S09 - Session P3 - Impacts and assesment of urban horticulture on sustainability of food systems - Risk assessment for heavy metals in community gardens of the city of Teresina, Brazil

Authors: Vito Aurelio Cerasola *, Lucrecia Pacheco Batista, Nicola Michelon, Francesco Orsini, Giuseppina Pennisi, Francineuma Ponciano de Arruda, Gilmo Vianello, Livia Vittori Antisari, Giorgio Gianquinto

Urban Agriculture (UA) contributes actively to food security cities worldwide. Urban crops can be polluted by heavy metals (HMs) emitted by several sources, therefore to assess the health risk linked to HMs contamination is a crucial priority. The present study assessed the HMs contamination risk in five community gardens within the city of Teresina, Brazil, three within the city, one in peri-urban fringes and one from the nearby rural area. In each garden soils and vegetables (lettuce, coriander and chives) were sampled and total HMs concentration determined. HMs contamination risk was assessed for both soil and vegetables, performing respectively the Geoaccumulation Index (Igeo) and Health Risk Index (HRI). Moreover, the effect of two cropping systems (traditional soil versus simplified soilless system) on HMs pollution was investigated. Although the highest pollution level was detected in high-traffic urban area, Ni and Pb were mainly absorbed by plants grown in the rural soil. Soilless system limited the absorption by plants of Ni, Tl an Mo, but increased the uptake of Pb and Zn. The study shows that pollutants uptake by plants was not related only to the total HMs concentration in topsoil, and more information on the bioavailable fraction are needed when risk assessment is performed. Therefore, strategies aimed at the reduction of bioavailability of the pollutants in soil are recommended in urban agriculture. Overall, the Health Risk Index demonstrates that the vegetables grown in the city of Teresina can be considered safe for children's consumption