Research & reports

Gizaw Ebissa, Aramde Fetene, Hayal Desta · City and Environment Interactions · Ethiopia

Treated wastewater from the plant serving Bole Lemi Industrial Park (BLIP) in Addis Ababa, Ethiopia was sampled at the treatment plant's influent and effluent and analyzed using a treated wastewater quality index (TWWQI) to assess suitability for urban irrigation agriculture. The aggregate TWWQI classified the water as 'very poor' for urban irrigation agriculture, with heavy metals contributing 85% of that grade, nutrient load 4%, salinity 8%, and miscellaneous contaminants 4%. Discrete indices varied: heavy metals scored 'very polluted', nutrients 'excellent', salinity 'poor', and miscellaneous contaminants 'good'. Contaminant removal efficiency ranged from 30% to 100% (58% in aggregate), and some contaminants showed higher concentrations in the effluent than the influent, indicating the treatment plant failed to remove them. Cr3+, Cl− and TDS contributed most to the poor rating, and the plant was found to need upgrading to increase removal efficiency.

Michel Shengo Lutandula⃰, Fabien Ilunga Mpanga · The Global Environmental Engineers · Democratic Republic of Congo (or Africa)

In Katuba municipality, Lubumbashi, Democratic Republic of Congo, irrigation water, soil, and harvested amaranth from an area of urban amaranth cultivation were analyzed for chemical and microbiological pollutants. Water and amaranth were polluted on both mineral and microbial fronts, while soil was not; water samples contained Paramecia, Entamoeba histolytica eggs, fecal contamination indicator germs, mesophilic flora, and pathogens including Aeromonas hydrophila and Pseudomonas aeruginosa. Amaranth cobalt concentrations exceeded quality standards and the plants were contaminated with Paramecia, Entamoeba histolytica eggs, Escherichia coli, and Klebsiella planticola, leading to the conclusion that consuming these amaranths poses health risks to the population.

Peter Sanjo Adewale, Sunday Clement Olubunmi Makinde, V. Kusemiju, Olawole O. Obembe · Journal of sustainability and environmental management · Nigeria

This study measured and compared lead (Pb), cadmium (Cd) and manganese (Mn) concentrations in soil and leafy vegetables (Amaranthus hybridus, Celosia argentea, Corchorus olitorius) using atomic absorption spectrophotometry at Urban Expressway Farms (UEF) and Peri-urban Road Farms (PRF) in Lagos State, Nigeria. It found the highest Pb concentration (0.93+/-0.06) in Celosia argentea at UEF, and the highest Cd (0.51+/-0.11) and Mn (0.98+/-0.02) concentrations in Amaranthus hybridus at UEF, with Pb in Celosia argentea 5 m from the expressway and Cd in Amaranthus hybridus 10 m from the expressway exceeding WHO/FAO permissible levels; heavy metal residue levels were driven more by farm location than by vegetable type, and the study calls for regular monitoring to prevent consumption of contaminated leafy vegetables and recommends farmers cultivate fields farther from expressways.

Ande O.T, Adetunji A. M, Akinpelu M. E, Senjobi B.A · Journals & Books Hosting (International Knowledge Sharing Platform) · Nigeria

Ibadan metropolis, Nigeria, home to about 6 million people, has raised growing concern over lowland soils in its periurban area, where much of the industrial waste transported by the River Ona is deposited; these soils are used for dry-season farming and contribute to food security. This study aimed to characterize periurban lowland soils around Ibadan and determine their vulnerability to industrial pollution, using a 50m x 50m grid with surface samples taken at 50m intervals, plus representative profile pits described using the USDA method, and particle-size and chemical analyses (phosphorus, nitrogen, exchangeable cations Ca/Mg/Na/K, manganese, and heavy metals including lead, copper, zinc, chromium, iron, and cadmium). Results showed the floodplain's surface soil was fertile, with high nitrogen (0.35 cmol/kg), phosphorus (51.25 cmol/kg), and potassium (0.61 cmol/kg), and phosphorus levels ranging from very high to toxic, between 28.99 and 87.70 ppm. Average heavy metal concentrations were lead 34.30 mg/kg, zinc 171.20 mg/kg, iron 83.97 mg/kg, copper 19.11 mg/kg, manganese 31.10 mg/kg, chromium 0.69 mg/kg, and cadmium 0.3 mg/kg. Predicted soil-to-plant heavy metal transfer coefficients (Pb 35-343; Cr 0.46-4.6; Zn 171-1712; Cu 19-191; Fe 83-840; Mn 31-281; Cd 0.1-10) indicated crops grown in the area could contain toxic levels of these metals; however, high yields and healthy plant condition observed in the field, together with farmer interviews, suggested that the high phosphorus level (28.99-87 ppm) may have inhibited uptake of some metals such as lead, zinc, and copper.

John Jacob, Samuel E. Kakulu · American Journal of Chemistry · Nigeria

Soil and vegetable samples (spinach, jute mallow, and tomato) were collected from farms and gardens across 20 zones within Kaduna, Nigeria, plus two rural control villages about 30 km from the city, and analyzed for heavy metals by Flame Atomic Absorption Spectrophotometer. Pollution Load Index results showed soils in the city farms were moderately enriched with cadmium and chromium and strongly enriched with lead and nickel from anthropogenic sources. Mean soil concentrations of lead and cadmium exceeded WHO/FAO permissive limits for agricultural soil (nickel and chromium did not), while vegetable metal concentrations exceeded the permissive limits for every metal except nickel — a finding flagged as concerning given the toxicity of lead and cadmium in particular, which have no known biological use.

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.

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.