Changes in nutrient loads (N, P and Si) in the São Francisco estuary after the construction of dams

The aim of this study was to investigate the post-dam conditions of the loads and yields of dissolved inorganic nitrogen (DIN), orthophosphate (DIP, silicate (DSi) and total phosphorous (TP) in the Lower São Francisco river estuary (NE-Brazil) after the river was regulated to a constant flow by the dams. Loads and yields of monthly measurements performed from November 2000 to March 2002 at a gauging station downstream of the dams (80 km from the coast) showed 4.1 x 10³ t/yr and 0.006 t/km² /yr of DIN, 0.2 x 10³ t/yr and 0.002 t/km² /yr of DIP, and 448 x 10³ t/yr and 0.71 t/km² /yr of DSi, respectively. Over the last 15 years, DIN loads reduced by 94 % and DSi by 31%. The river turned into an oligotrophic system with primary production limited by nitrogen and nutrient yields being among the lowest of Brazilian coastal rivers.

Bibliographic Details

Main Authors:	Medeiros,Paulo Ricardo Petter, Knoppers,Bastiaan Adriaan, Cavalcante,Geórgenes Hilário, Souza,Weber Friederichs Landim de
Format:	Digital revista
Language:	English
Published:	Instituto de Tecnologia do Paraná - Tecpar 2011
Online Access:	http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132011000200022
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