Lichens as Biomonitors of Heavy-Metal Pollution

Abstract

The scientific understanding of the atmospheric deposition of pollutants (ie, metals, dust, acid fumes, etc.) is constantly evolving. Hence, there is an increasing demand for air quality monitoring techniques that can be easily applied with the aim to validate standard dispersion models. In view of this, lichens, if properly calibrated, can give valuable information about the elements’ atmospheric deposition of vast geographical areas (see for reviews [1e7]). In general, bioindicators are organisms that can be used for the qualitative determination of human-generated impacts, while biomonitors are used with the aim to have quantitative information and they can be classified as sensitive or accumulative [2,4,6]. Sensitive biomonitors are used to estimate the biological effects of pollutants by measuring changes at community or population level, ecological performance, morphology, alteration in the activity of enzyme systems, and photosynthetic or respiratory activities [4,6e8]. They can be used as integrators of the stress caused by contaminants and can act as preventive alarm systems [7]. Bioaccumulators have the ability to store contaminants in their tissues and can be used for the integrated measurement of the concentration of contaminants in the environment. The bioaccumulation process is, then, the result of the equilibrium of intake/discharge of contaminants from and into the surrounding environment [4,7]...