Hg and As in Continental and Marine Sediments from Southern Tuscany
429
environments. Estimations of anthropic changes,
and the necessary regulatory framework to cut
down emissions and releases, must be based on
reliable data on the capacities of natural reservoirs, as well as on the fluctuations in the content
of chemical elements that may occur even under
undisturbed conditions.
This paper covers the environmental and
health effects that marked geochemical anomalies may entail, in general; particular attention
will be paid to new examples dealing with Hg
and As distribution in stream and marine sediments from the Tuscany region, both on land and
in the Tyrrhenian Sea in front of this region.
Tuscany is in fact. one of the areas in the world
that is richest in thermal manifestations and in
hydrothermal metal deposits. and it is thus supposed to have significant anomalies of all trace
elements that are selectively mobilized and
deposited under hydrothermal conditions.
Mercury Anomalies
in Stream Sediments, Marine Sediments
and Marine Biota from Tuscany Region
Among old maps from geochemical exploration
surveys, applied to environmental issues, it is
worth mentioning the one, which shows the distribution of Hg in the stream sediments from
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Fig. 2. Mercury distribution in
marine sediments from the
Tyrrhenian Sea. Notice the low
content found in samples north
of Elba Island and the huge
anomalies in correspondence to
Ombrone, Albegna and Fiora
rivers (from Baldi et aI. 1979)
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