Conclusions

Increased As concentrations (111-277 mg/kg) in the
surface layer of the bottom sediments were found near
the ships wreck W.1 and W.3 and mostly, and just in
areas where the metal objects occur in the mud. The
sources of arsenic could be thin–wall containers, shells
and bombs with As–containing agents depressurized
during they remained at surface of the bottom. Such
distribution of arsenic could be reckoned as indicator
of leakage of As– containing warfare agents to the
marine environment. The state of metal objects
(probably, shells, bombs, containers) were buried in
the mud at depth 1-2 m from the surface is unknown.
It is desirable to conduct special study of these objects
in future.

Elevated As concentration (up to 101 mg/kg) was
found also and in the Baltic Sea far from the known
dumps sites. In such samples, arsenic could be included
into Fe and Mn oxyhydroxides, which may
contain up to 653 mg/kg As, or included into ferric
sulphides, which may contain up to 440 mg/kg As.
Both hydro–oxides and sulphides are authigenous
formations, which have no relations to CW.

The CW dumps site in the Bornholm Basin at
present time is not the immediate threat for the
marine environment, as well as not the obstacle for
hydro–engineering activity outside of this area. The
environmental monitoring in the Bornholm Basin is
necessary to continue for detecting the tendency for
any changes.

Acknowledgements

Authors are grateful to the crews of the MS Fritz Reuter
and the RV Professor Shtokman and collaborators
of Department of Atlantic Geology of AB IO
RAS Djuraboy Fidaev, Sergey Isachenko, Tatyana
Konovalova, Julia Polosina, Galina Romanova, Anelia
Adamovich, Irina Klimentyeva and others who helped
us and made sampling, chemical and grain–size analysis
and compiled figures, tables and other materials for
this article. We express our gratitude to reviewers Drs
Helmar Kunzendorf (Copenhagen), Birger Larsen
(Copenhagen) and Henry Vallius (Helsinki) for the
valuable comments.