Conference Year of the dolphin in Europe 2007
Keynotes and download of the presentations
Koschinski, Sven
Risks to porpoises from detonation of WW II ammunition
- It is a common method to detonate unexploded ordnance (UXO). This poses a threat to the marine environment by creating noise and contaminating water with derivates of explosive substances.
- Underwater explosions represent the loudest point sources of anthropogenic noise in the marine environment.
- Underwater explosions represent the loudest point sources of anthropogenic noise in the marine environment.
- Source level, signal rise time, duration of the sound, and sound radiation have to be modelled in order to assess whether marine mammals are at risk. Dual sound exposure criteria with respect to peak pressure and SEL have to be developed in order to avoid hearing damage in marine mammals (based on avoidance of TTS).
- If marine protected areas or marine mammal habitat are in the range of injury and hearing damage, effective mitigation measures are needed.
Possible mitigation measures are:
- Underwater bubble curtains reduce pressure wave and SPL. This reduces the zone of injury and hearing loss and enables methods to effectively deter marine mammals (e. g. using pingers).
- Recovery of UXO from the marine environment (e. g., by freezing the explosives, photolytic degradation of the organic and nitrogenous components of explosives in a solvent, or by using robotics).