Distribution of Major and Trace Elements in a Tropical Hydroelectric Reservoir in Sarawak, Malaysia

Abstract

This paper reports the metals content in water, sediment, macroalgae, aquatic plant, and fish of Batang Ai Hydroelectric Reservoir in Sarawak, Malaysia. The samples were acid digested and subjected to atomic absorption spectrometry analysis for Na, K, Mn, Cr, Ni, Zn, Mg, Fe, Sn, Al, Ca, As, Se, and Hg. The total Hg content was analysed on the mercury analyser. Results showed that metals in water, sediment, macroalgae, aquatic plant, and fish are distinguishable, with sediment and biota samples more susceptible to metal accumulation. The distributions of heavy metals in water specifically Se, Sn, and As could have associated with the input of fish feed, boating, and construction activities. The accumulation of heavy metals in sediment, macroalgae, and aquatic plant on the other hand might be largely influenced by the redox conditions in the aquatic environment. According to the contamination factor and the geoaccumulation index, sediment in Batang Ai Reservoir possesses low risk of contamination. The average metal contents in sediment and river water are consistently lower than the literature values reported and well below the limit of various guidelines. For fishes, trace element Hg was detected; however, the concentration was below the permissible level suggested by the Food and Agriculture Organization.

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

“…Hg is evidently higher in Barbonymus schwanenfeldii (average concentration 2.158 mg/kg), Puntioplites waandersii (1.921 mg/kg), Cyclocheilichthys apogon (1.934 mg/kg), and Hemibagrus planiceps (2.397 mg/kg) in dry weight. Among these, Barbonymus schwanenfeldii, Cyclocheilichthys apogon, and Hemibagrus planiceps could also be found in the environment of Batang Ai where the Hg level reported was relatively lower at 0.07, 0.13, and 0.34 mg/kg (in dry weight), respectively [34]. As observed, Hemibagrus planiceps tends to accumulate Hg corroborating the findings of Sim et al [34] at Batang Ai, possibly due to its diet nature as a bottom feeder [34].…”

“…The declining concentration at the dam wall is possibly associated with the reaerated environment. Sim et al [34] reveal similar observation with all elements detected at lower concentrations at the station after Batang Ai Dam. In terms of contamination status, there is minimal risk of contamination with geo consistently <0, CF and PLI < 1.…”

“…Statistically, no significant different is established in Hg between stations ( > 0.05). The average concentration of Hg in Bakun is relatively lower than that reported in Batang Ai (0.367 g/L) [34].…”

“…Among these, Barbonymus schwanenfeldii, Cyclocheilichthys apogon, and Hemibagrus planiceps could also be found in the environment of Batang Ai where the Hg level reported was relatively lower at 0.07, 0.13, and 0.34 mg/kg (in dry weight), respectively [34]. As observed, Hemibagrus planiceps tends to accumulate Hg corroborating the findings of Sim et al [34] at Batang Ai, possibly due to its diet nature as a bottom feeder [34]. C. apogon, B. schwanenfeldii, and P. waandersii are also found to accumulate considerable Hg likely associated with their carnivorous diet.…”

Assessment of Trace Metals Distribution in Lake Kenyir, Malaysia

“…Unfortunately, these previous studies focused mainly on the dissolved form of trace metals, therefore, only dissolved trace metals were used for comparison in Table-2. Trace metals in Lake Kenyir and tropical hydroelectric reservoir [20] fell into Class I of the NWQS, which indicates a natural level of trace metals in their water bodies. For Lakes Sembrong [21] and Chini [22], some of the trace metal concentrations (i.e.…”