Heavy metal concentration in sage plants cultivated on an urban green roof or roadside location as affected by substrate type and fertilization
The increasing heavy metal environmental pollution of recent years has raised public and scientific interest due to the hazardous impact on human health. Simultaneously, the tendency for urban agriculture is growing, raising the issue of safety for food produced in burdened with pollutants environments. Aim of the present study was to investigate and assess heavy metal concentrations in leaves of sage plants (Salvia οfficinalis) cultivated at different urban locations. Rooted stem cutting were planted in April 2012 in plastic containers 40×60×22 cm (two plants per container), with a green roof infrastructure fitted (moisture retention and protection of the insulation mat, drainage layer and filter sheet) and placed half of them on a fully exposed third floor flat roof at the Agricultural University of Athens and the other half in the botanic garden of the Agricultural University of Athens alongside a main road with average traffic, in Athens, Greece. Two types of substrates were used, 40% peat:60% perlite and 30% cotton gin trash compost:10% peat:60% perlite (v/v), with the same depth of 12 cm. Half of the containers in each substrate were fertilized monthly with Nutrileaf 20-20-20, 4 g L-1. The experiment lasted six months. At the end of the experiment the concentrations of lead (Pb), nickel (Ni), copper (Cu), zinc (Zn) and manganese (Mn) in the leaves of plants grown alongside the road were higher, but in most cases (75%) not statistically significantly, compared to those of plants grown on the roof, independently of substrate type and fertilization. In particular, the concentration of Zn in leaves of plants alongside the road was higher compared to that of plants grown on the roof, on both substrate types independently of fertilization, while Pb concentration was higher in leaves of plants grown alongside the road when fertilization was applied, and Mn concentration was higher only in the peat-perlite substrate that received fertilization. It is pointed out that the concentrations of both Ni and Pb detected in leaves of all plants, independently of planting site, substrate type and fertilization applied, were exceeding the FAO/WHO safety thresholds for edible plant tissues.
Papafotiou, M., Koutri, A. and Massas, I. (2017). Heavy metal concentration in sage plants cultivated on an urban green roof or roadside location as affected by substrate type and fertilization. Acta Hortic. 1189, 439-442
cotton gin trash compost, xerophyte Mediterranean herb, Salvia οfficinalis, urban horticulture