TEMPORAL VARIATIONS OF PARTICULATE METALS IN THE TAGUS RIVER ESTUARY

Reporting on the distribution of particulate metals in the Tagus River Estuary, this study includes: (i) variation in the amount of fluvial material and its elemental composition with river flow; (ii) the effect of tide on the longitudinal distribution of suspended sediment concentration and particulate metals; and (iii) the determination of metal-depth profiles in the bottom sediment along the estuary. Our observations show that the elemental composition of fluvial suspended sediments and their transport to the estuary vary seasonally and annually. In the estuary, the distributions of suspended sediment and particulate metals fluctuate on semi-diurnal and fortnightly timescales. Bottom sediments respond to changes in tidal current and river flow, as evidenced by variable metal-depth profiles. © 1990.