Source Of Cadmium Research Articles

Application of integrated spatial approaches for studying the vegetation alternation’s effect on the reclaimed land of contaminated zinc mine

The Mae Tao basin, Thailand has been considered to be a remote cadmium (Cd) - contaminated area since 2002. This area has been reported as the largest zinc deposition area so that the explicit potential cadmium source has not been detected. According to the reports from both government and private sectors, the zinc mine in the middle of the basin were determined to be one of the cadmium contributors in the area. From 2014, the mine closure operation has been conducted, thus the study on the selection of cover vegetation in the area has not been accomplished. In this study, the integrated approaches between MINESITE 3D, Geographic Information System (GIS) application and remote sensing techniques, were assigned to simulate the repetition of the vegetation over the reclaimed area. The study demonstrates that using the grass type vegetation for the reclamation of the area can largely reduce the potential erosion of the mine with a range from 89.70 to 94.45%. The results also demonstrate that the young vetiver grass cannot effectively reduce the potential erosion. Additionally, the study on the development of the supporting practice over the mining production area should be further conduct.

Concentration, Source, and Total Health Risks of Cadmium in Multiple Media in Densely Populated Areas, China.

Cadmium (Cd) is a non-essential and harmful element to humans. Cadmium contamination is a serious issue for human health, especially in densely populated agroecology areas. In this study, the investigation of an agroecology area was conducted to gain insight into the relationship between Cd in wheat and soil and then evaluate the Cd total risk for human health. The soil samples and their matching wheat samples, underground water samples, and atmospheric deposition (air) samples were collected from a wheat-growing area in an agroecology plain. The cadmium concentration in the four types of media, in order, was air > soil > wheat > water. The mean concentration of the geoaccumulation index (Igeo) showed that the total Cd in soil (Cd-T) and Cdair reached a mild and moderate pollution level. The results of the correlation and principal component analysis (PCA) showed that the majority of Cdwheat originated from Cd-2 (exchangeable), Cd-4 (humic acid-bound), and Cd-7 (residual). Furthermore, the results of the stepwise multiple linear regression (SMLR) showed that three fractions were primarily controlled by Cd-T: clay, cation exchange capacity (CeC), and total organic carbon (TOC). In addition, the total cancer risk (CR) of Cd in multiple media was, in the order wheat > water > soil > air. It is noteworthy that the Cd content in underground water and wheat by the ingestion pathway posed cancer risks to the local residents and provided a comprehensive insight into multiple media environment management. Furthermore, it provides a very significant basic study for detailed research into the mobility and transformation for factions.

Cd isotope fractionation during tobacco combustion produces isotopic variation outside the range measured in dietary sources

Cadmium production has risen 1000-fold in the past 100 years, from under 20 to over 20,000 tons per year, causing anthropogenically-mobilized Cd to overwhelm natural sources in global cycling. Cadmium has no known biological function in humans, yet has biochemical behaviors similar to zinc and manganese, making exposure detrimental to human health. Identifying and quantifying the sources of Cd for human sub-populations is key to reducing exposures. Cadmium stable isotopes may provide a method for tracing Cd sources throughout the environment and the human body, but at present the limited database for high precision Cd isotopic compositions is inadequate to support such an analysis. Here, we provide new Cd isotope data on dietary sources, cigarette smoking components, and environmentally relevant standard reference materials. Results indicated that minor but significant variations are observed in food products (e.g., peanuts, sunflower seeds, spinach, kale, lettuce, cocoa powder; ~0.9‰ at 4 amu) that may be useful for tracing contamination in agricultural soils. In contrast, Cd isotope fractionation during smoking is larger (~6‰ at 4 amu) and has implications for tracing cadmium sources from tobacco combustion in the environment and throughout the human body. The primary inhaled component of cigarette smoke contains highest delta values (δ116/112Cd or δ114/110Cd ~5.2‰), while the second-hand smoke and cigarette ash have the lowest delta values (δ116/112Cd or δ114/110Cd ~−0.9‰). Used cigarette butts have δ114/110Cd ~2.4‰, in between the values measured in ash/s hand smoke and the inhaled smoke components. The high delta values of the inhaled smoke indicate that Cd isotopes may be used to determine the extent of Cd exposure due to smoking in human biological samples. This study provides new data for previously uncharacterized isotopic reservoirs that can be included in future studies of Cd source-exposure tracing.

Atmospheric deposition as a source of cadmium and lead to soil-rice system and associated risk assessment

Atmospheric deposition of heavy metals is widely documented and has been connected to adverse ecological and health impacts. The influence of atmospheric deposition on the soil–rice system in a typical urban agglomeration region was studied continuously through a field contrast experiment for two years. The results showed that the Cd and Pb in rice grains is mainly from soil, but Cd and Pb from the atmospheric deposition should be a focus of attention. The bioavailable content of heavy metals in atmospheric deposition is higher than that in corresponding surface soil. Atmospheric deposition contributed 10.8–47.7% of the Cd and Pb in brown rice, and 13.7–60.3% of the Cd and Pb in rice leaves was from atmospheric deposition. In the traffic area, a high deposition site, the contributions of atmospheric depositions to heavy metals in rice plants were higher than those from abandoned mine area and suburban area. Atmospheric deposition also consistently decreased the pH (0.17–0.66) and increased the exchangeable Cd (27.1–62.1%) and Pb (3.3–26.1%) in surface soil. In addition, the health risk index (HRI) of rice consumption was also increased as a result of the different atmospheric depositions of heavy metals, which accounted for 40.0% and 35.5% of Cd and Pb at the high deposition site, respectively. These findings demonstrate the potential influences of atmospheric deposition on the soil–crop system and human health, and can also provide a useful reference for developing the emission control strategies.

Natural variation in the promoter of OsHMA3 contributes to differential grain cadmium accumulation between Indica and Japonica rice.

Rice is a major source of cadmium (Cd) intake for Asian people. Indica rice usually accumulates more Cd in shoots and grains than Japonica rice. However, underlying genetic bases for differential Cd accumulation between Indica and Japonica rice are still unknown. In this study, we cloned a quantitative trait locus (QTL) grain Cd concentration on chromosome 7 (GCC7) responsible for differential grain Cd accumulation between two rice varieties by performing QTL analysis and map-based cloning. We found that the two GCC7 alleles, GCC7PA64s and GCC793-11 , had different promoter activity of OsHMA3, leading to different OsHMA3 expression and different shoot and grain Cd concentrations. By analyzing the distribution of different haplotypes of GCC7 among diverse rice accessions, we discovered that the high and low Cd accumulation alleles, namely GCC793-11 and GCC7PA64s , were preferentially distributed in Indica and Japonica rice, respectively. We further showed that the GCC7PA64s allele can be used to replace the GCC793-11 allele in the super cultivar 93-11 to reduce grain Cd concentration without adverse effect on agronomic traits. Our results thus reveal that the QTL GCC7 with sequence variation in the OsHMA3 promoter is an important determinant controlling differential grain Cd accumulation between Indica and Japonica rice.

Ultrastructural and metabolic disorders induced by short-term cadmium exposure in Avicennia schaueriana plants and its excretion through leaf salt glands.

Environmental cadmium (Cd) sources have increased in mangrove sediments in recent decades, inducing cellular damage to many plants. Avicennia schaueriana is abundant in mangrove sites and has been subject to Cd contamination. The possible effects of Cd toxicity and the structural and physiological disturbances to this plant were studied. Can this plant express early cellular tolerance mechanisms to such metal contamination? Seedlings of A.schaueriana were collected from sites of their natural occurrence, placed in plastic pots containing nutrient solution for 60days, and subsequently exposed to increasing Cd concentrations for 5days under experimental conditions. The anatomical, ultrastructural and physiological changes induced by Cd were analysed. Cd accumulated mainly in the root system and in pneumatophores, stems and leaves, induced differential accumulation of mineral nutrients, but did not induce necrosis or changes in leaf anatomy. However, there was a decrease in starch grains and an increase in deposited electron-dense material in the cortex and vascular bundles. Cd induced both increases in calcium (Ca) content in shoots and Ca oxalate crystal precipitation in leaf mesophyll and was detected in crystals and in the secretion of salt glands. Our observations and experimental results provide evidence of Cd tolerance in A.schaueriana. As a new feature, despite the clear cellular physiological disorders, this plant is able to eliminate Cd through leaf salt glands and immobilise it in Ca crystals, representing fast mechanisms for Cd exclusion and complexation in leaves in heavy metal coastal polluted marine ecosystems.

Structural and optical properties of novel CdSe nanoparticles produced via a facile synthetic route: Studies on the effects of cadmium sources

We report on the successful synthesis of CdSe nanoparticles (NPs) via a facile aqueous approach. Investigation on the effects of various cadmium sources in the precursor solution on the CdSe NPs is discussed. The structural and morphological properties characterized by the X‐ray diffraction (XRD) and scanning electron microscope (SEM) displayed good features of the as‐prepared CdSe NPs. The XRD pattern displayed a pure zinc blende crystal structure for all samples, with the most crystalline sample observed for CdSe NPs prepared using anhydrous cadmium chloride. The estimated crystallite sizes were below 6 nm for all the CdSe NPs samples. Mixed shapes of spherical and nanorods of varying sizes were observed from the SEM images for the as‐prepared NPs prepared using different cadmium sources. The optical studies conducted by photo‐spectroscopy pointed out the CdSe NPs prepared using anhydrous cadmium chloride gave the best optical properties. The emission wavelengths were in the range 565 to 574 nm while the optical band gaps were in the range 2.94 to 3.23 eV for all the as‐prepared CdSe NPs samples. All the samples, however, displayed quantum confinement effects giving room for further fabrication and engineering to suit specific applications in the biological field. The obtained results demonstrated that aqueous phase synthetic route employed in this study could be successfully adopted for production of high‐quality CdSe NPs because of its facile and inexpensive nature.

Effect of cultivar type and soil properties on cadmium concentrations in potatoes

ABSTRACTPotatoes are a staple food in New Zealand and a contributing source of dietary cadmium (Cd), although there is little information nationally on the soil and plant factors that affect Cd concentrations in the crop. We measured Cd concentrations in 10 commercial potato cultivars grown in three field sites across New Zealand and assessed the soil factors that affect Cd concentrations. Cadmium concentrations in potato tubers ranged from 0.004 to 0.574 mg kg−1 DW (0.001–0.113 mg kg−1 FW), although overall Cd concentrations were lower than the maximum limit of 0.1 mg kg−1 FW for human consumption. There were significant differences (2.8-fold) in Cd concentrations between potato cultivars, although these varied by site. No significant relationships were found between soil properties and Cd concentrations in potatoes. Management of Cd in potatoes is likely to be most effective by avoiding growing high-Cd-accumulating cultivars in soils with elevated Cd. Further studies could determine if other management factors such as irrigation or type and rates of fertiliser affect Cd concentrations in potatoes.

Map-based cloning of a new total loss-of-function allele of OsHMA3 causes high cadmium accumulation in rice grain.

Rice (Oryza sativa) is a major dietary source of the toxic metal cadmium (Cd). Reducing Cd transfer from soil to the rice grain is important for food safety. Rice cultivars vary widely in their Cd accumulation, but the genetic basis for this variation is not fully understood. Based on field and pot experiments comparing 26 rice cultivars, we identified a cultivar with high Cd accumulation in grain (BG367, coded as W4) and a cultivar with low grain Cd accumulation (Huajingxian 74, coded as W0). W4 showed a higher Cd translocation from roots to shoots than W0. Using chromosome single segment substitution lines derived from the two cultivars, we mapped a quantitative trait locus for Cd accumulation in grain to a 400 kb region in chromosome 7. Using yeast expression assays and transgenic complementation, we identified OsHMA3 as the causal gene at this locus. Compared with OsHMA3W0, OsHMA3W4 has a deletion of 14 amino acids predicted to be in the ATP binding domain. OsHMA3W4 showed a complete loss of transport activity for Cd in yeast assays. Taking our findings together, we have identified a new allele of OsHMA3 with a total loss-of-function, resulting in greatly elevated Cd translocation to rice shoots and grain.

Preparation and photoelectric properties of cadmium sulfide quantum dots**Project supported by the Equipment Pre-research Fund under the Equipment Development Department (EDD) of Chinaʼs Central Military Commission (CMC) (Grant No. 1422030209), the Innovation Team Program of NORINCO Group (Grant No. 2017CX024), and the National Natural Science Foundation of China (Grant Nos. 61106098 and 11864044).

Cadmium sulfide quantum dots (CdS QDs) are widely used in solar cells, light emitting diodes, photocatalysis, and biological imaging because of their unique optical and electrical properties. However, there are some drawbacks in existing preparation techniques for CdS QDs, such as protection of inert gas, lengthy reaction time, high reaction temperature, poor crystallinity, and non-uniform particle size distribution. In this study, we prepared CdS QDs by liquid phase synthesis under ambient room temperature and atmospheric pressure using sodium alkyl sulfonate, CdCl2, and Na2S as capping agent, cadmium, and sulfur sources respectively. This technique offers facile preparation, efficient reaction, low-cost, and controllable particle size. The as-prepared CdS QDs exhibited good crystallinity, excellent monodispersity, and uniform particle size. The responsivity of CdS QDs-based photodetector is greater than , which makes them suitable for use as ultra-violet (UV) detectors.

Cadmium Accumulation in Peruvian Cacao (Theobroma cacao L.) and Opportunities for Mitigation

Crops are the main source of toxic cadmium for humans due to uptake from naturally or anthropogenically polluted soils. Chronic Cd ingestion causes kidney, liver, and skeletal damage along with an increased risk of cancer. Cacao is known to accumulate Cd and may therefore be potentially harmful to human health. Consequently, cocoa production on intensely polluted soils should be avoided. Cocoa products from South America in particular often exceed the limits for Cd, but the factors that drive Cd uptake are as yet poorly studied. In this study, we measured Cd concentrations in defatted cocoa powder from unfermented seeds of 40 different trees on 20 farms in the Huanuco Region, Peru, and associated the Cd levels with the farms’ soil, field management, and nearby vegetation diversity. The mean Cd concentration found in cocoa of the study region was 2.46 mg kg−1 with a range of 0.2–12.56 mg kg−1. The maximum content measured was an order of magnitude higher than the allowed limit of 1.5 mg kg−1 and was the highest reported so far in the literature. Soil Cd content was the most relevant driver of Cd concentration in cacao. In addition, fertilizer use caused significantly higher Cd concentration in cocoa. Higher biodiversity of herbs was positively correlated with Cd contents in cocoa. The study shows that, apart from the known correlation of soil conditions with Cd accumulation in cacao seeds, changes in fertilization and plant composition may be promising measures to counteract Cd contamination in regions with high soil Cd content.

Effects of multi- Deposition on the structural and optical properties of CdS nanocrystalline thin film prepared by CBD technique.

Cadmium sulfide (CdS) nanocrystalline thin films have been prepared by chemical bath deposition (CBD) technique on commercial glass substrates at 70ºC temperature. Cadmium chloride (CdCl2) as a source of cadmium (Cd), thiourea (CS(NH2)2) as a source of sulfur and ammonia solution (NH4OH) were added to maintain the pH value of the solution at 10. The characterization of thin films was carried out through the structural and optical properties by X-ray diffraction (XRD) and UV-VIS spectroscopy. A UV-VIS optical spectroscopy study was carried out to determine the band gap of the nanocrystalline CdS thin film and it showed a blue shift with respect to the bulk value (from 3.9 - 2.4eV). In present work effects of thickness on the structural and optical properties of CdS nanocrystalline thin films were discussed.

Heavy metals content and distribution in basil (Ocimum basilicum L.) as influenced by cadmium and different potassium sources

Despite the fact that cadmium (Cd) is a non-essential element for plants, it can influence nutrients and affect human health. Potassium (K) can influence the transportation of heavy metals (HMs) in soil-plant systems. Here, a greenhouse experiment was conducted to evaluate the effect of Cd and K fertilizers on the different partitioning forms of HMs, their concentrations, uptake in the shoots and roots of Ocimum basilicum. Treatments comprised 2 levels of Cd (0 and 40 mg kg−1) and three levels of K (0, 100, and 200 mg kg−1) from three sources, i.e. KCl, K2SO4, and K-nano-chelate. 40 mg Cd kg−1 increased the shoot (above ground parts) Cd concentration. Addition of K as KCl, K2SO4, and K-nano-chelate increased the presence of Cd in shoots by 86, 82 and 76%, respectively, compared to the control. Using the nano-chelate of K can increase the accumulation of Cd in plants grown on contaminated soils to lesser content than that of the other forms of K. Application of 40 mg Cd kg−1 reduced the concentration of Zn, Cu, and Mn in the shoot, but increased shoot Fe concentration. Transfer factor (TF), which is the ratio of metal concentration in shoot to its concentration in root, of the studied HMs, was significantly affected by Cd and K treatments. Therefore, the proper form and dose of chemical fertilizers should be applied in Cd-contaminated soils.

Dietary Cadmium Intake and Sources in the US.

Cadmium (Cd) is a toxic heavy metal that can contribute to numerous diseases as well as increased mortality. Diet is the primary source of Cd exposure for most individuals, yet little is known about the foods and food groups that contribute most substantially to dietary Cd intake in the US. Therefore, the objective of this study was to estimate dietary Cd intake and identify major food sources of Cd in the US population and among subgroups of the population. Individuals aged 2 years and older from the National Health and Nutrition Examination Survey (NHANES) 2007–2012 were included in this study (n = 12,523). Cd intakes were estimated from two days of 24-h dietary recalls by matching intake data with the Cd database of the Food and Drug Administration (FDA)’s Total Diet Study 2006 through 2013. The average dietary Cd consumption in the population was 4.63 μg/day, or 0.54 μg/kg body weight/week, which is 22% of the tolerable weekly intake (TWI) of 2.5 μg/kg body weight/week. Greater daily Cd intakes were observed in older adults, males, those with higher income, higher education, or higher body mass index. The highest Cd intakes on a body weight basis were observed in children 10 years and younger (38% of TWI), underweight individuals (38% of TWI), and alcohol non-consumers (24% of TWI). The food groups that contributed most to Cd intake were cereals and bread (34%), leafy vegetables (20%), potatoes (11%), legumes and nuts (7%), and stem/root vegetables (6%). The foods that contributed most to total Cd intake were lettuce (14%), spaghetti (8%), bread (7%), and potatoes (6%). Lettuce was the major Cd source for Caucasians and Blacks, whereas tortillas were the top source for Hispanics, and rice was the top contributor among other ethnic subgroups including Asians. This study provides important information on the dietary Cd exposure of Americans, and identifies the groups with the greatest dietary Cd exposure as well as the major sources of dietary Cd among sociodemographic subgroups.

Copper and other heavy metals in grapes: a pilot study tracing influential factors and evaluating potential risks in China

In this study, grapes (Vitis vinifera L.) were systematically sampled across the main grape-producing areas in a nationwide survey of China. Grapes from special regions, such as heavy metal polluted areas (e-waste dismantling area) and pesticide free areas (courtyard) were also collected to make a comparison. Grape skins and pulps were separated to evaluate influence of accumulation behavior, environmental transport and water cleaning efficiency to heavy metals. Levels of copper in grape skins (5.02 ± 3.18 μg/g) were higher than in pulps (3.74 ± 1.48 μg/g). Only high level of copper in two grape skins (sampled from an e-waste dismantling area) showed obvious decrease during water clean-up procedure, indicating the influence of air deposition. Statistical analysis showed no significant difference in the copper levels of grapes from markets, courtyards and e-waste dismantling areas. Concentrations and sources of chromium (Cr), manganese (Mn), nickel (Ni), cadmium (Cd), lead (Pb) and arsenic (As) were also analyzed. Higher levels of these heavy metals were observed in grape skins than pulps. Finally, we evaluated the risk of ingesting heavy metal through grapes using the estimated daily intake (EDI). No health risk was found by consuming grapes according to the data from this study.

Influence of cadmium precursor concentrations on the structural, optical and electrochemical impedance properties of CdZnS thin films

Thin films of cadmium zinc sulfide (CdZnS) were deposited on microscopic glass substrates using the chemical bath deposition method and the effects of the Cd precursor concentrations on the morphological, structural and optical properties of the films were studied. The surface morphology as revealed by scanning electron microscope showed closely packed nano particles randomly spread on the surface of the glass substrates. The x-ray diffraction studies showed that the thin films were polycrystalline and the crystallite sizedecreased with increase in the concentration of the Cd precursor. While the optical absorbance decreased, the bandgap energy increased as the concentration of the cadmium source increased. Electrochemical studies were performed by cyclic voltammetry analysis and impedance measurements at low frequency ranges. Simulation model on the impedance model was carried out to obtain a more quantitative analysis of the data. The ternary CdZnS thin film developed in this work could be useful as window layer in solar cell fabrication.

Effect of Cadmium Source on the Structure and Optical Properties of CdTe Quantum Dots

Effect of Cadmium Source on the Structure and Optical Properties of CdTe Quantum Dots

Nramp5 expression and functionality likely explain higher cadmium uptake in rice than in wheat and maize

Cereals are the main dietary source of cadmium (Cd). Rice grains often contain higher levels of Cd than other cereals, but the reasons are unknown. The aims of this study were to compare Cd uptake, translocation and influx kinetics between rice, wheat and maize and to investigate whether the expression and functionality of Nramp5 genes differ between the three crop species. Two cultivars each of rice, wheat and maize were grown hydroponically and exposed to a range of Cd concentrations. Nramp5 genes were cloned from the three plants and their expression levels determined. The Cd transport activities of Nramp5 proteins were tested in yeast. Under hydroponic conditions, Cd uptake in rice was 2.5–8.1 and 1.1–3.6 times that of wheat and maize, respectively. The maximum Cd influx velocity of rice was 6.5 and 2.2 times that in wheat and maize, respectively. Wheat showed the lowest Cd uptake but the highest Cd root-to-shoot translocation. The absolute expression level of OsNramp5 in rice roots was 4–5 times that of TaNramp5A and TaNramp5D in wheat or ZmNramp5 in maize. All Nramp5 proteins were localized to the plasma membrane. When expressed in yeast, OsNramp5 showed a greater Cd transport activity than wheat or maize Nramp5. Rice has a greater Cd uptake ability than wheat or maize, likely because OsNramp5 is more highly expressed and the protein has a higher Cd transport activity than wheat or maize Nramp5.

CdS QD-CQD co-sensitized TiO2 solar cells: preparation and photoelectrochemical properties

ABSTRACTCdS quantum dot and ZnS quantum dot as passivation layers were deposited on the surface of TiO2/C-TiO2/TiO2 multilevel structure photoanode. And solar cells were assembled by using the photoanode. The photoanodes were characterized by X-ray diffraction, transmission electron microscope, fourier transform infrared and ultraviolet-visible adsorption spectra. Photoelectrochemical properties of devices were tested by electrochemical workstation. The results show that the optimum conditions for the photoelectric performance of the device are cadmium acetate as the cadmium source and sensitization 9 times, and the TiO2 film layer is 3 layers. Under such process conditions, the short-circuit current density (Jsc) is 2.28 mA/cm2, open-circuit voltage (Voc) is 0.30 V, fill factor (FF) is 0.45, and photoelectric conversion efficiency (η) is 0.14%. After introducing carbon quantum dots, the filling factor is increased by 100% to 0.40, and the all-optical conversion efficiency is improved by 28%, to 0.18%.

Source Contribution Analysis and Collaborative Assessment of Heavy Metals in Vegetable-Growing Soils.

Source quantification of heavy metals in farmland is essential for developing and implementing restoration strategies. We used various data analyses to identify and quantify sources of arsenic, cadmium, chromium, copper, mercury, nickel, lead, and zinc in vegetable-growing soils. A new method of collaborative assessment, combining soil environmental quality and agricultural product safety, showed that approximately 5.20% of cultivation systems were multi-contaminated by heavy metals. The nonlinear relationship between pollution sources and the comprehensive contamination situation was established, deriving from a fitted bivariate model. The model revealed that anthropogenic sources and natural origins accounted for 65.8-86.0 and 34.2-14.0% of the comprehensive pollution, respectively. These results suggested that both human activities and natural factors contributed to the decline of local soil quality and the influence of the former was more substantial than that of the latter.