A study had been carried out to determine Cu, Zn, Cd, Hg and Pb concentrations in the muscle and fins of four elasmobranchs species namely spot-tail sharks, milk sharks, whitespotted bamboo sharks and whitespotted guitarfish from Pulau Kambing LKIM Fishery Complex, Kuala Terengganu, Malaysia. Zinc level was found to have the highest concentration whereas Cd had the lowest concentration in both organs. By comparing both organs, metals concentrations in fins of all elasmobranchs species were higher than muscle. Result obtained was compared with the guidelines set by Malaysian Food Regulation and the provisional tolerable weekly intake was also determined. Current study recommends that the muscle of whitespotted bamboo shark from Kuala Terengganu Waters is likely not to be consumed due to it exceeded the allowable consumption guideline. Finding of this paper is very useful as it provides the baseline data on the pollution status of elasmobranchs in Kuala Terengganu Waters.
In this research, we modify a previously developed assay for the quantification molybdenum blue to determine whether inhibitors to molybdate reduction in bacteria inhibits cellular reduction or inhibit the chemical formation of one of the intermediate of molybdenum blue; phosphomolybdate. We manage to prove that inhibition of molybdate reduction by phosphate and arsenate is at the level of phosphomolybdate and not cellular. We also prove that mercury is a physiological inhibitor to molybdate reduction. We suggest the use of this method to assess the effect of inhibitors and activators to molybdate reduction in bacteria.
Muscle, stomach and gill from four dominant fish species, Mytus nemurus, Pristolepis fasciata, Ompok bimaculatus and Osteochilus hasseltii, caught from Bebar peat swamp forest river were analyzed for mercury (Hg). The concentration of Hg was measured with a fast and sensitive Flow Injector Mercury Spectrometer (FIMS). The average Hg concentration of all species caught was 0.169 microg g(-1) dry weights, lower than a limit for human consumption recommended by the World Health Organization, 0.5 microg g(-1) dry weights. The mean concentration of Hg was relatively high in stomach (0.28 +/- 0.12 microg g(-1) dry weights) followed by gill (0.17 +/- 0.06 microg g(-1) dry weights) and lowest in muscle (0.05 +/- 0.02 microg g(-1) dry weights). The positive relationship of Hg with fish length and weight suggesting that the accumulation of Hg were formed in the fish.
It is important to monitor the concentration of toxic metals in the Sungai Kuantan as it serves many communities in terms of domestic, fisheries and agriculture purpose. In order to determine the distributions of dissolved and particulate As and Hg in Sungai Kuantan and evaluate its changes temporally and spatially, water samples were collected from the surface and bottom layers in a grid of 9 stations from estuary towards the upstream of Sungai Kuantan from May 2012 till October 2012. The dissolved metals were pre-concentrated using Chelex-100 while particulate metals were digested using Teflon bomb and subsequently were analyzed using ICP-MS. Dissolved As ranging from 4.650 to 36.894 µg L-1 while dissolved Hg ranging from BDL to 0.011 µg L-1. Particulate As and Hg varied from 0.650 to 86.087 mg L-1 and BDL to 5.873 mg L-1, respectively. Higher concentration of the dissolved elements were found mainly in October 2012 and particulate elements concentration mostly higher in May 2012. The source of the studied metals in the river may be the run-off from the effluent discharges and other natural sources. The toxic elements studied in Sungai Kuantan waters were still below the Interim Marine Water Quality Standard (INWQS) permissible limits.
The selected trace metals in the soft tissue of Thais clavigera from 11 sampling sites along the coastal waters of the east coast of Peninsular Malaysia were studied. Significant inter-spatial variations in trace metals were recorded. Sites with relatively high concentrations of the contaminant metals Hg, Cd, Pb and Zn are correlated to their close proximity to industrial and urban sites or to boating and aquaculture activities. This could possibly be contributed by the high growth of industrial activities like port and sewage release. Interspatial comparison with previous studies indicated lower measurement. Meanwhile, comparison with other studies around the world also designated lower values except for Zn. The metal accumulation patterns indicated an enrichment of essential metals over non-essential metals. Comparison of metal concentration with maximum permissible limits of toxic metals in food established in different countries, as well as Malaysian Food Act 1983 and Food Regulations 1985 Fourteen Schedule, indicated the values were well within safety levels.
An effective organoalkoxysilanes-grafted lignocellulosic waste biomass (OS-LWB) adsorbent aiming for high removal towards inorganic and organic mercury (Hg(II) and MeHg(II)) ions was prepared. Organoalkoxysilanes (OS) namely mercaptoproyltriethoxylsilane (MPTES), aminopropyltriethoxylsilane (APTES), aminoethylaminopropyltriethoxylsilane (AEPTES), bis(triethoxysilylpropyl) tetrasulfide (BTESPT), methacrylopropyltrimethoxylsilane (MPS) and ureidopropyltriethoxylsilane (URS) were grafted onto the LWB using the same conditions. The MPTES grafted lignocellulosic waste biomass (MPTES-LWB) showed the highest adsorption capacity towards both mercury ions. The adsorption behavior of inorganic and organic mercury ions (Hg(II) and MeHg(II)) in batch adsorption studies shows that it was independent with pH of the solutions and dependent on initial concentration, temperature and contact time. The maximum adsorption capacity of Hg(II) was greater than MeHg(II) which respectively followed the Temkin and Langmuir models. The kinetic data analysis showed that the adsorptions of Hg(II) and MeHg(II) onto MPTES-LWB were respectively controlled by the physical process of film diffusion and the chemical process of physisorption interactions. The overall mechanism of Hg(II) and MeHg(II) adsorption was a combination of diffusion and chemical interaction mechanisms. Regeneration results were very encouraging especially for the Hg(II); this therefore further demonstrated the potential application of organosilane-grafted lignocellulosic waste biomass as low-cost adsorbents for mercury removal process.
The presence of heavy metal in food chains due to the rapid industrialization poses a serious threat on the environment. Therefore, detection and monitoring of heavy metals contamination are gaining more attention nowadays. However, the current analytical methods (based on spectroscopy) for the detection of heavy metal contamination are often very expensive, tedious and can only be handled by trained personnel. DNA biosensors, which are based on electrochemical transduction, is a sensitive but inexpensive method of detection. The principles, sensitivity, selectivity and challenges of electrochemical biosensors are discussed in this review. This review also highlights the major advances of DNA-based electrochemical biosensors for the detection of heavy metal ions such as Hg(2+), Ag(+), Cu(2+) and Pb(2+).
In the present study, ion imprinted polymer monoliths (IIPMs) were developed to overcome the limitations of ion imprinted polymer particles (IIPPs) used for the removal of Hg(II) ions from waste water samples. The adsorbents preparation, characterization and Hg(II) removal were very well reported. The IIPMs on porogen optimization was prepared using the molding technique with Hg(II) as a template ion, [2-(methacryloyloxy)ethyl]trimethylammonium cysteine (MAETC) as ligand, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylamide (EGDMA) as cross-linker, benzoyl peroxide as an initiator and methanol and acetonitrile as porogen in the polypropylene tube (drinking straw) as mold. The IIPMs prepared with higher volumes of porogen were indicated to have a good adsorption rate for the Hg(II) removal along with good water permeability and larger porosity as compared to a lower volume of porogen. The IIPMs prepared using the binary porogen were able to improve the porosity and surface area of the monolithic polymers as compared to the single porogen added IIPMs. Finally, we indicate from our analysis that the IIPM having the efficient capacity for the Hg(II) ions is easy to prepare, and has higher water permeability along with high porosity and high adsorption capacity and all these factors making it one of the suitable adsorbent for the successful removal of Hg(II) ions.
This study applied the use of sequential extraction technique and simple bioaccessibility extraction test to quantify the bioavailable fractions and the human bioaccessible concentration of metals collected from nine stations in surface sediment of the Langat River. The concentrations of total and bioaccessible metals from different stations were in the range of 0.49-1.04, 0.10-0.32 μg g-1 for T-Cd, Bio-Cd, respectively, and 12.9-128.03, 2.06-8.53 μg kg-1 for T-Hg, Bio-Hg, respectively. The results revealed highest R-Bio-Cd in Banting station (55.3 %), while the highest R-Bio-Hg was in Kajang station (49.61 %). The chemical speciation of Cd in most sampling stations was in the order of oxidisable-organic > residual > exchangeable > acid-reducible, while speciation of Hg was in the order of exchangeable > residual > oxidisable-organic > acid-reducible. The correlation matric of mean content showed that the TOM, particle size and Mg++ in polluted surface sediments was highly correlated with total mercury. The PCA showed that the main factors influencing the bioaccessibility of Hg in surface sediments were the sediment TOM, F1 (EFLE) and F3 (oxidation-organic), while the factor influencing the bioaccessibility of Cd was the F3 (oxidation-organic) and T-Cd.
This study is to determine total mercury in edible tissues of eight species of cephalopods and 12 species of crustaceans purchased from 11 identified major fish landing ports and wet markets throughout Peninsular Malaysia. The concentration of mercury was measured by cold vapor atomic absorption spectrometry (AAS) technique using the Perkin Elmer Flow Injection Mercury System (FIMS-400). In general, the mercury levels were low with concentrations in cephalopods ranging from 0.099 to 2.715 mg/kg dry weight (or 0.0184-0.505 mg/kg wet weight) and in crustaceans ranging from 0.057 to 1.359 mg/kg dry weight (or 0.0111-0.265 mg/kg wet weight). The mercury levels showed no significant differences (P > 0.05) between species for both cephalopods and crustaceans. There was no significant correlation between mercury concentrations and the body size of individual for both groups as well. Comparisons with mercury levels obtained found from other previous studies and/or species noted that they were of the same magnitude or relatively low compared to various locations reported worldwide.
The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K2Cr2O7), silver sulfate (AgSO4), and mercury (HgSO4) sulfate in addition to large volumes of both reagents and samples. The method relies on the release of oxygen from dichromate on heating which is consumed by carbon associated with organic compounds. The method risks environmental pollution by discharging large amounts of chromium (VI) and silver and mercury sulfates. The present method used potassium monochromate (K2CrO4) to generate the K2Cr2O7 on demand in the first phase. In addition, miniaturizing the procedure to semi microanalysis decreased the consumption of reagents and samples. In the second phase, mercury sulfate was eliminated as part of the digestion mixture through the introduction of sodium bismuthate (NaBiO3) for the removal of chlorides from the sample. The modified method, the potassium monochromate closed-tube colorimetry with sodium bismuthate chloride removal (KMCC-Bi), generates the potassium dichromate on demand and eliminates mercury sulfate. The semi microanalysis procedure leads to a 60% reduction in sample volume and ≈ 33.33 and 60% reduction in monochromate and silver sulfate consumption respectively. The LOD and LOQ were 10.17 and 33.90 mg L-1 for APHA, and 4.95 and 16.95 mg L-1 for KMCC-Bi. Recovery was between 83 to 98% APHA and 92 to 104% KMCC-Bi, while the RSD (%) ranged between 0.8 to 5.0% APHA and 0.00 to 0.62% KMCC-Bi. The method was applied for the UV-Vis spectrometry determination of COD in water and wastewater. Statistics was done by MINITAB 17 or MS Excel 2016. ᅟ Graphical abstract.
An optical sensor for Hg(II) monitoring using a complex of zinc dithizonate immobilised on XAD 7 which is based on reflectance spectrophotometry has been developed in this study. Measurements were made using a kinetic approach whereby the reflectance signal is measured at a fixed time of 5 min. The sensor could be regenerated using a saturated solution of KCl in 1 M sulphuric acid. The sensor was found to have an optimum response at pH 3.0 with respective measurement repeatability and probe-to-probe reproducibility of 1.53% and 5.26%. A linear response was observed in the Hg(II) concentration range of 0.0-180.0 ppm with a calculated limit of detection (LOD) of 0.05 ppm. The results obtained for aqueous Hg(II) determination using this probe were found to be comparable with the well-established method of atomic absorption spectrometry.
Ninety-nine samples of common Chinese medicines were purchased from Chinese medical shops in Singapore and Malaysia and analyzed for mercury, lead, copper, cadmium, cobalt, iron, and nickel. The majority of these medicines were manufactured in China, Hong Kong, and Malaysia. A few of them were of Singapore and Taiwan origin. Atomic absorption method (both flame and flameless) was used for the analyses. Mercury was found to be present in high concentrations in several of the medicines that were for oral consumption.
To investigate the interaction of zinc oxide nanoparticles (ZnO NPs) with fly ash soil (FAS) for the reduction of metals from FAS by Parthenium hysterophorus were studied. The average accumulation of metals by P. hysterophorus stem were Fe 79.6%; Zn 88.5%; Cu 67.5%; Pb 93.6%; Ni 43.5% and Hg 39.4% at 5.5 g ZnO NP. The concentration of ZnO NP at 1.5 g did not affect the metals accumulation, however at 5.5 g ZnO NP showed highest metal reduction was 96.7% and at 10.5-15.5 g ZnO NP of 19.8%. The metal reduction rate was R max for Fe 16.4; Zn 21.1; Pb 41.9; Hg 19.1 was higher than Ni 6.4 and Cu 11.3 from the FAS at 5.5 g ZnO NP whereas, the reduction rate of Pb showed highest. With doses of 5.5 g ZnO NP the biomass increased upto 78%; the metal reduced upto 98.7% with the share of 100% ZnO NP from FAS. Further investigation with phytotoxicity the plant reactive oxygen species (ROS) production were affected due was mainly due to the recovery of metals from FAS (R2 = 0.99).
In this paper we have studied the acute toxicity effect of Hg on hybrid tilapia (Oreochromis niloticus). For this, the tissues of tilapia have been digested by means of acids in microwave oven and was analyzed by flameless atomic absorption spectrophotometer (FAAS). We have identified that the levels of Hg varied significantly in different tissues and the metal concentration was in the following order: liver > gills > muscles; of which the maximum level recorded for Hg was 0.799 mg/kg. We have also observed the alterations towards histopathological aspects in the gills and liver of treated fishes were studied using light and electron microscopy, subjected to the exposure of Hg for 24 h and furthermore we have also noticed the extent of the increased alterations during the 96 h of exposure to median lethal concentration LC50 (0.3 mg/L) a severe disorganization of epithelial cells and modifications of the structure of the secondary lamellae. Moreover the severity has also found to increase to sub-lethal concentration (0.03 mgHg/L) in 21 days of exposure; Liver was slightly affected by the contamination of Hg. Ultimately, histopathology is considered as a sensitive technique of bioaccumulation and for the observing the potential damage from Hg exposure.
Mercury is a toxic substance that is commonly used in skin lightening products. Various effects on humans have been observed, which affect both users and non-users. Many studies reported delayed diagnosis and treatment, even after weeks of hospitalization. The possible reasons are non-specific clinical manifestation and lack of awareness and knowledge regarding chronic mercury intoxication secondary to skin lightening products. A thorough history of mercury exposure is crucial. Physical assessment and relevant supporting tests are indicated to establish a diagnosis. Blood and urine mercury levels are an essential examination for diagnosis and monitoring of the progress and response to treatment. The primary treatment is the discontinuation of the skin lightening products. Chelation therapy is not mandatory and is usually indicated for symptomatic patients. The prognosis depends on the duration of the product use, concentration of mercury in the skin product, and the severity of clinical presentation.
A molybdenum reducing bacterium with the novel ability to decolorise the azo dye Metanil Yellow is reported. Optimal conditions for molybdenum reduction were pH 6.3 and at 34°C. Glucose was the best electron donor. Another requirement includes a narrow phosphate concentration between 2.5 and 7.5 mM. A time profile of Mo-blue production shows a lag period of approximately 12 hours, a maximum amount of Mo-blue produced at a molybdate concentration of 20 mM, and a peak production at 52 h of incubation. The heavy metals mercury, silver, copper and chromium inhibited reduction by 91.9, 82.7, 45.5 and 17.4%, respectively. A complete decolourisation of the dye Metanil Yellow at 100 and 150 mg/L occurred at day three and day six of incubations, respectively. Higher concentrations show partial degradation, with an approximately 20% decolourisation observed at 400 mg/L. The bacterium is partially identified based on biochemical analysis as Bacillus sp. strain Neni-10. The absorption spectrum of the Mo-blue suggested the compound is a reduced phosphomolybdate. The isolation of this bacterium, which shows heavy metal reduction and dye-decolorising ability, is sought after, particularly for bioremediation.
This study aimed to determine the amount of the fish (Oreachromi sp, Clarias sp. and Pangasius sutchii) consumption in Malaysia; the quantity of heavy metal residues (arsenic, cadmium, mercury and plumbum) in the fish and the level of the risk exposure. About 1440 respondents from six main production districts were randomly interviewed and the body weight of the respondents was also measured. A total of 240 ready to eat fish from food premises were also stratified randomly sampled where each sample was weighted to determine the average weight of one serving unit sold at food premises. The heavy metal residues were analyzed using Inductively Coupled Plasma–Optical Emission Spectrometer (ICP-OES) Optima 4300 DV (German). The level of heavy metals risk exposure was calculated as the percentage value of ’Provisional Tolerable Weekly Intakes’ (PTWI) and recalculated using computer programme @Risk 4.5 Excel (Palisade, USA). The result showed that 60.3% of the respondents consumed the fish. The level of heavy metal risk exposures were calculated as very low i.e. 0.14% (As), 0.31% (Cd), 0.09% (Hg) and 0.78% (Pb).