Chemical flux to the coast of Bangladesh – a review

Abstract

This paper deals with the state of chemical flux to the coast of Bangladesh from ex-situ-, in-situ- point and non-point sources of geogenic and anthropogenic origin. Except for ex-situ chemical flux, no in-situ chemical flux to the coast of Bangladesh has been studied. The major elemental dissolved flux contributed by the Ganges-Brahmaputra-Meghna (GBM) river system to the coast of Bangladesh accounts for about ~5% (152 × 10⁶ t.yr⁻¹) of the annual global dissolved chemical flux to the oceans by rivers. This river system also contributes ~115 × 10³ t.yr⁻¹ of dissolved fluoride and ~105 × 10³ t.yr⁻¹ of dissolved phosphate to the coast of Bangladesh. The GBM river system is also one of the highest sediment dispersal systems of the world and transports about 1060 million tons of sediments to the coast of Bangladesh each year. Studies showed that DDT in zooplankton, fish and bottom sediments from the Bay of Bengal also occurs in the range of 4.0 to 5.9 ppb, 0.3 to 8.6 ppb and 0.032 to 720 ppb respectively. Since the coastal ecosystems are sensitive to chemical changes in the aquatic environment, estimation of chemical flux to the coast of Bangladesh is important.