Author(s): Pacheco, João Miguel Asseiceiro Silva
Date: 2015
Persistent ID: http://hdl.handle.net/10400.5/11169
Origin: Repositório da UTL
Subject(s): urban gardens; heavy metals; urban agriculture; contamination; vegetables
Author(s): Pacheco, João Miguel Asseiceiro Silva
Date: 2015
Persistent ID: http://hdl.handle.net/10400.5/11169
Origin: Repositório da UTL
Subject(s): urban gardens; heavy metals; urban agriculture; contamination; vegetables
Mestrado em Engenharia do Ambiente - Instituto Superior de Agronomia
The use of urban gardens for vegetable production has been increasing over the last few years. Due to present and past anthropogenic activities there is cause for concern regarding contamination of the soils, water and plants in these locals. This work was performed within the broader scope of a project between the Lisbon city council, LNEC and Instituto Superior de Agronomia to analyze the contamination of some selected urban gardens in the Lisbon area. In the present thesis we report the results of the determination of heavy metals (Cd, Cu, Cr, Ni, Pb and Zn) from different vegetables collected in 8 urban gardens. The obtained results show there is no serious contamination problem with regard the studied heavy metals. All the Cd levels detected in the different plants were well below the limits imposed by law for edible fresh leaf vegetables. With regard to Pb, only a few samples exceeded the allowed limits, but usually in the non-edible parts (like roots in leaf vegetables). As for Cu, although a few samples exceeded the selected reference value, none of the samples had Cu levels that could be considered toxic. This study confirmed that the uptake of heavy metals is highly dependent not only on the plant part under study but also on the plant species, among other factors. The determination of the average daily intake of Cd due to lettuce consumption also confirmed that there is no toxicity problem with regard to this heavy metal. Globally, the gardens with higher contents of heavy metals in the plants were Chelas 1, CRIL and Granja 1 and 2. This could be due to their location, near major roads with heavy urban traffic. It can thus be concluded that, in the selected urban gardens in the Lisbon area, no significant heavy metal contamination exists