Metals in urban soils of Sevilla: seasonal changes and relations with other soil components and plant contents

Thirty-five soils of urban Seville, Spain, were sampled and analyzed to determine the distribution of heavy metals in the city and their possible relation to various soil components. Urban metals (those resulting from human activity) and organic matter were strongly related, while non-urban metals were related to clay and carbonate contents, probably because of originating in soil parent material. Organic matter contributes to accumulation of urban metals either by retention of metals deposited from the atmosphere, dust, or human activities, or by addition of organic amendments that may contain such metals. Concentrations of lead, copper, and zinc at several sites exceeded established limits, but levels in grass were lower than those reported as normal in the literature. High soil metal concentrations may not necessarily be bioavailable.