Heavy Metal Accumulation and Anthropogenic Impacts on Tolo Harbour, Hong Kong

The surficial sediments in Tolo Harbour, Hong Kong, lie at the extreme landward end of a highly indented shallow marine bay. During the late Pleistocene and early Holocene this was a confluence area for several rivers, with marine flooding taking place between 8000 and 6000 years. B.P. Anthropogenic contamination with Cu, Pb and Zn has resulted in a pollution gradient that suggests major inputs from the Tai Po area to the north-west of Tolo Harbour, with further contamination inputs being derived from Shatin to the south-west. Core data for these metals demonstrate an increasing contamination trend over the last few decades. Ni also increases within cores, but spatial trends are less distinct. Cr exhibits no spatial or temporal pattern and probably reflects natural lithospheric contributions only. Cd occurred at very low levels. Generally pollution problems are moderate rather than extreme, but the area faces increasing urban pressures.