Hanna Landquist

Evaluating the needs of risk assessment methods of potentially polluting shipwrecks

Shipwrecks deteriorate and the probability of a release of oil increases with time on the sea floor. The potential leakage is a risk to the marine environment and may also have social and economic consequences. The purpose of this study was to evaluate existing methods for risk assessment of shipwrecks and suggest a generic risk assessment framework. A risk assessment is necessary for providing decision support on remediation actions and thus enabling an efficient use of available resources. Existing risk assessment methods aimed for assessing shipwrecks were evaluated by comparison to relevant parts of an international standard on risk management. The comparison showed that existing methods lack several key components of risk assessment procedures. None of the evaluated methods provide a comprehensive risk assessment for potentially polluting shipwrecks and few take into account uncertainty and sensitivity. Furthermore, there is a need to develop risk assessment methods considering long-term effects of continuous release of oil into the marine environment. Finally, a generic comprehensive framework for risk assessment of shipwrecks is suggested.

A fault tree model to assess probability of contaminant discharge from shipwrecks

Shipwrecks on the sea floor around the world may contain hazardous substances that can cause harm to the marine environment. Today there are no comprehensive methods for environmental risk assessment of shipwrecks, and thus there is poor support for decision-making on prioritization of mitigation measures. The purpose of this study was to develop a tool for quantitative risk estimation of potentially polluting shipwrecks, and in particular an estimation of the annual probability of hazardous substance discharge. The assessment of the probability of discharge is performed using fault tree analysis, facilitating quantification of the probability with respect to a set of identified hazardous events. This approach enables a structured assessment providing transparent uncertainty and sensitivity analyses. The model facilitates quantification of risk, quantification of the uncertainties in the risk calculation and identification of parameters to be investigated further in order to obtain a more reliable risk calculation.

Low concentrations of PAHs induce tolerance in nitrifying bacteria

The ability of marine microbes to develop tolerance to polycyclic aromatic hydrocarbons (PAHs) was examined in a 90-day experiment. PAH levels in sediment were increased 0.3 and 1.6 times compared to the control sediment. Day 30, 60 and 90 the microbes were re-exposed to PAHs in a short-term toxicity test to detect tolerance, where nitrification and denitrification were used as endpoints. In addition, molecular analysis of the microbial communities was performed to detect possible differences in proportions of nitrifying bacteria compared to total bacterial abundance (amoA/rpoB-ratio) between treatments and control. We here show PAH-induced tolerance in nitrifying microbial communities after 60 and 90 days of pre-exposure, as potential nitrification EC10-values were significantly higher in the low treatment (L) after 60 days and in both treatments after 90 days compared to control. Tolerance development in denitrification was not detected. Furthermore, the developed tolerance resulted in reduced nitrification efficiency, compared to control. It was also shown that the induced tolerance produced dissimilar amoA/rpoB-ratio between treatments and control, indicating that development of tolerance changed the community composition and that the development time depended on initial exposure. The results from this study have implications for future studies or environmental monitoring programs of long-term oil and PAH-contaminated sites. The possibility for development of tolerance needs to be taken into account and potential nitrification can be used for evaluation of marine microbial health. Furthermore, changed proportions of nitrifying microbes can alter the capacity of ammonium oxidizing in benthic marine sediments.

VRAKA—A Probabilistic Risk Assessment Method for Potentially Polluting Shipwrecks

Shipwrecks around the world contain unknown volumes of hazardous substances which, if discharged, could harm the marine environment. Shipwrecks can deteriorate for a number of reasons, including corrosion and physical impact from trawling and other activities, and the probability of a leakage increases with time. Before deciding on possible mitigation measures, there are currently few comprehensive methods for assessing shipwrecks with respect to pollution risks. A holistic method for estimating environmental risks from shipwrecks should be based on well-established risk assessment methods and should take into account both the probability of discharge and the potential consequences. The purpose of this study was therefore to present a holistic risk assessment method for potentially polluting shipwrecks. The focus is set to developing a method for estimating the environmental consequences of potential discharges of hazardous substances from shipwrecks and to combine this with earlier research on a tool for estimating the probability of discharge of hazardous substances. Risk evaluation should also be included in a full risk assessment and is the subject of further research. The consequence assessment was developed for application in three tiers. In Tier 1, the probability of discharge and possible amount of discharge are compared to other shipwrecks. In Tier 2, a risk matrix, including a classification of potential consequences, is suggested as a basis for assessment and comparison. The most detailed level, Tier 3, is based on advanced tools for oil spill trajectory modeling and sensitivity mapping of the Swedish coast. To illustrate the method an example application on two wrecks is presented. Wreck number 1 present a lower probability of discharge and a lower consequence in a Tier 1 and Tier 3 assessment. For the Tier 2 consequence assessment, the two example wrecks present equal consequence. The tool for estimating the probability of discharge of hazardous substances from shipwrecks, and the approach for consequence estimation, offers a comprehensive method for assessing the risks presented by potentially polluting shipwrecks. The method is known as VRAKA (short for shipwreck risk assessment in Swedish) and provides decision support, facilitating prioritization of risk mitigation measures enabling efficient use of available resources.

Bayesian updating in a fault tree model for shipwreck risk assessment

Shipwrecks containing oil and other hazardous substances have been deteriorating on the seabeds of the world for many years and are threatening to pollute the marine environment. The status of the wrecks and the potential volume of harmful substances present in the wrecks are affected by a multitude of uncertainties. Each shipwreck poses a unique threat, the nature of which is determined by the structural status of the wreck and possible damage resulting from hazardous activities that could potentially cause a discharge. Decision support is required to ensure the efficiency of the prioritisation process and the allocation of resources required to carry out risk mitigation measures. Whilst risk assessments can provide the requisite decision support, comprehensive methods that take into account key uncertainties related to shipwrecks are limited. The aim of this paper was to develop a method for estimating the probability of discharge of hazardous substances from shipwrecks. The method is based on Bayesian updating of generic information on the hazards posed by different activities in the surroundings of the wreck, with information on site-specific and wreck-specific conditions in a fault tree model. Bayesian updating is performed using Monte Carlo simulations for estimating the probability of a discharge of hazardous substances and formal handling of intrinsic uncertainties. An example application involving two wrecks located off the Swedish coast is presented. Results show the estimated probability of opening, discharge and volume of the discharge for the two wrecks and illustrate the capability of the model to provide decision support. Together with consequence estimations of a discharge of hazardous substances, the suggested model enables comprehensive and probabilistic risk assessments of shipwrecks to be made.

Infrastructure, Marine Spatial Planning and Shipwrecks

In association to the shipping industry there is a broad infrastructure that is connected with multiple activities, e.g., transportation, building and recycling. This infrastructure services the industry, for example ports, and its connected transport network, fairways and canals. The infrastructure activities also entail various environmental issues, such as land use, air emissions, noise, erosion and increased water turbidity. From an environmental perspective, ships have different impacts during the various phases of their lifetimes. Building ships is a highly energy demanding process, and various environmental issues are connected to ship yards. Moreover, when ships are scrapped, the workers typically work under very crude conditions, and often no environmental concern is exercised. To facilitate the effective use of ocean near-shore areas and avoid conflicts among stakeholders, marine spatial planning (MSP) can be applied. Marine spatial planning is a process that views a system and its potential usages from both spatial and temporal perspectives and can facilitate the implementation of ecosystem-based management plans, avoiding conflicts and creating opportunities between various actors in the area. This concept is now being introduced in many countries. Shipwrecks represent a hidden problem that must be addressed. Several thousand shipwrecks litter the ocean floor, containing massive amounts of oil and other toxic chemicals.

Sustainable management of oil polluting wrecks and chemical munitions dump sites

Dumped chemical weapons that are corroding and exposed to the marine environment can cause contamination and health risks for marine fauna and humans. This paper describes some of the work that is done in the EU-DAIMON (Decision Aid for Marine Munitions) project including the development of a decision support method and previous field results that indicate that bottom trawling re-suspend sediments and spread contaminants and that recently caught fish at the Maseskar dump site contains detectable concentrations of chemical weapons from World War II.

Methods and Tools for Environmental Assessment

Selecting measures to reduce the overall environmental impact associated with shipping can be a difficult task, and a systematic approach is needed. There is risk of sub-optimisation and counteraction of different measures with one another if decisions are made based on fragmented decision support. An example of a system effect is the long lifetime of ships, which slows the introduction of new technologies. Therefore, design and retrofits must fulfil not only present but also future requirements for environmental sustainability. This chapter describes the basic details of several methods and tools that can be used in environmental assessments within the shipping industry. The methods and tools described are grouped into three categories: (1) procedural tools, (2) analytical tools and (3) aggregated tools. Examples of procedural tools are environmental impact assessment, multi-criteria decision analysis and risk management; life cycle assessment (LCA) and environmental risk assessment are examples of analytical tools. Aggregated tools include indicators, indices, and footprints.