Concentration of heavy metals in urban allotment soils and their uptake by selected vegetable crop species - a case study from Gorzów Wielkopolski, Poland

Abstract

Due to the growing popularity of urban agriculture, it is important to understand the influence of the quality of urban soils and crops cultivated on them. This study analyses the content of heavy metals – micronutrients (Cu, Fe, Mn, Ni, Zn) and toxic heavy metals (Cd, Cr, Pb), in samples of soils and three vegetable crops (carrot, lettuce, and tomato) grown in allotment gardens (AGs) in Gorzów Wielkopolski, a medium-sized Polish city with an average level of industrialisation. Emphasis was laid on the transfer of toxic heavy metals from soil to vegetables since they are the most exposed to environmental pollution while being an essential part of the human diet and. The content of heavy metals in the topsoil in the allotment gardens was diversified and was arranged in a descending order of Fe> Zn> Mn> Cu = Pb> Ni = Cr> Cd. The soil was not contaminated with heavy metals. The highest accumulation of micronutrients and toxic heavy metals was found in lettuce leaves, whereas the lowest was in tomato fruits. The lettuce leaves also had a particularly high Fe content. Hence, bearing in mind food safety, we can recommend to grow vegetables with fruits as edible parts in the allotment gardens located in Gorzów Wielkopolski. The values of the health risk quotient (HQ) for Cd and Pb in the carrots and lettuce grown in all the AGs were greater than 1 and posed a health risk for consumers. The HQ values for Cd, Pb, Ni, and Cr in the tomatoes grown in all the AGs were less than 1, which indicated no health hazard and safe consumption.