A review of sustainable sanitation systems in Africa

Access to proper sanitation is still elusive in many parts of Africa. While significant improvement in global sanitation has been realised, the sanitation situation in Africa is still appalling with almost 20 % of the population reported to still practice open defecation in Sub Saharan Africa. The impacts of poor sanitation systems range from negatively impacting natural resources water quality, to causing health risks to the populations involved. Obviously, the current sanitation systems have gaps and can barely help the situation, which points to the necessity of a paradigm shift in the wastewater management to include interventions that would make proper sanitation achievable for all. Such interventions include decentralisation and resource recovery, which will not only produce environmentally acceptable effluents, but are also pertinent in achieving decreased costs for sanitation systems, hence making them more affordable. The decentralised system is cheaper than the centralised system, mainly due to decreased sewer needs and combining it with resource recovery. This provides an opportunity of decreasing costs further due to the several economic benefits attached to the recovered products. Whereas sanitation involves both wastewater and solid waste, this review paper discusses the current sanitation situation in Africa and proposes a wastewater management plan that could contribute to improvement for small agricultural communities. The plan encourages zero waste generation through decentralisation and recovery of water, energy and by-products such as nutrients and organics relevant to the local community. Apart from the proposed technological strategies, a winning sanitation management plan should also be appreciated and supported by all stakeholders, which can be achieved through proper communication and integration of local user needs.     

The partitioning of Africa: statistically defined biogeographical regions in sub‐Saharan Africa

Aim To test whether it is possible to establish a common biogeographical regionalization for plants and vertebrates in sub‐Saharan Africa (the Afrotropical Region), using objective multivariate methods. Location Sub‐Saharan Africa (Afrotropical Region). Methods We used 1° grid cell resolution databases for birds, mammals, amphibians and snakes (4142 vertebrate species) and c. 13% of the plants (5881 species) from the Afrotropical Region. These databases were analysed using cluster analysis techniques to define biogeographical regions. A β(sim) dissimilarity matrix was subjected to a hierarchical classification using the unweighted pair‐group method with arithmetic averages (UPGMA). The five group‐specific biogeographical regionalizations were compared against a regionalization developed from a combined database, and a regionalization that is maximally congruent with the five group‐specific datasets was determined using a consensus classification. The regionalizations were interpreted against measures of spatial turnover in richness and composition for the five datasets as well as the combined dataset. Results We demonstrate the existence of seven well‐defined and consistent biogeographical regions in sub‐Saharan Africa. These regionalizations are statistically defined and robust between groups, with minor taxon‐specific biogeographical variation. The proposed biogeographical regions are: Congolian, Zambezian, Southern African, Sudanian, Somalian, Ethiopian and Saharan. East Africa, the West African coast, and the transitions between the Congolian, Sudanian and Zambezian regions are unassigned. The Cape area in South Africa, Afromontane areas and the coastal region of East Africa do not emerge as distinct regions but are characterized by high neighbourhood heterogeneity, rapid turnover of species and high levels of narrow endemism. Main conclusions Species distribution data and modern cluster analysis techniques can be used to define biogeographical regions in Africa that reflect the patterns found in both vertebrates and plants. The consensus of the regionalizations between different taxonomic groups is high. These regions are broadly similar to those proposed using expert opinion approaches. Some previously proposed transitional zones are not recognized in this classification.     

Trends in Demographic and Health Survey data quality: an analysis of age heaping over time in 34 countries in Sub Saharan Africa between 1987 and 2015

Objective

This paper evaluates one aspect of data quality within DHS surveys, the accuracy of age reporting as measured by age heaping. Other literature has explored this phenomenon, and this analysis build on previous work, expanding the analysis of the extent of age heaping across multiple countries, and across time.

Results

This paper makes a comparison of the magnitude of Whipple’s index of age heaping across all Demographic and Health Surveys from 1986 to 2015 in Sub-Saharan Africa. A random slope multilevel model is used to evaluate the trend in the proportion of respondents within each survey rounding their age to the nearest age with terminal digit 0 or 5. The trend in the proportion of misreported ages has remained flat, in the region of 5% of respondents misreporting their age. We find that Nigeria and Ghana have demonstrated considerable improvements in age reporting quality, but that a number of countries have considerable increases in the proportion of age misreported, most notably Mali and Ethiopia with demonstrate increases in excess of 10% points.

     

Impacts of intensifying or expanding cereal cropping in sub‐Saharan Africa on greenhouse gas emissions and food security

Cropping is responsible for substantial emissions of greenhouse gasses (GHGs) worldwide through the use of fertilizers and through expansion of agricultural land and associated carbon losses. Especially in sub‐Saharan Africa (SSA), GHG emissions from these processes might increase steeply in coming decades, due to tripling demand for food until 2050 to match the steep population growth. This study assesses the impact of achieving cereal self‐sufficiency by the year 2050 for 10 SSA countries on GHG emissions related to different scenarios of increasing cereal production, ranging from intensifying production to agricultural area expansion. We also assessed different nutrient management variants in the intensification. Our analysis revealed that irrespective of intensification or extensification, GHG emissions of the 10 countries jointly are at least 50% higher in 2050 than in 2015. Intensification will come, depending on the nutrient use efficiency achieved, with large increases in nutrient inputs and associated GHG emissions. However, matching food demand through conversion of forest and grasslands to cereal area likely results in much higher GHG emissions. Moreover, many countries lack enough suitable land for cereal expansion to match food demand. In addition, we analysed the uncertainty in our GHG estimates and found that it is caused primarily by uncertainty in the IPCC Tier 1 coefficient for direct N₂O emissions, and by the agronomic nitrogen use efficiency (N‐AE). In conclusion, intensification scenarios are clearly superior to expansion scenarios in terms of climate change mitigation, but only if current N‐AE is increased to levels commonly achieved in, for example, the United States, and which have been demonstrated to be feasible in some locations in SSA. As such, intensifying cereal production with good agronomy and nutrient management is essential to moderate inevitable increases in GHG emissions. Sustainably increasing crop production in SSA is therefore a daunting challenge in the coming decades.     

Developing wetland inventories in southern Africa: A review

The status of wetland inventory effort and availability of maps and other data sources is reviewed for the ten countries of southern Africa: Angola, Bostwana, Lesotho, Malawi, Mozambique, Namibia, South Africa, Swaziland, Zambia and Zimbabwe. The aims and strategies for inventory are discussed and the main survey methods compared. Prior to commissioning new inventory work careful collation of existing maps and imagery is recommended together with targeting of strategic inventory at Province level, reserving high resolution effort only for certain important sites.     

Sexual systems in gymnosperms: A review

The aim of this study was to update figures for the presence of dioecy among the gymnosperms and investigate its correlation with climate, growth form, pollination and seed dispersal syndromes, and risk of extinction. Dioecy was found in almost 65% of contemporary gymnosperm species, a higher percentage than previous estimates. It dominates in 8 of the 12 families. As in angiosperms, dioecious gymnosperms are particularly common in climbers and are more commonly found in tropical climates. Analysis of the degree of threat using IUCN red list categories showed that the proportion of threatened species is higher in dioecious than in monoecious species only in temperate climate. The high sensitivity of dioecious species to environmental changes associated with human activity in temperate climate may explain this phenomenon. The monophyly of extant gymnosperms and the relatively small number of species (about 1000) create the possibility of treating them as a model group in investigating the evolution of sexual systems.     

Mycotoxins: food contamination, mechanism, carcinogenic potential and preventive measures

Mycotoxins constitute a large number of naturally occurring fungal secondary metabolites with very diversified toxic effects in humans and animals. Among many mycotoxins discovered, aflatoxins, ochratoxin A, sterigmatocystin and several others are identified as carcinogens; several others were found to be mutagenic. Nevertheless, aflatoxin B1 has been found to be one of the most potent carcinogens and contamination of aflatoxins in the food supply is still a major concern. Whereas extensive studies have been made on aflatoxins, little is known about the mode of action of other carcinogenic and mutagenic mycotoxins. Recent progress on research for the carcinogenic and mutagenic mycotoxins is presented in this review with emphasis on their contamination in foods, their carcinogenic potential to humans, and the mode of action as well as possible preventive measures.     

Traditional treatment for mental illness in Africa: A review

The publication of The Quest for Therapy in Lower Zaire (University of California Press) by John M. Janzen (with the collaboration of William Arkinstall), and African Therapeutic Systems (Crossroads Press), edited by Z. A. Ademuwagun, John A. A. Ayoade, Ira E. Harrison and Dennis M. Warren, calls attention to recent research findings which indicate that mentally ill persons, particularly schizophrenics, may recover more rapidly and fully in non-industrialized societies than they do in industrialized ones. The books by Janzen and Ademuwagen et al. will be examined as contributions to a growing body of information on native African therapeutic practices. Evidence relating to the apparently benign course of psychosis in Africa will be examined, and various explanations for this pattern will be evaluated. Finally, some guidelines for future research will be suggested.     

Fire in sub‐Saharan Africa: The fuel,cure and connectivity hypothesis

Aim

Past analyses of satellite‐based fire activity in tropical savannas support the intermediate fire–productivity hypothesis (IFP), which posits a close correlation with estimates of total net primary productivity in drier savannas and declines towards the extremes. However, these analyses ignore the distinct roles played by herbaceous and woody vegetation in fire ignition and spread. We hypothesize that, as herbaceous vegetation provides the primary fuel, fire activity in African savannas is asymptotically correlated with herbaceous production. Conversely, woody production affects fires indirectly through effects on herbaceous production and its connectivity. In contrast to the IFP, we propose the fuel, cure and connectivity (FCC) conceptual model for tropical fire activity. The FCC model makes explicit the distinct role of herbaceous and woody fuels, avoiding the confounding interpretation of the role of total production, while providing opportunities to quantify fuel curability, effects of trees on herbaceous fuel growth and connectivity, and human management.

Location

Sub‐Saharan Africa (SSA).

Time period

2003–2015.

Major taxa studied

Woody and herbaceous vegetation.

Methods

We used boosted regression tree analysis to test competing models explaining fire activity: (a) aggregate fuel loads; and (b) partitioned woody and herbaceous fuel loads; both derived from MODIS leaf area index.

Results

Herbaceous fuel load was consistently most influential, providing more explanatory power than overall biomass in fire activity. Fuel curability rated second, then human population density (HPD), and woody biomass was least important. We observed an asymptotic relationship between herbaceous fuel load and fire activity consistent with the FCC model; trees promote fires at low densites but suppress fires at higher densities; fires were rare in wetter regions, emphasizing the need for fuel to cure; and fires were concentrated in areas of low human population, underscoring the crucial role of land management.

Conclusions

The proposed FCC framework provides a more nuanced understanding of fire activity in tropical ecosystems, where herbaceous biomass is the key determinant of fire activity.     

Soil‐dwelling insect pests of tree crops in Sub‐Saharan Africa,problems and management strategies—A review

This review aims to draw the attention of researchers, ecologists and farmers to the threats of soil‐dwelling insect pests on important tree crops in sub‐Saharan Africa, with a special focus on termites. It synthesizes the information on the effects of various factors affecting soil pest occurrence and damage, suggesting that the resultant undesirable effects of soil pests in this region are largely as a result of indiscriminate tree cutting, slash‐and‐burn agriculture and indiscriminate use of pesticides. Major insect orders, their host ranges and the nature of damage on selected tree crops are described. This study further critiques existing soil pest management practices, showing that majority of soil pest management practices are ineffective. Thus, management strategies like “attract and kill” approach based on entomopathogenic fungi need to be studied, developed and emphasized for the management of soil insect pests in sub‐Saharan Africa. A conclusion section attempts to offer suggestions for ways in which future work on soil pests in sub‐Saharan Africa could proceed.     

Early food production in Africa

The study of early food production in sub-Saharan Africa is at least as challenging as it is rewarding. Problems arise in large degree from the scarcity of relevant archeological material, particularly the remains of domesticated plants from prehistoric sites. This is attributable to several factors, including poor preservation, difficulties in recovering such material, and the limited amount of work so far invested in obtaining it. But, problems notwithstanding, fresh data and new methodological approaches have revealed aspects of early African food production that are interesting in themselves, as well as in global perspective. For example, contrary to what occurred in most other parts of the world, livestock herding in Africa often predated the earliest evidence of cultivation of domesticated plants. Moreover, the initial spread of food production throughout much of sub-Saharan Africa was accompanied by iron, rather than lithic, technology. This overview of current knowledge about early African food production is aimed at highlighting developmental patterns while also exposing limitations in our understanding of these patterns. Because of Africa's vast size, uniform coverage in reasonable depth of all parts of the continent is not possible. Thus, for example, I will not explicitly cover the complex neolithic record from Africa's Mediterranean region. Instead, I will generally concentrate on bodies of data and lines of investigation that characterize distinctive features of the African version of initial steps in raising crops and animals.     

Plio-Pleistocene Carnivora of northwestern Africa: A short review

The fossil record of northwestern African carnivores is very patchy. The richest assemblage is that of the Late Pliocene of Ahl al Oughlam, with more than 20 species belonging to the main modern families. Some additions to its study are made here. The rather poor Early Pleistocene faunas are mainly marked by the arrival of a large Canis. A fauna of modern type, with example, the duo Hyaena–Crocuta, settles in the Earliest Pleistocene site of Tighenif, where some older elements linger on (Homotherium), beside some taxa of doubtful affinities, like a large Panthera, and a strange canid close to Nyctereutes, dominant at this site as well as at the slightly younger ones of Thomas and Oulad Hamida Quarries in Casablanca. All these faunas consist mostly of African taxa, together with a Palaearctic component whose importance increases towards the end of the Pleistocene.     

Water status and growth phenology of a Saharan shrub in north Africa

An experimental study of the relationship between the phenological phases, water relations and climatic conditions was conducted on one shrub species, Spartidium saharae, in Saharan ecosystem of southern Tunisia. The results show that the water potential remained significantly higher than that recorded in other desert shrubs. However, a relationship between the water potential of S. saharae and precipitation was not evident suggesting that access to permanent ground water may be a factor of this decoupling. Although shoot elongation of the species occurred outside the wet season, water shortage induced a decrease in fruit production.     

Immunoaffinity column clean-up techniques in food analysis: A review

This review provides a critical assessment of the applications of immunoaffinity columns for sample clean-up in the field of food safety. The performance of immunoaffinity columns are compared in terms of specificity, binding capacity and recovery, and commercial disposable columns are contrasted with home-made columns. Areas covered include multiple-use of columns, multiple-analyte columns, use with automated systems and validation of IAC methods. Publications illustrating the many varied applications of IAC for sample clean-up in the areas of mycotoxins, veterinary drug residues, pesticide residues, environmental contaminants and vitamins have been compiled, comparing extraction methods, achievable recovery, and illustrating the variety of end-detection methods that have been employed.     

Combined biological hydrogen-producing systems: A review

Possible ways for combining various biological processes of biohydrogen production are described. Some of these processes are being intensively studied now, whereas others are theoretically feasible, but have not been studied. A special focus is on the factors that influence the efficiency of coupled systems.     

A systematic review of vegetation phenology in Africa

The study of vegetation phenology is important because it is a sensitive indicator of climate changes and it regulates carbon, energy and water fluxes between the land and atmosphere. Africa, which has 17% of the global forest cover, contributes significantly to the global carbon budget and has been identified as potentially highly vulnerable to climate change impacts. In spite of this, very little is known about vegetation phenology across Africa and the factors regulating vegetation growth and dynamics. Hence, this review aimed to provide a synthesis of studies of related Africa's vegetation phenology and classify them based on the methods and techniques used in order to identify major research gaps. Significant increases in the number of phenological studies in the last decade were observed, with over 70% of studies adopting a satellite-based remote sensing approach to monitor vegetation phenology. Whereas ground based studies that provide detailed characterisation of vegetation phenological development, occurred rarely in the continent. Similarly, less than 14% of satellite-based remote sensing studies evaluated vegetation phenology at the continental scale using coarse spatial resolution datasets. Even more evident was the lack of research focusing on the impacts of climate change on vegetation phenology. Consequently, given the importance and the uniqueness of both methods of phenological assessment, there is need for more ground-based studies to enable greater understanding of phenology at the species level. Likewise, finer spatial resolution satellite sensor data for regional phenological assessment is required, with a greater focus on the relationship between climate change and vegetation phenological changes. This would contribute greatly to debates over climate change impacts and, most importantly, climate change mitigation strategies.     

Floating drug delivery systems: A review

The purpose of writing this review on floating drug delivery systems (FDDS) was to compile the recent literature with special focus on the principal mechanism of floatation to achieve gastric retention. The recent developments of FDDS including the physiological and formulation variables affecting gastric retention, approaches to design single-unit and multiple-unit floating systems, and their classification and formulation aspects are covered in detail. This review also summarizes the in vitro techniques, in vivo studies to evaluate the performance and application of floating systems, and applications of these systems. These systems are useful to several problems encountered during the development of a pharmaceutical dosage form. Published: October 19, 2005