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.

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.

Cecilia Herbón, María Teresa Barral, Remigio Paradelo · Applied Sciences · Spain (Santiago de Compostela)

The concentrations of trace elements Cu, Pb, Zn, Ni, Cr, and As were investigated in 55 urban soils in Santiago de Compostela, northwestern Spain. While most soils showed higher trace element concentrations than regional backgrounds, they were not classified as contaminated according to Spanish regulations. However, geoaccumulation index values indicated low to moderate pollution levels in most soils, with Cu, Pb, and Zn highest in city center green areas, and Cr and Ni linked to parent material lithology.

Cécile Le Guern, Liliane Jean‐Soro, Béatrice Bechet, Thierry Lebeau, Dorine Bouquet · Land Degradation and Development · France

Urban allotment gardens in Nantes, France, were found to have soil contamination, with lead (Pb) levels ranging from 100–400 mg kg−1, posing health risks. Local actors collaborated to characterize soil, evaluate sanitary risks, and discuss management options. The most frequent solution was replacing polluted soils with clean soils, while other strategies included on-site management of excavated soil, non-accumulative cropping, or changing land use.

Marta Bożym · Ochrona Środowiska i Zasobów Naturalnych · Poland

A study measuring heavy-metal content (cadmium, lead, copper, zinc, nickel, chromium) in compost and resident earthworms sampled from home composters and allotment gardens in the Opole region of Poland. The compost samples themselves were not contaminated with heavy metals and stayed within Polish legal limits for solid organic fertilizers. However, metal accumulation in earthworms varied by metal: the bioaccumulation factor (BAF) was high for cadmium, lead and zinc, while no accumulation was found for nickel, chromium or copper. The authors conclude that earthworm species native to Poland, such as Eisenia fetida, can serve as potential bioindicators of metals in the environment.

Andrew Hursthouse, T. E. Leitão, Annette Voigt, Avigail Heller, Béatrice Bechet, Paulo Brito da Luz · HAL (Le Centre pour la Communication Scientifique Directe) · Europe

This chapter overviews factors influencing the chemical, physical, and biological status of soils, water, and the biosphere in urban allotment gardens. It highlights that urban garden soils, water, and biosphere are affected by pollution due to their location in city centers or suburbs, with traffic infrastructure and industrial zones widely identified as impacting soil and water quality. Concerns over long-term risks from pollutant transfer (mainly metals) from soil to plants in these uncontrolled environments have been widely publicized.

B. Jankiewicz, B. Ptaszyński · Polish Journal of Environmental Studies · Poland

This study determined the levels of bioavailable and total chromium (III) and chromium (VI) in the soil of an allotment garden located in the center of Łódź, Poland. Chromium was measured using the spectrophotometric method and atomic absorption spectrometry. The research also examined the effects of iron and copper ions on the determination results.