Assessment of Heavy Metals in Water, Sediment, and Fishes of a Large Tropical Hydroelectric Dam in Sarawak, Malaysia

Hindawi Publishing Corporation Journal of Chemistry Volume 2016, Article ID 8923183, 10 pages http://dx.doi.org/10.1155/2016/8923183 Research Article Assessment of Heavy Metals in Water, Sediment, and Fishes of a Large Tropical Hydroelectric Dam in Sarawak, Malaysia Siong Fong Sim, Teck Yee Ling, Lee Nyanti, Norliza Gerunsin, Yiew Ee Wong, and Liang Ping Kho FacultyofResourceScience&Technology,UniversitiMalaysiaSarawak,94300KotaSamarahan,Sarawak,Malaysia Correspondence should be addressed to Siong Fong Sim; [email protected] Received 11 November 2015; Accepted 18 January 2016 Academic Editor: Yuangen Yang Copyright © 2016 Siong Fong Sim et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Bakun Hydroelectric Dam in Sarawak is one of the world highest concrete rock filled dams. This paper reports the heavy metals concentrations in water, sediment, and fishes of Bakun Dam. Water and sediment samples were collected from 11 stations and 6 fish species were caught. The samples were digested with open acid digestion and the metals contents were analysed using an atomic absorption spectrophotometer and mercury analyser. The method was validated based on certified reference materials. A higher concentration of Fe and Mn was detected in downstream water with significant longitudinal variation. Cu, Zn, and Hg were present in trace amount. All elements analysed were consistently found in sediment with no risk of contamination. For fish, Hemibagrus planiceps was characterised by higher affinity for Hg accumulation. The concentrations detected in all fish species were withinthe permissible guideline of 0.5 mg/kg. The health risk assessment suggested that Barbonymus schwanenfeldii, Puntioplites waandersii, Cyclocheilichthys apogon,andHemibagrus planiceps were characterised by hazard index > 1 implying possible adverse effects. The amount of fish recommended for adults and children was in the range of 500–775 g/week and 33–135 g/week, respectively. 1. Introduction silicoaluminate. When pH of the water is low, the dissolution of Al is enhanced thereby increasing its concentration in Dams and reservoirs are mainly built for irrigation, power water. Dams and reservoirs also play an important role in generation, flood control, and water supply. There are cur- facilitating the transportation of heavy metals. When water rently more than 58,000 dams built all over the world with is released from a dam, resuspension of deposited sediments China recording the highest number. In Malaysia, there are under high flow rate tends to carry heavy metals downstream. about80existingdamsandthenumberisanticipatedto In Peru, the acid mine drainage from adjacent mining district increase due to the escalating demand for electricity [1]. A wasflusheddownstreamfromUpamayoDam,contributing dam is considered a large dam if it is greater than 15 m with a 3 to high concentrations of copper (Cu) and zinc (Zn) in storage capacity of more than 1 Mm . sediment [3]. Dams and reservoirs can serve as a sink for accumulation Impoundment of a dam inevitably involves large area of heavy metals. Their mobility and availability in aquatic of inundation that fosters an environment with accelerated environments are primarily controlled by water quality microbial decomposition. This, in turn, may trigger the parameters including pH, dissolved oxygen and organic mat- 3+ transformation of inorganic Hg to organic mercury that can ter content. In anoxic hypolimnion, the ubiquitous Fe and be bioaccumulated and biomagnified along the food chain 4+ 2+ Mn in sediment are readily reduced into dissolving Fe [4]. Fishes affected by mercury accumulation have been 2+ and Mn leading to elevated concentrations in overlying found to take 20–30 years to restore to the background level water [2]. As the elements diffuse upward into oxic level, after impoundment [5, 6]. Considering the possible conse- theyareoxidizedandreprecipitated.Alisalsoanelement quences, the geochemical behaviour of heavy metals in dams that is naturally abundant in sediment, occurring as insoluble and reservoirs has been continuously reported worldwide: 2 Journal of Chemistry Belaga R South China Sea iver Brunei Sabah S9 S8 Sarawak S7 Bakun Dam Indonesia N S10 S11 S6 Belepeh River 48 ∘ 2 S5 | S4 Murum River S3 Balui River S2 S1 Murum Besuar River Dam Linau River Kaluan River Kebhor River Paran River Taman River Bukau River Bulan River Jawau River N Betong River 18 Bahau River ∘ 2 | N Penuan River (km) Malarang River 01020 Lebuwa River ∘ 114∘12 |113 45 E | E Figure 1: The locations of sampling stations. Dobczycki reservoir [7]; Rybnicki reservoir [8]; Manwan, is less severe in warmer areas. As a matter of fact, there are Dachaoshan, and Nuozhadu dams [9, 10]; Quiberon Bay relatively fewer reports on the fate of Hg in tropical reservoirs. Water [11]; Dicle and Batman dam [12]; Shahid Rajaee dam Therefore,theobjectiveofthisstudyistodeterminetheheavy [13]; Masinga Dam [14]. metals concentrations in water, sediment, and fishes of Bakun Bakun Hydroelectric Dam, situated on the Balui River, Hydroelectric Dam. Sarawak, Malaysia, is the one of the highest concrete rock filleddams(205m)intheworldwithacatchmentareaof 2 2. Materials and Methods 14,750 km . The dam is built for power generation. It is 2 impounded in 2010 where the flooded area is over 695 km , 2.1. Sampling. Water and sediment samples were collected approximately the size of Singapore [15, 16]. Despite its upstream, in the reservoir, and downstream of Bakun Hydro- substantial size and economic potential, the geochemical electric Reservoir in Nov. 2014 as indicated in Figure 1. distribution of heavy metals in the dam is scarcely known. It is Note that Bakun Dam is cascading with a new dam located revealed that tropical climates of high temperature and high upstream at the Murum River (Murum Hydroelectric Dam, rainfall throughout the year could lead to elevated leaching impounded in 2013). The GPS coordinates of the sampling rates upstream causing the accumulation of heavy metal in stations are summarised in Table 1. reservoirs [17]. Besides, tropical hydroelectric dams are also Triplicate water samples (1 L) were collected from sub- predicted to be more susceptible to mercury transformation surface into polyethylene bottles and acidified with 5 mL of as tropical soil is naturally rich in mercury [18, 19]. This 2M HNO3. The corresponding pH and dissolved oxygen postulation however contradicts the findings of Yingcharoen content were measured in situ using YSI multiparameter and Bodaly [20] who conclude that the transformation of Hg waterqualitymeter.Submergedsedimentatleast30cmbelow Journal of Chemistry 3 Table 1: The corresponding GPS coordinates of respective stations. Sampling station GPS coordinates Description ∘ ∘ ST1 N02 40 16.1 E114 17 22.0 Near to the power house of Murum Dam ∘ ∘ ST2 N02 41 31.9 E114 11 47.9 Approximately10kmawayfromST1 ∘ ∘ ST3 N02 42 28.8 E114 10 54.3 Near to the reservoir (transitional zone; water begins to be stagnant) ∘ ∘ ST4 N02 41 52.1 E114 01 36.1 Reservoir ∘ ∘ ST5 N02 42 22.8 E114 01 14.3 Reservoir ∘ ∘ ST6 N02 44 43.9 E114 02 26.5 Reservoir ∘ ∘ ST7 N02 46 21.7 E114 01 41.4 NeartothepowerhouseofBakunDam(4.3kmfromBakunDam) ∘ ∘ ST8 N02 46 37.9 E113 59 23.3 Right above Metjawah (Lubok Metjawah) ∘ ∘ ST9 N02 46 05.2 E113 54 23.0 Lahanan Long Semuang ∘ ∘ ST10 N02 44 36.5 E113 50 21.8 Above Longhouse Kejaman Neh ∘ ∘ ST11 N02 42 02.9 E113 46 46.32 Below Belaga Town Table 2: The number of samples and corresponding length and weight of various fishes. Fish species Local name Number of individuals Range of weight (g) Range of length (cm) Cyclocheilichthys armatus Boeng 10 15.7–230.5 9.1–28.1 Barbonymus schwanenfeldii Tenggadak 16 182–520 12.4–36.5 Puntioplites waandersii Mengalan 17 59.6–520 18.6–33.4 Pangasius micronemus 771.7–52023.1–39.3 Cyclocheilichthys apogon Boeng 101 22.8–135 12.5–17.2 Hemibagrus planiceps Baong 20 74.5–285 23.6–38.9 the water level was collected using a grab sampler and stored was acid washed before use. The digested samples were in plastic bags. Fish samples were caught using the netting subjected to metal analysis including copper (Cu), zinc (Zn), method from the Balui River, Linau River, and Long Baagu. iron (Fe), and manganese (Mn) using an atomic absorption The total length and weight were recorded and the species spectrophotometer (Thermo Scientific iCE 3000). The total were identified according to Mohsin and Ambak [21], Kottelat mercury (Hg) was determined using a mercury analyser and Whitten [22], Rainboth [23], and Inger and Chin [24]. (Perkin Elmer, FIMS 400). Table 2 summarises the species and the range of total length ∘ and weight. All samples were stored in a cooler box at 4 C 2.3. Quality Control and Method Validation. For every batch for transportation to the laboratory. At the laboratory, the ∘ of digestion, a blank was prepared to monitor contamination samples were kept at −20 C until further analysis. and the method efficiency was determined according to the certified reference materials (CRM) of stream sediment 2.2. Acid Digestion and Metal Analysis. Water samples were (STSD-1) and fish muscle (ERM-BB422). The recovery per- filtered through 0.45 m membrane filters and digested centages attained for the reference materials of sediment and according to the standard method of APHA [25]. 5 mL of fish are between 97–102% and 90–120%, respectively, meeting HNO3 was added to 100 mL of sample and the sample was the acceptable recovery of 80–120% recommended by the put to slow boil on a hotplate to 10–20 mL until the solution Environmental Agency [27]. is clear. The sample was then left to cool, filtered through In this paper, the metal contents were measured accord- 0.45 m membrane filters, and diluted to 100 mL. The metal ing to dry weight to ensure consistencies.

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