Nowadays there is a special need to improve the ability to predict the effects of anthropogenic activities on aquatic systems. In this framework, diffuse pollution in harbour areas caused by hydrocarbon releases is an issue of major interest because of its associated problems.

The stochasticity and heterogeneous chemical composition of these contaminant events has limited the development of new quantitative and probabilistic methodologies. These methodologies should be capable to: (i) reflect the inherent spatial and temporal variability of this kind of events; and, (ii) relate the response of the different environmental compartments (i.e. water, sediment and biota) with the pressure.

The methodological approaches to assess the environmental risk in areas under continuous and moderate levels of pollution over the time are scarce. However, diffuse sources are recognized by several authors as a significant introduction of pollution and effects (Petrosillo et al., 2009; Ondiviela et al., 2012).

For this reason, the main objective of this project is to gain knowledge on environmental risk analysis of hydrocarbon releases. To achieve this, it is intended to improve the available tools to estimate the environmental impact, as a combination of the extension of the potentially affected area and the magnitude of the environmental effects generated.

In this context, the implementation of probabilistic models of hydrocarbons transport and the validation of environmental risk assessment procedures are proposed. Moreover, the real environmental impact generated by oil diffuse sources will be assessed by analysing the concentration of pollutants in the water and/or sediments samples and the response and status of biological communities potentially affected.

The tasks planned in the project will be carried out in two different scenarios: a) the Repsol monobuoy and pier in Tarragona harbour (Cataluña), as a specific source of hydrocarbon diffuse contamination; and b) different marinas along the Spanish coast (Cantabria), smalls harbour slightly affected by hydrocarbon releases but with a constant basal contamination.