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Heavy metals content in paraphilometroides nemipteri from south China sea may influence level of glutathione and p38 protein expression

Sains Malaysiana, 2018;47:1393-1400.

Numerous studies have shown that parasites potentially become bio-accumulators for heavy metals. The heavy metals
content in parasite-infected fish was reported to be lower compared to the parasite non-infected fish. Evaluation of heavy
metal content in Nemipterus peronii and Paraphilometroides nemipteri was performed using ICP-OES. Our result has
shown that arsenic was the most abundance heavy metal content in muscle N. peronii and P. nemipteri, suggesting that
the parasite has the ability to accumulate heavy metals. Heavy metals were reported to induce oxidative stress where
glutathione and p38 protein may be involved. Thus, expression of the p38 protein was determined using western blot
technique and glutathione content was measured fluorometrically. The p38 expression in P. nemipteri of Pulau Kambing
was higher compared to P. nemipteri of Besut has shown that the parasite may exposed to stress. Glutathione content
showed no significant changes due to detoxification mechanism occurred in the parasite. In this study, we could conclude
that P. nemipteri could be a bio-accumulator, whereas p38 protein and glutathione as indicator of stress level in the
parasite that exposed to the heavy metals.

Matched MeSH terms: Metals, Heavy
Fulltext Marginal Gap Evaluation of Metal Onlays and Resin Nanoceramic Computer-Aided Design and Computer-Aided Manufacturing Blocks Onlays

Abdul Hamid NF, Wan Bakar WZ, Ariffin Z

Eur J Dent, 2019 Feb;13(1):17-21.
PMID: 31170751 DOI: 10.1055/s-0039-1688740

OBJECTIVE: This study was carried out to assess and compare the marginal gap of conventionally used metal onlays and new resin nanoceramic (RNC) (Lava Ultimate block) onlays.
MATERIALS AND METHODS: This is an in vitro study using two extracted sound human mandibular molars. One tooth was prepared to receive the metal onlays and another one for the RNC onlays which were fabricated using the computer-aided design and computer-aided manufacturing (CAD/CAM) technology. Twelve metals and 12 ceramic onlays were fabricated before they were placed at their respective preparation and examined under the Leica stereomicroscope, M125C (Leica Microsystems, Wetzlar, Germany) for a marginal analysis. The gap width was measured at 10 predefined landmarks which included 3 points on the buccal and lingual surfaces each and 2 points each on the mesial and distal surfaces, respectively.
STATISTICAL ANALYSIS: Mann-Whitney post hoc test was used for statistical analysis (P ≤ 0.05).
RESULTS: Overall, the RNC onlays showed significant lower marginal gap with the exception of the landmarks 5 and 6 (on distolingual) and no significant difference at landmark 7 (on midlingual). It was observed that the marginal gap were all within the clinically acceptable limit of 120 μm.
CONCLUSIONS: Based on the results obtained, it can be concluded that the RNC CAD/CAM onlays are a promising alternative to the metal onlays.

Matched MeSH terms: Metals
Synthesis of graphene flakes over recovered copper etched in ammonium persulfate solution

Nizam MK, Sebastian D, Kairi MI, Khavarian M, Mohamed AR

Sains Malaysiana, 2017;46:1039-1045.

The synthesis of high quality graphene via economic way is highly desirable for practical applications. In this study, graphene flake was successfully synthesized on Cu/MgO catalyst derived from recovered Cu via etching in ammonium persulfate solution. Recovered Cu acted as efficient active metal in Cu/MgO catalyst with good crystal structure and composition according to XRD and XRF results. FESEM, EDX, HRTEM, Raman spectroscopy and SAED analysis were carried out on the synthesized graphene. The formation of single, bilayer and few layer of graphene from Cu/MgO catalyst derived from recovered Cu was feasible.

Matched MeSH terms: Metals
Modelling for determination of fe uptake by brassica chinensis jusl var. Parachinensi (bailey) tsen & lee (flowering white cabbage)

Ahmad Mahir R, Arfah A, Rozaimah Z, Siti Adyani S, Khairiah J, Ismail B

Sains Malaysiana, 2017;46:2305-2313.

The study was conducted to determine the best model suitable for the determination of ferrum uptake in Brassica chinensis (flowering white cabbage). A nonlinear regression model was selected to determine the amount of ferrum absorbed by each part of the Brassica chinensis plant namely the leaves, stems and roots. The Levenberg-Marquardt method was used to perform the nonlinear least square fit. This method employs information on the gradients and hence requires specification of the partial derivatives. A suitable model was obtained from the exponential regression model. The polynomial model was found to be appropriate for leaves, the mono-exponential model was suitable for stems and the simple exponential model for roots. The residual plots and the normal probability plots from each of the models indicated no substantial diagnostic problems, so it can be concluded that the polynomial and exponential regression models provide adequate fit to determine data on heavy metal uptake by the flowering white cabbage.

Matched MeSH terms: Metals, Heavy
Fulltext Copper Nanowires as Highly Efficient and Recyclable Catalyst for Rapid Hydrogen Generation from Hydrolysis of Sodium Borohydride

Hashimi AS, Nohan MANM, Chin SX, Khiew PS, Zakaria S, Chia CH

Nanomaterials (Basel), 2020 Jun 12;10(6).
PMID: 32545513 DOI: 10.3390/nano10061153

: Hydrogen (H2) is a clean energy carrier which can help to solve environmental issues with the depletion of fossil fuels. Sodium borohydride (NaBH4) is a promising candidate material for solid state hydrogen storage due to its huge hydrogen storage capacity and nontoxicity. However, the hydrolysis of NaBH4 usually requires expensive noble metal catalysts for a high H2 generation rate (HGR). Here, we synthesized high-aspect ratio copper nanowires (CuNWs) using a hydrothermal method and used them as the catalyst for the hydrolysis of NaBH4 to produce H2. The catalytic H2 generation demonstrated that 0.1 ng of CuNWs could achieve the highest volume of H2 gas in 240 min. The as-prepared CuNWs exhibited remarkable catalytic performance: the HGR of this study (2.7 × 1010 mL min-1 g-1) is ~3.27 × 107 times higher than a previous study on a Cu-based catalyst. Furthermore, a low activation energy (Ea) of 42.48 kJ mol-1 was calculated. Next, the retreated CuNWs showed an outstanding and stable performance for five consecutive cycles. Moreover, consistent catalytic activity was observed when the same CuNWs strip was used for four consecutive weeks. Based on the results obtained, we have shown that CuNWs can be a plausible candidate for the replacement of a costly catalyst for H2 generation.

Matched MeSH terms: Metals
Fulltext A Near Zero Refractive Index Metamaterial for Electromagnetic Invisibility Cloaking Operation

Islam SS, Faruque MRI, Islam MT

Materials (Basel), 2015 Jul 29;8(8):4790-4804.
PMID: 28793472 DOI: 10.3390/ma8084790

The paper reveals the design of a unit cell of a metamaterial that shows more than 2 GHz wideband near zero refractive index (NZRI) property in the C-band region of microwave spectra. The two arms of the unit cell were splitted in such a way that forms a near-pi-shape structure on epoxy resin fiber (FR-4) substrate material. The reflection and transmission characteristics of the unit cell were achieved by utilizing finite integration technique based simulation software. Measured results were presented, which complied well with simulated results. The unit cell was then applied to build a single layer rectangular-shaped cloak that operates in the C-band region where a metal cylinder was perfectly hidden electromagnetically by reducing the scattering width below zero. Moreover, the unit cell shows NZRI property there. The experimental result for the cloak operation was presented in terms of S-parameters as well. In addition, the same metamaterial shell was also adopted for designing an eye-shaped and triangular-shaped cloak structure to cloak the same object, and cloaking operation is achieved in the C-band, as well with slightly better cloaking performance. The novel design, NZRI property, and single layer C-band cloaking operation has made the design a promising one in the electromagnetic paradigm.

Matched MeSH terms: Metals
Fulltext Ambient factors influencing Photovoltaic module temperature in Klang valley

Hedzlin Zainuddin, Maisarah Ismail, Nurul Hidayah Bostamam, Muhamad Mukhzani Muhamad Hanifah, Mohamad Fariz Mohamad Taib, Mohamad Zhafran Hussin

Science Letter, 2016;10(2):23-25.
MyJurnal

The study is conducted to evaluate the significance of solar irradiance, ambient temperature and relative humidity as predictors and to quantify the relative contribution of these ambient parameters as predictors for photovoltaic module temperature model. The module temperature model was developed from experimental data of mono-crystalline and poly-crystalline PV modules retrofitted on metal roof in Klang Valley. The model was developed and analyzed using Multiple Linear Regressions (MLR) and Principle Component Analysis (PCA) Techniques. Solar irradiance, ambient temperature and relative humidity have been proven to be the significant predictors for module temperature. For poly-crystalline PV module, the relative contribution of solar irradiance, ambient temperature and relative humidity are 64.28 %, 17.45 % and 12.64 % respectively. For mono-crystalline PV module, the relative contribution of solar irradiance, ambient temperature and relative humidity are 66.12 %, 17.46 % and 12.48 % respectively. Thus, there is no significant difference in terms of relative contribution of these ambient parameters towards photovoltaic module temperature between poly-crystalline and mono-crystalline PV module technologies.

Matched MeSH terms: Metals
Fulltext On the Role of Processing Parameters in Producing Recycled Aluminum AA6061 Based Metal Matrix Composite (MMC-AlR) Prepared Using Hot Press Forging (HPF) Process

Ahmad A, Lajis MA, Yusuf NK

Materials (Basel), 2017 Sep 19;10(9).
PMID: 28925963 DOI: 10.3390/ma10091098

Solid-state recycling, which involves the direct recycling of scrap metal into bulk material using severe plastic deformation, has emerged as a potential alternative to the conventional remelting and recycling techniques. Hot press forging has been identified as a sustainable direct recycling technique that has fewer steps and maintains excellent material performance. An experimental investigation was conducted to explore the hardness and density of a recycled aluminum-based metal matrix composite by varying operating temperature and holding time. A mixture of recycled aluminum, AA6061, and aluminum oxide were simultaneously heated to 430, 480, and 530 °C and forged for 60, 90, and 120 min. We found a positive increase in microhardness and density for all composites. The hardness increased approximately 33.85%, while density improved by about 15.25% whenever the temperature or the holding time were increased. Based on qualitative analysis, the composite endures substantial plastic deformation due to the presence of hardness properties due to the aluminum oxide embedded in the aluminum matrix. These increases were significantly affected by the operating temperature; the holding time also had a subordinate role in enhancing the metal matrix composite properties. Furthermore, in an effort to curb the shortage of primary resources, this study reviewed the promising performance of secondary resources produced by using recycled aluminum and aluminum oxide as the base matrix and reinforcement constituent, respectively. This study is an outline for machining practitioners and the manufacturing industry to help increase industry sustainability with the aim of preserving the Earth for our community in the future.

Matched MeSH terms: Metals
Tape seagrass (Enhalus acoroides) as a bioindicator of trace metal contamination in Merambong shoal, Johor Strait, Malaysia

Sidi N, Aris AZ, Mohamat Yusuff F, Looi LJ, Mokhtar NF

Mar Pollut Bull, 2018 Jan;126:113-118.
PMID: 29421077 DOI: 10.1016/j.marpolbul.2017.10.041

Revealing the potential of seagrass as a bioindicator for metal pollution is important for assessing marine ecosystem health. Trace metal (111Cd, 63Cu, 60Ni, 208Pb, 66Zn) concentrations in the various parts (root, rhizome, and blade) of tape seagrass (Enhalus acoroides) collected from Merambong shoal of Sungai Pulai estuary, Johor Strait, Malaysia were acid-extracted using a microwave digester and analysed via inductively coupled plasma-mass spectrometry (ICP-MS). The ranges of trace metal concentrations (in μgg-1 dry weight) were as follows: Cd (0.05-0.81), Cu (1.62-27.85), Ni (1.89-9.35), Pb (0.69-4.16), and Zn (3.44-35.98). The translocation factor revealed that E. acoroides is a hyperaccumulator plant, as its blades can accumulate high concentrations of Cd, Cu, Ni, and Zn, but not Pb. The plant limits Pb mobility to minimize Pb's toxic impact. Thus, E. acoroides is a potential bioindicator of metal pollution by Cd, Cu, Ni, and Zn in estuarine environments.

Matched MeSH terms: Metals/analysis; Metals, Heavy/analysis*
Fulltext Transfer free graphene growth on SiO2 substrate at 250 °C

Vishwakarma R, Rosmi MS, Takahashi K, Wakamatsu Y, Yaakob Y, Araby MI, et al.

Sci Rep, 2017 03 02;7:43756.
PMID: 28251997 DOI: 10.1038/srep43756

Low-temperature growth, as well as the transfer free growth on substrates, is the major concern of graphene research for its practical applications. Here we propose a simple method to achieve the transfer free graphene growth on SiO2 covered Si (SiO2/Si) substrate at 250 °C based on a solid-liquid-solid reaction. The key to this approach is the catalyst metal, which is not popular for graphene growth by chemical vapor deposition. A catalyst metal film of 500 nm thick was deposited onto an amorphous C (50 nm thick) coated SiO2/Si substrate. The sample was then annealed at 250 °C under vacuum condition. Raman spectra measured after the removal of the catalyst by chemical etching showed intense G and 2D peaks together with a small D and intense SiO2 related peaks, confirming the transfer free growth of multilayer graphene on SiO2/Si. The domain size of the graphene confirmed by optical microscope and atomic force microscope was about 5 μm in an average. Thus, this approach will open up a new route for transfer free graphene growth at low temperatures.

Matched MeSH terms: Metals
The fate and transport of arsenic species in the aquatic ecosystem: a case study on Bestari Jaya, Peninsular Malaysia

Mana SCA, Fatt NT, Ashraf MA

Environ Sci Pollut Res Int, 2017 Oct;24(29):22799-22807.
PMID: 27987120 DOI: 10.1007/s11356-016-8195-7

The field of arsenic pollution research has grown rapidly in recent years. Arsenic constitutes a broad range of elements from the Earth's crust and is released into the environment from both anthropogenic and natural sources due to its relative mobility under different redox conditions. The toxicity of arsenic is described in its inorganic form, as inorganic arsenic compounds can leach into different environments. Sampling was carried out in the Bestari Jaya catchment while using a land use map to locate the site, and experiments were conducted via sequential extraction and inductively coupled plasma optical emission spectroscopy to quantify proportions of arsenic in the sediment samples. The results show that metals in sediments of nonresidual fractions, which are more likely to be likely released into aquatic environments, are more plentiful than the residual sediment fractions. These findings support the mobility of heavy metals and especially arsenic through sediment layers, which can facilitate remediation in environments heavily polluted with heavy metals.

Matched MeSH terms: Metals, Heavy
Enhancement of CO2 adsorption on biochar sorbent modified by metal incorporation

Zubbri NA, Mohamed AR, Kamiuchi N, Mohammadi M

Environ Sci Pollut Res Int, 2020 Apr;27(11):11809-11829.
PMID: 31975005 DOI: 10.1007/s11356-020-07734-3

This work is scrutinizing the development of metallized biochar as a low-cost bio-sorbent for low temperature CO2 capture with high adsorption capacity. Accordingly, single-step pyrolysis process was carried out in order to synthesize biochar from rambutan peel (RP) at different temperatures. The biochar product was then subjected to wet impregnation with several magnesium salts including magnesium nitrate, magnesium sulphate, magnesium chloride and magnesium acetate which then subsequently heat-treated with N2. The impregnation of magnesium into the biochar structure improved the CO2 capture performance in the sequence of magnesium nitrate > magnesium sulphate > magnesium chloride > magnesium acetate. There is an enhancement in CO2 adsorption capacity of metallized biochar (76.80 mg g-1) compare with pristine biochar (68.74 mg g-1). It can be justified by the synergetic influences of physicochemical characteristics. Gas selectivity study verified the high affinity of biochar for CO2 capture compared with other gases such as air, methane, and nitrogen. This investigation also revealed a stable performance of the metallized biochar in 25 cycles of CO2 adsorption and desorption. Avrami kinetic model accurately predicted the dynamic CO2 adsorption performance for pristine and metallized biochar.

Matched MeSH terms: Metals
Synthesis and evaluation of antibacterial activity of transition metal-oleoyl amide complexes

Farhan N, Al-Maleki AR, Sarih NM, Yahya R

Bioorg Chem, 2023 Nov;140:106786.
PMID: 37586131 DOI: 10.1016/j.bioorg.2023.106786

Recent studies show that some metal ions, injure microbial cells in various ways due to membrane breakdown, protein malfunction, and oxidative stress. Metal complexes are suited for creating novel antibacterial medications due to their distinct mechanisms of action and the variety of three-dimensional geometries they can acquire. In this Perspective, the present study focused on new antibacterial strategies based on metal oleoyl amide complexes. Thus, oleoyl amides ligand (fatty hydroxamic acid and fatty hydrazide hydrate) with the transition metal ions named Ag (I), Co (II), Cu (II), Ni (II) and Sn (II) complexes were successfully synthesized in this study. The metals- oleoyl amide were characterized using elemental analysis, and fourier transforms infrared (FTIR) spectroscopy. The antibacterial effect of metals- oleoyl amide complexes was investigated for Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) by analysing minimum inhibitory concentration (MIC), minimal bactericidal concentration (MBC), and scanning electron microscopy (SEM). The results showed that metal-oleoyl amide complexes have high antibacterial activity at low concentrations. This study inferred that metal oleoyl amide complexes could be utilised as a promising therapeutic antibacterial agent.

Matched MeSH terms: Metals
Assessment of heavy metals contamination in Mamut river sediments using sediment quality guidelines and geochemical indices

Mohammad Ali BN, Lin CY, Cleophas F, Abdullah MH, Musta B

Environ Monit Assess, 2015 Jan;187(1):4190.
PMID: 25471626 DOI: 10.1007/s10661-014-4190-y

This paper describes the concentration of selected heavy metals (Co, Cu, Ni, Pb, and Zn) in the Mamut river sediments and evaluate the degree of contamination of the river polluted by a disused copper mine. Based on the analytical results, copper showed the highest concentration in most of the river samples. A comparison with Interim Canadian Sediment Quality Guidelines (ICSQG) and Germany Sediment Quality Guidelines (GSQG) indicated that the sediment samples in all the sampling stations, except Mamut river control site (M1), exceeded the limit established for Cu, Ni, and Pb. On the contrary, Zn concentrations were reported well below the guidelines limit (ICSQG and GSQG). Mineralogical analysis indicated that the Mamut river sediments were primarily composed of quartz and accessory minerals such as chalcopyrite, pyrite, edenite, kaolinite, mica, and muscovite, reflected by the geological character of the study area. Enrichment factor (EF) and geoaccumulation index (Igeo) were calculated to evaluate the heavy metal pollution in river sediments. Igeo values indicated that all the sites were strongly polluted with the studied metals in most sampling stations, specifically those located along the Mamut main stream. The enrichment factor with value greater than 1.5 suggested that the source of heavy metals was mainly derived from anthropogenic activity such as mining. The degree of metal changes (δfold) revealed that Cu concentration in the river sediments has increased as much as 20 to 38 folds since the preliminary investigation conducted in year 2004.

Matched MeSH terms: Metals, Heavy/analysis*; Metals, Heavy/standards
Development of surface plasmon resonance sensor for determining zinc ion using novel active nanolayers as probe

Fen YW, Yunus WM, Talib ZA, Yusof NA

Spectrochim Acta A Mol Biomol Spectrosc, 2015 Jan 5;134:48-52.
PMID: 25004894 DOI: 10.1016/j.saa.2014.06.081

In this study, novel active nanolayers in combination with surface plasmon resonance (SPR) system for zinc ion (Zn(2+)) detection has been developed. The gold surface used for the SPR system was modified with the novel developed active nanolayers, i.e. chitosan and chitosan-tetrabutyl thiuram disulfide (chitosan-TBTDS). Both chitosan and chitosan-TBTDS active layers were fabricated on the gold surface by spin coating technique. The system was used to monitor SPR signal for Zn(2+) in aqueous media with and without sensitivity enhancement by TBTDS. For both active nanolayers, the shift of resonance angle is directly proportional to the concentration of Zn(2+) in aqueous media. The higher shift of resonance angle was obtained for chitosan-TBTDS active nanolayer due to a specific binding of TBTDS with Zn(2+). The chitosan-TBTDS active nanolayer enhanced the sensitivity of detection down to 0.1 mg/l and also induced a selective detection towards Zn(2+).

Matched MeSH terms: Metals/analysis; Metals/metabolism
Corrosivity and leaching behavior of controlled low-strength material (CLSM) made using bottom ash and quarry dust

Naganathan S, Razak HA, Hamid SN

J Environ Manage, 2013 Oct 15;128:637-41.
PMID: 23845957 DOI: 10.1016/j.jenvman.2013.06.009

This paper reports the corrosivity and leaching behavior of CLSM made using two different industrial wastes i.e. bottom ash from an incineration facility and quarry dust. The leachate samples were derived from fresh and hardened CLSM mixtures, and studied for leaching and electrical resistivity. The release of various contaminants and the consequent environmental impact caused by the contaminants were studied by the measurement of contaminants in the bleed, in the leachate at 28 days, and on the leachate derived from crushed block and whole block leaching done over a period of 126 days. Results indicated that the CLSM mixtures are non corrosive; diffusion was the leaching mechanism; and the contaminants were found to be moderate to low mobility.

Matched MeSH terms: Metals/analysis; Metals/chemistry
Thermoluminescence responses of photon- and electron-irradiated lithium potassium borate co-doped with Cu+Mg or Ti+Mg

Alajerami YS, Hashim S, Ramli AT, Saleh MA, Saripan MI, Alzimami K, et al.

Appl Radiat Isot, 2013 Aug;78:21-5.
PMID: 23644162 DOI: 10.1016/j.apradiso.2013.03.095

New glasses Li2CO3-K2CO3-H3BO3 (LKB) co-doped with CuO and MgO, or with TiO2 and MgO, were synthesized by the chemical quenching technique. The thermoluminescence (TL) responses of LKB:Cu,Mg and LKB:Ti,Mg irradiated with 6 MV photons or 6 MeV electrons were compared in the dose range 0.5-4.0 Gy. The standard commercial dosimeter LiF:Mg,Ti (TLD-100) was used to calibrate the TL reader and as a reference in comparison of the TL properties of the new materials. The dependence of the responses of the new materials on (60)Co dose is linear in the range of 1-1000 Gy. The TL yields of both of the co-doped glasses and TLD-100 are greater for electron irradiation than for photon irradiation. The TL sensitivity of LKB:Ti,Mg is 1.3 times higher than the sensitivity of LKB:Cu,Mg and 12 times less than the sensitivity of TLD-100. The new TL dosimetric materials have low effective atomic numbers, good linearity of the dose responses, excellent signal reproducibility, and a simple glow curve structure. This combination of properties makes them suitable for radiation dosimetry.

Matched MeSH terms: Metals/radiation effects*; Metals/chemistry*
Use of the Multispecies Freshwater Biomonitor to assess behavioral changes of Poecilia reticulata (Cyprinodontiformes: Poeciliidae) and Macrobrachium lanchesteri (Decapoda: Palaemonidae) in response to acid mine drainage: laboratory exposure

Mohti A, Shuhaimi-Othman M, Gerhardt A

J Environ Monit, 2012 Sep;14(9):2505-11.
PMID: 22868673 DOI: 10.1039/c2em10902f

The behavioral responses of guppy Poecilia reticulata (Poeciliidae) and prawn Macrobrachium lanchesteri (Palaemonidae) individuals exposed to acid mine drainage (AMD) were monitored online in the laboratory with a Multispecies Freshwater Biomonitor™ (MFB). These responses were compared to those to reference water acidified to the respective pH values (ACID). Test animals in the juvenile stage were used for both species and were exposed to AMD and ACID for 24 hours. The stress behaviors of both test animals consisted mainly of decreased activity in AMD and increased activity in ACID, indicating that the metals in the AMD played a role as a stress factor in addition to pH. The locomotor activity levels of guppies and prawns for the ACID treatment were higher than the locomotor activity levels for the AMD treatment with increasing pH value. For guppies, significant differences were observed when specimens were exposed to AMD and ACID at pH 5.0 and 6.0; the percentage activities were only 16% and 12%, respectively, for AMD treatment, whereas for ACID treatment, the percentage activities were 35% and 40%, respectively, similar to the value of 36% for the controls. Similar trends were also observed for prawns, for which the percentage activities were only 6% and 4%, respectively, for AMD treatment, whereas for ACID treatment, the percentage activities were 31% and 38%, respectively, compared to 44% in the controls. This study showed that both species are suitable for use as indicators for ecotoxicity testing with the MFB.

Matched MeSH terms: Metals/analysis; Metals/toxicity
Fulltext Chemical speciation and potential mobility of heavy metals in the soil of former tin mining catchment

Ashraf MA, Maah MJ, Yusoff I

ScientificWorldJournal, 2012;2012:125608.
PMID: 22566758 DOI: 10.1100/2012/125608

This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.

Matched MeSH terms: Metals, Heavy/analysis; Metals, Heavy/chemistry*
Toxicity of eight metals to Malaysian freshwater midge larvae Chironomus javanus (Diptera, Chironomidae)

Shuhaimi-Othman M, Yakub N, Umirah NS, Abas A

Toxicol Ind Health, 2011 Nov;27(10):879-86.
PMID: 21402654 DOI: 10.1177/0748233711399318

Fourth instars larvae of freshwater midge Chironomus javanus (Diptera, Chironomidae) were exposed for a 4-day period in laboratory conditions to a range of copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), nickel (Ni), iron (Fe), aluminium (Al) and manganese (Mn) concentrations. Mortality was assessed and median lethal concentrations (LC(50)) were calculated. LC(50) increased with the decrease in mean exposure times, for all metals. LC(50)s for 96 hours for Cu, Cd, Zn, Pb, Ni, Fe, Al and Mn were 0.17, 0.06, 5.57, 0.72, 5.32, 0.62, 1.43 and 5.27 mg/L, respectively. Metals bioconcentration in C. javanus increases with exposure to increasing concentrations and Cd was the most toxic to C. javanus, followed by Cu, Fe, Pb, Al, Mn, Zn and Ni (Cd > Cu > Fe > Pb > Al > Mn > Zn > Ni). Comparison of LC(50) values for metals for this species with those for other freshwater midges reveals that C. javanus is equally or more sensitive to metals than most other tested dipteran.

Matched MeSH terms: Metals/pharmacokinetics; Metals/toxicity*

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