Concentrations of heavy metals in river water and sediment were investigated in nine estuaries along the
coast of Bohai Bay, Northern China. Multivariate statistical techniques such as principal component analysis
and cluster analysis, in combination with metal concentration analysis and correlation analysis, were
used to identify the possible sources of the metals and the pollution pattern in nine estuaries along the
coast of Bohai Bay. The environmental risks of metals, evaluated by sediment quality guidelines and background
values, revealed Hg contamination in the estuaries. However, levels of Cd in estuarine sediments
were low, and they were less than those levels in river sediments, partly due to the high mobility and
dilution of river or seawater. Cd did not contribute to sediment deposits in estuaries. High organic matter
from effluents from large municipal sewage treatment plants was predominantly responsible for restricting
Hg mobility from the river to Bohai Bay.