Trace metals in the soil and in Quercus ilex L. leaves at anthropic and remote sites of the Campania Region of Italy

Abstract

The concentrations of Cd, Cr, Cu and Pb were measured in leaves of Quercus ilex L. and in the soils collected from 15 sites of the Campania Region of Italy of two different typologies (anthropic and remote), in order to evaluate: (1) the effect of translocation and/or direct deposition from air on leaf element concentrations; and (2) the suitability of the studied matrices as pollution monitors. The available fractions of the studied elements in the soils were also measured. The accumulation factor (anthropic/remote sites) was calculated to evaluate the element accumulation, both in leaves and soils, at the anthropic sites compared to the remote sites. The concentration factor (leaf/soil) was used to investigate the translocation of the element from soil to leaves. Cd and Cr soil contents at the remote sites were higher than at the anthropic ones; in contrast, at the latter, Cd and Cr leaf concentrations were higher than at the remote sites. Cu and Pb concentrations were greater both in the soils and in the leaves of the anthropic sites as compared to the remote ones. The differences between the two site typologies were statistically different with the exception of Cu soil contents. The concentrations of Cu and Pb in the leaves and in the soils were significantly correlated. Available Cd, Cu and Pb fractions were significantly correlated to the total soil contents. Moreover, available Cu in the soil was significantly correlated to Cu leaf concentrations. All the studied elements appear to be taken up in relevant measure directly from the air at the anthropic sites. The translocation from roots to leaves could be relevant only for Cu. Q. ilex leaves appear better biomonitors than soil in the investigated area. The soil background contents of all the studied elements hid the input of trace elements from the air. In addition, soil contents reflect a mixture of past and recent inputs, whereas leaf contents reflect the element inputs for a known exposure time.