Artigo de peri??dico
A model of recent sedimentation in the Cananeia???Iguape estuary, Brazil
Registro en:
1569-4860
8
10.1016/S1569-4860(05)08034-4
Autor
SAITO, R.T.
FIGUEIRA, R.C.L.
TESSLER, M.G.
CUNHA, I.I.L.
Resumen
Coastal systems, in particular estuaries, are the first depositional environment to receive sediments transported by
rivers to the coastal ocean. As a consequence of the geochemical processes involved, a part of the sediment may be
deposited in the estuary and the remainder flows into the ocean, being transported and deposited under the influence
of tides and maritime currents. This study was carried out in the Cananeia???Iguape estuary on the southern coast
of S??o Paulo state, Brazil. The vertical distribution of 210Pb and 137Cs in sediments has been used as a tool for
estimating the sedimentation rates in the coastal environment. Concentrations of 210Pb and 137Cs, as well as heavy
metals (lead, zinc, copper) were determined in four sediment cores collected in the Cananeia???Iguape estuary. The
estimated sedimentation rates were from 5.3 mm yr???1 to 12.7 mm yr???1. The highest sedimentation rate obtained
for Valo Grande corresponds with an accelerated expansion of the sand and clay banks of the Mar Pequeno channel,
a growth of the mangrove areas, and a decrease in the depth of the main channel of navigation, a fact that has been
affecting the navigation in the area very seriously. The data obtained for the metals showed a sedimentary dynamics
in agreement with that obtained in the studies of sedimentation rates, thus contributing to the understanding of the
hydrodynamic mechanisms of the system.