Study of mercury pollution near a thermometer factory using lichens and mosses.

Mercury has a widespread environmental distribution, originating both from anthropogenic and natural processes. Once in the air, mercury can be widely dispersed and transported to longer distances. In the environment mercury can exist in a number of physical and chemical forms with toxicity is well known to be highly dependent on chemical form (Clarkson, 1997). As a consequence, considerable effort and progress has been made in the development of techniques for the separation and identification of individual mercury species in environmental samples (Sanchez Uria and SanzMedel, 1998). Biomonitoring using lichens and mosses is an effective method for assessing the levels of atmospheric trace element pollution including mercury (Merian, 1991; Conti and Cecchetti, 2001; Horvat et al., 2000) as lichens and mosses pick up nutrients directly from ambient air and deposition retaining many trace elements (Ruhling and Tyler, 1968). In this work, mercury contamination due to a mercury thermometer-making factory situated in the hill station Kodaikkanal (about 2120 m above mean sea level), in a southern state of India, was investigated using lichen (Parmelia sulcata) and moss (Funaria hygrometrica) samples. The content of mercury in these samples collected from different sites was determined using CV-AAS mercury analyzer and ICP–QMS in order to obtain information on the extent of mercury contamination. As mercury undergoes extensive transformation into various forms as it cycles among the atmosphere, land and water (Ebadian et al., 2001), we have carried out investigations to establish the chemical form of mercury—elemental (Hg), inorganic (Hg) or organic—in these chosen biomonitors.