Marine air: shipping emissions in ports and their impact on local air quality. A case study on the ports of Delfzijl and Eemshaven.

Summary Ships translocate organisms across the world via on-board ballast water. When a ship releases its ballast water these organism are released as well. They might have the advantage of not having any natural enemies in their new environment and they may have impacts on ecology, economy and health. A species is able to be introduced in a new environment when it has a coastal donor area in which it occurs naturally, a coastal recipient area in which it is introduced and possibly will establish, and it needs to have an introduction vector that circumvents a natural spread barrier for that particular species. A species is able to establish when the abiotic conditions in donor and recipient area are similar and the biotic conditions are dissimilar. In order to significantly reduce new species introductions by ship ballast water, the International Maritime Organization developed the Ballast Water Management Convention. This convention demands from the shipping industry, when it will come into force, the management of the on-board ballast water in such a way that a reduced amount of viable organism propagules is released in a new environment. In special circumstances ships can be exempted from ballast water management. For possibly being exempted ships must sail between specific ports or places or an area must be enclosed. Before an exemption is granted the risk of the ballast water that is being translocated must be assessed. In the shipping sector arguments are posed that the North Sea is ecologically homogeneous and ex-emption must be possible in the North Sea region. For the North Sea region it is not determined how to apply the regulations of the Ballast Water Convention and whether exemptions are possible. A risk assessment approach for the North Sea is required to assess the possibilities of exemptions in the North Sea. A risk assessment approach needs to include the risk determining abiotic and biotic conditions and properties of the North Sea. The North Sea is a marginal shallow sea. The waters in the southern part are more turbulent than waters in the northern part, creating higher species abundance in the north. A residual anti-clockwise current flows through the area, which enters the North Sea near the Shetland Islands and which leaves the North Sea off the Norwegian coast. The consequences of this current result in a reduced likelihood for species to move naturally from east to west, which indicates that the North Sea is not homogeneous. Water temperature and salinity are believed to be major determinants in the ability for a species to survive. The water temperature in different places in the North Sea is in the same order of magnitude. The salinity is high in the middle between the shores of the North Sea and reduces when nearing the coasts. This means the North Sea itself will be a barrier for coastal and estuarine species to travel across the area, as these species are adapted to lower water salinities. Due to the tidal conditions in the estuaries species that live in estuaries are adapted to a wider range of salinities and might be able to survive in other areas with a wide range of salinities. The Convention suggests the inclusion of species-specific data concerning occurrence and spread of target species across the donor area, the life history of a species, physiological tolerances of a species, species habitat types, and type of diet. This is unknown for many species that might be translocated via ship ballast water. Some data that is available is patchy distributed and collecting this data is not easy. Species of which more data is available are within the group of benthic species. Species of this group have caused major invasions in several regions of the world having great impacts. Benthic species are more bound to a specific area and due to that they are more susceptible to be introduced in other areas. In the North Sea area different areas with different compositions of benthic species can be identified, meaning that the North Sea, with regards to the spread of species, is not homogeneous either. This patchy benthic species distribution can be extrapolated to the estuarine areas in which the ballast water is taken in and is released. The main risk determinants of the vector are: the volume of the released ballast water (incl. viable individuals), the ability of species to survive the voyage, the voyage duration, and the frequency a ship releases ballast water originating from the same donor port. This study includes the evaluation of three North Sea models whether these models can be used as ballast water exemption risk assessment model. When this is the case, these models in turn will be an accessible tool in the risk assessment procedures. The first model is DUE Innovator II which is a ballast water exchange model. Ballast water exchange is a form of ballast water management. This model can be used to model the abiotic determinants of ballast water risk. This model is able to make comparisons between values of the risk parameters in order to determine the risk of the exchanged ballast water. To calculate the risk of ballast water and the species within the ballast water, making comparisons of abiotic and biotic factors is important. However, the principles and requirements for exchange risk assessment are different from the principles and requirements for exemption risk assessment. The model determines the risk for the marine area of the North Sea, while for exemption risk assessment the risk for coasts and estuaries is important. Another model is a hydrodynamic model from DHI. This is a physical transportation model of the North Sea. It models the likelihood of a start or end position of a particle drifting in the North Sea. This model does not include many of the determinants of exemption risk and models the transportation in the marine area, not the coastal area. Therefore, this model is not suitable in the exemption risk assessment. The third model is GETM_ERSEM, which models the biology and physical-chemical processes of the North Sea and the interaction between these two. This model can be used to model the biotic determinants for the risk assessment. However, it must be known which species to include and whether data about these species is available. Secondly, the model must describe the coastal and estuarine areas as well as the marine water body. This model is not able to make comparisons between the biotic conditions of a source and release area. None of the models is describing the vector and its determinants. This and the above indicate that the models in this form are not suitable as ballast water exemption risk assessment model. It turned out that the North Sea is not one homogeneous area and that the risk based on the assess-ment of water temperature and salinity would be high, as the differences between the source and release areas in the North Sea region are not great. The risk would be high as well based on the biotic determinants of the risk assessment, as the benthic species in the North Sea are not evenly distributed across the area, so there is a difference in biology between source and release area. Ballast water risk for the North Sea is high and exemptions are not likely to be granted within the North Sea area.