Simulation of Organic Pollutants: First Step towards an Adaptation to the Malacca Strait

Abstract

For the simulation of the transport of persistent organic pollutants (POPs), a set of numerical models has been adapted and applied to the Malacca Strait and the adjacent South China Sea and Java Sea. As a fi rst step, a model experiment, namely input of POPs into model region only via rivers, was performed, because realistic input data regarding concentrations, sources and sinks of POPs for the marine environment as well as different other parameters responsible for the fate of POPs in the ocean were not yet available. Firstly, a numerical hydrodynamical model has been applied to the region of interest to simulate the hydrological situations as realistically as possible. Secondly, a numerical model for the fate and transport of POPs has been run on the basis of the hydrodynamical model results to simulate the dispersal of two differently behaving POPs, i.e., γ-HCH and PCB 153, from river input only. It is shown that only a clear seasonal but hardly annual variation is present in the model results for the currents and for the total POP concentrations. Despite permanent riverine input, the seasonal pattern of total POP concentration in water repeats in the simulation results year after year without further accumulation indicating that a quasi-steady state has been reached. Tidal mixing leads to vertically homogeneous concentrations except in deeper areas of northern Malacca Strait. Furthermore, the concentration distributions of PCB 153 in water show similar patterns but lower values than γ-HCH.