Research & reports

María Roo, Cecilia Herbón, Juan Pedro Martín‐Sanz, María Teresa Barral, Remigio Paradelo Núñez · Journal of Soils and Sediments · Spain (Santiago de Compostela)

This study analyzed the chemical extractability and bioaccessibility of five trace metals (Pb, Cu, Zn, Ni, Cr) in 55 urban soils from Santiago de Compostela, Spain, across various land uses. The availability of trace metals in these soils was found to be very low. Plant-available and bioaccessible Cu and Zn were higher in urban garden soils compared to other uses, supporting hypotheses that Cu, Pb, and Zn originate from anthropogenic pollution.

Antonio Peña‐Fernández, M. Carmen Lobo, María de los Ángeles Peña, Guillermo Torrado Durán, Mark D. Evans, Tiziana Sgamma, Tomás Cámara Pastor, Gurminderjeet S. Jagdev · Journal of Xenobiotics · United Kingdom

This study evaluated hazardous metal(loid)s in 121 wild mushroom fruiting-body units collected from urban and peri-urban green spaces in Leicester/Leicestershire, UK. Copper, manganese, and zinc were detected in all units, while cadmium and lead were found in 117/121 and 106/121 units respectively, indicating the widespread presence of these contaminants. Taxon-level profiles showed marked heterogeneity, and under a 300 g fresh-weight week−1 consumption scenario, cadmium represented 47.3% of the EFSA tolerable weekly intake in the pooled edible population and 50.9% in Agaricus bitorquis.

Ayhan Horuz, Güney Akınoğlu · · Turkey

A Turkish book chapter arguing that agriculture-derived air pollution, compounded by growing industrial and urban pollutant loads, is threatening food production, product quality, and food security by directly and indirectly impairing plant growth and development. It notes that population growth, energy production, transportation, waste management, and biomass burning have substantially increased atmospheric organic and inorganic pollutants, pushing air quality beyond acceptable limits in many regions. The first part evaluates the effects on agroecosystems of tropospheric (ground-level) ozone, PM2.5 and PM10, nitrogen oxides (NOx), sulfur dioxide (SO2), agricultural ammonia (NH3), and volatile organic compounds (VOCs), detailing how tropospheric ozone suppresses photosynthesis causing yield losses in staple crops such as wheat and soybean, and how particulate matter directly and indirectly affects soil and plant health, alongside the effects of acid rain and nitrogen deposition on soil fertility, water quality, and ecosystem balance, assessed against the four pillars of food security—availability, access, utilization, and stability. The second part discusses integrated policy approaches, industrial emission control technologies, and low-emission transport systems at the macro level, alongside agricultural strategies such as precision farming, improved fertilizer management, and innovative production techniques, and the role of green infrastructure in urban planning.

Christoph Koch, Maria da Glória Arrais Peter · Environmental Challenges · Germany

This citizen science study analyzed inorganic pollutants in private garden soils in central Germany, including front and backyards. Elevated levels of lead and copper were found in one-third of the samples, and zinc in two-thirds. Chromium and nickel concentrations were also elevated in a quarter of the samples, with some readily available substances exceeding limit values.

Corina Başnou, Geovana Mercado, Åsa Ode Sang, Thomas B. Randrup, Verónica Fabio, Adrián Cabezas, Arnau Lluch, Marc Montlleó, Juan Miguel Kanai, Riccardo Saraco, Olívia Bina, Tom Wild · Nature-Based Solutions · Europe

An overview and guidance for air pollution indicators in nature-based solutions (NBS) for urban green planning and public health were provided, using three case studies in Europe and Latin America. The study noted that approaches including multidimensional indicators in research, planning, and policies are limited, and national standards for some air pollutants are missing with little evidence for health effect thresholds. Findings also indicated that knowledge of pollutant uptake in edible plants can suggest potential human exposure risks.

Dariusz Gruszka, Katarzyna Szopka, Cezary Kabała · Land · Poland (Wroclaw)

This study in Wroclaw, Poland, investigated the quality of constructed technogenic soils in urban gardens located on a reclaimed clay pit. Despite beneficial physicochemical properties and high fertility in the topsoil layers, the soils were seriously contaminated with trace elements, including zinc (up to 1700 mg kg−1), lead (920 mg kg−1), copper (740 mg kg−1), cadmium (5.1 mg kg−1), mercury (7.4 mg kg−1), and arsenic (5.1 mg kg−1). This contamination, likely from industrial and urban waste used for mine infilling, compromises soil quality and poses potential health and ecological risks.

Katja Hombrecher · Gefahrstoffe Reinhaltung der Luft · Germany

A pilot study in Germany investigated the impact of road traffic emissions on food plants grown near roads. Bioindicators like kale, chard, Lollo Rosso, and lettuce were exposed for four weeks at four roadside locations and compared to plants in a garden away from roads. While pollutant levels generally did not exceed background or EU maximum limits, significant traffic-related inputs of PAK 4, antimony, aluminum, chromium, and vanadium, and lesser inputs of copper, iron, and lead were detected compared to the control. The findings indicate a potential contamination risk for certain vegetable plants from road traffic.

Izabella Pisarek, Kamila Śmieszkoł, Aleksandra Cichoń, Magdalena Śliwa, Dżoana Latała-Matysiak, Katarzyna Łuczak, Grzegorz Kusza · Journal of Ecological Engineering · Poland

A 2025 study assessed the impact of a railway line on soil quality, particularly heavy metal content, at the "Hutnik" family allotment gardens in Zawadzkie, Poland. Twenty research plots were set out near a forest complex (reference) and near railway infrastructure (a potential emission source), with soil samples collected from a depth of 0-25 cm and analyzed for total zinc (Zn), copper (Cu), lead (Pb), chromium (Cr), and nickel (Ni). Elevated concentrations of copper, zinc, and lead were found in soils close to the railway line, and based on the chemical analysis data, the study concludes that railway transport may pose a greater threat to the environment than previously expected.

Jacek Antonkiewicz, Iwona Paśmionka, Grzegorz Szychowski · Soil Science Annual · Poland

Following a flood that inundated allotment gardens in Nysa, southern Poland, for up to 14 days after the water rose on 14 September 2024, researchers analyzed 12 soil samples collected in early spring 2025 from two allotment garden sites. Most soils were found limed and disinfected, with high organic matter but low total potassium, sodium and sulfur. Zinc and copper concentrations exceeded the average for Polish arable soils, pointing to use of materials enriched with these elements.

Jarosław Chmielewski, Barbara Gworek, Alicja Walosik, Magdalena Florek-Łuszczki · Annals of Agricultural and Environmental Medicine · Poland

Soil (N=196) and root vegetable (N=94) samples from 16 allotment gardens in Warsaw, Poland, were analyzed for manganese, zinc, copper, lead and cadmium and assessed for health risk. Parsley, carrots, beetroots and celery grown in these gardens accumulated elevated levels of all five metals, and the health risk assessment found an increased risk of carcinogenic effects from cadmium and lead in consumers of these root vegetables; the authors conclude consumption of vegetables from the examined gardens should be very limited or eliminated from the diet entirely.

Javier Bayo, Joaquín López-Castellanos, Marta Doval-Miñarro, Sonia Olmos · Scientific Reports · Spain

An ATR-FTIR analysis of 11 commercial compost products found microplastics in every sample, averaging 137.65 ± 6.01 items/kg dry weight and up to 631.14 mg/kg. Eco-labeled composts had significantly lower microplastic abundance, size, and concentration than non-eco products. Microplastic concentration correlated negatively with pH and nitrogen content and positively with organic matter content.

Chmielewski J., Wszelaczyńska E., Pobereżny J., Florek-Łuszczki M., Gworek B. · Sustainability · Poland

The study sampled 112 items — 72 vegetable and 40 fruit — from 16 allotment gardens in Warsaw and measured Fe, Mn, Zn, Cu, Pb and Cd. Vegetables accumulated markedly more heavy metals than fruits, and leafy vegetables grown near high-traffic roads carried the highest Pb, Cd and Zn. Lead exceeded permissible limits by six to twelve times and cadmium by one to thirteen, leading the authors to advise against growing tomatoes in urban settings. Only trace amounts appeared in fruits, and the Hazard Index rated the fruits alone as safe. The paper calls for continuous monitoring of urban garden soils, remediation of contaminated ground and safer growing practices.

Sabina Rossini Oliva, Rafael López Núñez · Environmental Science and Pollution Research · Spain (Andalusia)

This study evaluated potentially toxic elements (PTEs) in vegetables and topsoils from urban gardens in Seville, Cordoba, Huelva, and a mining area (Riotinto), Spain, comparing them with market and peri-urban samples. Soils in the mining area and cities generally showed higher contamination with As, Cr, Cu, Pb, and Zn compared to other locations. Despite this, all PTE concentrations in vegetables from the studied urban gardens, including those from As-contaminated soils, were below health-based guidance values and market levels (except lettuce), and human health risk assessments indicated safe consumption.

Elliot Buckminster, Charlotte Breckenridge, Thomas Sedgwick · International Journal of Research in Agronomy · United Kingdom

This research quantified soil-to-plant transfer factors for six heavy metals (Cd, Pb, Zn, Cu, Ni, Cr) in lettuce, spinach, and carrot across 20 peri-urban agricultural sites in Berkshire, UK, from 2021-2022. Cadmium exhibited the highest mean transfer factor (0.31), and at 4 of 20 sites, cadmium concentrations in lettuce exceeded the EU maximum limit of 0.20 mg/kg fresh weight. Soil pH was a strong predictor for Cd and Zn transfer factors, with TFs increasing below pH 6.0.

Cosimo Dondini, Xavier Úbeda, Giacomo Certini, Marcos Francos · Journal of Soils and Sediments · Spain (Barcelona)

This study analyzed soils from ten urban gardens in Barcelona, Spain, with a special focus on possible contaminants. Irrigation water was also analyzed, and some of the waters contained a high concentration of salts and nitrites, which are listed as a pollutant. While three tests for heavy metals did not attest to significant pollution, other toxic elements not considered in this study could come from road transport gases or the port of Barcelona. Overall, the soil quality was concluded to be suitable for growing vegetables.

Simone Trimmel, Stefan Wagner, Laura Feiner, M. Feiner, Daniela Haluza, Rebecca Hood‐Nowotny, Ulrike Pitha, Thomas Prohaska, Markus Puschenreiter, Philipp Spörl, Andrea Watzinger, Elisabeth Ziss, Johanna Irrgeher · Environmental Science and Pollution Research · Europe

A study of urban gardens in Vienna, Austria, building on a previous study of eleven gardens in the city that found elevated lead (Pb) levels in some soil and plant samples. This work examined the elemental composition of soil and plants from two of the affected gardens one year after compost amendment. ICP-MS analysis of tomato fruit skin, pulp and seeds showed only minor variations in elemental composition unlikely to affect food safety, whereas radishes showed a tendency toward contaminant accumulation in root tips and leaves. Washing lettuce significantly reduced levels of potentially toxic elements including Be, Al, V, Ni, Ga and Tl, underscoring the importance of washing garden produce before consumption; compost amendment was associated with reduced Zn, Cd and Pb levels in radish bulbs. Lead isotope ratios in soil and spinach leaf samples from the earlier study, assessed by MC-ICP-MS, showed a direct linkage between the Pb isotopic signatures in soil and spinach leaves, supporting their use as tracers of Pb sources in the environment.

Anne-Kristin Løes, Sebastian Eiter, Tatiana Rittl · Environmental Sciences Europe · Europe

Using soil data from ten peri-urban case farms near Oslo and Bergen, Norway, this study estimated how quickly potentially toxic element (PTE) concentrations would rise in soil under intensive application of compost or digestate from food waste, composted garden waste, or horse and poultry manure applied annually to meet a theoretical carrot crop's nitrogen, phosphorus and potassium demand. Under this intensive fertilization scenario, Norwegian soil quality limits for PTEs would be reached within 20-85 years, faster in soils with more organic matter, with limits reached first for copper and zinc, both essential micronutrients. The urban waste-based fertilizers were also found to be poorly balanced in macronutrients, with rates covering potassium demand leading to high phosphorus and nitrogen surpluses. The study concludes Norway's PTE regulations are stricter than the EU's and do not support recycling organic matter and nutrients from urban waste.

Elżbieta Skorbiłowicz, Piotr Ofman, Mirosław Skorbiłowicz, Marcin Sidoruk, Urszula Tarasiuk · Water · Poland

This study assessed heavy metal contamination in 96 surface sediment samples collected from urban, agricultural, and forested areas of the Bug River catchment in Poland between July 2018 and 2020, measuring metals (Zn, Pb, Cr, Ni, Cu, Fe, Mn, Cd) by atomic absorption spectroscopy and applying the geoaccumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). Urban sediments showed significantly higher heavy metal concentrations than agricultural or forested areas, with cadmium reaching up to 2.5 mg/kg; the average Igeo for cadmium was 0.24 in agricultural areas and 0.15 in urban areas, while the highest PLI values, reaching a maximum of 0.33, occurred in urban areas, and statistical analysis showed both urban emissions and agricultural activities significantly influenced heavy metal presence in the sediments.

Riccardο Petrini, Lisa Ghezzi, Simone Arrighi, Lisa Genovesi, Chiara Frassi, Luca Pandolfi · International Journal of Environmental Research and Public Health · Italy (Tuscany)

Trace elements were measured in soil and groundwater in the Fornaci di Barga urban area, Tuscany, Italy. Results indicate that Cu, Zn, and Cd are the main contaminants in surface soil, likely originating from airborne particulate matter deposition from metallurgical activity. Risk assessment considering soil ingestion and dermal contact exposure routes revealed that the cadmium Hazard Quotient approaches unity for children, and the cadmium risk-based concentration is only slightly lower than the maximum concentration measured in soil.

Jonathan Stubberfield, Mads Troldborg, E. Louise Ander, N.M.J. Crout, Scott D. Young, Rupert Hough · Agronomy · United Kingdom

This study investigated the influence of gardening routines on health benefits and risks among 120 urban gardeners in the UK. Participants showed a correlation between autumn/winter gardening activity and fruit/vegetable consumption, with higher physical activity levels and lower BMI than average. However, while gardening offers health benefits, the health risks from gardening on soils mildly contaminated with cadmium and lead may outweigh these benefits, requiring formal consideration within a risk management framework.

Sara R. Healy, Eric R. Morgan, Joaquín M. Prada, Martha Betson · Food and Waterborne Parasitology · United Kingdom

This proof-of-concept study investigated the presence of Toxocara spp. eggs on 82 'ready-to-eat' vegetable samples (lettuce, spinach, spring onion, celery) from 16 community gardens in southern England. Two lettuce samples tested positive for Toxocara spp. eggs, showing an overall prevalence of 2.4% for vegetable samples and 6.5% specifically for lettuce. This study is the first to demonstrate Toxocara spp. eggs on vegetables grown in community gardens in the UK and Europe, highlighting biosecurity and zoonotic risks.

Michael Hardman, Andrew Clark, Graeme Sherriff · Agronomy · United Kingdom

Using a qualitative approach across the UK's largest urban farm and a range of other urban agriculture (UA) sites, this study examined the barriers to upscaling city farming. Evidence pointed to urban soil contamination and hesitation about growing crops in cities as a core issue preventing UA from scaling up, alongside public hesitancy and financial barriers, despite the practice's potential social, environmental and economic value through job creation, biodiversity enhancement and shorter food supply chains. The paper concludes that public hesitation, financial barriers and soil quality prevent development, and calls for a more pragmatic approach to these barriers.

Sabina Rossini Oliva, Rafael López Núñez · Agronomy · Spain

This study investigated potential toxic element contamination in food and soils from urban and rural gardens in Seville, Spain, including urban gardens in a mining area. Soils from mining gardens were the most contaminated. While arsenic, cadmium, and lead concentrations in studied vegetables did not exceed legal maximum levels, high levels of barium (up to 42 mg kg−1) and zinc (up to 123 mg kg−1) were found in leafy green vegetables like chard and lettuce, indicating a need for further study on associated human health risks.

Marta Crispo, Miriam C. Dobson, Roscoe S. Blevins, William Meredith, Janice A. Lake, Jill L. Edmondson · Environmental Pollution · United Kingdom

Heavy metal (HM) and metalloid concentrations were assessed in 200 urban horticultural soils across ten UK cities. HM were found to be widespread, with most concentrations below UK soil screening values (C4SLs). However, 83% of lead (Pb) concentrations exceeded C4SLs, which is a significant concern. Bioavailable HM concentrations represented a small fraction (0.01–1.8%) of total concentrations, and black carbon (BC) and organic carbon (OC) were suggested to contribute to HM immobilization.

Iwona Makuch-Pietraś, A. Wójcikowska-Kapusta · Land · Poland

This research investigated the distribution, bioavailability, and total forms of zinc (Zn) in soils from domestic and family allotment gardens across six cities in south-eastern Poland. It found that horticultural treatments had a greater impact on sandy soils, and higher Zn contents were present in humus horizons. High values of concentration and Igeo indices indicated significant Zn pollution in these soils, with bioavailable zinc forms being notably high.