Contribution of chemical inputs on the trace elements concentrations of surface soils in urban allotment gardens

Purpose Urban soil contamination by heavy metals is one of the foremost challenges for urban soil quality, especially in the urban agriculture context. Urban gardening is a common practice in many industrialized and developing countries. How sources of soil contamination relate to inputs and influence the heavy metal content in soils, however, is not established yet. Materials and methods This study aims to assess the potential of pesticide applications (such as Bordeaux mixture) on soil quality. A set of 104 allotment gardens was selected in three cities in France, and topsoil was sampled and analyzed. Results and discussion The four most abundant metals in urban vegetable garden topsoils were Zn, Pb, Cu, and Cr. The past and/or present industrial and urban activities are not the only cause of the metal contamination in urban vegetable garden soils. Gardens, where pesticides such as the Bordeaux mixture are being used showed significantly higher total Cu values in soils (78 mg kg(-1)compared with 49 mg kg(-1)for untreated gardens). Conclusions Even though the risk of metal contamination through vegetable consumption is usually considered low, we clearly identified indicators of anthropogenic Cd, Cu, Pb, and Zn pollution due to pesticides inputs. This link was particularly strong between the use of Bordeaux mixture and increases Cu levels.

Automated summary

Urban soil contamination by heavy metals is a major challenge for urban soil quality, especially in the context of urban agriculture. The study found that the most abundant metals in urban vegetable garden soils are Zn, Pb, Cu, and Cr, and the use of pesticides such as Bordeaux mixture can significantly increase copper levels in the soil.