Research & reports

Haruna Haruna · · Africa

A study of soils irrigated with sewage water on Fadama floodplain land in northern Nigeria used sequential extraction to determine the mobility and availability of cadmium, copper, nickel, lead and zinc. The residual fraction held the largest pool of all five metals, but 2.7-70.2% was present in the potentially available, non-residual fraction. Contamination by cadmium and nickel was less severe than by lead, copper and zinc, and mobility/bioavailability ranked Pb > Zn > Cu > Ni > Cd.

Mark Matsa, Thomas Marambanyika · Journal of Environmental Extension · Africa

A study assessing concentration levels of lead (Pb), cadmium (Cd) and sulphides (SO2) within and around Gweru's sole official waste dumpsite in Zimbabwe. Harsh economic conditions in the city have driven further expansion of urban agriculture on open spaces, with residents growing staple food crops such as maize and sweet potatoes for subsistence on numerous plots surrounding the dumpsite; the study states that ingesting crops grown near the dumpsite is likely to put residents' lives at risk. Soil sampling points along transects on and around the dumpsite were randomly selected using ArcView GIS, with sulphide concentrations measured by Leco machine and lead and cadmium by atomic absorption spectrometer. Independent t-test results showed the concentration levels of the three pollutants were significantly elevated from one sampling point to the next, within and around the dumpsite.

Y. A. Iyaka, SE Kakulu · African Research Review · Nigeria

This study determined the levels of copper (Cu) and zinc (Zn) in soil samples collected from cultivated farmlands near abandoned industrial sites in Minna and Bida, Niger State, Nigeria, using flame atomic absorption spectrophotometry. Concentrations ranged from 12-89 mg Cu kg-1 and 2.8-41 mg Zn kg-1 for Minna, and 2.4-6.5 mg Cu kg-1 and 0.57-36 mg Zn kg-1 for Bida. Apparent accumulation of Cu was found in Minna cultivated farmlands, with a mean Cu content of 24 ± 22 ppm, which was almost five times that of the control soils. Other mean values were similar to soil background averages.

Adedeji Adedeji, H Oludare, Ademiluyi · Journal of Geography and Regional Planning · Nigeria

This discussion of urban agriculture and urban land use planning in metropolitan Lagos, Nigeria, frames urban agriculture as a crisis response and survival strategy for the urban poor that contributes to food security, while stating that urban agriculture production systems can pose risks to public health and the environment through inappropriate or excessive use of agricultural inputs — including pesticides, nitrogen, and raw organic matter containing heavy metal residues. It recommends that urban land use planners promote multifunctional land use and greater community participation in managing urban open spaces.

Erastus K. Kang’ethe, Delia Grace, Thomas F. Randolph · East African Medical Journal · East Africa

This study synthesizes current knowledge on urban agriculture (UA) in East Africa, focusing on its human health impact. It identifies UA as an important source of food security, but notes that many zoonotic and food-borne diseases are associated with it, with a lack of evidence on human health impact and management. Major constraints include illegality and limited access to inputs and markets, indicating a need for more research to understand both positive and negative health impacts.

Pay Drechsel, Olufunke Cofie, R. van Veenhuizen, Theophilus O. Larbi · Irrigation and Drainage · West Africa

Informal irrigation in urban and peri-urban agriculture (UPA) in West Africa offers benefits but is often hindered by water pollution, threatening public health. A multi-stakeholder process implemented since 2005 in six West African cities, including Accra, Ghana, aimed to integrate UPA into sustainable urban development. However, an internal lesson learned was that local partners may not prioritize every project, and capacity-building efforts might not provide expected incentives for commitment.

Halidou Koanda · Infoscience (Ecole Polytechnique Fédérale de Lausanne) · Sub-Saharan Africa

In Sub-Saharan Africa, faecal sludge management practices are often financially unviable due to widespread lack of municipal involvement, paucity of legal provisions, and absence of stakeholder coordination. This leads to indiscriminate dumping of faecal sludge in urban areas or its untreated use in urban agriculture. These practices pose permanent and serious health risks and contaminate scarce ground and surface water. This research aims to develop an innovative strategic planning approach for sustainable urban faecal sludge management to minimize public health and environmental risks.

Tony Binns, Roy Maconachie, Adamu Idris Tanko · Land Degradation and Development · Nigeria (Kano)

This paper examines health and environmental concerns associated with urban and peri-urban agriculture (UPA) in Kano, Nigeria. Empirical evidence indicates that industrial and domestic toxins are reaching dangerously high levels, leading to significant pollution of soils and water channels. This raises serious questions about the sustainability of UPA and the long-term health implications of toxin exposure.

Ogunyemi Awodoyin, Taliat Opadeji · Emirates Journal of Food and Agriculture · Nigeria (Ibadan)

A 2003 study in Ibadan, Nigeria, investigated heavy metal contamination of Amaranthus cruentus L. grown on domestic refuse landfill soils. Lead (Pb) and Cadmium (Cd) concentrations in soils from four landfill sites and a control site ranged from 110.5 to 678.5ppm for Pb and 2.01 to 3.20ppm for Cd. Metal accumulation in Amaranthus cruentus L. tissues was proportionate to soil Pb concentrations, while Cd levels in crop tissues exceeded soil levels. Crop growth and yield were significantly reduced due to Pb and Cd contamination, leading to the conclusion that Ibadan landfills are unsafe for Amaranthus cruentus cultivation, with heavy metal concentrations in the vegetable tissues much higher than FAO/WHO dietary allowances.