Flushing time of solutes and pollutants in the central Great Barrier Reef lagoon, Australia

The flushing time of the central Great Barrier Reef lagoon was determined by using salinity as a tracer and developing both an exchange model and a diffusion model of the shelf exchange processes. Modelling suggests that the cross- shelf diffusion coefficient is approximately constant for the outer half of the lagoon but decays rapidly closer to the coast. The typical outer- shelf diffusion coefficient is similar to 1400 m(2) s(-1), dropping to less than 100 m(2) s(-1) close to the coast. Flushing times are around 40 days for water close to the coast and 14 days for water in the offshore reef matrix.