Effect of an organic amendment on availability and bio-accessibility of some metals in soils of urban recreational areas

A composted biosolid from wastewater treatment was added to soils of two public parks of Sevilla, and successive samples were taken during one year. In one of the parks, a second addition of biosolid was carried out after the first year. The soil contents in metals (pseudo-total) and their plant-available and oral bio-accessible fractions were significantly altered when the soils were amended with biosolid. Increase of the bio-accessible metal contents represents a deterioration of the environmental quality of recreational areas, where hand-to-mouth transfer of pollutants to children is likely to occur, although part of the metals added might be leached by rainfall or irrigation. The limits established in several countries for metal contents of soils in recreational areas are often exceeded after application of the biosolid. A careful study of the metal contents of recycled wastes is thus recommended before being used for green area maintenance.

Research highlights► Metal bio-accessibility in urban soils is significant for quality of life of citizens. ► Some metal-rich amendments can alter metal availability in urban soils. ► Metal contents of amendments in recreational areas must then be kept to a minimum. ► A case study of a composted biosolid used in urban green areas of Sevilla is given.