Baltic Sea

Baturin G. N., Emelyanov, E. M., Kunzendorf, H., 1995.
Authigenous deposits in the sediments. In E. M. Emelyanov,
Ch. Christiansen, O. Michelsen (eds), Geology of
the Bornholm Basin, Aarhus Geoscience 5, 189-194.
CARION NPF, 2005. Technique of performance of measurements
of a mass fraction of metals in powder tests of
sea bottom sediments by a method X-Ray Fluorescence
Spectrometry. M-002/2005. Certificate of Compliance
№ 242/57-2005. Mendeleyev Institute for Metrology
(VNIIM).

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.

For clay and shale the average background content
of As is normally 10 mg/kg. Examined samples from
the Bornholm Basin, based also on the data shown by
Emelyanov and Kravtsov (2007), contain from 1 to
277 mg/kg As (see Tables 2, 3). The highest As value
(277 mg/kg) was found in the mud from “hot spot” of
the P-181 area in the Bornholm Basin, located about
500 m to the south from W.3 shipwreck.

Sapropel and sapropel–like mud is common not only
in the Bornholm Basin but also in many other Baltic
Sea basins. In the Bornholm Basin this mud contains
up to 7.87% Corg, 7.08% Fe, 0.86% Mn (Table 2). Two
mud samples taken near the shipwreck (stations 26S
and 47) contained 17.7 and 41.5% Fe respectively
(Table 3). Apparently these sediments might have
some metal scrap corrosion products. Ignoring these
outliers, Fe concentration varies in a much narrower
range–between 0.05-7.08%.

Material underlying this article is based on samples
of bottom sediments taken from the Bornholm
CW dumpsite during implementation of MERCW
Project: explorations on R/Vs Professor Shtokman
and Centaurus in 2006 and 2007 and on the chartered
German vessel Fritz Reuter in 2008. Sampling stations
in the Bornholm Deep were chosen on the basis of
earlier data about arsenic distribution and location
of the shipwrecks that had been obtained during
1997–2005 and subsequently studied in AB IO RAS
(Paka 2004; Emelyanov, Kravtsov 2007). 178 samples
of sediments from the Bornholm Basin were subject to
chemical analysis in AB IO RAS (Emelyanov 2007;
Emelyanov, Kravtsov 2007). This included grain
size analysis of sediments and determination of the
following 18 elements contained in the sediments:
Corg, Ntotal, Ptotal, Ca, Mg, K, Na, Fe, Mn, Ti, Cu, Zn, Co,
Ni, Cr, Cd, Pb, As. The central part of the CW dumps
site (encircled area at Fig. 1) was further referred to
as “hot spot”.

The Bornholm Basin with water depth of about 100
m is located east of the island of Bornholm, in the
south–western Baltic Sea. It has its boundaries at
50030’–55045’N and 14030’–16030’E. The basin is
assumed to be bordered by 50 m isobaths (Fig.1) thus
covering the area of 14 000 sq. km. It is surrounded
by shallow bottom areas with depth ranging between
25 and 30 m. Saline and dense waters occasionally
penetrating to the Baltic from the North Sea, find
their way from the Danish passages first to the Arkona
Basin with depth of about 46 metres, then entering the
Bornholm Basin through the Bornholm Gat channel.
The Słupsk Trench is another considerably deep basin
to the east of the Bornholm Basin, separated from the
latter by a moraine ridge, thus forming Słupsk Sill with
its ridge coming at the depth of 56 m.

BALTICA Volume 23 Number 2 December 2010

Emelyanov, E. M., Kravtsov, V. A., Savin, Y. I., Paka, V. T., Khalikov, I. S., 2010. Influence of chemical weapons and warfare agents on the metal contents in sediments in the Bornholm Basin, the Baltic Sea. Baltica, 23 (2), 77-90. Vilnius.