"Kamau Mburu Benson, Wanjiku Ngucia Christine","doi":"10.5897/ajest2021.3078","DOIUrl":"https://doi.org/10.5897/ajest2021.3078","url":null,"abstract":"","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82370350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimizing community participation in the management of Yala Wetland Ecosystem, Lake Victoria Basin, Kenya: The Yala Hub Framework","authors":"O. O. Douglas, A. Victor","doi":"10.5897/ajest2020.2940","DOIUrl":"https://doi.org/10.5897/ajest2020.2940","url":null,"abstract":"Wetlands are particularly important environmental assets whose sustainability requires meaningful participation of the riparian communities in their management. Yala Wetland is an important resource whose key challenges involve land and water resource use for competing interests which prompted Siaya and Busia County regional Governments to initiate preparation, a Land Use Plan (LUP)/Strategic Environmental Assessment (SEA) to resolve these. A LUP/SEA Framework with Yala Project Advisory Committee (YPAC) for local communities guided the planning process and implementation. Concurrently, an action research was conducted to assess the level and effectiveness of Yala Wetland community participation in the SEA/LUP processes and improve the outcomes. Research data was derived from 410 respondents from 60 local community groups, 34 key informant interviews, 187 students and satellite images. The Spectrum of Public Participation Model revealed that wetland communities’ participation was at lower levels (Inform (17%) and Consult (83%) while the measure of effectiveness on 10 indicators were poor (20%) and unsatisfactory (80%) thus not meaningful nor effective. Consequently, Yala Hub Framework was developed, occasioning significant improvements in the final LUP. The study concluded that effective community participation determines and influences effective implementation of decisions made and that increased participation through deliberate intervention will eventually increase the effectiveness of community development and encourage longterm sustainability.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88439894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Variability of the magnetospheric electric field due to high-speed solar wind convection from 1964 to 2009","authors":"Inza Gnanou, Christian Zoundi, Salfo Kaboré, F. Ouattara","doi":"10.5897/ajest2021.3075","DOIUrl":"https://doi.org/10.5897/ajest2021.3075","url":null,"abstract":"Focusing on the classification of solar winds into three types of flux: (1) slow winds, (2) fluctuating winds, and (3) high speed-solar winds HSSW (V ≥ 450 km/s on average day), the influence of the convection electric field (E M ) via the flow of HSSWs during storms in the internal magnetosphere and on the stability of magnetospheric plasma at high latitudes was investigated. The study involved 1964-2009 period, which encompasses solar cycles 20, 21, 22 and 23. The results show a weak correlation of the frozen electric field profiles with the HSSWs overall solar cycles and a very large number of HSSWs recorded in cycle 23. Particular attention has been paid to solar cycle 22 which rather presents a fairly disturbed profile with sudden variations in solar flux and E M field; however, solar cycle 21 records the lowest level of HSSW. Overall, over all the studied solar cycles, it can be seen that the E M field from HSSWs of very low intensity increases progressively from solar cycle 20 to cycle 23, respectively with a minimum occurrence of 8.48% and a maximum of 9.36%. The results reached show, on one hand, that the magnetosphere is very stable from 15:00UT to 21:00UT, and on the other hand, that there is a significant transfer of mass in the night sector (21:00UT-24:00UT) than on the day side (00:00UT-15:00UT) for all solar cycles over the long period of 45 years.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"98 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81230071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Isotherms, kinetic and thermodynamic studies of methylene blue adsorption on chitosan flakes derived from African giant snail shell","authors":"Abidoye Olafadehan Olaosebikan, Ehigimetor Bello Victor, O. A. Kehinde, Morufat Bello Adebukola","doi":"10.5897/ajest2021.3065","DOIUrl":"https://doi.org/10.5897/ajest2021.3065","url":null,"abstract":"In the present study, modeling of 19 adsorption isotherms, 8 kinetic models and thermodynamics of methylene blue (MB) adsorption on chitosan flakes synthesized using Archachatina marginata shell wastes was investigated in a batch mode. The operational parameters’ effects on the MB adsorption were studied. The model parameters were statistically analyzed using 10 error functions. The choices of the best fitted adsorption and kinetic models were based on the comparison of the sum of normalized error (SNE) and two statistical tools of information-based criteria. The 5-p Fritz-Schlüender isotherm best fitted the experimental adsorption data of MB on chitosan flakes based on SNE whereby maximum adsorption capacity, axm q , of 143.6660 mg/g was obtained. The adsorption rate of MB on chitosan flakes was kinetically described by pseudo second-order model at all initial concentrations of MB investigated, with film diffusion being the rate-controlling step and the adsorption process chemisorption-influenced. The calculated thermodynamic parameters, kJ/(mol K), negative 0 G  values revealed that the adsorption of MB onto chitosan flakes was physical, endothermic, spontaneous, energetically favorable and exergonic. The reaction mechanism of the adsorption of MB onto chitosan flakes was proposed taking cognizance of the electrostatic force of attraction between the negatively charged surface of the chitosan (biosorbent) and the positively charged MB. alkaline medium by varying pH values using 0.1 M HCl and 0.1 M measured by a pH meter. The effect of initial concentration of MB solution on the % removal of methylene blue (MB) was investigated by using 10 to 60 mL with a fixed amount of 0.1 g of biosorbent (chitosan) at contact time of 30 min, agitated using a mechanical orbit shaker set at 120 rev/min and ambient temperature of 30  2°C. The impact of contact time was carried out within 4 h durations at a fixed mass of 0.1 g chitosan and room 30  2°C. The thermodynamics study, which is hinged on the effect of variation of in within the ranges of 30 to 90°C at a fixed MJ  regression","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79923555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterizing groundwater vulnerability in developing urban settings using DRASTIC-LuPa approach: A case study of Aba City, Nigeria","authors":"Dickson Ijioma Uche, Wendland Frank, Herd Rainer","doi":"10.5897/ajest2021.3068","DOIUrl":"https://doi.org/10.5897/ajest2021.3068","url":null,"abstract":"The impact of certain unregulated land-use activities harms the quality of water resources and reduces the sufficiency of drinking water in many developing countries. This study aimed to capture the impact of such activities and evaluate the specific groundwater vulnerability using a modified DRASTIC approach. The DRASTIC-L u P a was proposed and implemented for Aba City, Nigeria by incorporating land-use and the impact of pumping layers to the “intrinsic” DRASTIC parameters. The results of the analysis revealed that the area classified as “low” was 15 and 79.1% as “medium” and 5.9% as “high” vulnerability classes for the DRASTIC. Whereas for the DRASTIC-L u P a model 3.2% for “low”, 54.3% for “medium”, 41.8% for “high” and 0.7% for “very high” were found. The transitions in the vulnerability classes of areas displaying “high” and “very high” found in the DRASTIC-L u P a model represent the impact of urban hotspots observed in the area. This result implies that groundwater protection measures should be implemented in the area designated with “low” and “medium” vulnerability classes and used for abstracting clean water for drinking purposes. The proposed model enhances the predictability and guarantees better transferability of the approach in urban settings with similar urban trends.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"110 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81640658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Uroclhoa mosambincensis: A potential native phytoremediator for soils contaminated with arsenic","authors":"Isabel Ventura Guilundo Sónia, Alberto Aduge Marta, Enes Manuel Simango Edmilson, Maguengue Domingos, Rodríguez Suárez Esnaider, Marília Martins Célia, António Quilambo Orlando","doi":"10.5897/ajest2020.2942","DOIUrl":"https://doi.org/10.5897/ajest2020.2942","url":null,"abstract":"Industrial development has caused the contamination of the environment, leading to biodiversity loss and human health concerns. The use of native plants and/or their associated microbiota is a sustainable solution for reducing or transforming contaminants into less harmful forms. This study was conducted to evaluate the remedial potential of Uroclhoa mosambincensis in soils contaminated with arsenic. In a greenhouse experiment, seedlings of U. mosambincensis were divided into four treatments of increasing arsenic concentration. It was found out that in U. mosambicensis, although most physiological parameters were affected, in 200 mg.kg -1 arsenic trioxide concentration (As2O3) an increase in 23.3% of leaf biomass was observed. Chlorophyll A was not significantly affected by the presence of arsenic. It was also verified that the increase in arsenic concentration stimulated the removal of arsenic from soil to plant tissues at a percentage of 10.8, 27.7 and 30.2 higher in each treatment. This indicates the arsenic accumulator character of U. mosambicensis and its potential use for remediation of soils contaminated with arsenic.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74739440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}