D4.3 - Models intercomparison

Maritime transport represents more than 80% of the international trade volume (UNCTAD, 2017). Apart from crude oil, tanker trades of refined petroleum products, chemicals and gas have increased by 4% over the 2019-2021 period, with a 5.6% growth in Liquefied Natural Gas (LNG) trade (UNCTAD, 2022). The volume of hazardous and noxious substances (HNS) is thus constantly rising with an increased risk of accidental spillages potentially associated with marine pollutions, whether in ports or in the open sea. In the event of an incident and a spill in the environment, information on the fate of the chemical(s) involved is essential to better anticipate the risks incurred by responders and populations, the impacts on the environment as well as the appropriate response techniques (Mamaca et al., 2009). Chemicals accidentally spilled into the marine or aquatic environment generally undergo physical-chemical modifications that will characterize their behaviour and fate. As observed by Mamaca et al. (2004) and Le Floch et al. (2011), these modifications are dependent on the intrinsic parameters of the product involved, the in situ environmental parameters (temperature, density and salinity of the water) and the met-ocean conditions (e.g. sea state, wind speed, marine currents). A few hours following the spill short-term effects may thus occur such as spreading, natural dispersion in the water column (dissolution, emulsification) and evaporation into the atmosphere. Longer term degradation (e.g. polymerisation, biodegradation) and sedimentation processes can then follow, depending on the persistence and the nature of the substance. One of the main concerns is that around 2,000 different types of HNS are regularly shipped in bulk or package forms (Purnell, 2009) which thus make difficult to capture their behaviour if accidentally released in the environment. Of the wide variety of HNS traded, volatile and gaseous substances are particularly problematic for marine pollution response authorities. The release of such substances at sea can indeed lead to the formation of toxic, flammable, or explosive gas plumes – sometimes invisible to the naked eye – that can travel large distances and pose risks over a wide area in relatively short timescales. Yet, key information on the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities and the environment when allowing a shipping casualty to dock at a place of refuge remain poorly known. The MANIFESTS EU-project is part of this context.

Report, Open Access, PDF available

Models, Modelling