| Abstract | A study to evaluate the existing quality of seawater and possible impacts of the Laem Chabang Deep Sea Port Project on the marine ecosystem was conducted. Effects of seasonal variation on seawater quality was analyzed on the basis of the following parameters: color, odor, pH, salinity, temperature, dissolved oxygen, total and suspended solids, BOD, COD, TOC, total kjehldahl nitrogen, total phosphorus, Hg, As, Cd, Cr, DDT, PCBs, oil and grease, faecalis coliform, and chlorophyll a. It was found out that the concentration of most of the quality parameters did not vary significantly. Further, results of the analysis indicated minimal concentrations of organic pollutants and tolerable levels of pesticides and heavy metals except cadmium and chromium. The quality of water thereby meets the standard for fishing, swimming, and navigational purposes. An assessment of the potential impacts of the deep sea port development project on marine ecosystem was done to identify the resources that will be affected adversely so that control and mitigation measures can be considered thoroughly. |