Source Of Cadmium Research Articles

Vegetation and Cold Trapping Modulating Elevation-dependent Distribution of Trace Metals in Soils of a High Mountain in Eastern Tibetan Plateau.

Trace metals adsorbed onto fine particles can be transported long distances and ultimately deposited in Polar Regions via the cold condensation effect. This study indicated the possible sources of silver (Ag), cadmium (Cd), copper (Cu), lead (Pb), antimony (Sb) and zinc (Zn) in soils on the eastern slope of Mt. Gongga, eastern Tibetan Plateau, and deciphered the effects of vegetation and mountain cold condensation on their distributions with elevation. The metal concentrations in the soils were comparable to other mountains worldwide except the remarkably high concentrations of Cd. Trace metals with high enrichment in the soils were influenced from anthropogenic contributions. Spatially, the concentrations of Cu and Zn in the surface horizons decreased from 2000 to 3700 m a.s.l., and then increased with elevation, whereas other metals were notably enriched in the mid-elevation area (approximately 3000 m a.s.l.). After normalization for soil organic carbon, high concentrations of Cd, Pb, Sb and Zn were observed above the timberline. Our results indicated the importance of vegetation in trace metal accumulation in an alpine ecosystem and highlighted the mountain cold trapping effect on trace metal deposition sourced from long-range atmospheric transport.

Using an epiphytic moss to identify previously unknown sources of atmospheric cadmium pollution

Urban networks of air-quality monitors are often too widely spaced to identify sources of air pollutants, especially if they do not disperse far from emission sources. The objectives of this study were to test the use of moss bio-indicators to develop a fine-scale map of atmospherically-derived cadmium and to identify the sources of cadmium in a complex urban setting. We collected 346 samples of the moss Orthotrichum lyellii from deciduous trees in December, 2013 using a modified randomized grid-based sampling strategy across Portland, Oregon. We estimated a spatial linear model of moss cadmium levels and predicted cadmium on a 50m grid across the city. Cadmium levels in moss were positively correlated with proximity to two stained-glass manufacturers, proximity to the Oregon–Washington border, and percent industrial land in a 500m buffer, and negatively correlated with percent residential land in a 500m buffer. The maps showed very high concentrations of cadmium around the two stained-glass manufacturers, neither of which were known to environmental regulators as cadmium emitters. In addition, in response to our findings, the Oregon Department of Environmental Quality placed an instrumental monitor 120m from the larger stained-glass manufacturer in October, 2015. The monthly average atmospheric cadmium concentration was 29.4ng/m3, which is 49 times higher than Oregon's benchmark of 0.6ng/m3, and high enough to pose a health risk from even short-term exposure. Both stained-glass manufacturers voluntarily stopped using cadmium after the monitoring results were made public, and the monthly average cadmium levels precipitously dropped to 1.1ng/m3 for stained-glass manufacturer #1 and 0.67ng/m3 for stained-glass manufacturer #2.

Study the effect of thiourea concentration on optical and structural properties of CdS-nanocrystalline thin films prepared by CBD technique

Nano crystalline CdS thin films have been deposited on glass substrate employing chemical bath deposition technique by varying thiourea concentration in two different cadmium sources as cadmium chloride (S1) and cadmium acetate (S2). The aim of this research is to investigate the effect of thiourea concentration on optical and structural properties of the deposited CdS thin films. XRD analysis reveals that the CdS thin films fabricated by using S1 have zinc blende cubic structure and S2 have hexagonal as well as cubic structure. UV–vis studies demonstrate that as the thiourea concentration increases transmission spectra shift towards the shorter wavelength and optical band gap of CdS thin films also increases from 2.45 to 2.71eV in S1 and 2.65–2.74eV in S2. In absorption spectra, a blue shift in the band gap was observed which indicates the formation of CdS nanoparticles measured as 31–9.91nm in S1 and 30–15.02nm in S2.

CdS nanoparticles with high photocatalytic property synthesized by a new liquid–liquid method

CdS nanoparticles with high uniformity have been synthesized through a new liquid–liquid approach, using dimethyl sulfoxide and the mixture of oleyl amine and oleic acid as separate solvents, more convenient inorganic cadmium salt as cadmium source, and sulfur powder as sulfur source. The process can be conducted under mild conditions. It is found that the initial Cd/S molar ratio of precursor plays important role in controlling particle size. Higher concentration of sulfur precursor results in the larger particle size. The obtained colloidal CdS nanocrystals show obvious absorption and fluorescence in visible light region. When using methylene blue as degradation agent, the obtained CdS nanoparticles exhibit high photocatalytic ability.

Effect of bath temperature and concentration of buffer salt on the optoelectronic characteristics of CdS thin films synthesised by chemical bath deposition method

CdS thin films were deposited onto glass substrate by the chemical bath deposition method, using cadmium chloride (CdCl2) as a source of cadmium, thiourea (CS(NH2)2) as a source of sulphur, ammonium nitrate (NH4NO3) as buffer salt and ammonia as pH controller and complexing agent. The effects of the deposition temperature and the concentration of ammonium nitrate on the structural, compositional, optical and optoelectrical properties of CdS thin films were investigated. The optimised sample was utilised for fabrication of photodetectors. A high photosensitivity and a short response time was reported for the photodetectors based on the sample with the bath temperature of 65°C and concentration of ammonium nitrate of 1.5 M compare with the other samples.

Synthesis and optical properties of glass with cadmium sulfide nanoparticles

A new approach to the synthesis of silicate glass with cadmium sulfide (CdS) nanoparticles has been developed. It has been demonstrated that replacement of cadmium sulfide with cadmium oxide and zinc sulfide used as sources of cadmium and sulfur allows a substantial reduction of sulfur volatilization during the melting. The produced samples have been investigated by the methods of spectrophotometry in the ultraviolet and visible ranges of the optical range. Thermal treatment of the samples at temperatures exceeding the glass formation point initiates the growth of CdS nanoparticles, which results in the increase of their average size from 3 to 5.2 nm and a significant shift of the fundamental absorption edge to the longer wavelength range from 380 to 480 nm.

Effect of a controlled food-chain mediated exposure to cadmium and arsenic on oxidative enzymes in the tissues of rats.

ObjectiveThe present study aims to investigate the effect of cadmium and arsenic through a controlled food chain on the activities of some oxidative enzymes (Sulphite oxidase SO, Aldehyde oxidase AO, Monoamine oxidase MO and Xanthine oxidase, XO) in the liver, kidney, testes, heart and brain of rats.Materials and methodsFish (the first trophic level) were exposed to both metals (singly and in mixture) using cadmium chloride (CdCl2) as the source of cadmium and arsenic trioxide (AS2O3) as the source of arsenic at a concentration of 0.4 mg of metals/100 ml of water for 1 month and then sacrificed. The contaminated fish were then used as a source of protein in compounding the experimental diet to which the rats (the second trophic level) were exposed to for a period of 1 and 3 months. The Cd- and As-load in the feed and tissues of rats as well as the activities of the oxidative enzymes were subsequently analyzed in the various tissues after both period of exposure.ResultsMetal analysis on the tissues of rats showed that the metals accumulated more in the liver than in other organs after the 1 month exposure but accumulated more in the kidney after the 3 months exposure. The activities of the oxidative enzymes in the liver were significantly (P < 0.05) decreased in all test groups after the 1 and 3 months exposure. However, after the 1 month exposure, the kidney, testes and heart showed an initial increase in the activities of these enzymes which were decreased after the 3 months exposure. In the brain, the activities of these enzymes were increased in both duration of study.ConclusionFrom the results obtained in the current study, it could be concluded that exposure to cadmium and arsenic through the food chain leads to accumulation of these metals in the tissues of experimental rats leading to the inhibition of oxidative enzymes, thus affecting several normal metabolic processes.

Electrochemical Deposition of CdTe Semiconductor Thin Films for Solar Cell Application Using Two-Electrode and Three-Electrode Configurations: A Comparative Study

Thin films of CdTe semiconductor were electrochemically deposited using two-electrode and three-electrode configurations in potentiostatic mode for comparison. Cadmium sulphate and tellurium dioxide were used as cadmium and tellurium sources, respectively. The layers obtained using both configurations exhibit similar structural, optical, and electrical properties with no specific dependence on any particular electrode configuration used. These results indicate that electrochemical deposition (electrodeposition) of CdTe and semiconductors in general can equally be carried out using two-electrode system as well as the conventional three-electrode system without compromising the essential qualities of the materials produced. The results also highlight the advantages of the two-electrode configuration in process simplification, cost reduction, and removal of a possible impurity source in the growth system, especially as the reference electrode ages.

Relationships between Cadmium in Tissues of Cacao Trees and Soils in Plantations of Trinidad and Tobago

The primary source of cadmium in cocoa beans has been linked to its direct uptake by the cacao plant from cadmium contaminated soils. This research was conducted to evaluate and interpret significant relationships between cadmium levels in tissues of the cacao plant and soils from cocoa-growing areas in Trinidad and Tobago. Total (HNO3-extractable) concentrations of cadmium in both tissues and soils were determined. The levels of cadmium measured varied in the order: leaves > pods > shells > nibs > soil. Cadmium levels in all the cacao tissues analyzed were significantly (p < 0.05), positively and strongly correlated with each other. Additionally, significant (p < 0.05) positive relationships were also identified between Cd in cacao tissues and corresponding total HNO3-extractable Cd levels in soils. These findings suggest that they can possibly be used as predictive tools for assessing Cd levels in cacao.

Effects of automobile battery wastes on physicochemical properties of soil in Benin City, Edo State

Difference in soil qualities has been noticeable in many soils due to anthropogenic sources, especially of automobile battery wastes. This study examines the effects of automobile battery wastes on the physicochemical properties of the soil. Soil samples for this study were collected in triplicates from three battery chargers’ workshops: Adolor, Edaiken and Uwelu in Benin City, Edo State at 0-15cm depth, in the months of August, September and October. The soil physicochemical parameters analyzed indicate variations of values in the contaminated soil over uncontaminated soil (control). Among the parameters examined, conductivity was significantly (P<0.01) higher in the contaminated soil (59.3- 184mho/cm) than in the uncontaminated soil. Notably, a more acidic pH value of 3.7-4.5 was also recorded beyond standard limits of 6.5~8.5. Meanwhile phosphorus was relatively high (1.95-3.35) and nitrogen (0.08-0.15) was low as against the control value of 2.71 and 0.18 respectively. Heavy metals such as Lead (Pb), Zinc (Zn), Cadmium (Cd), Chromium (Cr) and Copper (Cu) were present in different concentrations in contaminated soil sample which ranges from far above acceptable standard limit between (0.288-0.875, 0.757- 1.342, 0.108-0.279, 0.718-1.062 and 0.272-0.518 mg/kg) compared to their values in the control soil sample having 0.003, 0.125, 0, 0 and 0.063 mg/kg respectively. Battery wastes were found to be significant sources of Cadmium and Chromium, as none of both was detected in the control soil sample. The daily activities of auto-mechanic battery workshops have negative impacts on soil physicochemical properties. Note, the soil in mechanic battery workshops needs urgent cleanup to minimize contamination of ecological materials and public health implication. This work will prove valuable in providing baseline information for further soil quality monitoring studies in study area KEYWORDS : Physicochemical, Heavy metals, Battery wastes, Contaminated and uncontaminated soil.

Fabrication of CdSe sensitized SnO2 nanofiber quantum dot solar cells

In the present study, we report a cost-effective quantum dot solar cells based on a combination of electrospinning and successive-ionic-layer-adsorption and reaction (SILAR) methods. CdSe nanocrystals are deposited on electrospun SnO2 nanofibers by SILAR method using CdCl2 as the cadmium source and Na2Se as selenium source. The as-prepared materials are characterized by spectroscopy and microscopy. CdSe deposited SnO2 electrodes are also characterized by spectroscopy and microscopy. Cells are fabricated with platinum (Pt)-sputtered FTO glasses used as the counter electrodes and polysulfide solution used as the electrolyte. The efficiency of the cells is studied for different number of SILAR cycles. Current density–voltage (J–V) measurements on a cell having CdSe deposition of 7 SILAR cycles and SnO2 coating area 0.25cm2 showed an overall power conversion efficiency of 0.29 % with a photocurrent density (JSC) of 5.32mA cm−2 and open circuit voltage (VOC) of 0.23V under standard 1Sun illumination of 100mWcm−2 (AM 1.5G conditions). This is improved by carefully coating SnO2 film without losing the structures. Also ZnS passivation layer is coated to obtain an improved efficiency of 0.48% with JSC of 4.68mAcm−2, and VOC of 0.43V.

Comparative study of heavy metals concentration in topsoil of urban green space and agricultural land uses.

The main objective of this study was to determine the concentration of cadmium, chromium, copper, nickel, lead, and zinc in surface soils of two land uses including agricultural and urban green space in Semnan Province, Iran. For this purpose, the soil samples of 27 urban green space and 47 agricultural fields were collected and analyzed. The correlation coefficients, analysis of variance, principal component analysis, cluster analysis, and geoaccumulation index were utilized to compare the mean values in the two land uses and pinpoint the possible sources of contamination in the study area. The average contents of Cd, Cu, Cr, Ni, Pb, and Zn in green space soils were 0.1, 24.9, 78.7, 28.2, 22.1, and 82.1mg/kg, respectively, while the mean concentrations of Cd, Cu, Cr, Ni, Pb, and Zn in agricultural soils were 0.3, 24.3, 83.7, 33.3, 18.1, and 80.4mg/kg, respectively. The mean concentrations of lead, copper, and zinc were higher in urban green space in comparison with those of agricultural fields, while it was vice versa for chromium, cadmium, and nickel. In general, significant, but weak, correlations were observed between Zn with Pb (r=0.53) and Cu (r=0.61) and Ni with Cr (r=0.55) and Cu(r=0.51). The main sources of contamination turned out to be both natural and anthropogenic as the results of correlation coefficients, principal component analysis, and cluster analysis showed. That is to say, chromium and nickel had emanated from natural while the sources of cadmium, lead, and zinc could be attributed to anthropogenic activities. For the case of copper, both natural and anthropogenic activities were influential; however, the role of human activities was more effective. The results of contamination assessment showed that heavy metal contamination in agricultural land use was higher than green space indicating the role of human activities in this respect.

Changes in metabolites in maize seedlings under chlorsulfuron and cadmium stress

SUMMARYThe herbicide chlorsulfuron is commonly applied to cereals and may persist in alkaline soil long enough to damage subsequent sensitive crops. Sewage water, a potential source of the heavy metal cadmium (Cd), is used to irrigate agricultural soils in many developing countries. The current work evaluated the effects of the residual herbicide chlorsulfuron and Cd on maize seedlings, with particular attention to the mechanism of their action on plant growth. Maize seeds were planted in soil that had been sprayed with chlorsulfuron and Cd, after which residues in both seedlings and the soil were measured. The chlorsulfuron dose was correlated with the amount of residue found in seedlings but not in the soil. In all, 39 metabolites were identified in seedlings using the Automated Mass spectral Deconvolution and Identification System software program and the retention index method. The combination of chlorsulfuron and Cd significantly reduced multiple metabolites in the shikimate pathway, malic acid and citric acid production in the tricarboxylic acid cycle, and lactic acid, glucose, aspartic acid, asparagine and 3-glycerophosphoric acid production. In addition, chlorsulfuron caused an increase in multiple amino acids, including tyrosine, methionine and asparagine, and a marked decrease in caffeic and cinnamic acids (the secondary metabolites derived from the shikimate pathway and galactose). Finally, chlorsulfuron and Cd stress markedly increased shikimate acid, decreased 3-glycerophosphoric acid and caused negative correlations between the amounts of phenylalanine and tyrosine and those of quinic- and cinnamic-acid. In conclusion, chlorsulfuron and Cd did not have a synergistic effect on maize seedlings; rather, the combination of these pollutants had an antagonistic effect on some amino acids.

High Quality CdS Thin Film Growth by Avoiding Anomalies in Chemical Bath Deposition for Large Area Thin Film Solar Cell Application.

Many high efficiency thin-film solar cells incorporate a thin layer of CdS in the device structure to form a heterojunction. Chemical bath deposition (CBD) is the most preferred method of deposition especially for large area thin film solar cells. This study explored the effects of ammonium sulfate on the CdS film produced by CBD using cadmium sulfate as the cadmium source. The concentration of ammonium sulfate was varied from 0 M up to 0.006 M. The resulting optical, structural and surface morphological properties of the films were characterized. Results have shown that the films obtained at higher concentrations of ammonium sulfate were smoother and the occurrence of pinholes was also reduced. Agglomeration of CdS particles that is usually present in films deposited using cadmium sulfate as a precursor was also noticeably reduced. It was also observed that the rate of deposition also increased, resulting in a thicker film for identical deposition time and temperature. The average thickness of the films produced ranged from 60 nm to 180 nm.

Recommended Rice Intake Levels Based on Average Daily Dose and Urinary Excretion of Cadmium in a Cadmium-Contaminated Area of Northwestern Thailand

This study was performed to investigate the dose-response relationship between average daily cadmium dose (ADCD) from rice and the occurrence of urinary cadmium (U-Cd) in individuals eating that rice. This was a retrospective cohort designed to compare populations from two areas with different levels of cadmium contamination. Five-hundred and sixty-seven participants aged 18 years or older were interviewed to estimate their rice intake, and were assessed for U-Cd. The sources of consumed rice were sampled for cadmium measurement, from which the ADCD was estimated. Binary logistic regression was used to examine the association between ADCD and U-Cd (cut-off point at 2 µg/g creatinine), and a correlation between them was established. The lowest estimate was ADCD = 0.5 µg/kg bw/day [odds ratio (OR) = 1.71; with a 95% confidence interval (CI) 1.02–2.87]. For comparison, the relationship in the contaminated area is expressed by ADCD = 0.7 µg/kg bw/day, OR = 1.84; [95 % CI, 1.06–3.19], while no relationship was found in the non-contaminated area, meaning that the highest level at which this relationship does not exist is ADCD = 0.6 µg/kg bw/day [95% CI, 0.99–2.95]. Rice, as a main staple food, is the most likely source of dietary cadmium. Abstaining from or limiting rice consumption, therefore, will increase the likelihood of maintaining U-Cd within the normal range. As the recommended maximum ADCD is not to exceed 0.6 µg/kg bw/day, the consumption of rice grown in cadmium-contaminated areas should not be more than 246.8 g/day. However, the exclusion of many edible plants grown in the contaminated area from the analysis might result in an estimated ADCD that does not reflect the true level of cadmium exposure among local people.

Electro-Plating and Characterisation of CdTe Thin Films Using CdCl2 as the Cadmium Source

Cadmium telluride (CdTe) thin films have been successfully prepared from an aqueous electrolyte bath containing cadmium chloride (CdCl2)·H2O and tellurium dioxide (TeO2) using an electrodeposition technique. The structural, electrical, morphological and optical properties of these thin films have been characterised using X-ray diffraction (XRD), Raman spectroscopy, optical profilometry, DC current-voltage (I-V) measurements, photoelectrochemical (PEC) cell measurement, scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-Vis spectrophotometry. It is observed that the best cathodic potential is 698 mV with respect to standard calomel electrode (SCE) in a three electrode system. Structural analysis using XRD shows polycrystalline crystal structure in the as-deposited CdTe thin films and the peaks intensity increase after CdCl2 treatment. PEC cell measurements show the possibility of growing p-, i- and n-type CdTe layers by varying the growth potential during electrodeposition. The electrical resistivity of the as-deposited layers are in the order of 104 Ω·cm. SEM and AFM show that the CdCl2 treated samples are more roughness and have larger grain size when compared to CdTe grown by CdSO4 precursor. Results obtained from the optical absorption reveal that the bandgap of as-deposited CdTe (1.48–1.52) eV reduce to (1.45–1.49) eV after CdCl2 treatment. Full characterisation of this material is providing new information on crucial CdCl2 treatment of CdTe thin films due to its built-in CdCl2 treatment during the material growth. The work is progressing to fabricate solar cells with this material and compare with CdTe thin films grown by conventional sulphate precursors.

Direct Synthesis of P3Ht/Cds Nanocomposites with End-Functionalized P3Ht as the Template

In this article, we report a direct synthetic route to prepare P3HT/CdS nanocomposites with cadmium acetate dihydrate (Cd(OOCCH3)2.2H2O) used as the cadmium source, sulfur powder (S) as the sulfur source, dichlorobenzene (DCB) and dimethyl sulfoxide (DMSO) as cosolvents, phosphonic ester end-functionalized P3HT as a conjugated polymer template. The as-prepared P3HT/CdS nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, X-ray diffraction (XRD) patterns, transmission electron microscope (TEM), ultraviolet-visible (UV-vis) and photoluminescence (PL) spectra. The results showed that the size and distribution of CdS nanocrystals were not only temperature-dependent, but also greatly influenced by the S/Cd molar ratio. CdS nanocrystals were dispersed uniformly in the P3HT/CdS nanocomposites, which indicated that end-functionalized P3HT could be used as a template to prevent CdS from aggregating effectively. The occurrence of charge transfer at the P3HT/ CdS interface was evident from UV-vis absorption and PL studies, which indicated that ionic bonding between CdS nanocrystals and phosphonic ester end-functionalized P3HT can promote the transfer of charge in P3HT/ CdS nanocomposites. Therefore, it is a promising method to simplify the procedure for large-scale synthesis of organic-inorganic nanocomposites used in solar cells with high photoelectric conversion efficiency.

Potential risk of cadmium in a soil-plant system as a result of long-term (10 years) pig manure application

Animal manure may be a primary source of cadmium (Cd) to Chinese farmlands because abnormally high values of Cd were observed in various manures. In this study, we evaluated the potential risk of Cd in soil-plant (maize and soybean) system as a result of the long-term (10 years) application of pig manure (PM). During 10 years, the loading rate of Cd through PM application ranged from 26.33–131.50 g/ha/year, while the crops removal rate of Cd was relatively small in comparison to the quantity of Cd supplied by PM application (1.03–4.36 g/ha/year). The PM ap plication significantly increased total Cd concentration in soil. Although the Cd levels did not exceed the Chinese soil quality criteria (1.0 mg/kg dry matter (DM)), it would only take less than two years to reach this limit at high PM application rate. The same trend was also observed for the Cd concentration in maize and soybean. More seri ously, Cd concentration in grain of soybean was higher than the threshold values for animal and human ingestion (0.2 mg/kg DM). Based on a mass balance calculation, we found that atmospheric deposition was also an important source of Cd in the experimental area (10.27 g/ha/year). Moreover, the application of PM enhanced the leaching loss of Cd, but they were still fairly small (0.34–0.73 g/ha/year).

Mild, one-step hydrothermal synthesis of carbon-coated CdS nanoparticles with improved photocatalytic activity and stability

Carbon-coated CdS (CdS@C) nanoparticles were conveniently prepared by a one-step hydrothermal carbonization method at temperature as low as 130 °C, in which cadmium acetate and glucose were used as the cadmium and carbon sources, respectively, and thiourea was used as the sulfur source and catalyst for the hydrothermal carbonization of glucose. The prepared CdS@C particles possess a smaller size, better dispersion, and more uniform distribution than pure CdS particles prepared under the same conditions. Furthermore, the hydrothermal carbonization of glucose easily induces the prior formation of metastable cubic CdS crystals. In addition, the carbonaceous species coated on the surface of CdS expands the range of absorption light and slightly decreases the band gap of CdS, as well as reduces the recombination of the photogenerated electron-hole pairs of CdS and its photo-oxidative corrosion, which can improve the photocatalytic activity and stability of CdS for the photo-oxidative degradation of methyl orange in aqueous solution under visible light irradiation.

Toxic effects of two sources of dietborne cadmium on the juvenile cobia, Rachycentron canadum L. and tissue-specific accumulation of related minerals

In the present study, juvenile cobia, Rachycentron canadum L. were fed diets contaminated by two different sources of cadmium: squid viscera meal (SVM-Cd, organic form) and cadmium chloride (CdCl2–Cd, inorganic form). The Cd concentrations in fish diet were approximate 3.0, 5.0 and 10.0mg Cd kg−1 for both inorganic and organic forms. In the control diet (0.312mg Cd kg−1 diet, Cd mainly come from fish meal), no cadmium was added. The experiment lasted for 16 weeks and a statistically significant inverse relationship was observed between specific growth rate (SGR) and the concentration of dietary Cd. The SGR of cobia fed a diet with SVM-Cd increased at the lowest doses and decreased with the increasing level of dietary SVM. Fish fed diet contaminated SVM-Cd had significantly higher SGR than those fed diets contaminated CdCl2–Cd among the high Cd level diets treatments. The dietary Cd levels also significantly affected the survival rate of the fish.Among the hematological characteristics and plasma constituents, glutamic-pyruvic transaminase activities and alkaline phosphatase activities in serum and liver increased and hepatic superoxide dismutase activity decreased with the increasing dietary Cd levels. The cobia fed diet contaminated by high level of CdCl2–Cd had significantly higher ALP activity than cobia fed diet contaminated by high level of SVM-Cd. The results from these studies indicate no differences in toxicity response to dietborne SVM-Cd and CdCl2–Cd at a low level of Cd. However, at a higher level, cobia was more sensitive to dietborne CdCl2–Cd than SVM-Cd. Based on quadratic regression of SGR, The Cd concentrations was 3.617mg kg−1 in the optimal diet, Cd source was SVM (126mg Cd kg−1 in SVM) which stimulate the growth of cobia and the added level was determined to be 26.7g kg−1 diet in the present study. Cd accumulations in the kidney of cobia fed both types of Cd were higher than other tissues, and the order of Cd accumulation in tissues were kidney>liver>intestine>gill>muscle. Iron accumulation in liver and kidney and calcium accumulation in vertebra and scale were also significantly affected by dietary Cd levels.