Total mercury concentration in biota of the Gulf of
Thailand are shown in Table 7. In the coastal area, almost
all mercury concentration in fish were lower than
0.2 lg/g wet. These concentrations could be regarded as
a natural background of mercury in fish in general.
Nevertheless fishes in the off shore area, in the vicinity of
natural gas platforms, exhibited higher mercury concentrations.
These fishes were caught and analyzed recently
(ARRI, 1998). Between 5% and 10% of fish at
Erawan and Funan platforms had mercury concentrations
higher than 0.5 lg/g. This concentration is the
maximum permissible concentration in fish set by the
FAO. The biological magnification of mercury was
mentioned in several reports. Fish of higher trophic
levels bore higher residue than those in the lower trophic
levels. This suggests that mercury might be concentrated
in the same manner as organic compounds such as organochlorine
compounds, i.e. passed through and amplified
along the food chain.