摘要
the present study analyzed ph, eh, electric conductivity, chloride, silica, phosphate, k, na, ca, mg, fe, zn, ni, co, mn, pb, cu, cr, li and cd in draining waters making part of smaller creeks located in the northeastern amazonas state. the waters have black colour, are predominantly acid and slightly reductive and have low content in dissolved elements. otherwise they are chemically heterogeneous and reflect the geological environment. the sio2, na and k are the most abundant dissolved constituents, especially on the drainages farther north belonging to uatumˋ, urubu basins and canoas stream, which drain the rocks of 芍gua branca and mapuera intrusive suite, iricoum谷 group and prosperanˋa, nhamund芍, manacapuru, pitinga formations. smaller streams, which drains alter do chˋo formation sediments, exclusively, are the most diluted ones. the analysed trace elements present very low concentrations.