Chemical analysis of dumped chemical warfare agents during the MODUM project

Abstract

MODUM project continued the work on monitoring of the chemical weapons (CW) dumped in the Baltic Sea started in previous projects. As a new aspect, on board analysis methods – headspace gas chromatography-mass spectrometry (GC–MS) and capillary electrophoresis (CE) – were developed and tested in laboratory conditions and during cruises. The GC–MS method could be successfully applied on board to verify that collected sediment samples contained degradation products for sulfur mustard, one of the major chemical warfare agents dumped in Baltic Sea. This method could in future project be used during cruises to redirect sample collection in order to make most of the available ship time. Other part of the analysis task during MODUM project was the work done at the reach back laboratories. These analyses were done to both verify the results obtain on board and to fully identify the chemicals related to the sea-dumped CW agents. Reach back analysis of CW-related chemicals were done on sediment samples collected around a wreck in Bornholm Deep (same samples as analyzed on board) and on monitoring samples collected in Bornholm, Gotland and Gdańsk Deeps. The samples from Bornholm and Gotland Deeps are in line with previous findings. Samples from Gdańsk Deep are in line with previous findings that this area has been used as a dump site. Additionally, α-chloroacetophenone (CN) was found in the area for the first time. In addition to the analysis of CW-related chemicals, a new method was developed for measurement for arsenic concentrations in sediment samples. A method was also developed for arsenic speciation, which could help in estimation of the source of arsenic in the sediments.