WP4: Investigating the impacts of compounds typically contained in explosives (STVs) on the ecosystem
Institut für Toxikologie und Pharmakologie der Universität Kiel
Since blue mussels (Mytilus edulis) are filterfeeders, they also take up pollutants contained in seawater and accumulate them in their tissue, so that even small concentrations can be detected over longer time periods. Based on these observations, case scenarios for the input of these harmful substances (see WP3) can be developed. The mussels are deployed inside mussel bags in the delaboration areas before, during and after the delaboration (biomonitoring) and are analyzed in the lab after different time periods (between 2 weeks and 6 months), so that any environmental damages caused by the delaboration of ammunition can be detected immediately. These analyses are conducted by the Institute for Toxicology and Pharmacology at the University of Kiel and investigate the incorporation of toxic compounds typically contained in explosives (e.g. TNT and its degradation products) into the tissue of the blue mussels. The concentration of toxic metals used in triggers (lead (Pb) and mercury (Hg) are analyzed in close cooperation with WP3.
Aims and responsibilities
- Deployment of the mussel bags at different distances to the delaboration area before, during and after the delaboration in close collaboration with WP2
- Development of a reliable analytical routine using blue mussels (Mytilus edulis) as an indicator organism to detect explosives and their degradation products as well as toxic metals used in triggers in the water column
- The analysis of mussel samples with respect to ecologically relevant toxic releases of chemical compounds typically contained in explosives and their degradation products
- The determination of an environmentally “acceptable” contamination also considering current and dilution factors during the delaboration process
- Assessing the environmental hazards and consequences (man and biota) of the delaboration process
The main goal of WP4 is to establish a scientifically sound long-term monitoring programme during the environmentally friendly underwater delaboration of dumped munitions and in addition to ensure the protection of the affected ecosystem during all phases of the project.
For the first time in the world, it has been possible to establish an active biomonitoring with mussels in a munition dumping ground and to prove that TNT and its metabolites from sunken explosives pass into the mussels tissue.
For this purpose moorings with mussel bags on the seabed and in one meter of ground height were deployed at defined distances around a pile of about 70 moored mines with the aid of research divers. Another mooring has been installed in an area where targeted explosions scattered large quantities of explosives (hexanite) on the seabed (see figure).
Fig1: For our investigations we constructed moorings with two mussel bags at each mooring and placed these moorings adjacent to the corroding mines in Kolberger Heide near Kiel Bay. • Mussels are placed next to the mines in two different water depths • Mussels are recovered several month after deployment.
The mussels were replaced at intervals of approximately three months and analysed in our laboratory after extraction with GC/MS-MS on their body burden with explosives. In mussels, deployed at the mine mound, we found amounts of 4-ADNT up to 10 ng/g wet weight (Appel et al., 2018). In mussels, directly deployed at open hexanite, TNT and the metabolites 2-ADNT and 4-ADNT could be detected. The total content of explosives is with approximately 300 ng/g mussel tissue wet weight 30 times higher than in mussels exposed at the mine mound (Strehse et al., 2017)Thus, loose explosives on the seafloor dispense noticeably higher amounts of toxic chemicals into its environment than explosives in corroding containers. With this system, we proved unequivocally that these toxic explosives accumulate in the marine biota resp. in the marine food chain and thereby pose a possible risk to the marine ecosphere and human health.
Fig.2: Left: Mussels (Mytilus edulis) were placed at different distances to a mine mound, as indicated by the red dots and collected after about three months. The TNT metabolite 4-amino-2,6-dinitrotoluene (4-ADNT) was detected in mussels in concentrations of 3-8 ng/g (wet weight) at mooring positions 1-6. TNT itself as well as 2-ADNT were not detected. No trend or concentration gradient was observed with respect to distance or mussel placement at 0 m or 1 m above ground. [Exposition December 2016 – March 2017, 92 days] Right: The picture shows the position of a mooring (indicated by a white cross) near a piece of unexploded hexanite lying on the sea floor. Craters caused by controlled detonations during delaboration work in the southern part of the study area are visible in direct vicinity. © M. Kampmeier/Geomar. In addition to 4-ADNT, we were now able to detect TNT itself as well as two other metabolites: 2-ADNT and 2,4-DA-6-NT (2,4-diamino-6-nitrotoluene). Interestingly, we found more than 25 times as many 4-ADNT as in the mussels directly at the mines (moorings 1-6). Summing up the contents of all STVs of mooring 7 results in more than 50 times as much STV as the mussels have on average at moorings 1 - 6.
D. Appel, J.S. Strehse, H.-J. Martin, E. Maser, „Bioaccumulation of 2,4,6-trinitrotoluene (TNT) and its metabolites leaking from corroded munition in transplanted blue mussels (M. edulis)”, Marine Pollution Bulletin, 135, p. 1072 ff., 2018.
J. S. Strehse, D. Appel, C. Geist, H.-J. Martin und E. Maser, „Biomonitoring of 2,4,6-trinitrotoluene and degradation products in the marine environment with transplanted blue mussels (M. edulis),“ Toxicology, 390, p. 117 ff., 2017.