C. Vale et al., MOBILITY OF CONTAMINANTS IN RELATION TO DREDGING OPERATIONS IN A MESOTIDAL ESTUARY (TAGUS ESTUARY, PORTUGAL), Water science and technology, 37(6-7), 1998, pp. 25-31
Citations number
16
Categorie Soggetti
Water Resources","Environmental Sciences","Engineering, Civil
During the construction of a New Bridge over the Tagus estuary 2.5 mil
lion tons of sediments were dredged, part of this quantity being conta
minated material. The extension and intensity of the water turbidity a
ssociated with dredging operating varied with the tidal conditions but
the resuspended material collected near the bucket dredger did not pr
esent a concentration increment in metals and PCB, when compared to th
e estuarine suspended sediments. The calculated distribution coefficie
nts suggest that some contaminants in solids neat the dredger were not
in equilibrium with the water. A 24-hour laboratory experiment demons
trated the complexity and quickness of anoxic sediments oxidation. In
such a short period of time metals in the solids change their fraction
ation. A second laboratory simulation showed that mussels accumulate m
etals and PCB congeners when placed in turbid aerated water. (C) 1998
IAWQ. Published by Elsevier Science Ltd.