Das Projekt "Der Ursprung natuerlicher Methylquecksilberverbindungen" wird vom Umweltbundesamt gefördert und von Universität Mainz, Institut für Geowissenschaften durchgeführt. Objective: Assessment of the biotic and abiotic methyl mercury formation in the freshwater and marine environment. Generxtent Biotic and Abiotic Processes are Responsible for the Formation of Methylal) larger research programme aimed to investigate to what extent biotic and abiotic processes are responsible for the formation of methyl mercury in freshwater and marine environments under field conditions of low and high natural environmental mercury concentrations. Attention will be paid to the questions whether the methyl mercury formation by bacteria does really occur in nature, and whether the abiotic methylation processes are playing an important role in methyl mercury formation under natural conditions.