Identification of the most influential factors in the Norwegian guidelines for risk assessment of dispersion of contaminants from sediments



The Norwegian guidelines for risk assessment of contaminated sediments are used to identify areas of concern where remediation may be needed to meet the governmental long-term goal of clean fjords and harbors along the Norwegian coastline. By a thorough sensitivity analysis, this study identifies the most influential factors and parameters for the Tier 2A model in this risk guideline, which are used to estimate fluxes of contaminants from sediments due to diffusion and bioturbation (Fdiff), resuspension caused by ship traffic (Fskipnorm), and uptake and predation of benthic biota (Forg). The sensitivity analysis is run for 36 different scenarios combining 3 different sizes of contaminated area, 3 harbor types, and 3 persistent organic pollutants, namely lindane (γ-hexachlorocyclohexane), benzo[a]pyrene, and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB-153), as well as the metal mercury (Hg). The most influential parameters vary from scenario to scenario, but generally 5 parameters appear to be particularly influential for the fluxes and transport estimated by the Tier 2A model: flux of organic carbon to sediment (OCsed), factor for increased diffusion due to bioturbation (a), sediment–water partitioning coefficient (Kd), benthic biota–water bioconcentration factor (BCFfisk), and mass of resuspended fine sediment during arrival or departure of a ship (msed). We also quantify which of the 3 fluxes (Fdiff, Fskipnorm, and Forg) dominate in the different scenarios. Our sensitivity analysis results can be used by authorities, problem owners, consultants, and environmental managers involved in contaminated sediment management to gain insight on the key processes and parameters and to focus their site-specific or laboratory-based measurement efforts on the key parameters and thus increase efficiency and reliability in the contaminated sediment risk assessment. Integr Environ Assess Manag 2011;7:657–667. © 2011 SETAC