Biblioteca: Cuenca Rapel

Rapel: A 30 years temperate reservoir. Eutrophication or contamination?

Autor / Institución Universidad de Chile; Irma Vila et al.,
Fecha 2000
Tipo Revista: Arch. Hydrobiol. Spec.
Tabla de contenidos Introduction; Methods; Results; Discussion;
Resumen Hydrologic conditions and an increase in incoming nutrients from human activities have enhanced the effect of copper sulfates from mine tailings flowing into the temperate monomictic lake Rapel (34' S), an hydroelectric reservoir constructed in 1968. Before copper additions, predictions pointed to rapid eutrophication processes. However, plankton community structure seemed to show conditioned responses to the presence of tailing metals, especially copper. An overall characterization of the lake showed major problems with continual hypolimnetic anoxia in summer during recent years. The sediments accumulating under these conditions exhibited elevated concentrations of methane; the intensive diffusive flux of this gas contributed to the anoxic conditions. It is also likely that substantial losses of sulfates and phosphates ocurred across the sediment-water interface. However, the presence of higher concentrations of copper in the water column prevented the dominance of specific algae such as bluegreens and some diatoms, and thus the general processes leading to rapid eutrophication were limited.
Datos del informe Autumn and winter phytoplankton total abundance (in Standard Units, S. U.xl0) at the different basins in Rapel reservoir and three sampling depths (1 is surface, 2 is limit of the euphotic zone and 3 is the deep sample) in 1977 and 1992; Total P-PO4 values (pg I-'); B. Total N-NO, (pg I-'), average values at Rapel reservoir; Total sulphates and total copper (mg 1-I) values at Rapel reservoir; Aulacoseira granulata: relative abundance in percentage (%) for autumn and winter periods at different depths and different basis at Rape1 reservoir in 1977 and 1992; Temperature and dissoived oxygen profiles. S,: dam sik; S,: 1000 m upstream; S,: 2500 m upstream; Chlorophyll-a values (mg Chl m2) at Rape1 reservoir; Phosphate, sulfate and anunonia diffusive flux at Rapel reservoir.
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