Trace elements in urban garden and health risks

12th Urban Environment Symposium, OSLO, NORVEGE, 01-/06/2016 - 03/06/2016During the last century, global urban populations have increased very rapidly. In the context of global changes and with the need of food supply and recreation areas for these urban populations, green areas are developing. Thus, allotment gardens are expanding worldwide. However, the garden location and soil quality, which have not been taken into account beforehand, can induce health risks.For many years, the city of Nantes supports the allotment gardening. Attentive to the potential health risks associated with this practice, for instance the consumption of vegetables grown on contaminated soil, the parks and gardens and environment department has launched a program to check the soil quality of its 24 gardens towards pollutants. In case of soil and vegetable contamination, soil management is foreseen.In this study, three gardens were investigated (Eglantiers, Contrie and Batignolles). Soil and vegetables samples were analyzed. The spatial distribution (horizontal and vertical) of As, Cu, Pb, and Zn, in the plots of the garden, was determined, completed by a historical analysis of the site. The studied elements were quantified using a portable X-ray fluorescence spectrometer. To assess the transfer of trace elements in vegetables, its accumulation in vegetable samples was assessed after a digestion with aqua regia and a determination by atomic absorption.Trace elements contents were mapped. Significant As and Pb anomalies were observed in several plots of the different gardens. Moreover, the results showed different origins for the pollution and different levels of vegetable transfer. The results for vegetables were compared with the European regulation that defines the maximum authorized concentration of some trace elements in vegetables destined to human consumption. Some concentrations in vegetables exceeded the threshold level (e.g. Pb 0.1 mg kg-1 fresh matter (FM))