EDAFOLOGÍA, Vol. 12 (1), pp. 29-42, 2005
ELEMENTOS TRAZA Y NUTRIENTES EN SUELOS Y HERBÁCEAS DE PARQUES Y ZONAS VERDES DE SEVILLA
F. MADRID, E. DÍAZ-BARRIENTOS, L. MADRID (*)
Instituto de Recursos Naturales y Agrobiología de Sevilla (C.S.I.C.), Apartado 1052, 41080 Sevilla, [email protected]
(*) Autor para correspondencia.
The use of urban soils, unlike the traditional agricultural use of soils in rural areas, is in most cases of a recreational and ornamental character. For that reason it is often forgotten or disregarded that urban soils have a direct influence on public health. Such urban soils receive significant inputs of pollutants from human activities, and they can enter organisms as airborne dust, by direct contact or even by ingestion. It is thus necessary to know the quality of urban soils, especially concerning pollutant concentration and availability.
Urban soils of Sevilla were sampled in 154 sites, 85 of them covered by grasses. Soils were characterised and their contents in potentially toxic metals (PTM) were measured, both by aqua regia digestion (pseudo totals) and by extraction with 0.05 M EDTA (available fraction). The concentrations of PTM in the grasses were also determined.
Most soils were found to be neutral, rich in lime, low organic matter contents and particle size distributions within the various loam classes.
An incipient or moderate pollution in Cu, Pb and Zn is observed, particularly within the historic quarters, as well as low contents of other PTM. Concentrations of PTM in the grasses are quite comparable to those commonly found in non-polluted areas. The relationship between metal grass contents and soil concentrations is highly significant only in the case of Cd or Zn, but not for the other metals.
Multivariate analysis shows that no relation exists between metals in soils and in plants in any case, but a strong association exists among the soil concentrations of Ba, Cu, Pb and Zn and that of organic matter.
It is concluded that urban soils of Sevilla show an incipient to moderate pollution with PTM in some sites, particularly in areas close to the historic centre, where a periodic monitoring is recommended. Application of some non-toxic material with metal-immobilising power might be convenient to reduce metal availability.
Key words: Urban soils, toxic metals, metals in grass, pollution.