Increasing Cadmium Concentration Research Articles

Lipid peroxidation and activity of some antioxidative enzymes in the root of maize (Zea mays) cultivated on cadmium contamination soil

In this study, we examined the tolerance capacity of Zea mays to cadmium pollution. Soil was treated with varied concentrations of Cadmium; 5 mg, 10 mg, 20 mg and 30 mg/kg soil and Zea mays planted. Root samples were collected in weeks 3, 4, 5 and 6. Activities of Peroxidase, catalase superoxide dismutase, and lipid peroxidation were investigated. Decrease in peroxidase activity was extremely significant (p <0.05) in weeks 4 and 5 while that of week 6 was not significantly (p > 0.05) different from normal. The decrease correlated with increase in Cadmium concentration. However, at the highest concentration of 30 mg/kg of soil the trend was not significant. Increase in the activity of catalase was recorded in weeks 3 and 6. This increase didn’t follow a particular trend but at higher concentration of Cd and long term exposure, it became apparent. There was a negative correlation between catalase activity and lipid peroxidation. In week 3, catalase activity was not significant (p > 0.05) and lipid peroxidation was significant (p < 0.05) while at week 4, catalase activity was significant (p < 0.05) and lipid peroxidation was not significant (p = 0.8432). Catalase activity was not significant (p = 0.2753) at week 5 and lipid peroxidation was significant (p = 0.0030). At week 6 when catalase activity became extremely significant (p < 0.05), lipid peroxidation had a p value of 0.0128. Generally no significant activity (p > 0.05) was observed for superoxide dismutase. A significant increase in absorption of cadmium (p = 0.0374) at 30mg/kg soil was observed between weeks 5 and 6. It was also observed that cadmium had no significant effect (p > 0.05) on the root weight during the period of study. It’s suggestive therefore Cadmiumcontamination of soil could affect growth of maize and induce oxidative stress.
 Key words: cadmium, reactive oxygen species, Thiobarbituric acid reactive species.

WITHDRAWN: Theoretical, spectroscopic study about evaluation of trace elements (zinc and cadmium) µmol/L for pregnant women of age bearing during trimester

The search for new variables useful in the diagnosis and follow-up of pregnant women from important areas in the field of research, where some studies focused on the case of pregnancy, while other research has focused on the assessment of some trace element, including zinc and the study of some of the contaminants including cadmium as variables in the course Tripartite pregnancies. Also Study the geometrical and structural composition (theoretical study). The program for calculations was selected GAMEES that conducted through the total energy of the molecule of hemoglobin and interaction with elements which include the lengths of the bonds and the angles between the bonds by using the methods of PM1 measured values. That showed a very close values, and so been adopted in subsequent calculations. This study was conducted on 80 pregnant women and the neonatal age, reviews of Al Zahraa birth hospital, Najaf governorate. The results of the study were as follows: 1. There was a significant decrease in zinc concentration at a probability level (p <0.05) in the first trimester of pregnancy compared with the study groups and the control group. 2. Significant increase in cadmium concentration at a potential level (p <0.05) in the second trimester of pregnancy compared with the study groups and control group.

Effects of cadmium stress at different concentrations on the reproductive behaviors of beet armyworm Spodoptera exigua (Hübner)

Insects are exposed to cadmium stress since cadmium pollution has increasingly become a serious global environmental issue. However, until now few studies have paid attention to the effect of heavy metals on insect reproductive behaviors. In our study, the courtship behaviors, mating behaviors and fecundity of beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae) exposed to different concentrations of cadmium in artificial diets at larval stage were studied. The results showed that cadmium stress changed the courtship rhythm by significantly advancing or delaying the courtship starting time. Low dose of cadmium (0.2 mg/kg) increased the courtship frequency in the first two scotophases, but in the fourth phase, the two cadmium treatments reduced the frequency. The total courtship duration was significantly shortened in the first six scotophases except high dose of cadmium treatment (51.2 mg/kg) in the sixth dark phase. Paired adults did not mate after the seventh scotophase under low cadmium exposure, while high cadmium stress made the paired adults just copulate in the first four scotophases. The daily mating rate and total mating rate decreased with the increase in cadmium concentration. The number of eggs of low cadmium treatment was higher than that of control, but the difference was not significant; the number of eggs in high cadmium treatment was lower than that of control and low cadmium treatment. Our results indicate that cadmium exposure can disrupt the courtship rhythm for females and has negative influences on copulation behavior and high cadmium stress can reduce fecundity. Hence, the insect population increase will be affected by heavy metal pollution. Our study will provide scientific reference for environmental risk assessment of heavy metal pollution.

Feasibility and comparative analysis of cadmium biosorption by living scenedesmus obliquus FACHB-12 biofilms

Microalgal biofilm has been recognized as a cost-effective biorsorbent for heavy metal and a promising method for microalgae-water separation. In this study, living suspended Scenedesmus obliquus FACHB-12 (isolated from southern China) and its biofilm with different carriers were investigated to remove cadmium from aqueous solution. S. obliquus FACHB-12 biofilm with luffa sponge carrier showed highest cadmium removal efficiency at 92.7% compared to biofilm with K3 carrier (75.3%) and significantly higher than suspended S. obliquus FACHB-12 (61.8%) in 2 h experiment with initial Cd2+ concentration at 3.0 mg/L at pH = 6.0 with 0.8 g/L of biomass under room temperature. S. obliquus FACHB-12 biofilm with K3 and luffa sponge carrier also demonstrated higher tolerance towards increased Cd2+ concentration with highest biosorption efficiency at 85.1% and 90.35% respectively under 20 mg/L of Cd2+, while suspended S. obliquus FACHB-12 biosorption efficiency achieved 81.4% under 10 mg/L of Cd2+ and started to decline over increased cadmium concentration. The adsorption kinetics for all experimental groups followed the pseudo-second-order adsorption model, with biosorption equilibrium favored in Langmuir isotherm. The maximum biosorption capacity estimated by Langmuir isotherm reached 133.14 mg/g biomass in S. obliquus FACHB-12 biofilm with luffa sponge carrier, followed by 78.76 mg/g with K3 carrier, and 60.03 mg/g with suspended S. obliquus FACHB-12. Results suggest an efficient, inexpensive microalgal biofilm with biological carrier system could enhance high cadmium removal for advanced wastewater treatment and provide a cost-effective method for microalgae harvesting process.

Calculations of selenium and cadmium concentration dependent elastic and thermal properties of zinc-blende specimens under CdxZn1-xSeyTe1-y quaternary system with density functional theory

First principle based investigations on mechanical and thermal properties have been executed for the zinc-blende specimens constituting the CdxZn1-xSeyTe1-y system. Elastic stiffness constants of specimens have been increased with increasing selenium concentration at any fixed cadmium concentration, while reverse tendencies have been observed with increasing cadmium concentration at any fixed selenium concentration. Hardness of specimens has been increased with increasing selenium concentration at any fixed cadmium concentration, while it has been decreased with increasing cadmium concentration at any fixed selenium concentration. The phonon dispersion spectra indicate dynamical stability in each binary, but instability in each ternary and quaternary alloy in their zinc-blende structures. Mechanical stability, elastic anisotropy, compressibility, ductility, plasticity, mixing of covalent and ionic bonding with prominent role of covalent over ionic, prominent role of bending over stretching in chemical bonds and central nature of interatomic forces have been observed in each compound. Calculated Debye temperature has established ZnSe as the hardest and CdTe as the softest among all the compounds. The anharmonic nature of interactions between the atoms in any compound has been confirmed with respective calculated Gruneisen parameter. The computed thermal conductivity and melting point temperature of each specimen have also been reported in the present article.

Effects of cadmium stress on DNA methylation in soybean

Epigenetics plays an important role in plant resistance to biotic and abiotic stresses, although few studies have focused on soybean epigenetics associated with cadmium stress. In this study, hydroponically grown soybean seedlings were treated with hydroponic nutrient solution containing various concentrations of CdCl2 (0.5, 5, 15 mg L−1) to investigate the effects of cadmium exposure on soybean genomic DNA methylation levels and patterns using methylation-sensitive amplified polymorphism (MSAP) analysis. Overall, the results revealed alterations of genomic DNA methylation levels and patterns in soybean seedlings under cadmium stress, with methylation level and methylation polymorphism rate both increasing in a dose-dependent manner with increasing cadmium concentration. The total methylation rates for genomic DNA of control (CK), S1 (0.5 mg L−T CdCl2), S2 (5 mg L−1 CdCl2) and S3 (15 mg L−1 CdCl2) groups were 27.92%, 29.78%, 33.2% and 35.79%, respectively, and methylation polymorphism rates were 14.46%, 16.57% and 18.15%, respectively. Thus, soybean cadmium stress-induced methylation changes mainly reflected increased genomic DNA methylation. After polymorphic methylated genomic DNA fragments were recovered from polyacrylamide gels, cloned and sequenced, sequence homology comparisons revealed that among 30 detected differentially methylated fragments, 15 sequences were highly homologous to genes encoding functional proteins already known to be associated with plant stress responses. These results indicate that soybean resists cadmium stress by increasing both the level of genomic DNA methylation and the genomic DNA remethylation rate. This work provides a methodological foundation for investigating molecular mechanisms underlying the soybean response to cadmium stress.

Evaluation of growth and biomass production of sorghum on cadmium contaminated paddy field

The use of agrochemicals that exceed doses and over-exploitation of land for an agricultural commodity contributes to increasing cadmium concentration. Sorghum is a multifunctional crop that can be potential as a heavy metal remediation plant. The study aimed to obtain potential sorghum varieties for phytoremediation of cadmium by assessing the growth and capacity of sorghum biomass in Cd contaminated paddy fields. The study was arranged in a complete randomized factor group with four replications. Six sorghum varieties tested were: Super 1, Samurai, Suri 3, Numbu, Kawali, and Hitam. These varieties were planted with cadmium contaminated rice fields. In general, sorghum varieties can grow in cadmium contaminated rice fields. Three of the six varieties tested namely Super 1, Samurai, and Kawali have advantages in growth such as plant height, leaf area, leaf chlorophyll content, plant growth rate, and net assimilation rate. Big biomass performance is also approved by these three varieties. The results in this study will be described and used as a reference to complement the ability of this variety in the absorption and accumulation ability.

The assessment of cadmium nitrate effect on morphological and cytogenetic indices of spring barley (Hordeum vulgare) seedlings

The influence of different concentrations of the heavy metal (Cd) − Cd(NO3)2 − on seedlings of four cultivars of the spring barley was studied (the length of shoots and roots, the percentage of germinated seeds and strong seedlings were estimated). The topic of this work is investigation of effects of cadmium nitrate doses range on seedlings of several cultivars of spring barley of different geographical origin and searching of the Cd critical dose. For realization of these goals, an analysis of visible changes of the plants morphology and cytogenetical analysis (for searching of the discovered morphological changes causes) are suitable. Cadmium enters plants organism by the root path, and with this, morphological and cytogenetic effects in the seedlings roots have the highest value. Suppression of growth processes was described with an increase in the dose of Cd, and the appearance of morphological anomalies of seedlings was noted. Thus, average shoots length was decreased twice on the Cd2+ concentrations range 0.15–0.4 mg mL−1; at the range from 0.4 to 0.7 mg mL−1, this index was maintained on the plateau, and at doses higher than 1 mg mL−1, a total suppression of shoots development was noted. Cytogenetic analysis was performed to clarify the reasons for the formation of these reactions. The increase in the yield of cytogenetic disorders was revealed with increasing cadmium concentration, and the blockage of proliferation in the late stages of mitosis was marked. High frequencies of multipolar mitoses, anomalous dividing of chromosomes, chromosome agglutinations and pathological anaphases have been indicated. At maximum dose, the frequency of cells with cytogenetic anomalies was 19 times higher than at control variant. Doses of Cd, which can be considered as not so harmful for plants, were estimated as 0.1–0.2 mg mL−1. 0.3–0.7 mg mL−1 caused significant inhibition of growth processes, while doses higher than 1 mg mL-1 can be considered as conditionally lethal ones. It is shown that the barley cultivars have a significant differentiation in their resistance to cadmium, and the probable causes of the formation of observed effects were considered on the basis of literature data. With this, the Cd dose of 0.35 mg mL−1 can be considered as critical and can be used for searching of barley cultivars, which have the high tolerance to Cd influence. In perspective, such cultivars can be used for agricultural production in the territories with the high rates of Cd soil pollution.

The mathematical model for forecasting the accumulation of heavy metals in pig production

The results of research represent the impact of extensive doses of heavy metals such as lead and cadmium in store pigs bodies. Heavy metals were fed jointly and individually in the doses exceeding the maximum allowable concentrations in the fodder by 10 and 20 times. Therefore, the process of intoxication of the biological object (a swine) by heavy metals is modeled in a way similar to that, which might occur as the result of environmental pollution. The study was performed in order to determine the targets and the extent of the impact of heavy metals exerted upon the body weight, weight of inner parts of the animal body, and the incorporation rate of heavy metals in the swine breeding products. Statistical processing of the obtained data allowed developing mathematical models and determining the correlational relationships between the aspects under investigation. It is determined that heavy metals exert an essential negative impact upon the rate of animal growth and the power of influence increases with the dose. It is also confirmed by a high value of correlational relationship between these parameters (the correlation coefficient (r) is 0.854). Thus, the body weight of swine during the latter of I-II stagesdecreased by 5.5 to 14.8% as it was compared to the control under the influence of hemotoxic substances. The extent of the impact was also dependent upon the toxin itself. Thus, the largest negative effect was observed both under the impact of cadmium only and of cadmium and lead taken together. The highest accumulation of heavy metals was observed in the liver and kidneys, whereas the lowest – in the muscles. The built regression equations showed that increasing of the dose of the relevant element in the fodder exerted the main impact on concentration of cadmium and lead in the body and meat. The content of cadmium in the fodder exerted an impact upon concentration of lead in the meat – with the increase of cadmium concentration the content of lead in the meat decreased. The results of the studies provide an overview of the targets and the extent of the impact exerted by heavy metals upon biological objects. The mathematical models may be used for prediction of the impact and the incorporation rate value of the hemotoxic substances in the swine breeding products. Key words: lead, cadmium, swine breeding products, ecocide environmental impact, migration of xenobiotic, mathematical model.

Mass spectrometry-based metabolomics investigation on two different indica rice grains (Oryza sativa L.) under cadmium stress

Cadmium is a toxic environmental pollutant that is readily absorbed by rice grains and poses serious threats to human health. The selection and breeding of rice varieties with low cadmium accumulation is one of the most economical and ecological methods to reduce cadmium exposure. In this study, two different indica rice grains under cadmium stress were subjected to mass spectrometry-based metabolomics analysis for the first time. When the cadmium concentration increased in rice grains, most carbohydrates and amino acids were down-regulated, except myoinositol that can prevent cadmium toxicity, which was up-regulated. d-Mannitol and l-cysteine were up-regulated with the increase of cadmium concentration in low-cadmium-accumulating rice. Also, organic acids were activated especially 13-(S)-hydroperoxy-9(Z),11(E),15(Z)-octadecatrienoicacid that is related to the alpha-linolenic acid metabolism and jasmonic acid production. The determination of biomarkers and characterization of metabolic pathways might be helpful for the selection of rice varieties with low cadmium accumulation.

Integrated assessment of biomarker responses in algae Chlorella sorokiniana exposed to copper and cadmium

Abstract. Rahayu TH, Nugroho AP. 2020. Integrated assessment of biomarker responses in algae Chlorella sorokiniana exposed to copper and cadmium. Biodiversitas 21: 3569-3575. Microalgae Chorella as a major producer in aquatic ecosystems has high probability ofth being exposed to metal pollutants. Metal exposure to algae can induce the formation of reactive oxygen species (ROS), leading to oxidative stress states. ROS trigger the responses of biomarkers of antioxidative enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). This study aims to develop an integrated biomarker response index and star plot for interpretation of the antioxidative enzyme responses in Chlorella sorokiniana. The microalgae was exposed to three concentrations of copper (Cu) and cadmium (Cd) for 48 h, respectively. The results showed that exposure to Cu and Cd caused an increase of protein content and activities of SOD and APX. Analysis of integrated biomarker response (IBR) showed a decrease in the value of IBR along with an increase in cadmium concentration but no similar pattern found in copper. The multiple factor analysis (MFA) approach showed that exposure to Cu 0.3 μmol L-1 for 48 h had high score of protein content and SOD activity in the first dimension. For the second dimension, exposure to Cu 1.6 µmol L-1 for 6 h had high score of APX and SOD activity.

The effect of Eleutherococcus senticosus (Rupr. et Maxim.) Maxim. extract on cadmium-induced toxicity in mice

The present study analyzed the effects of Eleutherococcus senticosus (Rupr. et Maxim.) Maxim. ethanol extract on long-term (6-week) intoxication induced by intraperitoneal injections of 0.05 LD 50 of cadmium chloride solution. The experiments were performed with white laboratory mice. Two groups of mice were injected with ethanol extract of E. senticosus: 0.05 LD 50 and 0.10 LD 50. Cadmium concentrations were investigated in blood, kidney, liver, spleen, heart, and skeletal muscle by atomic absorption spectroscopy. Long-term injections of Eleutherococcus senticosus (Rupr. et Maxim.) Maxim. ethanol extract combined with CdCl 2 led to significant increase of cadmium concentrations in the spleen, skeletal muscle, blood, kidney and liver of experimental mice. E. senticosus also decreased the mitotic activity of liver cells induced by cadmium.

Use of Pavo Cristatus (Peacock) Feather Powder as Adsorbent for Removal of Cadmium Ions from Aqueous Solution

Cadmium is one of the toxic heavy metal that is discharged into the surroundings by various routes such as sedimentary rocks, weathering and erosion of rock, earth’s crust, marine phosphate and phosphorites, forest fires etc. However battery manufacturing industry, plated containers, mining, auto exhaust, smelting of nonferrous metals, cigarettes ore dressing, and galvanized pipes are the main anthropogenic sources of cadmium heavy metal in environment. Ingestion of cadmium in human body increases the risk of many diseases. Many techniques have been applied for the removal of cadmium heavy metal ions from water. The aim of the current work is to propose economical material for effective cadmium ion removal from aqueous phase. A Pavo cristatus feather which is locally available and low-cost is used as an adsorbent for the removal of cadmium ions from water. The adsorption ability of Pavo cristatus feather has been investigated as a function of concentration of cadmium, pH of solution, adsorbate concentration, contact time and temperature. Maximum adsorption of cadmium on Pavo cristatus feather was observed at 5 pH of the solution. Adsorption of cadmium on Pavo cristatus feather was initially found to increase with increase in concentration of cadmium, time of contact and adsorbate concentration. The Langmuir, Freundlich and Temkin adsorption isotherm models were applied to analyse the experimental data. The experimental data was well fitted to Langmuir isotherm model. However, the maximum Langmuir adsorption capacity for cadmium on Pavo cristatus feather at pH 5 was 64.52 mg/g. The kinetics study was examined using the pseudo first order and pseudo second order kinetic models and was best described by the pseudo second order model. Thermodynamic parameters such as the change of Gibbs free energy, entropy and enthalpy of adsorption were also calculated. The study showed that Pavo cristatus feather can be used as a low cost and efficient adsorbent for removal of heavy metal ions from industrial wastewater/water. This material may also be utilized for removal of other toxic heavy mental ions from water.

Studies of Phytoremediation on Sasa argenteastriatus for Soil Cadmuium Pollution

In order to explore the Phytoremediation effect of Sasa argenteastriatus on cadmium-contaminated soil, pot experiments were conducted to study the growth and enrichment efficiency of Sasa argenteastriatus on cadmium-contaminated soil. The results showed that cadmium had a significant inhibitory effect on the growth of Sasa argenteastriatus, and the inhibitory effect increased with the increase of cadmium concentration. Cadmium content in roots, stems and leaves of Sasa argenteastriatus increased with the increase of exogenous cadmium, especially in roots. The order of cadmium enrichment efficiency was the same in different cadmium contaminated soils, all of them were leaves < stems < roots. And the cadmium enrichment coefficient in root was obviously higher than that in other organs. The research on growth and enrichment of Sasa argenteastriatus under cadmium stress provides theoretical basis and data support for its application in cadmium-contaminated areas.

Multiple metal exposure and platelet counts during pregnancy: A repeated measure study

BackgroundEvidence from animal and in vitro studies suggest that some metals interfere with normal platelet counts (PLT). However, limited human studies have investigated the association of metals and PLT, a marker of hematologic and hemostatic, particularly in susceptible populations such as pregnant women. ObjectivesOur purpose was to investigate the associations of repeated measures of 13 urinary metals with PLT during pregnancy. MethodsThe present study involved 3911 pregnant women participating in a prospective cohort study in Wuhan, China, from 2013 to 2016. We measured 13 metals in urine and PLT in blood samples collected in the first, second, and third trimester (median = 13, 24, and 35 weeks of gestation, respectively). Mixed linear models and general linear models were applied to analyze the associations between multiple metals and PLT during pregnancy. The odds ratio (OR) for gestational thrombocytopenia was examined using generalized estimating equations. ResultsAfter adjusting for other metals and covariates, the repeated measure analyses showed that decreased levels of PLT were associated with a 10-fold increase in urinary concentration of cadmium (Cd) [percent difference (%Δ) = −5.02, 95%CI = −9.53, −0.29], manganese (Mn) [percent difference (%Δ) = −4.63, 95%CI = −7.50, −1.67], and arsenic (As) [percent difference (%Δ) = −4.56, 95%CI = −8.11, −0.86]. Cross-sectional analyses by trimesters revealed that Cd was inversely associated with PLT through the three trimesters. In addition, Cd was associated with an increased OR of 1.80 (95%CI: 1.26, 2.56), 1.65 (95%CI: 1.05, 2.59), 1.54 (95%CI: 1.02, 2.33) for gestational thrombocytopenia in the first, second, and third trimester, respectively. ConclusionsOur study suggested an association of Cd, Mn, and As with decreased PLT during pregnancy. Particularly, Cd may increase the risk of gestational thrombocytopenia.

Effects of cadmium toxicity on sesame seed germination explained by various nonlinear growth models

This experiment was conducted to evaluate the effects of cadmium toxicity on the seed germination properties of sesame cultivars (Halil, Nazok Shakhei, Oltan, and Yellow White) using non-linear growth models. Seeds were germinated in petri dishes (90 mm diameter), with a double layered of filter paper soaked in distilled water as control treatment or cadmium (CdSO4) solutions in concentrations of 0, 100, 200, 400, 600, 800 and 1000 ppm. Each treatment was replicated four times and included 50 seeds in each petri dishes. Hyperbolastic growth models for the description of seed germination data were compared to Richards, Weibull, Logistic and Gompertz models. Our results revealed that all studied cultivars were germinated at the cadmium-polluted germination medium to a maximum of 200 ppm without reduction in germination fraction, while seed germination rate was decreased at this concentration compared to 0 and 100 ppm. Increasing cadmium concentration resulted in the germination fraction reduction from 1 to 0.4 at the 400 ppm. The recommended hyperbolastic growth model was type III or (H3) as it provided the best model with the lowest Corrected Akaike Information Criterion for cv. Halil (AICc = −14.6) and cv. Nazok Shakhei, (AICc = −14.2).

Optimization of plant hormonal balance by microorganisms prevents plant heavy metal accumulation.

Heavy metal contamination is a threat to global food safety. Reducing heavy metal uptake in plants is a promising way to make plants safer, yet breeding the right set of traits can be tedious. We test whether microorganisms are able to impact the plant's hormonal balance hereby helping to manage plant heavy metal uptake. We focus on ethylene, a plant hormone regulating plant stress tolerance and nutrition. We grew three phylogenetically distinct plants, Rumex palustris, Alcea aucheri and Arabidopsis thaliana, on a cadmium-spiked soil. Plants roots were coated with the bacterium Pseudomonas putida UW4, which degrades the precursor of ethylene, or an isogenic ACC deaminase-deficient mutant lacking this ability. We followed ethylene concentrations, plant growth and cadmium uptake. Wildtype bacteria reduced shoot cadmium concentration by up to 35% compared to the control, while the mutant increased cadmium concentration. This effect was linked to ethylene, which was consistently positively correlated with cadmium concentration. We therefore propose that bacteria modulating plant hormonal balance may offer new possibilities to improve specific aspects of plant phenotype, in the present context reducing heavy metal. They may thus pave the way for new strategies to improve food safety in a context of the widespread soil contamination.

Exposure to cadmium induced gut histopathological damages and microbiota alterations of Chinese toad (Bufo gargarizans) larvae

Cadmium (Cd) is highly hazardous to both terrestrial and aquatic life and it also has multiple negative impacts on amphibian tadpoles and frogs. However, its effects on gut health of amphibian tadpoles are still poorly understood. We used Chinese toad (Bufo gargarizans) tadpoles to examine the effects of chronic cadmium exposure on gut histology and intestinal microbiota by using regular histology analysis and high-throughput sequencing techniques. Tadpoles were exposed to cadmium concentrations at 0, 5, 100 and 200 μg L−1 from Gosner stage 26 to 38. Our results showed 100 and 200 μg L−1 cadmium exposure caused severe gut histopathological alterations while 5 μg L−1 cadmium exposure induced subtle intestine damage. Moreover, species diversity, taxonomic composition and community structure of gut microbiota were influenced by cadmium exposure. Species diversity and richness decreased gradually with the increase of cadmium concentration. Microbial communities of tadpoles in 100 and 200 μg L−1 cadmium exposure groups were remarkably different from those in control group. Furthermore, the relative abundances of prevalent phyla such as Proteobacteria, Bacteroidetes and Firmicutes and dominant genera such as Klebsiella and Aeromonas were also affected by cadmium exposure. We concluded that cadmium could be harmful to tadpole health by inducing intestinal damages and gut microbiota changes.

Use of Sorption Materials for Removing Cadmium from Water

Groundwater and surface water sometimes contain substances that do not occur frequently in such water. Such substances include some of the metals. Increased iron and manganese content is expected in groundwater; however, metals such as cadmium, nickel or arsenic in high quantities are not typical of this water. Still, there are sources where the occurrence of cadmium, arsenic and other metals is in concentrations exceeding the prescribed values for drinking water. Because of the toxicity of heavy metals, authors dealt with the possibilities of removing cadmium from water. There are many ways to remove heavy metals, however today iron hydroxide based granulated sorption materials are used due to their simplicity, efficiency and low economic demands. The laboratory experiments of the removal of cadmium from water were carried out at the Institute of Municipal Water Management, Faculty of Civil Engineering in Brno as part of a specific university research project. The aim of the experiment was to compare the ability of three sorption materials CFH 0818, Bayoxide E33 and GEH on the removal of cadmium from water. These materials were primarily designed to remove arsenic from water. Filtration columns filled with the mentioned sorbents were used for filtration. Drinking water was used as raw water during the measurement from the municipal water supply system in which increased cadmium concentration was achieved artificially by adding a chemical solution. During the experiment, the flow rate was set to reach the required retention time of 2.5, 5, 10 and 20 minutes taking into account the porosity of the media. The results of the laboratory measurement show that all three materials were able to reduce the concentration of cadmium deep below the limit laid down by Decree No. 252/2004 Coll. already at the shortest delay time. Contact filtration occurred unequivocally in all sorption materials during the removal of the cadmium.

Effect of Cadmium Dopant on Structure and Optical Properties of ZnO Thin Films Prepared by Spray Pyrolysis Technique

CdxZn1-xO (x = 0.00, 0.10 and 0.20) thin films were deposited on glass substrate by the chemical spray pyrolysis technique. The precursor solutions were obtained by varying the concentration of zinc acetate and cadmium acetate in double distilled water. Substrate temperature was fixed at 723K. The structure, surface morphology and optical properties of deposited films were studied using X-ray diffraction, Scanning electron microscope and UV–Visible spectrophotometer. All the films were polycrystalline in nature. The energy band gap of the films was decreased with increase in cadmium content. The influence of cadmium concentration in the films on the structure and optical properties were studied in this study.