Fish contamination and human exposure to mercury in the Tapajós River Basin, Pará State, Amazon, Brazil: a screening approach.

Abstract

In the Brazilian Amazon gold mining (“garimpos”), Hg is used to amalgamatefine gold particles from placer deposits., A 2:l or even greater Hg/Auamalgamation ratio were observed by Lacerda et al. (1995) from several“garimpos” in the Amazon. Hg loss from gold mining to local ecosystems wasestimated to reach 1,300 t in the Amazon, between 1980 and 1993 (Cid deSouza and Bidone, 1994). More than 50% of this Hg were used in “garimpos”located in the Tapajos river basin, in Para State, the most important gold miningarea in Northern Brazilian Amazon in the 80’s, when the peak in Amazon “goldrush” occurres. Generally, the released Hg° is incorporate into the riversediments. Environmental methylmercury (MeHg) arises largely, if not solely,from the methylation of inorganic mercury (Hg