Author(s)

A. da Costa Neto, D.M. Bonotto & F.L.A. Mesquita

Abstract

Geogenic factors affecting the selenium(1V) distribution in sediments from Madeira River basin, Brazil Abstract This investigation was carried out at the Madeira River basin, located in the state of Rondbnia, Brazilian Ama~on. Sediments from Madcira River between Teotbnio and Santo Antbnio waterfalls along 25 km upstream from Porto Velho: the capital of Rondbnia state, and from nine lakes located around Porto Velho municipality were cliemically analyzed for Se (IV) in order to evaluate the main factors affecting the Se(1V) distribution in the environment. Selenitc ion was chosen to investigate the selenium behavior in the area. because acid conditions are dominant there. The importance of clays, iron oxides. organic matter and minor refractory minerals was cvnsidered in order to esplain most of the obtained data. 1 Introduction Seleniuni was discovered in 18 17 by Berrelius and Gahn who used coppcr pyrites as a source of SOz for [he HISOJ nianut'acture and generated a residue containing a new

Keywords