Contribution of a medium-sized tropical river to the particulate heavy-metal load for the South Atlantic Ocean

The Para´ıba do Sul River is a medium-sized river, 1145 km in length with a drainage basin of 55 400 km2. The riverine fluxes of particulate metals ŽCu, Cr, Zn, Mn and Fe. were investigated over 24 months. Particulate matter samples were monthly collected from April 1994 to March 1996. The first 12-month period presented lower rainfall than the second, although both periods presented average precipitation lower than the regional average. The particulate matter flux in the second period Ž2 042 080 t. was 250% higher than the first period Ž821 489 t.. The same trend was observed for the associated metals, which presented higher fluxes in the second period. This study highlights the strong dependence of the transported mass on the rainfall, and consequently with the river water discharge. The Para´ıba do Sul River presents a low contribution to the world oceans, although the local contribution could be considered relevant.