All metals (except Cu) showed significantly
positive correlation with Hg, indicating their common
source and association with each other (Table
4). More importantly, Hg was more associated with
Zn (r = 0.811) and Cd (r = 0.715) than the other
metals. Most metal concentrations showed negative
correlation with sediment pH, calcium carbonate
and sand, whereas these showed positive correlation
with CEC, organic matter, Fe and Mn oxides,
silt and clay. The above correlations suggest
that organic matter, silt and clay were the major
metal sorbents of the sediments, whereas calcium
carbonate and sand acted as diluant materials of
the heavy metals in the sediments. Fe and Mn oxides
were also sorbents for most metals, but not for
Pb, Cd and Cu. However, organic matter content
was considered to be the most important controlling
factor in the abundance of Hg in the sediments
(r = 0.678), while clay was the most important sediment
component responsible for the abundance of
the other metals. This is because Hg exhibits stronger
affinity for organic matter in soils and sediments
(Schuster, 1991) than do soil inorganic components
(Yin et al., 1996). Copper showed no correlation
with other metals and sediment characteristics. This
suggests that there may be significant anthropogenic
sources of Cu to the coastal area.