Contamination of toxic metals in P. viridis mussels has been prevalently reported; hence, health risk assessment for consuming this aquaculture product as well as the surrounding surface seawater at its harvesting sites appears relevant. Since Kampung Pasir Puteh, Pasir Gudang is the major harvesting site in Malaysia, and because the last heavy metal assessment was done in 2009, its current status remains unclear. Herein, flame atomic absorption spectrometry and flow injection mercury/hydride system were used to determine the concentrations of Pb, Cd, Cu and total Hg in P. viridis mussels and surface seawater (January-March 2015), respectively. Significantly higher concentrations of these metals were found in P. viridis mussels (p
Bacterial based remediation of environmental toxicants is a promising innovative technology
for molybdenum pollution. To date, the enzyme responsible for molybdate reduction to Moblue
from bacteria show that the Michaelis-Menten constants varies by one order of magnitude.
It is important that the constants from newer enzyme sources be characterized so that a
comparison can be made. The aim of this study is to characterize kinetically the enzyme from a
previously isolated Mo-reducing bacterium; Bacillus pumilus strain Lbna. The maximum
activity of this enzyme occurred at pH 5.5 and in between 25 and 35 oC. The Km and Vmax of
NADH were 6.646 mM and 0.057 unit/mg enzyme, while the Km and Vmax of LPPM were 3.399
mM and 0.106 unit/mg enzyme. The results showed that the enzyme activity for Bacillus
pumilus strain Lbna were inhibited by all heavy metals used. Zinc, copper, silver, chromium,
cadmium and mercury all caused more than 50% inhibition to the Mo-reducing enzyme activity
with copper being the most potent with an almost complete inhibition of enzyme activity
observed.
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.
Seawater may be contaminated by harmful substances, including toxic elements released by human activities. The present study evaluates the total mercury and methylmercury concentrations and their correlations to fish body size in longtail tuna and short-bodied mackerel from Chendring, Kuantan, at east coast and Kuala Perlis at west costs of Peninsular Malaysia during May to November 2007. Total mercury and methylmercury in muscle tissue of 69 samples of longtail tuna and short-bodied mackerel, ranged from 0.180 to 1.460 μg/g and 0.0.169-0.973 μg/g and 0.251-1.470 μg/g and 0.202-1.352, whereas the methylmercury to total mercury ratio ranged from 70% to 83%, respectively. Samples of both species from the east coast showed higher levels of mercury compared to those from west coast. In all of the locations, significant positive correlations were found between fish body weight and mercury content (R(2) > 0.470). The estimated weekly intake of total mercury and methylmercury from the consumption 66.33 g/week of short-bodied mackerel and 18.34 g/week of longtail tuna (based on local dietry survey) was found to be lower than the maximum limit of 5 and 1.5 μg/kg bodyweight established by FAO/WHO and codex, respectively.
There are many essential and non-essential elements including metals and radionuclides present in vegetables. Howeve r, the accumulation of the several metals and radionuclides might cause the contamination to vegetables itself. Green m ustard (Brasissca rapa var. Parachinesis L.) was selected to represent the vegetable in this study. Objectives of this stud y are to determine the concentration of metals and radionuclides in the samples and to calculate the enrichment factor ( EF) and also to estimate the uptake, base on biological accumulation coefficient (BAC), for the various parts of selecte d vegetables. Three farmlands in the Cameron Highlands were studied namely Bharat, Kg Raja and Bertam area. The g reen mustard and soil samples were collected during the harvest season. Samples were dried, ground and sieved prior t o analysis. Analyses for both samples were done by using X-rays Fluorescence Spectroscopy (XRF) to measure the conc entration of Fe, Zn, Hg, U and Th. The concentration of all elements in the soils is lower than their concentration in the control soil, except for Zn, U and Th. The concentration of all elements in Green Mustard is lower than their concentrat ion in the soil where it was grown. The EF values in the Brasissca rapa var. Parachinesis L are lower than 2 except for U and Th, indicating some degree of contamination due to anthropogenic activities or naturally origin. The BAC values show that Zn and Hg were accumulated in the green mustard, depending on where the plant grows.
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 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.
Chronic exposure to mercury (Hg) can lead to cumulative impairments in motor and cognitive functions including alteration in anxiety responses. Although several risk factors have been identified in recent year, little is known about the environmental factors that either due exposure toward low level of inorganic mercury that may led to the developmental disorders. The present study investigated the effects of embryonic exposure of mercury chloride on motor function and anxiety-like behavior. The embryo exposed to 6 different concentrations of HgCl2 (7.5, 15, 30, 100, 125, 250nM) at 5hpf until hatching (72hpf) in a semi-static condition. The mortality rate increased in a dose dependent manner where the chronic embryonic exposure to 100nM decreased the number of tail coiling, heartbeat, and swimming activity. Aversive stimulus was used to examine the effects of 100nM interferes with the development of anxiety-related behavior. No elevation in both thigmotaxis and avoidance response of 6dpf larvae exposed with 100nM were found. Biochemical analysis showed HgCl2 exposure affects proteins, lipids, carbohydrates and nucleic acids of the zebrafish larvae. These results showed that implication of HgCl2 on locomotor and biochemical defects affects motor performance and anxiety-like responses. Yet, the potential underlying mechanisms these responses need to be further investigated which is crucial to prevent potential hazards on the developing organism due to neurotoxicant exposure.
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.
Chemical toxins and organic contaminants such as hydrocarbons and dyes are major global
contaminants with countless tones of those chemicals are created yearly with a significant
amount release to the environment. In this work we screen the ability of a molybdenum-reducing
bacterium isolated from contaminated soil to decolorize various azo and triphenyl methane dyes
independent of molybdenum reduction. Biochemical analysis resulted in a tentative identification
of the bacterium as Enterobacter sp. strain Zeid-6. The bacterium was able to decolorize the azo
dye Orange G. The bacterium reduces molybdate to Mo-blue optimally at pH between 5.5 and
8.0 and temperatures of between 30 and 37 oC. Other requirements include a phosphate
concentration of 5 mM and a molybdate concentration of 20 mM. The absorption spectrum of the
Mo-blue produced was similar to previous Mo-reducing bacterium, and closely resembles a
reduced phosphomolybdate. Molybdenum reduction was inhibited by copper, lead, mercury and
silver which showed 36.8, 16.9, 64.9 and 67.6% inhibition to Mo-reducing activity of
Enterobacter sp. strain Zeid-6, respectively. The resultant molybdenum blue spectrum closely
resembles the spectrum of molybdenum blue from the phosphate determination method. The
ability of this bacterium to detoxify molybdenum and decolorize azo dye makes this bacterium
an important tool for bioremediation.
We identified marine fish species most preferred by women at reproductive age in Selangor, Malaysia, mercury concentrations in the fish muscles, factors predicting mercury accumulation and the potential health risk. Nineteen most preferred marine fish species were purchased (n = 175) from selected fisherman's and wholesale market. Length, weight, habitat, feeding habit and trophic level were recognised. Edible muscles were filleted, dried at 80 °C, ground on an agate mortar and digested in Multiwave 3000 using HNO3 and H2O2. Total mercury was quantified using VP90 cold vapour system with N2 carrier gas. Certified reference material DORM-4 was used to validate the results. Fish species were classified as demersal (7) and pelagic (12) or predators (11), zoo benthos (6) and planktivorous (2). Length, weight and trophic level ranged from 10.5 to 75.0 cm, 0.01 to 2.50 kg and 2.5 to 4.5, respectively. Geometric mean of total mercury ranged from 0.21 to 0.50 mg/kg; maximum in golden snapper (0.90 mg/kg). Only 9 % of the samples exceeded the JECFA recommendation. Multiple linear regression found demersal, high trophic (≥4.0) and heavier fishes to accumulate more mercury in muscles (R (2) = 27.3 %), controlling for all other factors. About 47 % of the fish samples contributed to mercury intake above the provisional tolerable level (45 μg/day). While only a small portion exceeded the JECFA fish Hg guideline, the concentration reported may be alarming for heavy consumers. Attention should be given in risk management to avoid demersal and high trophic fish, predominantly heavier ones.
Response surface methodology (RSM) was used to determine the optimum experimental conditions to extract methylmercury from fish samples for GC analysis. The influence of four variables - acid concentration (3-12 M), cysteine concentration (0.5-2% w/v), solvent volume (3-9 ml) and extraction time (10-30 min) - on recovery of methylmercury was evaluated. The detection limit for methylmercury analysis using a microelectron capture detector was 7 ng g(-1) in fish samples. The mean recovery under optimum conditions was 94%. Experimental data were adequately fitted into a second-order polynomial model with multiple regression coefficients (r(2)) of 0.977. The four variables had a significant effect (p < 0.05) on the recovery of methylmercury from a reference material (BCR-463). Optimum conditions for methylmercury extraction were found using an acid concentration of 12.2 M, cysteine concentration of 2.4%, solvent volume of 1.5 ml and extraction time of 35 min. The validation of the developed method to analyze methylmercury in fish samples exhibited good agreement with mercury content in the samples.
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.
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+).
The DCA (Drug Control Authority), Malaysia, has implemented the phase 3 registration of traditional medicines on 1 January 1992, with special emphasis on the quality, efficacy, and safety (including the presence of heavy metals) in all pharmaceutical dosage forms of traditional medicine preparations. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation, containing Tongkat Ali, were analyzed for mercury content using cold vapor atomic absorption spectrophotometer. Results showed that 36% of the above products possessed 0.52 to 5.30 ppm of mercury and, therefore, do not comply with the quality requirement for traditional medicines in Malaysia. Out of these 36 products, 5 products that possessed 1.05 to 4.41 ppm of mercury were in fact have already registered with the DCA, Malaysia. However, the rest of the products that contain 0.52 to 5.30 ppm of mercury still have not registered with the DCA, Malaysia. Although this study showed that only 64% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to mercury, they cannot be assumed safe from mercury contamination because of batch-to-batch inconsistency.
A simple single-stage approach, based on the hydrothermal technique, has been introduced to synthesize reduced graphene oxide/titanium dioxide nanocomposites. The titanium dioxide nanoparticles are formed at the same time as the graphene oxide is reduced to graphene. The triethanolamine used in the process has two roles. It acts as a reducing agent for the graphene oxide as well as a capping agent, allowing the formation of titanium dioxide nanoparticles with a narrow size distribution (~20 nm). Transmission electron micrographs show that the nanoparticles are uniformly distributed on the reduced graphene oxide nanosheet. Thermogravimetric analysis shows the nanocomposites have an enhanced thermal stability over the original components. The potential applications for this technology were demonstrated by the use of a reduced graphene oxide/titanium dioxide nanocomposite-modified glassy carbon electrode, which enhanced the electrochemical performance compared to a conventional glassy carbon electrode when interacting with mercury(II) ions in potassium chloride electrolyte.
Charcoal production activities at the Matang Mangrove Forest Reserve (MMFR) in Peninsular Malaysia have a potential to emit volatile compounds such as Hg back into the ambient environment, raising concerns on the public health and safety. The present study was aimed at analyzing Hg concentration from different plant/animal tissues and sediment samples (in total 786 samples) to understand clearly the Hg distribution at the MMFR. Leaves of Rhizophora spp. showed higher Hg concentration with an increasing trend from young, to mature, to senescent and decomposing stages, which was possibly due to accumulation of Hg over time. The low Hg concentration in Rhizophora roots and bark suggests a limited absorption from the sediments and a meagre accumulation/partitioning by the plant tissue, respectively. In the case of mangrove cockles the concentration of Hg was lower than the permissible limits for seafood consumption. Although the mangrove gastropod - Cassidula aurisfelis Bruguière had rather elevated Hg in the muscle tissue, it is still less than the environmental safely limit. Beside the chances of atmospheric deposition for Hg, the sediment samples were found to be unpolluted in nature, indicating that in general the MMFR is still safe in terms of Hg pollution.
This paper presents the results of mercury analysis on 786 abiotic (surface sediments) and biotic (plant and animal tissues) samples collected from 10 sites at Matang Mangrove Forest Reserve in Peninsular Malaysia. Sediment samples were collected at the surface level from both river bank and forest understory. Whereas plant tissues obtained from Rhizophora apiculata Blume and Rhizophora mucronata L. consisted of leaves (in four stages namely young, mature, senescent and decomposing), bark and roots (divided into xylem, cortex and epidermis), the animal samples were represented by muscle tissue of the gastropod Cassidula aurisfelis Bruguière and the cockle Tegillarca granosa L. The mercury concentration measurements were obtained through a cold vapor atomic absorption spectrometer. The core data have been analysed and interpreted in the paper "Distribution of mercury in sediments, plant and animal tissues in Matang Mangrove Forest Reserve, Malaysia" [1].
Identification of Pelargonium radula as bioindicator for mercury (Hg) detection confers a new hope for monitoring the safety of drinking water consumption. Hg, like other non-essential metals, inflicts the deterioration of biological functions in human and other creatures. In the present study, effects of Hg on the physiology and biochemical content of P. radula were undertaken to understand the occurrence of the morphological changes observed. Young leaves of P. radula were treated with different concentrations of Hg-containing solution (0.5, 1.0 and 2.0 ppb) along with controls for 4 h, prior to further analysis. Elevated Hg concentration in treatment solution significantly prompted an increased accumulation of Hg in the leaf tissues. Meanwhile, total protein, chlorophyll and low molecular mass thiol contents (cysteine, glutathione and oxidized glutathione) decreased as Hg accumulation increased. However, phytochelatin 2 productions were induced in the treated leaves, in comparison to the control. Based on these findings, it is postulated that as low as 0.5 ppb of Hg interferes with the metabolic processes of plant cells, which was reflected from the morphological changes exhibited on P. radula leaves-the colour of the Hg-treated leaves changed from green to yellowish-brown, became chlorosis and wilted. Changes in the tested characteristics of plant are closely related to the Hg-induced morphological changes on P. radula leaves, a potential bioindicator for detecting Hg in drinking water.