The effects of estuarine pollution on heavy metals concentration in water, sediment and selected edible mollusc of Sarawak

Nur Atiqah, Binti Mohammad Yusoff (2013) The effects of estuarine pollution on heavy metals concentration in water, sediment and selected edible mollusc of Sarawak. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

Water pollution and heavy metals contamination have been increasingly reported worldwide, especially in aquatic environment. In order to understand the source of water and heavy metal pollution, it is important to determine the level of heavy metals in the aquatic ecosystem such as water, sediment and mollusc tissue. Two approaches were taken to address this Firstly was survey on the water quality parameters in six selected rivers to determine the heavy metals in water and sediment. This was carried out from 20 I 0 to 20 I I in the estuaries of six rivers namely Sematan River, Kayan River, Sarawak River, Rejang River, Lupar River and Saribas River. A total of five sampling stations were chosen for each river. Second approach was conducting a seasonal study of the water quality parameters and heavy metals content in water, sediment and mollusc tissue from two rivers namely Sematan and Sarawak Rivers for 12 months (May 20 10 to April 20 II). Both in-situ and ex-situ physico-chemical parameters such as temperature, pH, dissolved oxygen, salinity, turbidiry, nutrient, total suspended solid and heavy metals were measured and analyzed. Results obtained were compared to the National Water Quality Standard (NWQS) and DOE Water Quality Criteria for Malaysia. The Atomic Absorption Spectrophotometer (AAS) was used for the determination of heavy metals in water, mollusc tissue and sediment samples. Heavy metals of cadmium, chromium, lead, zinc, iron and copper were measured. The results of heavy metals concentration were then compared to the Malaysian Food act, (1983) and DOE Water Quality Criteria for Malaysia threshold level for aquatic life. The water quality parameters were classified from class I to class III under NWQS. The index of water quality (WQI) for Sematan River was 83 and classified as clean which is under class II while Kayan River, Sarawak River, Rejang River, Lupar River and Sari bas River were ranged fr m 72-80, thus classified as slightly polluted which is in the range of class II to class ilL For seasonal study, water parameters in Sematan River were classified from class I to class II while in Sarawak River the water parameters were classified from class I to class 1JI under NWQS. Water quality index (WQI) for Sematan River was 85 which indicate that it is clean and under class H while Sarawak River was 78 which is indicated that it is slightly polluted and under class II. ·arawak River showed the highest heavy metals concentration in water, sediment and mollusc tis ue compared to Sematan River. Certain heavy metals such as cadmium, copper, zinc and lead concentration in Sematan and Sarawak Rivers had exceeded the Malaysian Food Act, (1983) and DOE Water Quality Criteria for Malaysia River in certain months. C rrelation analysis for survey study was perfomed to determine whether the mollusc is able to use as bioindicator for heavy metal pollution. Based on the seasonal correlation study, shows that P()~vmesoda expansa, Meretrix meretrix and Cerilhidea oblusa were suitable and had the potential to be a good bioindicator for lead level and Meretrix meretrix was also suitable and had the potential as a good bioindicator for chromium level in Sematan River. In Sarawak River, Polymesodll expansa was suitable and had the potential to be good bioindicator for all heavy metals. Meretrix meretrix was suitable and had the potential to be the bioindicator for chromium and lead while Cerilhidea obtusa was found suitable and had the potential to be the bioindicator for copper.

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