S. Miserocchi et al., THE FATE OF HG CONTAMINATED SEDIMENTS OF THE RAVENNA LAGOON (ITALY) -FINAL BURIAL OR POTENTIAL REMOBILIZATION, Water science and technology, 28(8-9), 1993, pp. 349-358
Citations number
18
Categorie Soggetti
Water Resources","Environmental Sciences","Engineering, Civil
In the period 1957-77 a part of 100-200 tons of mercury as industrial
waste was discharged into a 10 km2 lagoon (''Pialassa Baiona'') connec
ted to the Ravenna harbor and the Northern Adriatic Sea (ItalY). Extre
mely high levels of Hg (up to 160 mug/g) were found in surface sedimen
ts, but the maximum values (up to 1114 mug/g) were detected in subsurf
ace layers, down to 80 cm, close to the industrial source, and values
of 1-2 mug/g were recorded in the fore-harbor, outside the lagoon. The
calculation of total Hg budget in sediments gave 38 tons of Hg being
stored within a contaminated area of 15 km2. The redistribution of pol
luted sediments would seem to be due mainly to the tidal action; more
than 80% of the total Hg discharged is confined in 10% of the area, i.
e. in the southern ponds close to the input point. The time necessary
for a restoration of the area was estimated by using different approac
hes of accumulation rate calculations (Pb-210, Hg peak). It appears th
at 40-50 years would be needed to clean the surface sediments of the R
avenna lagoon from the mercury contamination. We suggest that remedial
plans should be focused on the southem ponds.