12 Distribution of Cd, Pb, As and Hg in Oyster Tissue, Sediment and Water. . .
147
et al. 2005) so they can act as a sink to pollutants in bodies of waters like
rivers and creeks (USEPA 1992). The relatively high Pb level in stations 2, 4
and 6 in southeastern side and stations 11 and 12 in the northwestern side of
Lingayen Gulf can be due to anthropogenic activities conducted in the coastal
communities near the sampling station. The following sites are located closest to
the center of aquaculture activities in the province of Pangasinan which covered the
municipalities of Dagupan, Lingayen and Binmaley (southeastern side) and Bolinao
and Anda (northwestern side). In a survey conducted by Palma (1989) on the
patterns and aquaculture practices in the coastal municipalities adjoining Lingayen
Gulf she documented that, of the 13, 452 total hectarage of brackish water fishponds
in the Gulf, 69 % were located in these five municipalities. The site is also proximate
to two (Dagupan and Alaminos) of the four cities of Pangasinan which are the
province’s centers of commerce and trade. Further, the Pb traces can be associated
with lead-based gasoline residues from the fishermen’s motorized boat, which is
used for daily transportation and fishing operations. Tang et al. (2008) suggested
that anthropogenic-sourced Pb can be derived from lead sulfide ore deposits and is
released into the environment through the combustion of leaded gasoline and as a
by-product of industrial lead use. It was also suspected that damaged and lost or
unrecovered lead sinkers used in major fishing gears during fishing operations in
the Gulf to have partially contributed to the traces detected.
Total As species were determined in the study and significant (p < 0.05) levels
were detected in sediments for both monsoon and pre-monsoon seasons. With a
rapid growth in population, several studies reported that most As contaminations
were due to anthropogenic pollution (Lin and Hsieh 1999). Stations (3, 4, 10,
11, and 12) yielding high As traces comes mostly from first class or urbanized
municipalities. These areas are also the center of aquaculture activities in Lingayen
Gulf (Palma 1989). Population statistics show that 17.13 % (453,965) of the total
population (2,645,395) from 48 municipalities in Pangasinan resides in these five
municipalities (NSO 2007).
Traces of Hg on the other hand were only observed in sediment samples during
pre-monsoon and contamination was found to be location specific suggesting
that the values observed in the two distinctly separate stations (2 and 12) were
anthropogenic in nature. The bulk of fish cages and fish pen aquaculture activities
were concentrated within the vicinities of stations 2, 3 and 4 in southeastern and
stations 10, 11 and 12 in northwestern side of Lingayen Gulf. Some of the Hg traces
may come from impurities from pelleted commercial feeds that were used in the
fish farms. Seasonal increase in fish cage and fish pen operations in the Gulf were
evident during pre-monsoon season, thus more feed load inputs during these months
are expected. Monsoon season has also the lean months for aquaculture activities in
the Gulf since frequent flooding and strong water current during this period can
destroy the fish farm structures. The observed presence of small-scale gold panning
miners in the vicinities of stations 3 and 4 which are believed to be using Hg to
extract gold from ore deposits can be an evidence of location specific anthropogenic
activity accounting for the values detected.
147
et al. 2005) so they can act as a sink to pollutants in bodies of waters like
rivers and creeks (USEPA 1992). The relatively high Pb level in stations 2, 4
and 6 in southeastern side and stations 11 and 12 in the northwestern side of
Lingayen Gulf can be due to anthropogenic activities conducted in the coastal
communities near the sampling station. The following sites are located closest to
the center of aquaculture activities in the province of Pangasinan which covered the
municipalities of Dagupan, Lingayen and Binmaley (southeastern side) and Bolinao
and Anda (northwestern side). In a survey conducted by Palma (1989) on the
patterns and aquaculture practices in the coastal municipalities adjoining Lingayen
Gulf she documented that, of the 13, 452 total hectarage of brackish water fishponds
in the Gulf, 69 % were located in these five municipalities. The site is also proximate
to two (Dagupan and Alaminos) of the four cities of Pangasinan which are the
province’s centers of commerce and trade. Further, the Pb traces can be associated
with lead-based gasoline residues from the fishermen’s motorized boat, which is
used for daily transportation and fishing operations. Tang et al. (2008) suggested
that anthropogenic-sourced Pb can be derived from lead sulfide ore deposits and is
released into the environment through the combustion of leaded gasoline and as a
by-product of industrial lead use. It was also suspected that damaged and lost or
unrecovered lead sinkers used in major fishing gears during fishing operations in
the Gulf to have partially contributed to the traces detected.
Total As species were determined in the study and significant (p < 0.05) levels
were detected in sediments for both monsoon and pre-monsoon seasons. With a
rapid growth in population, several studies reported that most As contaminations
were due to anthropogenic pollution (Lin and Hsieh 1999). Stations (3, 4, 10,
11, and 12) yielding high As traces comes mostly from first class or urbanized
municipalities. These areas are also the center of aquaculture activities in Lingayen
Gulf (Palma 1989). Population statistics show that 17.13 % (453,965) of the total
population (2,645,395) from 48 municipalities in Pangasinan resides in these five
municipalities (NSO 2007).
Traces of Hg on the other hand were only observed in sediment samples during
pre-monsoon and contamination was found to be location specific suggesting
that the values observed in the two distinctly separate stations (2 and 12) were
anthropogenic in nature. The bulk of fish cages and fish pen aquaculture activities
were concentrated within the vicinities of stations 2, 3 and 4 in southeastern and
stations 10, 11 and 12 in northwestern side of Lingayen Gulf. Some of the Hg traces
may come from impurities from pelleted commercial feeds that were used in the
fish farms. Seasonal increase in fish cage and fish pen operations in the Gulf were
evident during pre-monsoon season, thus more feed load inputs during these months
are expected. Monsoon season has also the lean months for aquaculture activities in
the Gulf since frequent flooding and strong water current during this period can
destroy the fish farm structures. The observed presence of small-scale gold panning
miners in the vicinities of stations 3 and 4 which are believed to be using Hg to
extract gold from ore deposits can be an evidence of location specific anthropogenic
activity accounting for the values detected.