Trajectory estimation of an oil spill in ice-covered waters is essential for response planning and risk assessment. This paper presents the preliminary development of a new computational model for the estimation of spreading and surface transport of oil in the presence of ice. A new approach for the estimation of spreading in 0.8–0.95 ice concentration range is proposed. Additionally, for the first time the pumping of floating in‑leads oil onto or under ice floes with closing leads is modelled. The model is able to estimate the mobilization of under-ice oil and its potential subsequent surfacing and works as a stand-alone model with any rectangular-grid ice-ocean model. The model was used to simulate trajectories of two real-life spill events, a field experiment in the Barents Sea where oil and ice were observed to move together and an accidental spill in the Gulf of Finland. Model results were generally consistent with observations.

The Lumparn Bay, due to its nature, is prone both to natural and anthropogenic environmental pressures. It is a semi-enclosed rather large, but relatively shallow bay filled with glacial and postglacial sediments. Unlike any other areas in the world the seafloor in this area is filled with gas domes. Comparison with the chemistry of some 2000 surface core samples from the Gulf of Finland revealed that the concentrations of arsenic, cadmium, chromium, copper, mercury, molybdenum, nickel, lead, zinc, and sulphur from the Lumparn Bay were in general on a low level, indicating only minor pressures on the seafloor. However, when compared to established sediment quality guidelines there are a few points of possible concern as some samples exceed the probable effects level for arsenic and quite a few samples exceed the effects range – median level for nickel. Also a few comparably high molybdenum concentrations exceed the lowest effects level.

Organic pollution is a serious environmental problem for the coastal zones of seas. The study tested the hypothesis that allochthonous organic carbon derived from St. Petersburg wastewaters is a significant basal resource of carbon for the benthic food webs. We analyzed stable isotope composition of carbon and nitrogen in suspended organic matter in the Neva Estuary and in the tissues of macroinvertebrates and fish. The Stable Isotope Bayesian mixing model showed that waste waters were an important source of carbon for the most of consumers in the Neva Estuary. The autochthonous carbon produced by phytoplankton was a significant source of carbon only for some macroinvertebrates. The main consumers of the carbon derived from waste waters were tubificid worms, chironomid larvae and alien polychaete, which currently dominate in the zoobenthos of the estuary. These species replaced the former dominants, native crustaceans, which to a lesser extent use anthropogenic carbon.

Lagrangian trajectories of water parcels reconstructed using the TRACMASS model from three-dimensional velocity fields by the RCO model for 1965–2004 are used to analyse the temporal scales and the probability for the hits to the nearshore by pollution originating from a major fairway in the Gulf of Finland and transported by surface currents. Increasing the simulation length from 10 to 20days induces a linear increase in particle age, but the pattern of nearshore hits remains the same. A reasonable benefit can be reached by relatively small shifts of certain parts of the present fairway in a few locations. The overall probabilities do not reveal any trend for 1965–2004. The largest changes in the nearshore hits are revealed for the proportion of hits to the opposite nearshore areas. This feature probably reflects an abrupt turn of the geostrophic air-flow over the southern Baltic Sea by ~40° since 1987.

Solid Phase Microextraction (SPME) was applied to provide the first large scale dataset of freely dissolved concentrations for 9 polycyclic aromatic hydrocarbons (PAHs) in Baltic Sea sediment cores. Polydimethylsiloxane (PDMS) coated glass fibers were used for ex-situ equilibrium sampling followed by automated thermal desorption and GC–MS analysis. From the PAH concentrations in the fiber coating we examined (i) spatially resolved freely dissolved PAH concentrations (Cfree); (ii) baseline toxicity potential on the basis of chemical activities (a); (iii) site specific mixture compositions; (iv) diffusion gradients at the sediment water interface and within the sediment cores and (v) site specific distribution ratios. Contamination levels were low in the northern Baltic Sea, moderate to elevated in the Baltic Proper and highest in the Gulf of Finland. Chemical activities were well below levels expected to cause narcosis to benthos organisms. The SPME method is a very sensitive tool that opens new possibilities for studying the PAHs at trace levels in marine environments.

Existing models estimating oil spill costs at sea are based on data from the past, and they usually lack a systematic approach. This make them passive, and limits their ability to forecast the effect of the changes in the oil combating fleet or location of a spill on the oil spill costs.In this paper we make an attempt towards the development of a probabilistic and systematic model estimating the costs of clean-up operations for the Gulf of Finland. For this purpose we utilize expert knowledge along with the available data and information from literature. Then, the obtained information is combined into a framework with the use of a Bayesian Belief Networks. Due to lack of data, we validate the model by comparing its results with existing models, with which we found good agreement.We anticipate that the presented model can contribute to the cost-effective oil-combating fleet optimization for the Gulf of Finland. It can also facilitate the accident consequences estimation in the framework of formal safety assessment (FSA).

Major sources of pollution from shipping to marine environments are antifouling paint residues and discharges of bilge, black, grey and ballast water and scrubber discharge water. The dispersion of copper, zinc, naphthalene, pyrene, and dibromochloromethane have been studied using the Ship Traffic Emission Assessment Model, the General Estuarine Transport Model, and the Eulerian tracer transport model in the Baltic Sea in 2012. Annual loads of the contaminants ranged from 10⁻² tons for pyrene to 100 s of tons for copper. The dispersion of the contaminants is determined by the surface kinetic energy and vertical stratification at the location of the discharge. The elevated concentration of the contaminants at the surface persists for about two-days and the contaminants are dispersed over the spatial scale of 10-60 km. The Danish Sounds, the southwestern Baltic Sea and the Gulf of Finland are under the heaviest pressure of shipborne contaminants in the Baltic Sea.

Anthropogenic CO2 emissions are rapidly changing seawater temperature, pH and carbonate chemistry. This study compares the embryonic development under high pCO2 conditions across the south-north distribution range of the marine clam Limecola balthica in NW Europe. The combined effects of elevated temperature and reduced pH on hatching success and size varied strongly between the three studied populations, with the Gulf of Finland population appearing most endangered under the conditions predicted to occur by 2100. These results demonstrate that the assessment of marine faunal population persistence to future climatic conditions needs to consider the interactive effects of co-occurring physico-chemical alterations in seawater within the local context that determines population fitness, adaptation potential and the system resilience to environmental change.

Variations and trends in water quality parameters (total suspended matter and coloured dissolved organic matter) were examined in five harbours in the eastern Baltic Sea using satellite imagery collected from 2002 to 2011 by the Medium Resolution Imaging Spectrometer (MERIS) at full spatial resolution (300×300m). In the eastern Gulf of Finland harbours (Sillamäe, Kunda) the TSM monthly variations were related to monthly mean wind speed. In Tallinn harbour, which operates >6000 vessels annually, evidence of anthropogenic impacts was identified through inter-annual TSM variations. The vessel traffic footprint was ascertained from the significant correlation (R=0.66; p=0.035) between the number of annual vessel visits and mean annual TSM concentration. In the harbour of Pärnu, located close to the river mouth, inter-annual water quality variations in terms of the CDOM concentrations were affected by the mean annual river discharge levels of the Pärnu River.

We analyzed stable isotope composition of carbon and nitrogen of suspended organic matter (seston) and tissues of macroalgae, macroinvertebrates and fish from the coastal area of the highly eutrophic Neva Estuary to test a hypothesis that organic carbon of macroalgae Cladophora glomerata and Ulva intestinalis produced during green tides may be among primary sources supporting coastal food webs. The Stable Isotope Bayesian mixing model (SIAR) showed that consumers poorly use organic carbon produced by macroalgae. According to the results of SIAR modeling, benthic macroinvertebrates and fish mostly rely on pelagic derived carbon as a basal resource for their production. Only some species of macroinvertebrates consumed macroalgae. Fish used this resource directly consuming zooplankton or indirectly via benthic macroinvertebrates. This was consistent with the results of the gut content analysis, which revealed a high proportion of zooplankton in the guts of non-predatory fish.