Research & reports

Prem José Vazhacharickal, Martina Předotová, D. Chandrasekharam, Sharit K. Bhowmik, Buerkert, Andreas · Journal of Agriculture and Rural Development in the Tropics and Subtropics (University of Kassel) · India (Mumbai)

A study surveyed 38 railway gardeners to characterize urban and peri-urban agricultural production along railway tracks in the Mumbai Metropolitan Region. Irrigation water contained nutrients but also heavy metals such as lead, cadmium, and mercury, and pathogens like Escherichia coli. Heavy metal levels exceeded critical thresholds in surface soils for chromium, nickel, and strontium, and in produce for lead, cadmium, and strontium.

K.G. Rosin, Ravinder Kaur, Sushma Singh, Prabhat Kumar Singh, Digvijay Dubey · Procedia Environmental Sciences · India

A study was conducted in peri-urban agricultural sites around Faridabad, Haryana, India, to assess groundwater contamination and the contribution of salt/trace metal-laden irrigation waters. Mean EC, Cl, and F concentrations in root zone leachates were found to be far beyond permissible limits, and some trace metals posed a threat to deep percolating waters. However, due to existing cropping patterns and deeper water table depths, the groundwaters were not yet vulnerable to these salts/trace metals, and the presence of salts in the groundwaters was primarily geogenic.

Laura Knapp, Jodi L. Sangster, Shannon L. Bartelt‐Hunt · International Journal for Service Learning in Engineering Humanitarian Engineering and Social Entrepreneurship · United States (Omaha NE)

This study investigated the influence of lead hyperaccumulating plants on lead uptake by vegetables in an urban community garden in Omaha, NE, a region with significant lead contamination. Tomatoes, carrots, and amaranth were grown alongside sunflowers and mustard greens (hyperaccumulators) in lead-contaminated soil. Data showed higher lead concentrations in the hyperaccumulators and suggested that their presence might have impacted the amount of lead available to surrounding vegetation. Previous work at the garden detected lead in produce, indicating a potential exposure pathway for humans.

Kyle Kessler, Seth Umbenhauer, Alison R. Noble · Journal of the Pennsylvania Academy of Science · United States (Harrisburg)

Eight soil samples were collected from an urban land plot in Harrisburg, PA, to determine concentrations of copper, nickel, zinc, and lead and assess suitability for an urban garden. While copper, nickel, and zinc concentrations were below EPA recommended limits, lead concentrations ranged from 26 ± 1 mg/kg to 402+ mg/kg, with some samples exceeding EPA standards for heavy metals in home and vegetable gardens. This indicates potential lead contamination in the soil.

Chris Zimmerman · Soil Horizons · United States

A narrative article profiling the work of soil scientist Samantha Langley-Turnbaugh of the University of Southern Maine, investigating lead contamination in urban soils in Portland, Maine. It traces the concern to the Great Fire of 1866, whose lead paint ash was spread across the city and used as landfill to extend the Portland peninsula, compounded by the city's historical ties to lead-producing industries. The article states that, across US cities generally, lead paint and leaded gasoline are the primary sources of soil lead contamination, and that this contamination is becoming a concern as urban gardening expands.

Ines Vlahović, Ksenija Karlović · Agronomski glasnik ·

A survey conducted from May to August 2011 examined the frequency of poisonous and allergenic plant species at nine educational institutions in the town of Samobor, Croatia — three kindergartens, four elementary schools, one high school and one library. The survey identified 15 poisonous plant species, represented by 182 specimens, and 17 allergenic plant species, represented by 129 specimens.

Evaristo Mwaba Kapungwe · Open Journal of Metal · Africa

Water, soil, and crop samples were analyzed by atomic absorption spectrometry for lead, copper, cobalt, nickel, and chromium at two peri-urban wastewater-irrigation farming sites in Zambia: New Farm Extension in Mufulira Town, Copperbelt Province, and Chilumba Gardens in Kafue Town, Lusaka Province. Heavy metal levels in wastewater, soil, and food crops exceeded acceptable limits at both sites, confirming contamination and a potential human health risk from consuming the crops grown there.

Léon W. Nitièma, Boubacar Savadogo, Dramane Zongo, Aminata Kaboré, Poda Jean Noël, Alfred S. Traoré, Dayéri Dianou · Journal of Environmental Protection · Africa

This study examined the microbial quality of wastewater used for truck farming in Ouagadougou, Burkina Faso, testing for bacterial and parasitological fecal indicators during the dry-hot season (May) and the wet season (July) of 2012. Wastewater from three water reservoirs and two canals intensively used for truck farming was analyzed, and the same indicators were tracked through waste stabilization ponds at three treatment plants in the city. Concentrations of microbial indicators were significantly higher in the dry-hot season than the wet season across all sampling sites, with levels reaching up to 53,800 CFU/100ml for E. coli, 8,200-108,400 CFU/100ml for fecal coliforms, 650-45,000 CFU/100ml for fecal streptococcus, and 0-2.4 eggs/l for helminths. Through the waste stabilization ponds, significant microbial concentration drops of 82-100%, 78-98%, 60-100%, and 82-88% respectively were recorded between the anaerobic and maturation ponds. The results indicate that improving the refining performance of waste stabilization pond technology could help reduce the health risks associated with wastewater reuse in urban agriculture in developing countries.

G. N. Egwu, John O. Agbenin · Archives of Agronomy and Soil Science · Nigeria

A study in northern Nigeria assessed cadmium, lead, and zinc contamination in soils and leaf vegetables (amaranthus, lettuce) irrigated with untreated wastewater. Total cadmium and zinc concentrations in soils exceeded safe limits, and lead and cadmium in edible portions of amaranthus and lettuce exceeded safe limits for human consumption by 7–17 times. The permissible limit for lead established for agricultural lands may not be suitable to ensure produce safety in urban and peri-urban agriculture in Kano.

Ghulam Murtaza, Abdul Ghafoor, Muhammad Zia‐ur‐Rehman, Muḥammad Ṣābir, Asif Naeem · Communications in Soil Science and Plant Analysis · Global

This study investigated metal accumulation in plants grown in urban agricultural lands irrigated with untreated city effluent in developing countries. Sewage samples showed hazardous electrical conductivities, sodium adsorption ratios, and residual sodium carbonate for irrigation, although metal levels were near permissible limits. Critically, plants acquired metal contents that were greater than those found in the raw sewage or soils, indicating significant metal uptake.

Nahed N. Mahrous · The Journal of Pediatrics · Canada (Hamilton)

This project investigated metal, bacteria, and corn root interactions in metal-contaminated soils from Blackfrairs Community Garden and a Hamilton home. It found that bacterial numbers were lower than in uncontaminated soils, and bioavailable metal concentrations increased over time. High concentrations of metals were detected in grains, with copper, iron, and manganese accumulating in rhizospheres, and zinc distributed throughout root tissue in Blackfrairs plants.

Lori Leonard, W. J. S. Mwegoha, Charles Kihampa · International Journal of Plant Animal and Environmental Sciences · Tanzania (Dar es Salaam)

This study investigated public awareness and health risks from heavy metal pollution in vegetables irrigated with Msimbazi River water in Dar es Salaam, Tanzania. Over 71% of 35 respondents used the river for irrigation, and high levels of chromium, lead, and copper were detected in popular vegetables. 69% of respondents were unaware of industrial pollution, and 63% were unaware of potential health effects. The study found that 95.6% of adults, 30.7% of children aged 6-12, and 12.5% of children aged 2-6 were at risk of lead carcinogenic effects, while 5% of children aged 2-6, 2.8% of children aged 6-12, and 1.2% of adults were at risk from carcinogenic cadmium effects.

Aubin Ondo, Pascale Prudent, C. Massiani, Menye Biyogo, Mariane Domeizel, Jacques Rabier, François Eba · Journal of the Serbian Chemical Society · Gabon (Libreville)

An assessment of urban agriculture's impact on soil properties and metal uptake by leafy vegetables in Libreville, Gabon, found strong soil acidification and decreased nutrient/metal concentrations due to agricultural practices. Metal transfer to plants was significant, with amaranth accumulating more metals than other vegetables, though cadmium and lead were not detectable in plant tissues. Amaranth and roselle preferentially concentrated metals in their leaves.

Zbigniew Ziembik, Agnieszka Dołhańczuk-Śródka, Grzegorz Kusza · Proceedings of ECOpole · Poland

Soil samples were collected from the former "Piast" cement plant within Opole city borders, Poland, and nearby allotment gardens to study radioisotope activity concentrations. Naturally occurring radioisotopes and artificial Cs were found, with K and Cs showing the biggest radioactivity concentration. No significant differences in radionuclide activities were found between soil samples from the former industrial estate and the allotment gardens.

Johanna F. Lindahl · · Vietnam

The circulation of Japanese encephalitis virus (JEV) in pigs and mosquitoes was investigated around Can Tho city in Vietnam's Mekong Delta. Of 315 sows, 60% were JEV seropositive, and seropositivity was associated with more stillborn piglets in sows under 1.5 years old. Among 7885 mosquitoes collected in and around Can Tho city, seven pools collected near pigs tested positive for JEV, indicating co-circulation of JEV genotypes I and III. All 43 pigs sampled within Can Tho city were JEV seropositive, demonstrating that JEV can be a public health issue in urban areas.

Evaristo Mwaba Kapungwe · Indonesian Journal of Biotechnology (Universitas Gadjah Mada) · Zambia

This study investigated farming practices related to heavy metal contaminated wastewater irrigated farming in two peri-urban areas of Zambia: New Farm in Mufulira and Chilumba Gardens in Kafue. Data was collected by observing crop cultivation activities at field plots along transects in stratified land zones. The results revealed that farming practices were characterized by traditional land management and multiple cropping systems, influenced by agro-ecological factors and the availability of heavy metal contaminated wastewater, which has the potential to contaminate soils and crops.

Jodi L. Sangster, Andrew Nelson, Shannon L. Bartelt‐Hunt · International Journal for Service Learning in Engineering Humanitarian Engineering and Social Entrepreneurship · United States (Omaha)

Soil and vegetable samples were collected from a community garden in Omaha, Nebraska, which had known soil lead contamination. Total lead content was evaluated using atomic absorption spectroscopy, revealing lead concentrations in soil ranging from 4 to 574 ppm, with an average of 128.4 ppm in growing beds and 31.5 ppm in OmaGro compost. Lead was also present in vegetable samples at or below 16.25 ppm.

Adam J Long · Scholarship @ Claremont (The Claremont Colleges) · United States (Washington, DC)

This study investigated heavy metal soil contaminants in 13 urban community gardens in Washington, DC, analyzing 45 soil samples using X-ray fluorescence (XRF). While most samples fell below US EPA action levels for common contaminants, high concentrations of lead (above the US EPA action level of 400 ppm) were found in the native soil of three garden sites, meriting concern due to potential health problems in children.

Josh Beniston · The Knowledge Bank (The Ohio State University) · United States (Ohio)

An experiment on assessing and managing soil quality for urban agriculture was conducted during the 2011 and 2012 growing seasons on demolished vacant urban lots in Youngstown, Ohio. Soil compaction was identified as a primary constraint, with high bulk density values of 1.79 g cm⁻³ for in-ground plots and 1.55 g cm⁻³ for raised beds. Crop yield data from 2011 showed that both compost-amended and compost + biochar-amended plots had significantly greater crop yields than control plots, with compost + biochar plots achieving the highest harvest index values.

Y. Niang, S. Niang, Saliou Niassy, Y Dieng, Mohamed Gaye, K. Diarra · International Journal of Biological and Chemical Sciences · Senegal

This study assessed the effect of wastewater on the agronomical performance and hygienic quality of tomato and lettuce in Senegal, comparing it to tap water, irrigation modes, and fertilizers. While tomato showed no pathogenic germs with wastewater, lettuce watered with wastewater via aspersion contained significantly more pathogenic germs than those watered in draining mode. Significant differences in yield and fruit size were observed between lettuce treated with tap water and wastewater.

Nancy Karanja, Mary Njenga, G.K. Mutua, Carl Johan Lagerkvist, E. Kutto, JJ Okello · Journal of Agriculture Food Systems and Community Development · Kenya (Nairobi)

A study in three peri-urban sites in Nairobi, Kenya, assessed heavy metal, nitrate, and pesticide residue levels in wastewater-irrigated kale. Elevated levels of boron, cobalt, chromium, copper, lead, zinc, and nickel were found in vegetables at two sites, with high soil loadings of nickel, arsenic, lead, chromium, copper, and zinc attributed to chicken manure. Pesticide residues of diazinon, cypermethrin, biternol, and profenofos exceeded permissible limits in kale at one site, suggesting consumers may ingest significant amounts of contaminants.

Sebastian U. Ugbaje, John O. Agbenin · International Journal of Environmental Studies · Nigeria

A pot experiment in Zaria, northern Nigeria, evaluated the chemical forms and phytoavailability of Cr, Ni, and Pb in savannah soil amended with two urban wastes and planted with sorghum. While urban waste application increased total metal concentrations in the soil, only Pb uptake by sorghum increased, with no corresponding increases for Cr and Ni. A single application of urban wastes significantly increased Pb uptake by sorghum, raising concerns about the long-term consequences of such applications in urban and peri-urban agriculture, especially regarding children's exposure to Pb.

Iwona Makuch · Soil Science Annual · Global

This study investigated the influence of intensive horticulture on lead content and its fractions in soil profiles from house gardens, allotment gardens, and arable fields. It was not determined that the manner of usage had any influence on total lead content or its distribution in soil profiles. However, the usage manner did influence the content and distribution of lead fraction III, which is connected with organic matter, with humus horizons of garden soils showing the highest content.

Mirelys Rodríguez Alfaro, Olegário Muñiz Ugarte, Bernardo Calero Martín, A. Álvarez, Francisco Martínez Rodríguez, Teudys Limeres Jiménez, Mercedes Orphee Montoya, Adriana M. de Aguilar Accioly · DOAJ (DOAJ: Directory of Open Access Journals) · Cuba

This study evaluated the heavy metal content of Cadmium, Lead, and Nickel in organic fertilizers (composts from urban solid waste) and substrates, and their effect on vegetables grown in organoponics in Havana and Guantánamo, Cuba. Composts obtained from unsorted urban solid waste and the substrates prepared from them were found to contain heavy metals, especially Cadmium and Lead, above maximum permissible limits. It was concluded that these products should not be used for food production, as these metals translocate to the edible parts of the cultivated vegetables.

Catherine Rwamba Githuku · Abstracts of postgraduate thesis · Kenya (Nairobi)

This study investigated soil and crop pollution levels resulting from untreated wastewater reuse for irrigation in Kibera and Mailisaba wastewater irrigation farms in Nairobi, Kenya. Analysis of irrigation water, soil, and crop samples (maize, kales, black nightshade, arrowroots) revealed that the Electrical Conductivity (EC) of irrigation water at Mailisaba exceeded recommended levels. Farmers reported adverse effects on crops due to wastewater quality, and despite awareness of health risks, many farmers confessed to not using protective clothing.