Trend analysis of anthropogenic activities affecting trace metals deposition in core sediments from the coastal and four rivers estuary of Sarawak, Malaysia.

This study reports the concentrations of trace metals in core sediments profile from the coastal and four rivers estuary in the Kuching Division of Sarawak, Malaysia, and the controlling mechanisms influencing their availability in sediments of the studied area. The bonding of trace metals with non-mobile fractions was confirmed with the sequential extraction. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to measure the concentrations of the trace metals. Granulometric analyses were performed using normalized sieve apertures to determine the textural characteristics of the sediments. Enrichment factor was used to evaluate the level of metal enrichment. Heavy metals concentrations in sediment samples varied in the range: Pb (8.9-188.9 mg/kg d.w.), Zn (19.4-431.8 mg/kg d.w.), Cd (0.014-0.061 mg/kg d.w.), Ni (6.6-33.4 mg/kg d.w.), Mn (2.4-16.8 mg/kg d.w.), Cu (9.4-133.3 mg/kg d.w.), Ba (1.3-9.9 mg/kg d.w.), As (0.4-7.9 mg/kg d.w.), Co (0.9-5.1 mg/kg d.w.), Cr (1.4-7.8 mg/kg d.w.), Mg (68.8-499.3 mg/kg d.w.), Ca (11.3-64.9 mg/kg d.w.), Al (24.7-141.7 mg/kg d.w.), Na (8.8-29.4 mg/kg d.w.), and Fe (12,011-35,124.6 mg/kg d.w.). The estimated results of the enrichment factor suggested enrichments of Pb, Zn, and Cu in all the core sediment samples and depths at all sites. The other trace metals showed no enrichments in almost all the sampled stations. Continuous accumulation of Pb, Zn, and Cu metals over a period can be detrimental to living organisms and the ecology. The results obtained from the statistical analyses suggested that the deposition of trace metals in the studied sites is due to anthropogenic inputs from the adjacent land-based sources.

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

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.