Resumo

GARCIA ARAGON, Juan Antonio et al. Assessment of pollution by heavy metals and hydraulic storage capacity reduction by sediment filling of a mexican reservoir. Hidrobiológica [online]. 2007, vol.17, n.2, pp.127-138. ISSN 0188-8897.

José Antonio Alzate is the first reservoir over the Lerma river and most of the sediments eroded in the upper Lerma river basin, an highly urbanized area, are deposited there. Alzate reservoir, accomplish functions for flood control and for water irrigation supply downstream. Recently a bathymetric study was carried out in order to know the new bottom reservoir profile. These levels were compared with those existing before the dam construction in 1959 and the sediment volume accumulation was obtained. Also a sampling of bottom sediments was obtained in order to make an analysis by X ray fluorescence spectrometry to define possible pollution by heavy metals. This paper, discuss the high reduction in reservoir storage capacity (close to 50%) and the sediment pollution which defines the environmental risks associated with their removal. Taking into account the low pollution concentrations of heavy metals measured, which do not exceed the standard international criteria for sediment use in agriculture and the relatively low volume of dredging lower than 65 000 m³, it is recommended to dredge the area surrounding the intake structure for operation security, considering how important it is in the reservoir functioning.

Palavras-chave : Bathymetry; polluted sediments; heavy metals; reservoir.

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