ABSTRACT
Knowledge of trace elements and their role in the life-cycle is of great importance. Almost a hundred species of alkylated metals and metal(loid)s have been found in different ecosystems. The level of contaminants can be very low (at ng range per dm3 or kg) or very high and can come from
1Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas, 96010-610, Pelotas, RS, Brazil. aEmail: marcia.mesko@pq.cnpq.br bEmail: carlahartwig@yahoo.com.br 2Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil. cEmail: c_bizzi@yahoo.com.br dEmail: edson_muller@yahoo.com.br eEmail: fabioand@gmail.com fEmail: paoladeazevedomello@gmail.com *Corresponding author
natural sources or be a result of an enrichment. Whether through natural or anthropogenic activities, when metal ions enter the environment or living systems, only a fraction will remain as free ions. In general, the major portion will be complexed by ligands and can result in different species with specifi c behavior in the system, resulting in several bio(geo)chemical processes (Lobinski 1997, Hirner 2006). For example, natural methylation, which is generally prevalent in metal ions under specifi c conditions, can result in much more or less toxic species, depending on the element. Another example is the possibility of metal ions being incorporated into large molecular structures such as humic substances. On the other hand, due to different anthropogenic activities, some species can enter the environment, for example, lead and tin species (Cornelis et al. 2003, Hirner 2006).
