Comparative distribution of total mercury in water and sediment in selected rivermouths and some biota in Laguna de Bay, Philippines

Date

2002

Abstract

Laguna de Bay is the sink for all the industrial, agricultural and residental wastes from the communities around the lake. Mercury is among the pollutants that can be present in the industrial wastes. The levels of total mercury in sediment and water from selected rivermouths in the different bays of Laguna de Bay were determined. Shrimp, bivalves and fish were collected from the different bays and were also analyzed to total mercury. Among the fish samples pooled were ayungin, tilapia, kanduli and biya. The total mercury concentrations in the samples collected were associated with the natural and industrial activities in the different bay areas. AATotal mercury analysis was done using cold vapor-atomic absorption spectroscopy (CV-AA). The total mercury concentrations in water were non-detectable and levels in sediments ranged from non-detectable to 0.112 ug/g Hg. Sediment from Manila Bay had a total mercury concentration of 0.112 ug/g Hg but among the sediment samples from the rivermouths, sediment from Bay-Calauan River had the highest total mercury concentration (0.019 ug/g Hg). Non-detectable levels were determined from the sediment samples from Sta. Cruz and Pagsanjan Rivers.

11 Total mercury concentrations in sediments were within the acceptable limits of 0.4 ug/g Hg. The shrimp and tulya analyzed, those from Napindan Channel had the highest total mercury concentration (0.0070 ug/g Hg for shrimp and 0.0034 ug/g Hg for tulya) and the lowest was in shrimp from Tanay (0.0013 ug/g Hg). Total mercury concentrations of fish from the different bays showed mercury contamination but of relatively low levels and did not exceed the acceptable limit of 0.5 ug/g Hg. Biya from Sta. Rosa had the highest total mercury level (0.052 ug/g Hg) and the lowest level of 0.002 ug/g Hg was in tilapia from Tanay and Tunasan and biya from Sta. Cruz. Although the total levels of mercury in the water, biota and sediment analyzed were low and were within the acceptable limits, mercury may tend to accumulate in the body of the organisms when they are constantly exposed to it. However, accumulation depends on the size, age and the feeding habit of the organism. Mercury in fish and shrimp can find its way from tje base of the food chain to the end consumer when the shrimp or fish is eaten by another fish which is then eaten by a larger fish or by man or when tulya, a filter-feeder is eaten by man.

Document Type

Master Thesis

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 995 2002 E8 A69

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