Description: Chemical weapons dumped into the sea after World War II possess growing concern for the marine environment; metal shells of different chemical munitions lying on the bottom are severely corroded and dangerous contents pollute the sediments. Chemical warfare agents (CWAs), such as mustard gas and various arsenic-based compounds (e.g., Clark I and Adamsite) and their degradation products have been detected in noticeable concentrations in sediments at the major dumping sites at the Baltic Sea. Blue mussel caging approach was applied to assess environmental impact of thousands of tons of CWAs at the main dumping site at the Bornholm Basin. Due to the patchy occurrence of the CWAs in the sediments mussel caging method was chosen to deploy the organisms exactly at sites where high CWA concentrations were detected in sediments and to one reference site. Biomarkers representing different biological functions including antioxidant defence, biotransformation, neurotoxicity, lysosomal membrane stability, geno- and cytotoxicity, cellular energy allocation and condition index were investigated. Moreover, tissue concentrations of different CWAs and the possible metabolic derivatives of these compounds were analysed in mussels together with “classical” contaminants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and trace metals. Further, mussel cages were equipped with salinity, temperature and oxygen sensors to follow the fluctuations in the environmental parameters during the two and half month caging time. Environmental parameters indicated mixing of the near bottom water in the lower water layer where the cages were deployed (at 60 meters). Significant biomarker responses were observed at the two contaminated sites compared to the reference site indicating CWA induced effect on molecular and cellular level; however the possible anaerobic conditions and lower food availability in deep waters led to decreased bioenergetic status of the caged mussels. Results of the still on-going chemical analysis will be employed together with the biomarker responses and environmental data in the multi-level integrated impact assessment of the area.

Description: After World War II, large amounts of chemical weapons stored on German territory were dumped in the Baltic Sea by order of the allied forces . In addition of being a cheap method of disposal, the belief was that the vast amounts of waters in the oceans would neutralize and absorb the dangerous substances. At least 40.000 tonnes of chemical munitions containing an estimated 13.000 tonnes of chemical warfare agents were dumped in the Baltic Sea, primarily in the Bornholm Basin. Other official dumping sites were the Little Belt area and the Gotland Deep. There is evidence, however, that also other areas besides the offical CWA dumpsides are contaminated by chemical warfare agents (CWA). CWA were dumped as artillery shells, aircraft bombs or in containers; partly entire ships loaded with munitions were sunk. Today, munitions are in different stages of decomposition. Metal shells are corroding and contents are leaking into the environment at a rate that has not been measured so far, posing a possible risk for the Baltic Sea ecosystem. In previous studies, several CWAs of major concern for biota, such as inorganic arsenic and organo-arsenic compounds, have been found in the sediments within and around dumpsites (Missiaen et al. 2010). Unaware of this risk, human sea-bottom activities, such as bottom trawling, constructions of pipelines and cables as well as windfarms are increasingly claiming space within the contaminated areas. The aim of the present study was to increase knowledge on the bioavailability and biological effects of CWAs on fish, using a suite of biomarkers in an integrated approach.

Description: Munitions introduced to the sea during military activities, including naval combat and mine warfare represent only a fraction of military material present in seas and oceans. Huge amounts of obsolete conventional munitions and chemical munitions were dumped to the sea until 1975, when London convention put a stop of sea dumping. Such munitions are a threat for maritime workers, but also for environment. Corroding shells release toxic degradation products to sediments and bottom water, and unlike other contaminants, they cannot be reduced by land measures. Only removal of source can reduce the contamination. Much work has been done in the last decade, and mechanisms of toxicity and bioaccumulation are being recognized, as well as transport and spreading mechanisms. The full assessment of the risk associated with munitions now depends on broad application of developed techniques.

Description: After World War II, thousands of tons of highly toxic chemical warfare agents (CWA) were deposited in the Baltic Sea, the main dumping site locating in the Bornholm Basin. In the present study, Baltic mussels (Mytilus trossulus) were transplanted in the area in cages at two hotspot sites and a reference site at the depths of 35 and 65 m for 2.5 months to study bioaccumulation and biological effects of CWA possibly leaking from the corroding warfare materials. No traces of degradation products of the measured phenylarsenic CWA could be detected in the tissues of mussels. Nevertheless, several biochemical and histochemical biomarkers, geno- and cytotoxicity indicators, and bioenergetic parameters showed significant responses. The Integrated Biomarker Index calculated from the single biomarkers also showed a higher total response at the two hotspot areas compared to the reference site. Although no direct evidence could be obtained confirming the responses being caused specifically by exposure to CWA, the field exposure experiment showed unambiguously that organisms in this sea area are confronting environmental stress affecting negatively their health and this is likely related to chemical contamination, which is possibly connected to the sea-dumped CWA.

Description: Recently, sea-dumped chemical weapons (CWs) containing toxic chemical warfare agents (CWAs) have raised international attention. It is well known that CWAs are leaking from corroded munitions causing a risk to the surrounding marine environment, while the impact on marine biota is still unknown. In this study, cod (Gadus morhua) was used as a model species to study the possible bioaccumulation of phenylarsenic CWAs and their negative effects at multiple levels of biological organization on fish living in the vicinity of a major CWs dumpsite in the Bornholm Basin in the Baltic Sea. In total, 14% of the cod muscle samples collected close to the main dumpsite contained trace levels of phenylarsenic CWAs. However, most of the biomarkers measured did not show clear differences between this area compared with a lesser contaminated reference area. On the other hand, significant changes in some biomarkers were observed in individuals containing trace levels of CWA-related chemicals. The results gained in this study have significant importance for environmental risk assessment and for evaluating the risk of CWA contamination for human seafood consumers.

Description: Baltic mussels (Mytilus spp.) were exposed to the explosive trinitrotoluene (TNT) for 96 h (0.31–10.0 mg/L) and 21 d (0.31–2.5 mg/L). Bioaccumulation of TNT and its degradation products (2- and 4-ADNT) as well as biological effects ranging from the gene and cellular levels to behaviour were investigated. Although no mortality occurred in the concentration range tested, uptake and metabolism of TNT and responses in antioxidant enzymes and histochemical biomarkers were observed already at the lowest concentrations. The characteristic shell closure behaviour of bivalves at trigger concentrations led to complex exposure patterns and non-linear responses to the exposure concentrations. Conclusively, exposure to TNT exerts biomarker reponses in mussels already at 0.31 mg/L while effects are recorded also after a prolonged exposure although no mortality occurs. Finally, more attention should be paid on shell closure of bivalves in exposure studies since it plays a marked role in definining toxicity threshold levels.