Mercury emission into the atmosphere is a global concern due to its detrimental effects on human health in general. The two main sources of mercury emission are natural sources and anthropogenic sources. Mercury emission from natural sources include volcanic activity, weathering of rocks, water movement and biological processes which are obviously inevitable. The anthropogenic sources of mercury emission are from coal combustion, cement production and waste incineration. Thus, in order to reduce mercury emission it is appropriate to investigate how mercury is released from the anthropogenic sources and consequently the mercury removal technology that can be implemented in order to reduce mercury emission into the atmosphere. Many alternatives have been developed to reduce mercury emission and the recent application of activated carbon showed high potential in the adsorption of elemental mercury. This paper discusses the ability of activated carbon and variable parameters that influence mercury removal efficiency in flue gas.
Mercury contamination, especially of seafood, continues to attract public concern. Cysteine, NH2CH(CH2SH)COOH, is a naturally occurring hydrophobic amino acid that contains a thiol group. The purpose of our study was to investigate the use of the additive cysteine in fish diets to reduce mercury concentration in fish, and to observe the effectiveness of dietary cysteine in fish livers. Diets containing 1% and 10% cysteine successfully decreased mercury concentrations in fish compared with the 0% cysteine diet. The liver may have formed excessive lipid droplets or was unable to mobilize lipid stores during exposure to mercury; additional cysteine could help to mobilize excessive lipids in it.
Toxic elements such as mercury, arsenic, cadmium, and lead, sometimes called heavy metals, can diminish mental and central nervous system function; elicit damage to blood composition as well as the kidneys, lungs, and liver; and reduce energy levels. Food is considered one of the main routes of their entry into the human body. Numerous studies have been performed to examine the effects of common food processing procedures on the levels of toxic elements in food. While some studies have reported negative effects of processing, several have shown that processing practices may have a positive effect on the reduction of toxic elements in foodstuffs. A number of studies have also introduced protocols and suggested chemical agents that reduce the amount of toxic elements in the final food products. In this review, the reported methods employed for the reduction of toxic elements are discussed with particular emphasis on the chemical binding of both the organic and inorganic forms of each element in various foods. The molecular groups and the ligands by which the food products bind with the metals and the types of these reactions are also presented.
In this study, a potentiometric sensor composed of palm shell activated carbon modified with trioctylmethylammonium thiosalicylate (TOMATS) was used for the potentiometric determination of mercury ions in water samples. The proposed potentiometric sensor has good operating characteristics towards Hg (II), including a relatively high selectivity; a Nernstian response to Hg (II) ions in a concentration range of 1.0 × 10(-9) to 1.0 × 10(-2) M, with a detection limit of 1 × 10(-10) M and a slope of 44.08 ± 1.0 mV/decade; and a fast response time (~5 s). No significant changes in electrode potential were observed when the pH was varied over the range of 3-9. Additionally, the proposed electrode was characterized by good selectivity towards Hg (II) and no significant interferences from other cationic or anionic species.
Extraction of protease from a local ginger rhizome (Zingiber officinale var. Bentong) was carried out. The effect of extraction pH (6.4, 6.8, 7.0, 7.2, 7.6, 8.0, 8.4, and 8.8) and stabilizers (0.2% ascorbic acid, 0.2% ascorbic acid and 5 mM EDTA, or 10 mM cysteine and 5 mM EDTA) on protease activity during extraction was examined. pH 7.0 potassium phosphate buffer and 10 mM cysteine in combination with 5 mM EDTA as stabilizer were found to be the most effective conditions. The extraction procedure yielded 0.73% of Bentong ginger protease (BGP) with a specific activity of 24.8±0.2 U/mg protein. Inhibitory tests with some protease inhibitors classified the enzyme as a cysteine protease. The protease showed optimum activity at 60 °C and pH 6-8, respectively. The enzyme was completely inhibited by heavy metal cations such as Cu2+, and Hg2+. SDS stimulated the activity of enzyme, while emulsifiers (Tween 80 and Tween 20) slightly reduced its activity. The kinetic analysis showed that the protease has Km and Vmax values of 0.21 mg mL-1 and 34.48 mg mL-1 min-1, respectively. The dried enzyme retained its activity for 22 months when stored at -20 °C.
In large man-made reservoirs such as those resulting from hydroelectric dam construction, bacteria transform the relatively harmless inorganic mercury naturally present in soil and the submerged plant matter into toxic methylmercury. Methylmercury then enters food webs and can accumulate in organisms at higher trophic levels. Bats feeding on insects emerging from aquatic systems can show accumulation of mercury consumed through their insect prey. In this study, we investigated whether the concentration of mercury in the fur of insectivorous bat species was significantly higher than that in the fur of frugivorous bat species, sampled near hydroelectric reservoirs in Peninsular Malaysia. Bats were sampled at Temenggor Lake and Kenyir Lake and fur samples from the most abundant genera of the two feeding guilds-insectivorous (Hipposideros and Rhinolophus) and frugivorous (Cynopterus and Megaerops) were collected for mercury analysis. We found significantly higher concentrations of total mercury in the fur of insectivorous bats. Mercury concentrations also differed significantly between insectivorous bats sampled at the two sites, with bats from Kenyir Lake, the younger reservoir, showing higher mercury concentrations, and between the insectivorous genera, with Hipposideros bats showing higher mercury concentrations. Ten bats (H. cf. larvatus) sampled at Kenyir Lake had mercury concentrations approaching or exceeding 10 mg/kg, which is the threshold at which detrimental effects occur in humans, bats and mice.
This study aims to optimise the operating conditions for the supercritical fluid extraction (SFE) of toxic elements from fish oil. The SFE operating parameters of pressure, temperature, CO2 flow rate and extraction time were optimised using a central composite design (CCD) of response surface methodology (RSM). High coefficients of determination (R²) (0.897-0.988) for the predicted response surface models confirmed a satisfactory adjustment of the polynomial regression models with the operation conditions. The results showed that the linear and quadratic terms of pressure and temperature were the most significant (p < 0.05) variables affecting the overall responses. The optimum conditions for the simultaneous elimination of toxic elements comprised a pressure of 61 MPa, a temperature of 39.8ºC, a CO₂ flow rate of 3.7 ml min⁻¹ and an extraction time of 4 h. These optimised SFE conditions were able to produce fish oil with the contents of lead, cadmium, arsenic and mercury reduced by up to 98.3%, 96.1%, 94.9% and 93.7%, respectively. The fish oil extracted under the optimised SFE operating conditions was of good quality in terms of its fatty acid constituents.
Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°.
Introduction: Heavy metals and other contaminants in food have been a concern to food industries, consumers and governing authorities. The purpose of this study was to determine the levels of heavy metals and other elements in edible bird nests (EBNs). Methods: Raw and processed (commercial) EBNs were used in the study. Raw EBNs were collected directly from five house farms in Peninsular Malaysia - Kuala Sanglang (Kedah), Pantai Remis (Perak), Kluang Gohor), Kota Bharu (Kelantan) and Kajang (Selangor). Processed EBNs were pmchased from five Chinese traditional medicinal shops located in Peninsular Malaysia. The levels of 32 elements were determined by inductively coupled plasma-mass spectrometry and findings of the study were compared to the maximum regulatory limits set by the Standards and Industrial Research Institute of Malaysia (SIRIM) for EBNs. Results: Of the seven elements with maximum regulatory limits (As, Cd, Pb, Hg, Sn, Cu, Fe), one raw EBN was detected with mercury level of 70.180 ppb which was above the SIRIM permissible limit of 50 ppb. All the EBNs had iron levels above the SIRIM permissible limit of 30 ppb. The levels of the other 25 elements with no maximum regulatory limits (Ca, Mg, Na, K, P, Co, Cr, Mn, Mo, Se, Zn, Ag, Ba, Be, Bi, B, Li, Ni, Sb, Sr, Ti, U, V, Al, Zr) were also determined. Conclusion: The data obtained for the 25 elements with no permissible limits can serve as baseline data for further studies to establish their maximum regulatory limits.
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).
Unripe and ripe kundang fruits (Bouea macrophylla Griffith) is either consumed fresh or is cooked in Malaysia. In this study composition of unripe and ripe fruits (proximate, amino acids profile, minerals and heavy metal contents) were evaluated. Results obtained showed unripe kundang fruit to possess higher moisture, ash, crude lipid, crude fiber and crude protein contents than the ripe fruits. With regard to amino acid contents, unripe fruits had higher content of essential amino acids. The unripe and ripe fruits were found to be rich in essential minerals with potassium (K) to be in abundance. Heavy metals such as cadmium, nickel, mercury, lead and arsenic, were detected in trace amounts (< 5.0 mg/kg) in both unripe and ripe fruits. Through this investigation, it is concluded that both unripe and ripe fruits to posses’ adequate amount of nutritionally important compounds beneficial to human health and can be explored for commercial purposes.
Minamata disease is a well-known mercury contamination that happened in Japan in 1953. Due to demand during world war, second mercury disaster occurred in Niigata Prefecture in 1965. This is a review on the Niigata Minamata disease based on available documents and local expert opinions on the disaster. The aims of this paper are to record exposure history like the source of mercury in Agano River and specific fish that was associated with the disease. It is for an appraisal of the basic mercury exposure control, particularly to protect Japanese and world population during that time. There was indication that initial exposure limit for mercury was calculated incorrectly, and higher safe dose was applied. This epidemiological study is very useful and significant in comprehend the correct estimation of the human exposure to any hazardous substances.
Matched MeSH terms: Mercury; Mercury Poisoning, Nervous System
Blood pressure (BP) measurement was first recorded in 1700's by Hales who concluded that it was due to a pressure in the blood (1 , 2]. This is his well renowned discovery besides his other experiments on the capacity of ventricles and many other feature of circulatory system. The development of BP measurement was then rather quiet until about a century later. The accurate study of BP started with the introduction of mercury manometer by Poiseuille in 1800's who demonstrated that the arterial pressure was maintained in smaller arteries and that the blood flow through mesenteric bed did not depend on development of the venous change but varied directly with arterial pressure [3]. In the year of 1928, Poiseuille work was recognised when he won the gold medal of Royal Academy of Medicine for his doctoral dissertation on the measurement of BP using mercury manometer that was directly inserted with cannula filled with potassium bicarbonate as anticoagulant into an artery [3]. Later, his invention has enabled Carl Ludwig to develop kymograph, a method to record clinical physiological data including the BP measurements [3]. (Copied from article).
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.
Sediment is a great indicator for assessing coastal mercury contamination. This work profiled the magnitude of mercury pollution in the tropical estuaries and coastal sediments of the Strait of Malacca. Mercury was extracted through the ultrasound-assisted mercury extraction method and analyzed using the flow injection mercury system. The mean concentration of mercury in the sediment samples was 61.43 ± 23.25 μg/kg, ranging from 16.55 ± 0.61 to 114.02 ± 1.54 μg/kg. Geoaccumulation index revealed that a total of 13% of sampling sites were moderately enriched with mercury. The northern part of the Strait of Malacca had the highest mean mercury (Hg) concentration (76.36 ± 27.25 μg/kg), followed by the southern (64.59 ± 16.09 μg/kg) and central (39.33 ± 12.91 μg/kg) parts. Sediment mercury concentration in the current study was lower than other regions like Japan, China, Indian, east Mediterranean, and Taiwan. When compared to the Canadian interim marine and freshwater sediment, China's soil interim environmental guidelines, mercury contamination in the Strait of Malacca was found to be below these permissible limits. Sediment organic matter content was found to have significant correlation with sediment mercury concentration. This study could provide the latest benchmark of mercury pollution and prove beneficial to future pollution studies in relation to monitoring works in tropical estuaries and coastal sediments.
The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.
High-quality fish oil for human consumption requires low levels of toxic elements. The aim of this study was to compare different oil extraction methods to identify the most efficient method for extracting fish oil of high quality with the least contamination. The methods used in this study were Soxhlet extraction, enzymatic extraction, wet reduction, and supercritical fluid extraction. The results showed that toxic elements in fish oil could be reduced using supercritical CO2 at a modest temperature (60°C) and pressure (35 MPa) with little reduction in the oil yield. There were significant reductions in mercury (85 to 100%), cadmium (97 to 100%), and lead (100%) content of the fish oil extracted using the supercritical fluid extraction method. The fish oil extracted using conventional methods contained toxic elements at levels much higher than the accepted limits of 0.1 μg/g.
This study was conducted to determine the concentration of total mercury in the edible portion of 46 species of marine fish (n = 297) collected from selected major fish landing ports and wholesale markets throughout Peninsular Malaysia. Samples were collected in June to December 2009. Prior to analysis, the fish samples were processed which consisted of drying at 65 °C until a constant weight was attained; then, it was grounded and digested by a microwave digestion system. The analytical determination was carried out by using a mercury analysis system. Total mercury concentration among fish species was examined. The results showed that mercury concentrations were found significantly higher (p 20 cm) and were positively related with fish size (length and weight) in all fish samples. Despite the results, the level of mercury in marine fish did not exceed the permitted levels of Malaysian and JECFA guideline values at 0.5 mg/kg methylmercury in fish.
WO₃-decorated TiO₂ nanotube arrays were successfully synthesized using an in situ anodization method in ethylene glycol electrolyte with dissolved H₂O₂ and ammonium fluoride in amounts ranging from 0 to 0.5 wt %. Anodization was carried out at a voltage of 40 V for a duration of 60 min. By using the less stable tungsten as the cathode material instead of the conventionally used platinum electrode, tungsten will form dissolved ions (W(6+)) in the electrolyte which will then move toward the titanium foil and form a coherent deposit on the titanium foil. The fluoride ion content was controlled to determine the optimum chemical dissolution rate of TiO₂ during anodization to produce a uniform nanotubular structure of TiO₂ film. Nanotube arrays were then characterized using FESEM, EDAX, XRD, as well as Raman spectroscopy. Based on the FESEM images obtained, nanotube arrays with an average pore diameter of up to 65 nm and a length of 1.8 µm were produced. The tungsten element in the samples was confirmed by EDAX results which showed varying tungsten content from 0.22 to 2.30 at%. XRD and Raman results showed the anatase phase of TiO₂ after calcination at 400 °C for 4 h in air atmosphere. The mercury removal efficiency of the nanotube arrays was investigated by photoirradiating samples dipped in mercury chloride solution with TUV (Tube ultraviolet) 96W UV-B Germicidal light. The nanotubes with the highest aspect ratio (15.9) and geometric surface area factor (92.0) exhibited the best mercury removal performance due to a larger active surface area, which enables more Hg(2+) to adsorb onto the catalyst surface to undergo reduction to Hg⁰. The incorporation of WO₃ species onto TiO₂ nanotubes also improved the mercury removal performance due to improved charge separation and decreased charge carrier recombination because of the charge transfer from the conduction band of TiO₂ to the conduction band of WO₃.
Samples of mangrove snails Nerita lineata and surface sediments were collected from nine geographical sampling sites in Peninsular Malaysia to determine the concentrations of eight metals. For the soft tissues, the ranges of metal concentrations (μg g(-1) dry weight (dw)) were 3.49-9.02 for As, 0.69-6.25 for Cd, 6.33-25.82 for Cu, 0.71-6.53 for Cr, 221-1285 for Fe, 1.03-50.47 for Pb, and 102.7-130.7 for Zn while Hg as 4.00-64.0 μg kg(-1) dw(-1). For sediments, the ranges were 21.81-59.49 for As, 1.11-2.00 for Cd, 5.59-28.71 for Cu, 18.93-62.91 for Cr, 12973-48916 for Fe, 25.36-172.57 for Pb, and 29.35-130.34 for Zn while for Hg as 2.66-312 μg kg(-1) dw(-1). To determine the ecological risks on the surface habitat sediments, sediment quality guidelines (SQGs), the geochemical indices, and potential ecological risk index (PERI) were used. Based on the SQGs, all the metals investigated were most unlikely to cause any adverse effects. Based on geoaccumulation index and enrichment factor, the sediments were also not polluted by the studied metals. The PERI values based on As, Cd, Cu, Cr, Hg, Pb and Zn in this study were found as 'low ecological risk'. In order to assess the potential health risks, the estimated daily intakes (EDI) of snails were found to be all lower than the RfD guidelines for all metals, except for Pb in some sites investigated. Furthermore, the calculated target hazard quotients (THQ) were found to be less than 1. However, the calculated total target hazard quotients (TTHQ) from all sites were found to be more than 1 for high level consumers except KPPuteh. Therefore, moderate amount of intake is advisable to avoid human health risks to the consumers.