Suspended sediment yield and metal contamination in a river catchment affected by El Nino events and gold mining activities: the Puyango river basin, southern Ecuador

Details

Serval ID
serval:BIB_1C23FC7DEBB6
Type
Article: article from journal or magazin.
Collection
Publications
Title
Suspended sediment yield and metal contamination in a river catchment affected by El Nino events and gold mining activities: the Puyango river basin, southern Ecuador
Journal
Hydrological Processes
Author(s)
Tarras-Wahlberg N.H., Lane S.N.
ISSN
0885-6087
Publication state
Published
Issued date
2003
Volume
17
Number
15
Pages
3101-3123
Language
english
Notes
Publication type : Article
Abstract
The suspended sediment yield and the transfer of polluted sediment are
investigated for the Puyango river basin in southern Ecuador. This
river system receives metal (Cd, Cu, Hg, Ph and Zn) and cyanide
pollution generated by mining. and is associated with large-scale
hydrological variability, which is partly governed by El Ni (n) over
tildeo events. Field sampling and statistical modelling methods are
used to quantify the amount of mine tailings that is discharged into
the basin. Annual suspended sediment yields are estimated using a novel
combination of the suspended sediment rating method and Monte Carlo
simulations, which allow for propagation of the uncertainties of the
calculations that lead to final load estimates. Geochemical analysis of
suspended and river bed sediment is used to assess the dispersion and
long-term fate of contaminated sediment within the river catchment.
Knowledge of the inter- and intra-annual variation in suspended
sediment yield is shown to be crucial for judging the importance of
mining discharges, and the extent to which the resultant pollution is
diluted by river flows. In wet years, polluted sediments represent only
a very small proportion of the yield estimates, but in dry years the
proportion can be significant. Evidence shows that metal contaminated
sediments are stored in the Puyango river bed during low flows. Large
flood events flush this sediment periodically, both on an annual cycle
associated with the rainy season, and also related to El Ni (n) over
tildeo events. Therefore, environmental impacts of mining-related
discharges are more likely to be severe during dry years compared with
wet years, and in the dry season rather than the wet season. The
hydrological consequences of El Ni (n) over tildeo events are shown to
depend upon the extent to which these events penetrate inland. It is,
thus, shown that the general conclusion that El Ni (n) over tildeo
events can significantly affect suspended sediment yields needs
evaluation with respect to the particular way in which those events
affect a given catchment.
Keywords
suspended sediment, load estimate, El Nino, metals, environmental impact, Ecuador, NORTHERN PERU, COEUR-DALENE, SMALL-SCALE, RAINFALL, IMPACTS, LOADS, GEOCHEMISTRY, OSCILLATION, VARIABILITY, DISCHARGE
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Create date
03/02/2011 14:41
Last modification date
20/08/2019 12:52
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