Assessment of Metals in Water, Sediment and Fishes at Santubong Wetland

Adriana, Christopher Lee (2021) Assessment of Metals in Water, Sediment and Fishes at Santubong Wetland. Masters thesis, Universiti Malaysia Sarawak.

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Abstract

Metals are one of the hazardous contaminants in the environment. Santubong Wetland is located near a fishing village and human activities such as industrial, tourism, and fishing activities, thus it may receive various types of wastes from these activities. However, the status of the contamination level of metals in Santubong Wetland was unknown. Hence, this study was carried out to examine the concentrations of aluminium (Al), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and lead (Pb) in water and sediment during the wet and dry season, to investigate the concentration of non-essential metals (Cd and Pb) in fishes and to estimate the potential human health risk through the consumption of the fishes from Santubong Wetland. Three stations namely Buntal, Penambir and Demak were chosen in this study and the samplings were carried out once in each seasons; wet season (April 2017) and dry season (July 2017). Physicochemical water quality parameters were taken at each station. The water samples were collected using Van Dorn Water Sampler, the sediment samples were collected using Grab sampler and the fishes were caught using a three-layered gillnet. The water and sediment samples were analysed for Total Organic Carbon (TOC). The sediment samples were further analysed for Total Organic Matter (TOM) and Particle Size Analysis (PSA). The ecological risk was assessed using the ecological risk indices Geoaccumulation Index (Igeo), Potential Contamination Index (PCI) and Enrichment Factor (EF). Prior to metals analysis, the water samples were filtered and acidified while the sediment samples were digested. The fishes caught were identified and the muscle parts of the fishes were digested. All the digested samples were analysed using the Flame Atomic Absorption Spectrophotometer (FAAS). The Bioaccumulation Factor (BAF) in fishes was determined and the human health risk assessment was examined by using Provisional Tolerance Weekly Intake (PTWI), Health Risk Index (HRI), Hazard Index (HI) and safety limits based on a survey using questionnaires conducted in the wetland. Frequency of Food Occurrence was conducted to examine the feeding habit of the fishes. The concentrations of metals in the water and sediment were found to be spatially different and also varied seasonally due to the rainfall. The metal concentrations in the water ranged between 0.07- 5.16 mg/L, 0.02-0.03 mg/L, 0.004-0.02 mg/L, BDL-0.004 mg/L, 0.01-0.04 mg/L and 0.004-0.01 mg/L for Al, Cd, Cr, Cu, Ni and Pb respectively. The metal concentrations in the water were within the range of MMWQCS and NWQS except for Al. The metal concentrations in the sediment ranged between 1918.94-3421.77 mg/kg, 0.06-0.09 mg/kg, 6.85-16.52 mg/kg, 2.45-6.81 mg/kg, 2.84-6.20 mg/kg and 4.56-11.22 mg/kg for Al, Cd, Cr, Cu, Ni and Pb respectively. The sediment was in low to moderate contamination of metals. A total of 28 fish species were examined and the concentration of Cd was ranged between 0.13-1.57 mg/kg while the concentration of Pb was ranged between 0.38-7.44 mg/kg. The metals concentration in the fishes was also found to be related to the feeding habit. The BAF analysis showed that the Pb was accumulated higher than Cd. The concentration of Cd and Pb in Arius maculatus and Nibea soldado were found to be varied seasonally and spatially. Some fish species exceeded the recommended PTWI and safety limits by FAO/WHO (2004) and MFA (1983) for Cd and Pb. The HRI and HI values in some fish species were also exceeding 1. This suggests that regular consumption of the fishes in this area in large quantities for a long period might impose a bad effect on human health. Thus, the anthropogenic inputs from the human activities carried out in this wetland might have contributed to the concentration of metals in the water, sediment and fishes of this study. The information of this study will be useful for the effective management of this wetland so it can be protected from further deterioration.

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