Geochemical and Ecological Risk Assessment of Heavy Metals and Hydrocarbons in Sediments of the Coastal and Four Rivers Estuary of Kuching Division of Sarawak, Malaysia

Contamination of heavy metals and hydrocarbons in the coastal and estuarine sediment could harm water quality and aquatic organisms, leading to potential long-term health risks to the environment and humans. Thus, this study was carried out to determine the concentration of heavy metals, aliphatic hydrocarbons (AHs), and polycyclic aromatic hydrocarbons (PAHs) distribution in surface sediments and to establish baseline concentrations of heavy metals using core sediments from the coastal and four rivers estuary of the Kuching Division of Sarawak, Malaysia. Validated inductively coupled optical emission spectroscopy (ICP-OES) was used to determine heavy metals and their distribution in surface sediments was evaluated for eco-toxicological impacts. Source appointment of the heavy metals within the catchment area was determined using geochemical indices. The ICP-OES technique validated was appropriate and less laborious for determining the 12 metals of interest (i.e., Al, Mn, Ca, Cd, Cu, Fe, Cr, Ni, Co, Zn, and Pb) in the sediments. Heavy metal concentrations were recorded based on dry weight (d.w). The concentrations of heavy metals in core sediments varied in the range: Pb(8.9 – 188.9 mg/kg), Zn(19.4 – 431.8 mg/kg), Cd(0.014 – 0.061 mg/kg), Ni(6.6 – 33.4 mg/kg), Mn(2.4 – 16.8 mg/kg), Cu(9.4 – 133.3 mg/kg), Ba(1.3 – 9.9 mg/kg), As(0.4 – 7.9 mg/kg), Co(0.9 – 5.1 mg/kg), Cr(1.4 – 7.8 mg/kg), Mg(68.8 – 499.3 mg/kg), Ca(11.3 – 64.9 mg/kg), Al(24.7 – 141.7 mg/kg), Na(8.8 – 29.4 mg/kg), and Fe (12011 – 35124.6 mg/kg). The enrichment factor assessment suggested enrichment of Pb, Zn, Cu, As, Co, and Mg occurred at the top layer of the core sediments. Continuous accumulation of Pb and Cu metals over time can be detrimental to living organisms and the ecology. The pollution load index values indicated that the study area is unpolluted. Sediment quality guidelines (SQGs) compared to the detected heavy metals suggested no likely deleterious impact on bottom-dwelling living things. The risk index estimation in each study site showed a low ecological risk impact on the environment. The statistical analysis suggested that the deposition of As, Cd, Pb, Cu, Mn, and Zn in the study sites is due to anthropogenic inputs from the adjacent land-based sources while Fe, Al, Mg, Na, Ni, and Ba are from lithogenic origin. This study further explains the monitoring, sources, and risk assessment of hydrocarbons in surface sediments. Validation of the performance of gas chromatography flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS)showed that these techniques are in an excellent position to quantify aliphatic and polycyclic aromatic hydrocarbons, respectively. Total n-alkanes (C10 – C33) concentrations varied from 96.63 – 367.28 ng/g. The lowest and highest n-alkane content was observed at Santubong estuary (CZ10) and offshore of Batang Rambungan opposite small Satang Island (CZ2), respectively. The contents of PAHs varied from 12.54 – 21.20 ng/g. The highest PAH content was detected in the sediments of coastal site CZ8 (21.20 ng/g), whereas; the lowest content was recorded in the sediments of coastal site CZ3 (12.54 ng/g). The aliphatic diagnostic indices values showed hydrocarbon input from biogenic and petrogenic sources. The isomeric ratios values also indicated that PAHs in sediments are from a mixture of petrogenic and pyrogenic origins. The carcinogenic PAHs risk assessment suggested no risk impacts of carcinogenic PAHs in the study area. The findings of this study can be used to understand the sources and possible risks of hydrocarbons and provide information for safeguarding human health and aquatic bodies in coastal and estuary settings

Validation of the Atomic Absorption Spectroscopy (AAS) for Heavy Metal Analysis and Geochemical Exploration of Sediment Samples from the Sebangan River

This study was to validate the Atomic Absorption Spectroscopy (AAS) in the determination of heavy metals using surface sediments from the Sebangan (estuary of Sadong River), Sarawak State, Malaysia as a case study. Aqua regia procedure was used to extract the trace elements from the sediments. The Scanning Electron Microscope was used to analyse and investigate the microstructure morphology and chemical composition characterizations of the sediments. The results of the examination confirmed to the fact that the technique validated was appropriate and less laborious for the determination of the 12 metals of interest (Al, Mn, Ca, Cd, Cu, Fe, Cr, Ni, Co, Zn and Pb) in the sediment. Massive deposits of sharp teeth granite and quartz particles of distinct tetrahedral conformation with plus size were observed in the samples investigated

Vertical Profile Of Heavy Metal Concentration In Sediments From Sadong River, Sarawak, Malaysia

Several sources of heavy metals in the environment include biological, geochemical, geological and anthropogenic sources. A total of eighteen core sediments were taken from Sadong river, Sarawak, Malaysia. These samples were digested by acid extraction and thereafter subjected to atomic absorption spectrometry (AAS). This paper aims to determine the vertical profile of heavy metals in core sediments, infer the accumulation history and assess the possible sources of pollution. The results showed that Fe was the most abundant element while Cd had the lowest concentration. Sediment pollution assessment was carried out for the top layer using geoaccumulation index (Igeo), enrichment factor and contamination factor. EF values showed moderate to significant enrichment of heavy metals

Synthesis and Characterization of Single Phase ZnO Nanostructures Via Solvothermal Method : Influence of Alkaline Source

Single phase ZnO nanostructures were synthesized by a simple and low temperature solvothennal process from two different alkaline sources; Potassium hydroxide (KOH) and Sodium hydroxide (NaOH) with zinc acetate dihydrate (Zn(CH3COO)2·2H20) as precursor. This facile and rapid synthesis technique achieve high purity of Zinc oxide (ZnO) nanostructures in large scale negating the use of complex and high temperature routes. The synthesized particles were characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), Fourier Transfonn Infrared (FT-IR) Spectroscopy, and Ultraviolet Visible (UV-Vis) spectroscopy. ZnO synthesized using KOH and NaOH exhibit wurtzite hexagonal and flake-like nanostructures with average crystallite size of 11.0 nm and 14.9 nm respectively. The optical absorption spectra of the two samples showed absorption bands of 367.70 and 365.30 nm. The results showed the effect of alkaline sources on the surface morphology, structural and optical properties of ZnO

Biosynthesis, characterization, and antibacterial activity of ZnO nanoaggregates using aqueous extract from Anacardium occidentale leaf: comparative study of different precursors

Background Various parts of Anacardium occidentale plant possess curative qualities like antidiabetic, anti-inflammatory, antibacterial, antifungal, and antioxidant. Aqueous extract of this plant leaf was used in biosynthesizing zinc oxide (ZnO) nanoaggregates using two precursors of zinc salt (zinc acetate dihydrate [Zn(CH3COO)2∙2H2O] and zinc chloride [ZnCl2]). The synthesized ZnO samples were used in a comparative study to investigate the antibacterial activity against selected Gram-positive and Gram-negative microbes [Staphylococcus aureus, Exiguobacterium aquaticum (Gram +ve) and Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii (Gram −ve)]. The synthesized ZnO nanoaggregates from the two precursors were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDX) techniques. Results Micrographs of SEM and TEM confirmed nanoparticles agglomerated into aggregates. While spherical nanoaggregates were identified in samples prepared from Zn(CH3COO)2∙2H2O, flake-like structures were identified in samples synthesized from ZnCl2. Particle size determined by TEM was 107.03 ± 1.54 nm and 206.58 ± 1.86 nm for zinc acetate dihydrate and zinc chloride precursors respectively. ZnO nanoaggregate synthesized using zinc acetate as precursor gave higher antibacterial activity than its counterpart, zinc chloride with K. pneumonia recording the highest inhibition zone of 2.08 ± 0.03 mm (67.53%) whereas S. aureus recorded the least inhibition zone of 1.06 ± 0.14 mm (34.75%) for ZnO nanoaggregate from zinc chloride precursor. Also, antibacterial activity increases with increasing concentration of the extract in general. However, A. baumannii, E. aquaticum, and K. pneumoniae did not follow the continuity trend with regards to the 250 ppm and 500 ppm concentrations. Conclusion Biosynthesis of ZnO nanoaggregates using aqueous extract of A. occidentale leaf from zinc acetate dihydrate and zinc chloride as precursors was successful with the formation of nanospheres and nanoflakes. The study suggested that A. occidentale sp. could be an alternative source for the production of ZnO nanoparticles and are efficient antibacterial compounds against both Gram +ve and Gram −ve microbes with its promising effect against infectious bacteria

Distribution and Sources of Aliphatic Hydrocarbons in Sediments from Sadong River, Sarawak, Malaysia

Twenty-one surface sediment samples collected from Sadong River, Sarawak were analysed for aliphatic hydrocarbons. These hydrocarbons were recovered from sediment by Soxhlet extraction and then analysed using gas chromatography equipped with mass spectrometer (GC-MS). The sediments collected from Sadong River have high concentrations of total aliphatic hydrocarbons which ranged from 310.41 to 1296.43 g/g. Evaluation of various n-alkane indices such carbon preference index (CPI: 1.32 to 1.98) and average chain length (ACL: 26.26-27.19) showed that there was a predominance of petrogenic sources of n-alkanes in the river and biogenic origin n-alkanes from vascular plants. The petrogenic source of n-alkanes are predominantly heavy and degraded oil with fresh oil inputs. It is believed that the hydrocarbons originated from both natural and anthropogenic sources. The hydrocarbons were mostly transferred by lateral input than atmospheric movements

Synthesis, Characterization, and Antibacterial Activity of ZnO Nanoparticles from Organic Extract of Cola Nitida and Cola Acuminata Leaf

The study aimed at the synthesis and antibacterial activity of ZnO nanoparticles (NPs) from organic extracts of Cola nitida and Cola acuminata leaf using zinc chloride (ZnCl2) and zinc acetate dihydrate [Zn(CH3COO)2∙2H2O] as precursors on selected Gram positive and Gram negative microbes: Staphylococcus aureus, Exiguobacterium aquaticum, (Gram +ve) and Escherichia coli, Klebsielia pneumonia, Acinetobacter baumanni (Gram –ve). Spherical and flake-like nanostructures were recorded by Scanning Electron Microscopy (SEM) for C. acuminata and C. nitida respectively for the two precursors used. The average particle size and crystallite size determined by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) for C. acuminata and C. nitida were in the range of 32.15-43.26 nm; 69.12-84.26 nm and 14.69-17.12 nm; 23.68-23.96 nm respectively. Energy-dispersive X-ray spectroscopy (EDX), UV- visible spectroscopy (UV-vis), Atomic Absorption Spectroscopy (AAS) and Fourier-transform infrared spectroscopy (FT-IR) techniques were used to observe the purity and surface functional groups of the samples. Spectra peaks at 440-458 cm-1 and 364-370 nm confirmed the presence of ZnO in the samples by FT-IR and UV-vis, whereas AAS at 213.9 nm wavelength further confirmed elemental zinc with a percentage atomic weight of 71.37% as against 69.50%, 18.8% and 11.1% for Zinc, Oxygen and Carbon by EDX. Data from the antibacterial activity studies show an increase in inhibition rate as concentration of the ZnO NPs increases in concentration from 25-1000 ppm. ZnO NPs from the two extracts recorded the highest inhibition rate in Acinetobacter baumanni of approximately 88% and 49% using ZnCl2 and Zn(CH3COO)2∙2H2O respectively

Synthesis, Characterization, and Antibacterial Activity of ZnO Nanoparticlesfrom Organic Extract of Cola Nitida and Cola Acuminata Leaf

The study aimed at the synthesis and antibacterial activity of ZnO nanoparticles (NPs) from organic extracts of Cola nitida and Cola acuminata leaf using zinc chloride (ZnCl2) and zinc acetate dihydrate [Zn(CH3COO)2∙2H2O] as precursors on selected Gram positive and Gram negative microbes: Staphylococcus aureus, Exiguobacterium aquaticum, (Gram +ve) and Escherichia coli, Klebsielia pneumonia, Acinetobacter baumanni (Gram –ve). Spherical and flake-like nanostructures were recorded by Scanning Electron Microscopy (SEM) for C. acuminata and C. nitida respectively for the two precursors used. The average particle size and crystallite size determined by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) for C. acuminata and C. nitida were in the range of 32.15-43.26 nm; 69.12-84.26 nm and 14.69-17.12 nm; 23.68-23.96nm respectively. Energy-dispersive X-ray spectroscopy (EDX), UV-visible spectroscopy (UV-vis), Atomic Absorption Spectroscopy (AAS) and Fourier-transform infrared spectroscopy (FT-IR) techniques were used to observe the purity and surface functional groups of the samples. Spectra peaks at 440-458 cm-1and 364-370 nm confirmed the presence of ZnO in the samples by FT-IR and UV-vis, whereas AAS at 213.9 nm wavelength further confirmed elemental zinc with a percentage atomic weight of 71.37% as against 69.50%, 18.8% and 11.1% for Zinc, Oxygen and Carbon by EDX. Data from the antibacterial activity studies show an increase in inhibition rate as concentration of the ZnO NPs increases in concentration from 25-1000 ppm. ZnO NPs from the two extracts recorded the highest inhibition rate in Acinetobacter baumanni of approximately 88% and 49% using ZnCl2and Zn(CH3COO)2∙2H2O respectively

Validation of an analytical technique, distribution, and risk assessment of aliphatic and polycyclic aromatic hydrocarbons in surface sediments of the coastal and selected estuaries of Sarawak

This study explains a validation of an analytical technique, monitoring, and risk evaluation of hydrocarbons in surface sediments of the coastal and selected estuaries of Sarawak, Malaysia. The performance of an analytical methodology was validated for the evaluation of hydrocarbons in coastal and estuaries sediment samples. After the clean-up and separation process, GC-FID and GC-MS were used to quantify aliphatic and polycyclic aromatic hydrocarbon extracts, respectively. The suggested methodology is able to measure aliphatic and polycyclic aromatic hydrocarbons in samples at lower concentrations for example 10 ng/g. The precision of the technique was satisfactory as compared to 15% for most of the analytes. This method gives information concerning the distribution and characteristics of hydrocarbon contaminants in the coastal environment. In regard to monitoring and risk assessment, total n-alkane concentrations (C10–C33) varied from 96.63 to 367.28 ng/g dw. The lowest and highest nalkane content is observed at Santubong estuary (CZ10) and the coastal site CZ2, respectively. Simultaneously, the contents of ∑PAHs varied from 12.54 to 21.20 ng/g dw. The highest ∑PAH content is reported in the sediments of coastal site CZ8 (21.20 ng/g dw), whereas the lowest content is recorded in the sediments of coastal site CZ3 (12.54 ng/g dw). The outcome of the risk assessment suggested that there is no risk in all the studied locations. The findings from this study will help to understand the sources and possible risks of hydrocarbons in the coastal and estuary settings, and provide information for safeguarding human health and aquatic bodies in the studied area

Eco-toxic risk assessment and source distribution of trace metals in surface sediments of the coastal and in four rivers estuary of Sarawak

Background: Trace metals pollution in the coastal and estuarine sediment could harm water quality and aquatic organisms, leading to potential long-term health risks on the environment and humans. Thus, the purpose of this study was to conduct an assessment of selected trace metals in surface sediments of the coastal and in four rivers estuary in the Sarawak State of Malaysia to investigate their distribution, environmental risk, and potential source distribution. Results: Average concentrations of trace metals in sediment increased in the following order: Cd ˂ As ˂ Co ˂ Cu ˂ Ni ˂ Cr ˂ Zn ˂ Mn ˂ Mg ˂ Fe. The enrichment, contamination, and geo-accumulation index results showed that surface sediments were polluted with Zn and Mg. In contrast, the other metals (i.e., As, Fe, Mn, Ni, Cr, Cu, Co, and Cd) indicated background concentration to minor contamination. Generally, the pollution load index values showed that almost all the sampling sites were unpolluted with the selected trace metals. Sediment quality guidelines (SQGs) and risk indexes were employed to assess the ecotoxicological risk of trace metal contamination in the sediments. The results proved that studied trace metals are not likely to have a deleterious impact on bottom-dwelling organisms. Still, a further accumulation of trace metals such as Zn, Ni, and Cr with time may adversely afect bottom-dwelling organisms. The risk index results showed a low ecological risk to the study sites. The correlation analysis and principal component analysis indicated that nine studied trace metals have strong interrelationships, suggesting common pollution sources or similar geochemical characteristics. Conclusions: The study highlights the need to make tremendous eforts to monitor and control trace metal pollution in the coastal and estuarine area