Effectiveness of Dispersants for Coastal Habitat Protection as a Function of Types of Oil and Dispersant

Abstract

Oil spills in nearshore environments may eventually move into sensitive coastal habitats such as coastal marshes, and could impact marsh organisms. Application of dispersants to spilled oils in nearshore environments before the oil drifts into marshes was simulated, and effectiveness of dispersants’ relief of the impact of different oil types on salt marsh plants were investigated. The application of the dispersant JD-2000 significantly relieved the adverse effects of both No. 2 fuel oil and South Louisiana crude oil on the dominant salt marsh plant, Spartina alterniflora. Upon contact with plant leaves during the rising tide, the oils sharply reduced the photosynthetic rates of the plant, and increased the percentage of dead tissue. In contrast, the dispersed oils did not significantly affect the marsh plants compared to the no-oil control. However, the effectiveness of the relief of Corexit 9500 on the impact of crude oil was not as great as that of No. 2 fuel oil, although Corexit 9500 also significantly mitigated the impact of crude oil on the salt marsh plant. The current study indicates that dispersants are likely to be most effective in mitigating light fuel oil rather than the viscous crude oil, and have the potential as an alternative countermeasure sure to protect sensitive coastal habitats during nearshore oil spills.