Mj. Belzuncesegarra et al., CHEMICAL FORMS OF HEAVY-METALS IN SURFACE SEDIMENTS OF THE SAN-SIMON INLET, RIA-DE-VIGO, GALICIA, Journal of environmental science and health. Part A: Environmental science and engineering, 32(5), 1997, pp. 1271-1292
The surface sediments of the San Simon inlet of the Ria de Vigo in Gal
icia, north-west Spain contain heavy metal concentrations largely with
in the range to be expected if these metals were derived from detrital
inputs from soils and weathered granitic rocks. Thus, Cu ranged from
24-28 mu g g(-1), Cr from 37-69 mu g g(-1), Cd from 0.1-0.5 mu g g(-1)
, Ni from 12-29 mu g g(-1) and Zn from 71-151 mu g g(-1) of sediment.
For Pb, however, the range was 84-394 mu g g(-1) of sediment which is
well above the level which would be expected as background, indicating
the likelihood of anthropogenic inputs. Sequential fractionation indi
cates that relatively high proportions (similar to 40%) of this Pb are
associated with the oxide and carbonate fractions and may, therefore,
be potentially mobile. In contrast, Cr and Ni are found largely in th
e residual fractions (similar to 72 and 65%), whereas Cu is mainly ass
ociated with the organic/sulphide fraction (similar to 58%). The distr
ibution of Zn is somewhat similar to that of Pb. There is little evide
nce that diagenetic processes have significantly affected the various
metal forms in the sediments with the possible exception of the sites
closest to the sea.