U. K. Johnson, N. Imelda, M. M. Geoffrey, W. H. Caro, Mutiso Festus, Kioko D., Kimatu Josphert
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.
{"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}
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.
{"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}
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.
{"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}
Inza Gnanou, Christian Zoundi, Salfo Kaboré, F. Ouattara
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.
{"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}
Abidoye Olafadehan Olaosebikan, Ehigimetor Bello Victor, O. A. Kehinde, Morufat Bello Adebukola
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
研究了19条吸附等温线、8个吸附动力学模型和亚甲基蓝(MB)在壳聚糖薄片上的吸附热力学。研究了操作参数对吸附MB的影响。采用10个误差函数对模型参数进行统计分析。通过比较归一化误差(SNE)和两种信息化标准的统计工具，选择了最适合的吸附模型和动力学模型。5-p fritz - schlender等温线最符合壳聚糖薄片对MB的吸附实验数据，最大吸附量为143.6660 mg/g。采用拟二阶动力学模型描述了壳聚糖在不同初始浓度下的吸附速率，其中膜扩散为速率控制步骤，化学吸附影响吸附过程。计算得到的热力学参数kJ/(mol K)、负0 G值表明壳聚糖薄片对MB的吸附是物理吸附、吸热吸附、自发吸附、能量有利吸附和吸能吸附。利用0.1 M HCl和0.1 M pH值的不同pH值，考虑了带负电荷的壳聚糖(生物吸附剂)表面与带正电荷的MB.碱性介质之间的静电力吸引力，提出了壳聚糖薄片吸附MB的反应机理。研究了MB溶液初始浓度对亚甲基蓝(MB)去除率的影响。10 ~ 60 mL加入0.1 g固定量的生物吸附剂(壳聚糖)，接触时间为30 min，在120转/分钟的机械轨道搅拌器上搅拌，环境温度为302℃。在0.1 g壳聚糖的固定质量和2°C的室温条件下，在4 h内研究接触时间的影响。热力学研究，这是取决于在30至90°C范围内的变化的影响在一个固定MJ回归
{"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}
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.
在许多发展中国家，某些不受管制的土地使用活动的影响损害了水资源的质量，减少了饮用水的充足性。本研究的目的是捕捉这些活动的影响，并利用改进的DRASTIC方法评价具体的地下水脆弱性。通过将土地利用和抽水层的影响纳入到“内在”DRASTIC参数中，在尼日利亚的Aba市提出并实施了DRASTIC- l u P。分析结果显示，被划分为“低”的区域占15%，被划分为“中等”和“高”漏洞的区域占79.1%和5.9%。而对于DRASTIC-L u P，发现3.2%的模型为“低”，54.3%为“中”，41.8%为“高”，0.7%为“非常高”。在DRASTIC-L u P a模型中发现的“高”和“非常高”脆弱性等级的转变代表了该地区观测到的城市热点的影响。该结果表明，应在“低”和“中”脆弱等级地区实施地下水保护措施，并用于抽取清洁水供饮用。所提出的模型提高了可预测性，并保证了该方法在具有类似城市趋势的城市环境中具有更好的可转移性。
{"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}
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.
{"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}
Hydropower is cost effective environment friendly and worldwide proven sustainable energy source. Driven by streamflow stream flows, it is vulnerable to climate change and land use change. The hydropower production from the two-existing run-of-river hydropower projects on the Sondu Miriu River are vulnerable to rainfall variability and requires proper understanding of the climate change trends and policies to support sustainable hydropower development and put in place strategies for building resilience for the local communities. The objective of this paper is to examine climate change trends and their impacts on hydropower in the Sondu Miriu River basin. The methodology involved analysis of downscaled climate data from CORDEX for the period from 1950 to 2100, gridded data from Kenya Meteorological department for a period of 2007 to 2018, river flows data from Water Resources Authority for a period of 2007 to 2018 and hydropower output data from KenGen for a period of 2007 to 2018 to examine the climate change trends within the Sondu Miriu River basin and impacts on hydrology and hydropower. The results indicate that maximum and minimum annual temperature increased by 0.7 and 0.9°C, respectively between 1950 and 2005. Both the maximum and minimum annual temperatures are projected to increase by 1.9°C based on the RCP4.5 and RCP8.5 scenarios between 2006 and 2100 within the Sondu Miriu basin. Annual rainfall increased by 74.8 mm between 1950 and 2005. This is projected to increase by 24.7 and 117.8 mm based on RCP4.5 and RCP8.5 scenarios, respectively. For the period between 2007 and 2018, the observed maximum increased by 5°C while the minimum temperatures decreased by 1°C. The rainfall decreased by 193.14 mm while the mean daily river flows decreased by 0.3 m 3 /s annually during the same period. This resulted in the decrease of hydropower production by 8.3 GWh in Sondu Miriu HPP between 2007 and 2018 while the production reduced by 14.18 GWh for Sang’oro HPP between 2012 and 2018. Understanding climate change trends within Sondu Miriu River basin should guide the planning for hydropower development projects.
{"title":"An analytical assessment of climate change trends and their impacts on hydropower in Sondu Miriu River Basin, Kenya","authors":"W. Ochieng, C. Oludhe, S. Dulo, L. Olaka","doi":"10.5897/ajest2021.3064","DOIUrl":"https://doi.org/10.5897/ajest2021.3064","url":null,"abstract":"Hydropower is cost effective environment friendly and worldwide proven sustainable energy source. Driven by streamflow stream flows, it is vulnerable to climate change and land use change. The hydropower production from the two-existing run-of-river hydropower projects on the Sondu Miriu River are vulnerable to rainfall variability and requires proper understanding of the climate change trends and policies to support sustainable hydropower development and put in place strategies for building resilience for the local communities. The objective of this paper is to examine climate change trends and their impacts on hydropower in the Sondu Miriu River basin. The methodology involved analysis of downscaled climate data from CORDEX for the period from 1950 to 2100, gridded data from Kenya Meteorological department for a period of 2007 to 2018, river flows data from Water Resources Authority for a period of 2007 to 2018 and hydropower output data from KenGen for a period of 2007 to 2018 to examine the climate change trends within the Sondu Miriu River basin and impacts on hydrology and hydropower. The results indicate that maximum and minimum annual temperature increased by 0.7 and 0.9°C, respectively between 1950 and 2005. Both the maximum and minimum annual temperatures are projected to increase by 1.9°C based on the RCP4.5 and RCP8.5 scenarios between 2006 and 2100 within the Sondu Miriu basin. Annual rainfall increased by 74.8 mm between 1950 and 2005. This is projected to increase by 24.7 and 117.8 mm based on RCP4.5 and RCP8.5 scenarios, respectively. For the period between 2007 and 2018, the observed maximum increased by 5°C while the minimum temperatures decreased by 1°C. The rainfall decreased by 193.14 mm while the mean daily river flows decreased by 0.3 m 3 /s annually during the same period. This resulted in the decrease of hydropower production by 8.3 GWh in Sondu Miriu HPP between 2007 and 2018 while the production reduced by 14.18 GWh for Sang’oro HPP between 2012 and 2018. Understanding climate change trends within Sondu Miriu River basin should guide the planning for hydropower development projects.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76068133","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}
Mechanisms of the interannual variability of upwelling onset dates on the Petite-Cote of Senegal are investigated using daily NEMO model data outputs and NOAA ocean surface temperature observations (OISST). We first determined the phenology (onset dates, end dates, duration and occupied area of the upwelling) over the Petite-Côte located in south of the Senegalese coast. Our results show that upwelling in the Petite-Côte starts on average on 03-December (with a standard deviation of 13 days) and ends on average on 13-June (with a standard deviation of 11 days). Upwelling lasts, on average, 6 months in the region. The maximum upwelling intensity is noted on 15-May and the maximum occupied area exhibits a February-May plateau. We then performed a composite analysis based on the earliness of the upwelling setup dates to understand the mechanisms involved. Our results show that for the earliest upwelling years, we note a strengthening of the vertical velocities 3 weeks before the onset of the upwelling but we note especially an abnormal intensification of the coastal jet. The latter seems to be the initiator of the early onset of the upwelling in the region. These reinforcements are associated with a significant decrease in surface temperature (SST) and an intensification of northerly trade winds. of upwelling for all atmospheric and oceanic variables to better diagnose the behavior of the parameters for early upwelling years. Finally, for the composite analysis of the different variables, we apply a lanczos filter to the data at intra-seasonal timescale to remove frequencies greater than 90 days.
{"title":"Phenology and mechanisms of the early upwelling formation in the southern coast of Senegal","authors":"Wade Malick, Thiam Mamadou, Diba Ibrahima, Diop Bouya","doi":"10.5897/ajest2021.3071","DOIUrl":"https://doi.org/10.5897/ajest2021.3071","url":null,"abstract":"Mechanisms of the interannual variability of upwelling onset dates on the Petite-Cote of Senegal are investigated using daily NEMO model data outputs and NOAA ocean surface temperature observations (OISST). We first determined the phenology (onset dates, end dates, duration and occupied area of the upwelling) over the Petite-Côte located in south of the Senegalese coast. Our results show that upwelling in the Petite-Côte starts on average on 03-December (with a standard deviation of 13 days) and ends on average on 13-June (with a standard deviation of 11 days). Upwelling lasts, on average, 6 months in the region. The maximum upwelling intensity is noted on 15-May and the maximum occupied area exhibits a February-May plateau. We then performed a composite analysis based on the earliness of the upwelling setup dates to understand the mechanisms involved. Our results show that for the earliest upwelling years, we note a strengthening of the vertical velocities 3 weeks before the onset of the upwelling but we note especially an abnormal intensification of the coastal jet. The latter seems to be the initiator of the early onset of the upwelling in the region. These reinforcements are associated with a significant decrease in surface temperature (SST) and an intensification of northerly trade winds. of upwelling for all atmospheric and oceanic variables to better diagnose the behavior of the parameters for early upwelling years. Finally, for the composite analysis of the different variables, we apply a lanczos filter to the data at intra-seasonal timescale to remove frequencies greater than 90 days.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73816591","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}
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