Yanick Acha Acha, Messoe William Aurélien, Ajeagah Gidéon Aghaindum
Agriculture, which accounts for 70% of water abstractions worldwide, plays a major role in water pollution. Resulting pollution poses risks to aquatic ecosystems and humans. With the aim of evaluating the saprobic state of four hydro systems subject to pollution from intensive rubber cultivation, the present study was carried out within and around the Hevecam rubber plantation in Niete, South Region of Cameroon. The study was done from September 2019 to December 2020 with monthly sampling, physico-chemical water analysis and determination of ciliate diversity and distribution. Water in the study stations was acidic (6.40±0.31CU), with average temperature (25.20±0.56°C) and conductivity of up to 761.8 µs/cm. Conductivity values coupled with phosphates (up to 29.7 mg/L), herbicide residues are indicators of agricultural pollution on water quality. Station N2 showed the greatest ciliate abundance and species richness. The long dry season of 2020 showed the highest diversity and abundance. The saprobic index indicated moderate to high levels of organic pollution (2.16 to 3.67). Water quality was degraded with the impact of the agricultural pollution due to the presence of herbicide and fertilizer residues at stations N2 and N4. High levels of phosphates and nitrates have resulted in an increased organic load reflected in the saprobic indices; indicating average to high organic pollution.
{"title":"Use of ciliated protozoans in the saprobic evaluation of hydrosystems in an equatorial zone (South region of Cameroon)","authors":"Yanick Acha Acha, Messoe William Aurélien, Ajeagah Gidéon Aghaindum","doi":"10.5897/ajest2022.3117","DOIUrl":"https://doi.org/10.5897/ajest2022.3117","url":null,"abstract":"Agriculture, which accounts for 70% of water abstractions worldwide, plays a major role in water pollution. Resulting pollution poses risks to aquatic ecosystems and humans. With the aim of evaluating the saprobic state of four hydro systems subject to pollution from intensive rubber cultivation, the present study was carried out within and around the Hevecam rubber plantation in Niete, South Region of Cameroon. The study was done from September 2019 to December 2020 with monthly sampling, physico-chemical water analysis and determination of ciliate diversity and distribution. Water in the study stations was acidic (6.40±0.31CU), with average temperature (25.20±0.56°C) and conductivity of up to 761.8 µs/cm. Conductivity values coupled with phosphates (up to 29.7 mg/L), herbicide residues are indicators of agricultural pollution on water quality. Station N2 showed the greatest ciliate abundance and species richness. The long dry season of 2020 showed the highest diversity and abundance. The saprobic index indicated moderate to high levels of organic pollution (2.16 to 3.67). Water quality was degraded with the impact of the agricultural pollution due to the presence of herbicide and fertilizer residues at stations N2 and N4. High levels of phosphates and nitrates have resulted in an increased organic load reflected in the saprobic indices; indicating average to high organic pollution.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88340975","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}
Biabongo N. Pamphile, N. J. Ndjibu, Ekoko Vanshok, Ekulu N. Gédéon
The aim of this paper is to size the PFR reactor and to deduce the likely useful mass of the catalyst in the PBR for the production of hydrocarbons such as propane, butane and pentane from methanol via dimethyl ether (DME). The use of these reactors would require kinetic analysis, material balance, energy balance and then sizing. The interest in the chemical catalytic conversion of synthesis gas to gasoline suggests that the fuels industry may have come full circle from the time that synthesis gas from either natural gas or coal gasification were economic alternatives to crude oil. In this instance, cellulosic waste is the alternative raw materials that can be provided from DRCs logging waste and from agricultural activities. In the case of Muanda in the DRC, as in neighboring countries, the exploitation of black gold does not seem to have played any positive role in terms of development.
{"title":"Modeling and simulation of reactors in plug flow reactor (PFR) and Packed Bed Reactor (PBR) series for the conversion of methanol into hydrocarbons","authors":"Biabongo N. Pamphile, N. J. Ndjibu, Ekoko Vanshok, Ekulu N. Gédéon","doi":"10.5897/ajest2022.3091","DOIUrl":"https://doi.org/10.5897/ajest2022.3091","url":null,"abstract":"The aim of this paper is to size the PFR reactor and to deduce the likely useful mass of the catalyst in the PBR for the production of hydrocarbons such as propane, butane and pentane from methanol via dimethyl ether (DME). The use of these reactors would require kinetic analysis, material balance, energy balance and then sizing. The interest in the chemical catalytic conversion of synthesis gas to gasoline suggests that the fuels industry may have come full circle from the time that synthesis gas from either natural gas or coal gasification were economic alternatives to crude oil. In this instance, cellulosic waste is the alternative raw materials that can be provided from DRCs logging waste and from agricultural activities. In the case of Muanda in the DRC, as in neighboring countries, the exploitation of black gold does not seem to have played any positive role in terms of development.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"128 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86591756","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}
N. Zanga, Victor Kianfu Pwema, Nseu Bekeli Mbomba, Shango Mutambwe, J. Micha
In order to determine the diet of Nannothrissa stewarti in Lake Mai Ndombe, 667 specimens with total length between 9.0 and 49.84 mm were studied. These fish were sampled by active fishing during the 24 h cycle between September 2018 and October 2021. The vacuity (%) and intestinal coefficients were 38.71% and 0.69 ± 0.03, respectively, classifying N. stewarti as invertivorous. The calculated feeding indices showed that zooplankton are the essential prey (%F fi = 88.8; %IP = 90.0; and %IRI = 90.8) while phytoplankton are the incidential prey. Larvae feed on cyclopoid, copepods, and nauplius while adults consume cladoceras, copepods, rotifers and phytoplankton. This fish begins its feeding activity early in the morning (5:00 am), his stomach fills up around 1:00 pm and empties completely around 1:00 am. Thus, N. stewarti in various steps growing ages both males and females are zooplanktons feeders.
{"title":"Diet study of Nannothrissa stewarti (Poll Roberts, 1976) Clupeidae in Lake Mai-Ndombe, Democratic Republic of Congo","authors":"N. Zanga, Victor Kianfu Pwema, Nseu Bekeli Mbomba, Shango Mutambwe, J. Micha","doi":"10.5897/ajest2022.3120","DOIUrl":"https://doi.org/10.5897/ajest2022.3120","url":null,"abstract":"In order to determine the diet of Nannothrissa stewarti in Lake Mai Ndombe, 667 specimens with total length between 9.0 and 49.84 mm were studied. These fish were sampled by active fishing during the 24 h cycle between September 2018 and October 2021. The vacuity (%) and intestinal coefficients were 38.71% and 0.69 ± 0.03, respectively, classifying N. stewarti as invertivorous. The calculated feeding indices showed that zooplankton are the essential prey (%F fi = 88.8; %IP = 90.0; and %IRI = 90.8) while phytoplankton are the incidential prey. Larvae feed on cyclopoid, copepods, and nauplius while adults consume cladoceras, copepods, rotifers and phytoplankton. This fish begins its feeding activity early in the morning (5:00 am), his stomach fills up around 1:00 pm and empties completely around 1:00 am. Thus, N. stewarti in various steps growing ages both males and females are zooplanktons feeders.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"91 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75894851","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}
Declining quantity and quality of irrigation water coupled with increasing water demand are serious challenges facing paddy rice production in the world. Reuse of agricultural waste water is increasingly popular in paddy systems but few studies have been done with regards to its quality and effects on soil productivity and environmental risks. The aim of this study was to assess the suitability of effluents from the Mwea Irrigation scheme in Kenya for recycling within the scheme and for reuse in new areas downstream. Water was sampled from River Thiba intake (point 1, control) and waste water from farmers plots, Kiruara drain (point 2) and Thiba main drain (point 3). Corresponding adjacent soils were sampled and analyzed for important physico-chemical quality parameters. Results showed that the EC, TDS, TSS, Ca 2+ , Mg 2+ , K + , Na +, HCO 3- , NO 3- and SO 42- significantly (p<0.05) increased in wastewater as point 1< point 2< point 3. Whereas, 88.3% of Mwea rice farmers experienced water shortage during peak demand, 51.5% of them recycled wastewater from paddy fields. The soil total N and available P from the wastewater reuse sites increased by 48.4 and 400% respectively to amounts that could save fertilizer P application once every 3 seasons. The wastewater NO 3- concentrations increased above 8 mg/L likely to cause damage to N sensitive plants and eutrophication in the receiving water masses. The fresh water and wastewater in the Mwea scheme were suitable for irrigated rice production since all the nutrient parameters were within critical limits as recommended by FAO standards.
{"title":"Recycling Mwea irrigation water for sustainable agriculture","authors":"Joseph Onderi, B. Danga","doi":"10.5897/ajest2021.3070","DOIUrl":"https://doi.org/10.5897/ajest2021.3070","url":null,"abstract":"Declining quantity and quality of irrigation water coupled with increasing water demand are serious challenges facing paddy rice production in the world. Reuse of agricultural waste water is increasingly popular in paddy systems but few studies have been done with regards to its quality and effects on soil productivity and environmental risks. The aim of this study was to assess the suitability of effluents from the Mwea Irrigation scheme in Kenya for recycling within the scheme and for reuse in new areas downstream. Water was sampled from River Thiba intake (point 1, control) and waste water from farmers plots, Kiruara drain (point 2) and Thiba main drain (point 3). Corresponding adjacent soils were sampled and analyzed for important physico-chemical quality parameters. Results showed that the EC, TDS, TSS, Ca 2+ , Mg 2+ , K + , Na +, HCO 3- , NO 3- and SO 42- significantly (p<0.05) increased in wastewater as point 1< point 2< point 3. Whereas, 88.3% of Mwea rice farmers experienced water shortage during peak demand, 51.5% of them recycled wastewater from paddy fields. The soil total N and available P from the wastewater reuse sites increased by 48.4 and 400% respectively to amounts that could save fertilizer P application once every 3 seasons. The wastewater NO 3- concentrations increased above 8 mg/L likely to cause damage to N sensitive plants and eutrophication in the receiving water masses. The fresh water and wastewater in the Mwea scheme were suitable for irrigated rice production since all the nutrient parameters were within critical limits as recommended by FAO standards.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86397493","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}
F. Nalwanga, M. Sowman, P. Mukwaya, P. Musali, A. Nimusiima, I. Mugume
This paper explores the effects of climate variability on local communities living within and around Queen Elizabeth National Park (QENP), their coping mechanisms, and challenges encountered. Data was collected from 250 respondents through questionnaires administered to small holder farmers, salt miners, and fisher folks, as well as in-depth interviews and focus group discussions (FGDs) held with selected households in Katunguru, Lake Katwe, Kasenyi, and Kahokya parishes in and around the park. The results indicated that climate variability affects all households through long dry spells (drought), increased intensity of rain and occurrence of water related diseases. This resulted in decline in economic output in the context of reduced food availability, household incomes, and poor health of the household members. The results further showed that although diversification of livelihood activities was uniform, the coping mechanisms were heterogeneous across the three economic sectors. While the agricultural households engaged in agricultural intensification, fisher folks changed their fishing technologies, and salt miners drained their flooded saltpans. According to the findings of this study, the effects of climate variability were widespread across all households in and around the park. The study recommends that rural households be supported in a variety of activities in order to build capacity.
{"title":"Effects of climate variability on local communities living in and around Queen Elizabeth National Park, Uganda","authors":"F. Nalwanga, M. Sowman, P. Mukwaya, P. Musali, A. Nimusiima, I. Mugume","doi":"10.5897/ajest2021.3081","DOIUrl":"https://doi.org/10.5897/ajest2021.3081","url":null,"abstract":"This paper explores the effects of climate variability on local communities living within and around Queen Elizabeth National Park (QENP), their coping mechanisms, and challenges encountered. Data was collected from 250 respondents through questionnaires administered to small holder farmers, salt miners, and fisher folks, as well as in-depth interviews and focus group discussions (FGDs) held with selected households in Katunguru, Lake Katwe, Kasenyi, and Kahokya parishes in and around the park. The results indicated that climate variability affects all households through long dry spells (drought), increased intensity of rain and occurrence of water related diseases. This resulted in decline in economic output in the context of reduced food availability, household incomes, and poor health of the household members. The results further showed that although diversification of livelihood activities was uniform, the coping mechanisms were heterogeneous across the three economic sectors. While the agricultural households engaged in agricultural intensification, fisher folks changed their fishing technologies, and salt miners drained their flooded saltpans. According to the findings of this study, the effects of climate variability were widespread across all households in and around the park. The study recommends that rural households be supported in a variety of activities in order to build capacity.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76895879","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}
Reliable data on e-waste generation is important for environmentally sound management systems. This study models e-waste generation from existing data on electrical electronics imports, consumption and e-waste generation from Nigerian households. Structured questionnaires were used to obtain information on Electrical Electronic Equipment (EEE) use, reuse, and disposal from households in Nigeria households. Data from placed on the market (POM) were obtained from United Nations University (UNU) for five EEE types (TV, DVD player, refrigerator, desktop and laptop) in Nigeria between 1995 and 2019 using the apparent consumption method. A forecast up to 2020 and backcasts to 1980 were made based on these data. The lifetime profile for these five EEEs was modeled using the Weibull distribution function characterized by a time-varying shape parameter and a scale parameter. The POM data from 1980 to 2020 and the lifetime of the selected EEE from households were analyzed and fit into the Weibull lifetime distribution functions. The differences between reuse and non-reuse options show that around 54 million units of DVD players; 106 million units of CRT TV; 22 million units of the refrigerator; 11 million units of laptops and 24 million units of desktop computers would have been delayed from transiting into e-waste stream between 1981 and 2020 through reuse options.
{"title":"Effect of a modified lifetime model on e-waste generation in Nigeria under defined reuse options","authors":"O. Odeyingbo, C. P. Baldé, V. Forti","doi":"10.5897/ajest2021.3086","DOIUrl":"https://doi.org/10.5897/ajest2021.3086","url":null,"abstract":"Reliable data on e-waste generation is important for environmentally sound management systems. This study models e-waste generation from existing data on electrical electronics imports, consumption and e-waste generation from Nigerian households. Structured questionnaires were used to obtain information on Electrical Electronic Equipment (EEE) use, reuse, and disposal from households in Nigeria households. Data from placed on the market (POM) were obtained from United Nations University (UNU) for five EEE types (TV, DVD player, refrigerator, desktop and laptop) in Nigeria between 1995 and 2019 using the apparent consumption method. A forecast up to 2020 and backcasts to 1980 were made based on these data. The lifetime profile for these five EEEs was modeled using the Weibull distribution function characterized by a time-varying shape parameter and a scale parameter. The POM data from 1980 to 2020 and the lifetime of the selected EEE from households were analyzed and fit into the Weibull lifetime distribution functions. The differences between reuse and non-reuse options show that around 54 million units of DVD players; 106 million units of CRT TV; 22 million units of the refrigerator; 11 million units of laptops and 24 million units of desktop computers would have been delayed from transiting into e-waste stream between 1981 and 2020 through reuse options.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89504159","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}
Sonny Nyeko, S. Mlay, Judith Among, Abdallah Nyero
The management of electrical and electronic waste (E-waste) requires a collaborative approach against unsustainable electronic waste management. This paper attempts to assess the role of E-waste actors in regard to E-waste management sustainability by evaluating their course of action. It proposes an E-waste management conceptual framework based on key stakeholders and validates it with 346 top government employees in strategic positions across 10 Ugandan cities. The study utilized Partial Least Square (PLS) technique, a statistical analysis method well-known under Structural Equation Modeling (SEM), for data analysis. The calculated and considered model explains 48.5% of the variance in E-waste management sustainability. The results demonstrate that E-waste handlers role (β = 0.102, t = 2.004, p<0.05), financial institutions role (β = 0.268, t = 2.024, p < 0.05), local government role (β = 0.249, t = 3.612, p < 0.05), role of media (β = 0.316, t = 6.637, p < 0.05), and producer role (β = 0.144, t = 2.845, p<0.05) have significant influence on E-waste management sustainability. However, consumer role in E-waste (β = -0.051, t = 0.838, p > 0.01) had an insignificant influence on E-waste management sustainability, although, its importance is discussed. The attention of policymakers and waste management planners is drawn towards strengthening the Public-Private Partnerships (PPP), fast-tracking the implementation of the Extended Producer Responsibility (EPR) model as an E-waste management model and initiation of E-waste Web-based applications are some of the policy recommendations in this paper. This will ensure sound E-waste management practices for better public health and environmental outcomes.
电气和电子废物(电子废物)的管理需要一种协作方法，以防止不可持续的电子废物管理。本文试图通过评估其行动过程来评估电子废物行为者在电子废物管理可持续性方面的作用。它提出了一个基于关键利益相关者的电子废物管理概念框架，并在乌干达10个城市的346名高级政府雇员中进行了验证。本研究利用结构方程建模(SEM)中的统计分析方法偏最小二乘法(PLS)进行数据分析。经过计算和考虑的模型解释了电子废物管理可持续性方差的48.5%。结果表明，电子垃圾处理者的角色(β = 0.102, t = 2.004, p 0.01)对电子垃圾管理的可持续性影响不显著，但其重要性得到了讨论。政策制定者和废物管理规划者的注意力被吸引到加强公私合作伙伴关系(PPP)，快速实施生产者延伸责任(EPR)模式作为电子废物管理模式，以及启动电子废物基于网络的应用程序是本文的一些政策建议。这将确保健全的电子废物管理做法，以取得更好的公共卫生和环境成果。
{"title":"Towards a sustainable electronic waste management in Uganda: A stakeholder perspective","authors":"Sonny Nyeko, S. Mlay, Judith Among, Abdallah Nyero","doi":"10.5897/ajest2021.3088","DOIUrl":"https://doi.org/10.5897/ajest2021.3088","url":null,"abstract":"The management of electrical and electronic waste (E-waste) requires a collaborative approach against unsustainable electronic waste management. This paper attempts to assess the role of E-waste actors in regard to E-waste management sustainability by evaluating their course of action. It proposes an E-waste management conceptual framework based on key stakeholders and validates it with 346 top government employees in strategic positions across 10 Ugandan cities. The study utilized Partial Least Square (PLS) technique, a statistical analysis method well-known under Structural Equation Modeling (SEM), for data analysis. The calculated and considered model explains 48.5% of the variance in E-waste management sustainability. The results demonstrate that E-waste handlers role (β = 0.102, t = 2.004, p<0.05), financial institutions role (β = 0.268, t = 2.024, p < 0.05), local government role (β = 0.249, t = 3.612, p < 0.05), role of media (β = 0.316, t = 6.637, p < 0.05), and producer role (β = 0.144, t = 2.845, p<0.05) have significant influence on E-waste management sustainability. However, consumer role in E-waste (β = -0.051, t = 0.838, p > 0.01) had an insignificant influence on E-waste management sustainability, although, its importance is discussed. The attention of policymakers and waste management planners is drawn towards strengthening the Public-Private Partnerships (PPP), fast-tracking the implementation of the Extended Producer Responsibility (EPR) model as an E-waste management model and initiation of E-waste Web-based applications are some of the policy recommendations in this paper. This will ensure sound E-waste management practices for better public health and environmental outcomes.","PeriodicalId":7483,"journal":{"name":"African Journal of Environmental Science and Technology","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84771654","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 current anarchic exploitation of Marcusenius fish in the Malebo Pool located in the Congo River stands as a threat of extinction to certain species, while the ecology of most of them are hardly known. This study aims at evaluating the impact of environmental factors on the distribution of Marcusenius fish caught in six fishing stations in the Malebo Pool. Canonical correspondence analysis of environmental factors classified the stations into two groups, which differ in vegetation formation, bottom substrates, water current velocity, pH, suspended particles and in dissolved oxygen. Thus, the five stations located upstream and in the middle of the pool are characterized by low water current velocity, slightly acidic pH, bottom substrates composed of silt, plant debris, clay, silt and sand. The predominant Echinocloa and Eichhornia plant formations found in these sites provide shelter, food sources and impact on the distribution and abundance of seven Marcusenius species in Malebo pool. The rocky substrate of Kinsuka station associated with the plant formation dominated by Ledermanniella and Pennisetum, and a high-water current constitute a habitat that is not favourable for Marcusenius species.
{"title":"Impact of environmental features on the distribution of Marcusenius species (Pisces, Mormyridae) in Malebo Pool of Kinshasa in the Congo River","authors":"Métis Ntumba Mabedi Jean, Mbadu Zebe Victorine, Pwema Kiamfu Victor, Pigneur Lise-Marie, R. Johan, Micha Jean-Claude","doi":"10.5897/ajest2022.3102","DOIUrl":"https://doi.org/10.5897/ajest2022.3102","url":null,"abstract":"The current anarchic exploitation of Marcusenius fish in the Malebo Pool located in the Congo River stands as a threat of extinction to certain species, while the ecology of most of them are hardly known. This study aims at evaluating the impact of environmental factors on the distribution of Marcusenius fish caught in six fishing stations in the Malebo Pool. Canonical correspondence analysis of environmental factors classified the stations into two groups, which differ in vegetation formation, bottom substrates, water current velocity, pH, suspended particles and in dissolved oxygen. Thus, the five stations located upstream and in the middle of the pool are characterized by low water current velocity, slightly acidic pH, bottom substrates composed of silt, plant debris, clay, silt and sand. The predominant Echinocloa and Eichhornia plant formations found in these sites provide shelter, food sources and impact on the distribution and abundance of seven Marcusenius species in Malebo pool. The rocky substrate of Kinsuka station associated with the plant formation dominated by Ledermanniella and Pennisetum, and a high-water current constitute a habitat that is not favourable for Marcusenius species.","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":"90210789","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}
D. Wyss, K. Negussie, Antonia Staacke, Amadé Karnagel, Malin Engelhardt, M. Kappas
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.
{"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}
K. B. Vesselly, A. Opio, M. Mwanjalolo, F. Kansiime
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.
{"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}
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