1. Introduction
Heavy metal pollution is one world-wide environmental problem. It is believed that organisms in different
trophic levels are suffering from metal toxicities
[1]
. Accumulation of heavy metals in organisms shows different
tolerant capabilities among aquatic food webs
[2, 3]
and human health is under threats from exposure to heavy metals
through seafood intake
[4, 5]
. Use of leaded gasoline has caused a seven-folded increase of Pb content in ice layers in
Arctic area, and Hg pollution around Brazilian Amazon is attributed to gold fossicking
[6]
. Stream waters or crop
plants were also contaminated by heavy metals which were both edible
[7, 8]
.
Anthropogenic activities are believed to have led a rise of heavy metals in surface sediments
[9, 10]
and also to the
reduction of fishery yield in Bohai Sea
[11]
, which is a semi-enclosed sea located in northern China (Fig. 1) and is