Metallic Elements Cr Research Articles

Source apportionment of heavy metal and their health risks in soil-dustfall-plant system nearby a typical non-ferrous metal mining area of Tongling, Eastern China

The agricultural land-atmospheric dustfall-plant system around the mining area is at high risks of heavy metal pollution caused by mining-smelting activities. In this study, 118 samples (including rhizospheric soils, background soils, soil-forming parent rocks, crops, vegetables, medicinal plants and atmospheric dustfall) were collected nearby Tongling Cu-Fe-Au mining area, Eastern China. We studied the concentrations, migration, sources, and health risks through consumption of two main crops (corn and rice), six kinds of vegetables, and medicinal plants (Fengdan, Paeonia ostii) for six metal elements (Cu, Zn, Cr, Cd, Pb and Hg). Results revealed Cr and Cd in soils, and Cd, Cr, Pb, Cu and Zn in dustfall showed a relatively high contamination degree. The mean contents of Cr and Pb in corn kernels, as well as Cd, Cr and Pb in rice grains and all vegetables, and Cr in Fengdan cortex moutan exceeded the corresponding food safety limits in China. The transfer capability of Cr in corn kernels and rice grains, Pb in edible vegetables, and Cd in cortex moutan were the strongest, respectively. Health risk assessment results showed Cr had the greatest non-carcinogenic risk, followed by Pb and Cd. The results of pearson's correlation analysis (CA), hierarchical cluster analysis (HCA), and principal component analysis (PCA) indicated Zn-Cr, Pb and Cd-Cu-Hg in the plants might derive from different geochemical end-members. Source apportionment based on lead isotope showed that mining-smelting activities were the major source of Pb in atmospheric dustfall and agricultural soils, with the average contribution rates of 66% and 50%, respectively. Vehicle emissions from diesel fuels (50%–68%) and mining-smelting activities (16%–25%) contributed mainly to Pb accumulation in plants. Hence, our study suggested the accumulations of Pb in plants might be mainly from the direct foliar uptake of atmospheric Pb related to vehicle emissions and mining-smelting activities.

Trace metal Biomonitoring of algae (Ulva lactuca), and Mollusks (Patella caerulea ; Stramonita haemastoma ; Phorcus turbinatus) along the Eastarn-Algerian coast.

A total of six trace metal elements (Cd, Cr, Cu, Pb, Zn and Ni) were analyzed in the green algae Ulva lactuca (Linnaeus, 1753) and in the tissues of three gastropods: Stramonita hemastomas (Linnaeus, 1766), Phorcus turbinatus (Born 1778) and the limpet Patella caerulea (Linnaeus, 1758)sampled from four stations located along the coastal areas of eastern Algeria (North-Eastern Mediterranean Sea). Data were processed through multivariate approaches such as Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) on PCA factors. The results obtained showed a very het- erogeneous distribution of pollutants. Highly significant correlations were determined for the different species studied, depending on heavy metals, stations and seasons. In green algae, U. lactuca has been associated with higher levels of Ni, Cr and Zn in the sampling station ’St.T’, while an accumulation of Pb and Cu was detected in St.2. Cr was significantly higher in St.3. In winter and spring, mol- lusks had the highest contamination levels. Monodonta and Patella in the stations St.1, St.2 and St.3 showed higher contents in Ni, Zn and Cu, respectively. In addition, Thais and Patella in stations St.T and St.3had a higher contamination with Pb, Crand Cd, respectively. Statistical comparison was performed using the non-parametric Kruskall Wallis and Mann-Whitney tests. This work confirms that U. lactuca , S. haemastoma , P. turbinatus and P. caerulea are good biomonitoring tools of trace metal contamination in Mediterranean marine areas.

Thermal stability and electronic and magnetic properties of atomically thin 2D transition metal oxides

Two-dimensional (2D) transition metal oxides (TMOs) are an emerging class of nanomaterials. Using density functional theory and ab initio molecular dynamics (AIMD) simulations, we carried out a systematic study of atomically thin metal oxide phases with compositions MO, M2O3, and MO2, for transition metal elements Sc, Ti, V, Cr, and Mn. We identified nine thermally stable structures that may be realized as free-standing nanosheets: hexagonal h-Sc2O3, h-V2O3, and h-Mn2O3; hexagonal t-VO, t-CrO, and t-MnO; and square sq-TiO, sq-VO, and sq-MnO. The t-MO phases are novel hexagonal structures which emerged naturally from phase transformations observed during AIMD simulations. The 2D TMOs were found to exhibit a wide range of remarkable electronic and magnetic properties, indicating that they are bright candidates for electronic and spintronic applications. Most exceptional in this regard is h-V2O3, that is the only phase that has been experimentally realized so far, and was found to be a ferromagnetic half-metal with Dirac-cone-like bands.

Application of gold nanoparticles embedded in the amyloids fibrils as enhancers in the laser induced breakdown spectroscopy for the metal quantification in microdroplets

In this work Nanoparticle Enhanced Laser Induced Breakdown Spectroscopy (NELIBS) has been employed for quantitative metal detection using amyloid fibrils coated with gold nanoparticles as enhancers. Amyloid fibrils represent, from one hand, an extremely interesting system for novel technologies, ranging from water purification to medical applications, and on the other hand, an ideal system for investigating the performance of laser-matter interaction in biological systems. The results obtained in this work show the potentiality of NELIBS for the quantification at sub-ppm (mg/kg) level of metallic elements (Cr, Pb, Tl and Cd) even in the protein and/or biological environment, employing amyloid fibrils with gold nanoparticles. Moreover, the single-shot measurements reveal the promising use of this technique in applications where high sensitivity and/or limitation in the sample amount are demanded.

Heavy metal mobility and valuable contents of processed municipal solid waste incineration residues from Southwestern Germany

As conventional end-of-life disposal, municipal solid waste (MSW) incineration residues can be problematic due to potential release of toxic compounds into the environment. Using municipal solid waste incineration residues as urban-mine of valuable metals (e.g. precious metals) could provide a trash-to-treasure possibility. The objectives of the study are to (i) determine the contents of different contaminant metallic elements (Zn, Cu, Ba, Pb, Cr and Ni) in four size fractions of MSW incineration residues and discuss their mobility potential by using the modified BCR sequential extraction method; (ii) investigate the level of valuable critical contents (precious metals, rare earth elements, etc.) in these wastes. We also characterized mineralogy and elemental composition of four different grain size fractions (0–0.5, 0.5–2.0, 2.0–4.0 and 4.0–16.0 mm) of processed municipal solid waste incineration residue (PIR) from the Southwestern region of Germany, using X-ray fluorescence, X-ray powder diffraction and different spectroscopic techniques. Among all studied size fractions, grains smaller than 2 mm contained higher amounts of total extractable heavy metals in most cases. The most important finding of the study is that the total contents of Cu, Au and Pt in the incineration residues reached economically profitable levels (5.1 g/kg, 21.69 mg/kg and 17.45 mg/kg, respectively).

The Effect of Laser Power on the Interface Microstructure of a Laser Remelting Nano-SiC Modified Fe-Based Ni/WC Composite Coating

The plasma sprayed Fe-based Ni/WC composite coating on the surface of 45 steel was post-treated by laser remelting with the addition of nano-SiC. The effect of laser power on the interface microstructure of a laser remelting nano-SiC modified Fe-based Ni/WC composite coatings were researched. The metallographic structure, microscopic morphology, phase composition, and microhardness of the remelted layer were visually analyzed by metallographic microscope, scanning electron microscope (SEM), X-ray diffractometer (XRD), and microhardness tester, respectively. The results showed that the nano-SiC modified remelted coating was smooth and compact, and with no fine cracks. The remelted layer was mainly composed of [Fe,Ni], Cr, Fe0.04Ni0.36 phase. The metal elements Fe, Ni, Cr, and Si, and non-metallic element C, appeared to diffuse, and there was metallurgical bonding between the coating and the matrix. With the increase of laser power, the smaller the average grain size, the wider the half-peak height (FWHM), and the more obvious the grain refinement. When the laser power was 500 W, the interface metallurgical showed the best effect. Furthermore, the nano-sized SiC particles served as the core of the heterogeneous nucleation to refine the grains on the one hand, and promoted the formation of a hard intermediate phase in the coating on the other hand. Therefore, the laser remelting and the addition of nano-SiC particles greatly improved the microhardness of the coating. The larger the laser power, the smaller the microstructure characteristics and the fewer the number of holes. With increasing laser power, the hardness increased in general terms and the maximum hardness increased by 51%.

Influence of age on the bioaccumulation of heavy metals in Apodemus sylvaticus at Merja Zerga lagoon, Morocco.

The influence of age and sex on the bioaccumulation of heavy metals in Apodemus sylvaticus was studied in Merja Zerga lagoon in northern Morocco. Five trace metal elements (Zn, Pb, Cr, Cu and Fe) were quantitatively analyzed by Varian AA 240 atomic absorption spectroscopy with graphite furnace in three organs (Liver, Kidney and Heart) from animals of different age and sex. The maximum metal level of the analyzed samples was recorded in adults and was limited to 46.62 μg/g for Pb and 35.1 μg/g for Cu, while it reached 22.69 μg/g, 7.59 μg/g and 6.78 μg/g for Cr, Zn and Fe, respectively. Highly significant differences were found for bioaccumulation of heavy metals according to animal ages and no significant differences were observed between the two sexes among the studied animals. Our results revealed also the existence of a strong correlation (r > 0.65) between the majority of biometric parameters and the trace element concentrations. In general, we found that age is a critical factor in estimating the level of heavy metal pollution. Other characteristics such as habitat, feeding habits and anti-predator behavior of the species need to be studied.

The effect of metal ions doping on the electrochemical performance of molybdenum trioxide

Transition metal elements (Ni, Cu, Mn, Co and Cr) have been doped into the host structure of molybdenum trioxide via in situ hydrothermal method. The characterizations indicate that Ni and Cu doping has no influence on the structure of the host MoO3 while Co and Cr doping not only cause the crystalline phase transformation but also leads to the morphology change of the doped MoO3. These crystalline and morphology alteration have great impact on the electrochemical performance of the doped samples. The electrochemical tests demonstrate that the specific capacitance and the rate capability are enhanced after Ni, Cu and Mn doping while decline after Co and Cr doping, which may be caused by the structure and morphology change of MoO3 as well as the formation of SEI (solid electrolyte interface) layer after Cr doping. The results manifest that metal ions doping has great impact on the electrochemical property of host materials.

Theoretical design of magnetically ultrasensitive two-dimensional ZnO biosensor for in vivo NO detection by electron paramagnetic resonance technique

Nitric oxide (NO) is an important messenger molecule in physiological activities. In vivo detection of NO by the electron paramagnetic resonance (EPR) and electrochemistry is based on the variation of magnetization and conductivity in the presence of NO, respectively. In this paper, we focus on the adsorption of NO on the non-toxic zinc oxide with the intriguing two-dimensional structure, which is named as graphene-like zinc oxide (g-ZnO). According to our first-principles calculations, NO is physisorbed on the pristine g-ZnO with the binding energy of 0.24 eV. In order to improve the sensitivity of the NO detection, we employ the transition metal (TM) elements (Cr, Mn, Fe, Co, Ni, and Cu) to decorate g-ZnO, obtaining the TM-g-ZnO systems. It was found that the incorporation of TM significantly increases the binding energy of NO. Due to the coupling between the NO:2p orbital and the TM:3d orbitals, the variation of the total magnetization of TM-g-ZnO is as high as 0.62–3 μB per TM atom with the adsorption of NO, thus showing the sensibility to NO in terms of the magnetization. Furthermore, the calculated band structures show that the conductivity of TM-g-ZnO can be modulated in the presence of NO due to the hybridization between the NO molecular orbitals and the TM defective state in the band gap. Based on our results, the TM-g-ZnO systems show the promising application in NO sensing by the electron paramagnetic resonance (EPR) or electrochemistry.

Seasonal ambient air particulates and metallic elements (Cr, Cu, Zn, Cd, Pb) pollutants dry depositions fluxes predictions and distributions with appropriate models at a farmland site

This study compare dry deposition models to identify the best one for predicting the deposition of ambient metallic elements (Cr, Cu, Zn, Cd, Pb) at a characteristic farmland sampling site from Aug. 2013 to Jun. 2014.In this study, the collection models of Baklanov and Sorensen, Zhang, and Wood, as well as the vegetation collection model, are used to calculate the dry depositions velocities of 2.5, 10, 20, and 23 μm. These values were used to calculate the seasonal dry deposition fluxes of ambient air particulates and metallic elements.The results thus obtained indicate that the specified collection models are all suitable for predicting the dry depositions of large (10, 20 and 23 μm) ambient air particles and metallic elements (Cr, Cu, Zn, Cd and Pb). All of the models yielded better predictions of dry depositions velocities for particles of size 20 and 23 μm in winter than in other seasons than particles of other sizes.The Baklanov and Sorensen, Zhang, Wood and vegetation collection models all predict the least dry deposition of ambient air particles of size at 2.5 μm and all metallic elements. Moreover, this study further revealed that the particle size is the key parameter that influence the modelled dry depositions fluxes and resulted in the calculated/measured fluxes variations ratios for ambient air particles and metallic elements. Another influence parameter is the pollutants (particles, metallic elements) concentrations. When the particle size is fixed, the higher of the pollutants concentrations, the higher the calculated/measured fluxes ratios can be obtained at this farmland sampling site.

Heavy Metal Pollution of the Drinking Water Sources in the Liujiang River Basin, and Related Health Risk Assessments

The characteristics of heavy metal pollution in drinking water in the Liujiang river basin and its potential hazards on human health were investigated. In this study, the regular water-quality indices and the contents of metal elements Cd, As, Cr, Hg, Zn, Cu, Pb, Fe, and Mn in the Liujiang river and its main tributaries were detected from January to December of 2016. The health risks of drinking contaminated water were evaluated by the health risk assessment model recommended by the US EPA. The results showed that the concentrations of all of the aforementioned metal elements, except Hg, did not exceed the limits recommended by China's surface water environmental quality standard (GB 3838-2002). Pearson correlation analysis of the concentrations of metal elements indicated that Cd, Pb, As, and Fe may have similar sources, and Cu, Cr, Hg, and Zn may have source of diversity, while there was no significant correlation between the concentrations of metal elements and the pH value. The carcinogenic health risks posed by heavy metal elements in the Liujiang river basin in adults and children were 4.52E-04 a-1 and 5.91E-04 a-1, respectively, while the non-carcinogenic health risks were 8.96E-09 a-1 and 1.14E-08 a-1, respectively. The heavy metal elements in drinking water, on the basis of their average carcinogenic health risks, were ranked as Cr > As > Cd, and the risk levels ranged from 3.58E-06 to 1.21E-04 a-1; the risk values of Cr and As were higher than the maximum allowance levels recommended by ICRP (5.0×10-5 a-1). Simultaneously, the risk levels of the average non-carcinogenic health risks ranged from 3.53E-12 to 2.87E-09 a-1, and the range was lower than the maximum allowance levels recommended by EPA. Carcinogens, especially Cr and As, are the main causes of health risks in the aquatic environment of the Liujiang river basin, and should be prioritized as the main objects of aquatic environmental risk management in the Liujiang river basin.

Ambient air particulates-bound metallic elements sources identifications during winter and summer at a Science Park.

The ambient air particulates pollutants of total suspended particulates (TSP) and PM2.5 were collected by using PS-1 and Wilbur PM2.5 sampler, simultaneously during the year of 2015-2017 at a photoelectric factory in Science Park of central Taiwan. And those of the ambient air atmospheric metallic elements (Cr, Mn, Ni, Cu, Zn, Pb) concentrations which attached on the TSP and PM2.5 were analyzed by using inductively coupled plasma optical emission spectrometer. In addition, identifying anthropogenic and natural pollutants sources were conducted by using the enrichment factor (EF) and principal component analysis (PCA) methods. The results indicated that the average TSP and PM2.5 concentrations were ranked highest in winter season, while summer season was ranked lowest during the year of 2015-2016. In addition, the average highest metallic element concentrations were occurred in winter season for both TSP and PM2.5 during the year of 2015-2016, while the average lowest metallic elements concentrations in TSP and PM2.5 were also occurred in winter season during the year of 2016-2017. Moreover, the EF analysis results showed that the metallic element Zn came from anthropogenic emission source. As for metallic element Mn, the results showed that metallic element Mn was mainly attributed to natural emission in this study. Finally, the PCA results showed that metallic elements Cr, Zn and Pb were the dominant emissions metallic elements in this study. As for PM2.5, the results showed that the metallic elements Cr, Cu and Pb were the dominant emissions metallic elements at this HPB sampling site.

Particle Size Distribution and Human Health Risk Assessment of Heavy Metals in Atmospheric Particles from Beijing and Xinxiang During Summer

Under a condition of good air quality (AQI:55-90, PM10:37-97 μg·m-3, PM2.5:17-76 μg·m-3), six groups of 54 samples were collected using an Andersen cascade impactor from both the indoor and outdoor stations in Beijing and Xinxiang from June to August in 2016. The samples were digested by microwave digestion, and nine heavy metal elements (Pb, Cr, Ni, Cu, Zn, As, Cd, Mn, and Co) in the atmospheric particles were determined with an inductively coupled plasma source mass spectrometer (ICP-MS). The results showed that the enrichment index (0-3) of most elements were low in both cities except for Cd[15.0 (Beijing) and 8.47 (Xinxiang)]. Cr, Co, Cu, and Mn in the atmospheric particles from Beijing park, Cd, Pb, and Mn in the atmospheric particles from the Beijing office, Cr, Co, Ni, and As in the atmospheric particles from Xinxiang park, and all nine heavy metal elements in the atmospheric particles from roads in both cities were found to be more concentrated in the coarse fractions; however, Pb, Zn, Cd, Ni, and As in the atmospheric particles from Beijing park, Co, Zn, Ni, Cr, As, and Cu in the atmospheric particles from the Beijing office, Pb, Zn, Cd, Cu, and Mn in the atmospheric particles from Xinxiang park, and all nine metal elements in the atmospheric particles from the Beijing office showed the opposite pattern. The result of a human health risk assessment indicated that the carcinogenic risk of the five carcinogenic elements were all less than 10-4, but a lower potential cancer risk would also occur under long term exposure. For the four non-carcinogenic elements (Pb, Zn, Mn, and Cu), the non-carcinogenic health risk values of Pb, Zn, Mn, and Cu in the atmospheric particulates in Beijing were all far less than 1, which means the corresponding non-carcinogenic risk was negligible; and, except for Mn, there was no obvious non-carcinogenic risk from Pb, Zn, and Cu in the atmospheric particles of Xinxiang.

Inter-comparison of Chemical Composition and Originality of Atmospheric PM10 at Coastal Regions and Offshore Islands in the Subtropical East Asia

Inter-comparison on the chemical characteristics, spatiotemporal variation, and source originality of atmosphere PM10 at the coastal regions and offshore islands of subtropical region in East Asia was investigated. A total of six sampling sites including three coastal and three island sites over the Minjiang estuary were selected for simultaneously manually sampling PM10 to investigate the differences of coastal and island PM10 concentration, chemical properties, and emission sources. After sampling, an ion chromatographer (IC) was used to analyze the concentration of major anions (F−, Cl−, SO42−, and NO3−) and cations (NH4+, K+, Na+, Ca2+and Mg2+). The metallic elements (Na, Ca, Al, Fe, Mg, K, Zn, Cr, Ti, Mn, Ni, Pb, and Cd) of PM10 were measured with an inductively coupled plasma-atomic emission spectrometer (ICP-AES). The carbonaceous contents, including elemental, organic, and total carbons (OC, EC, and TC), of PM10 were analyzed with an elemental analyzer (EA). The source apportionment of PM10 was further resolved by a receptor model based on chemical mass balance (CMB). Field measurement results showed that high concentrations of PM10 (102 ± 25 μg/m3) were commonly observed from late fall to early winter. The PM10 concentration showed a consistently descending trend from the west coastline to the far east islands, with the highest PM10 concentration at the coastal site (Site HQ) and the lowest at the far east island site (Site DY) in all seasons. Secondary inorganic aerosols (SIAs) and crustal materials were two most abundant compounds in PM10. Increasing anthropogenic trace elements was commonly observed in spring and winter, while northern monsoons were blown. High OC/EC ratios showed that secondary organic aerosols (SOAs) could be formed in the atmosphere of Minjiang estuary. Results from CMB receptor modeling indicated that the major sources of atmospheric PM10 at the coastal and offshore island regions of the Minjiang estuary were soil dusts (13–33%), secondary aerosols (15–30%), transport emissions (11–17%), sea salts (8–27%), and agricultural debris burning (2–8%). Particularly, during the poor air quality periods, a rising contribution of industrial emissions (1–16%) was resolved, suggesting that atmospheric PM10 over the Minjiang estuary was mainly attributed to cross-boundary transport rather than local emissions.

Monitoring Heavy Metal Contents with Sphagnum Junghuhnianum Moss Bags in Relation to Traffic Volume in Wuxi, China.

Despite its small size, a moss bag can reveal the different temporal and spatial deposition patterns of pollutants at a particular site; therefore, researchers can use moss bags to determine pollution sources and to put forward strategies for pollution control. Although the use of moss bags to monitor atmospheric pollution has been widely reported in Europe, there are few such empirical studies in China. Thus, in this study, bags containing the moss Sphagnum junghuhnianum were used to assess the concentrations of heavy metals (chromium (Cr), copper (Cu), lead (Pb), vanadium (V), and zinc (Zn)) at five sampling sites (four roads and a forest park) during the summer and winter of 2012. According to the relative accumulation factor (RAF) and contamination factor (CF) results, pollution in winter was heavier than that in summer, and Cr was found to be the most contaminating, having the highest mean CF. There was a significant positive correlation (p < 0.05) between traffic volume and concentration for three heavy metals (Cr, Cu, and V) in winter, whereas a significant positive correlation (p < 0.05) was observed between traffic volume and concentrations for four heavy metal elements (Cr, Pb, V, and Zn) in summer, indicating a close relationship between heavy metal contents and traffic volume. Although there was substantial variation in the concentrations of the five heavy metals in the moss bags, significant correlations between heavy metals suggested that the contaminants originated from a common source, namely vehicle emissions. The results demonstrated that the four roads were subject to different degrees of pollution depending on the volume of traffic using each road. Therefore, the results of this study suggest that traffic volume is a major reason for heavy metal pollution.

Assessment of heavy metals in raw food samples from open markets in two African cities

The present study was performed to assess the level of biologically potent metallic elements (Al, Cd, Cr, Cu, Hg, Mn, Pb and Zn), metalloid (As) and non-metal (Se) in different raw food from open markets in Kinshasa (Democratic Republic of Congo) and Johannesburg (South Africa). Hundred twenty different food samples comprising of cabbage, bean, beef and fish were collected, digested in the microwave system and analysed for trace metals using ICP-OES, ICP-MS and mercury analyser. The obtained results were used to evaluate the health risk of these elements via consumption of foods. The investigation revealed that the mean level of trace elements ranged Al: 1.62 ± 0.32 to 52.10 ± 3.45, As: 1.62 ± 0.32 to 5.33 ± 1.04, Cd: 0.16 ± 0.09 to 3.93 ± 0.12, Cr: 0.58 ± 0.24 to 17.29 ± 2.03, Cu: 0.69 ± 0.15 to 15.70 ± 1.67, Hg: 1.53 ± 0.1 to 2.94 ± 0.23, Mn: 5.34 ± 1.37 to 18.31 ± 3.45, Pb: 0.16 ± 0.09 to 4.14 ± 1.08, Se: 0.18 ± 0.08 to 1.41 ± 0.97, Zn: 5.47 ± 1.83 to 75.12 ± 5.67 mg kg−1. The average values of As, Cd, Cr, Cu, Hg, Mn, Pb, Se and Zn in raw foods collected from Johannesburg market were significantly higher (p < 0.05) than those from the Kinshasa market. While the highest Al contents (p < 0.05) were found in the food sold in Kinshasa open market. The levels of most studied metals in the raw foods were exceeding the recommended maximum acceptable limit proposed by the Joint FAO/WHO Expert Committee on Food. The combined Target Hazard Quotients (THQ) values for all samples from both markets were greater than 1 which indicates a potential health risk to the local consumer.

Benthic foraminiferal assemblages as bio-indicators of metals contamination in sediments, Qarun Lake as a case study, Egypt

Qarun Lake, in the Fayoum Depression of the Western Desert of Egypt, lies within the deepest area in the River Nile flood plain. The drainage water in the Qarun Lake is derived from the discharge of the natural and artificial drainage systems in the Fayoum. Mixed domestic and agricultural pollutants, including heavy metals, nitrates, phosphates, sulfates and pesticides, are discharged into Qarun Lake. Forty-six samples, collected from the undisturbed layer of sediments were used for benthic foraminiferal analysis. Concentrations of some selected trace metal elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V, and Zn) were also determined. Statistical analysis of the abiotic variables (Texture distribution of sediments, Physico-chemical parameters, and metals concentrations) and of the biotic variables (distribution of benthic foraminiferal species) were also performed. The Q-mode cluster analysis of benthic foraminiferal distribution has provided evidence that the Qarun Lake can be subdivided into two cluster groups (A and B), reflecting environmental changes in the lake ecosystem. Cluster B can also be subdivided into two sub-clusters (B1 and B2). The presence of only pollution tolerant taxa with higher faunal density and lower diversity and the absence of the other foraminiferal assemblages in cluster A were attributed to the high concentration of trace metal elements and the strong environmental stress at the eastern and central parts of the Qarun Lake.

Evolution Characteristics and Environmental Significance of Heavy Metals in Sediments of Yanma Reservoir

The sediment column samples of Yanma reservoir were collected. The sedimentary age of the column sediments were confirmed based on radioisotope 210Pb dating means to calculate the deposition rate and to draw out the age trend chart of the quality changes of heavy metal elements and to analyse their related factors. According to the above data this study comparatively analysed the vertical distribution characteristics of five heavy metal elements ( Cr, Cu, Zn, As, Pb) and investigated the relationship between the change of heavy metal concentration and the changes of natural environment, human activities as well as explore its referential meaning, provided the basis for the ecological management of Yanma reservoir. The results showed that the main heavy metal pollutants of the Yanma reservoir were Zn and Cr, followed by Cu, Pb and As. The water environment has been polluted gradually since 1958 the Yanma reservoir established. During 1993 -1997, the metal elements were obviously enriched and the water quality of the reservoir deteriorated obviously. During 1994-2010, the water pollution of the reservoir had been weakened, and the water environment had been improved effectively.

Wet and dry deposition fluxes of heavy metals in Pearl River Delta Region (China): Characteristics, ecological risk assessment, and source apportionment

The atmospheric deposition of heavy metals poses serious risks to the ecological system and human health. To advance our knowledge of atmospheric dry/wet heavy metal deposition in the PRD region, monthly fluxes were examined based on soluble/insoluble fractions of five heavy metal elements (Cu, Pb, Cd, Cr and Zn) in samples collected from January 2014 to December 2015 at Guangzhou (urban) and Dinghushan (suburban) sites. The ratios of wet/dry deposition fluxes indicated that heavy metal deposition was governed by wet deposition rather than dry deposition in the PRD region. Affected by the shifting of the Asian monsoon, wet deposition fluxes exhibited significant seasonal variation between summer monsoon seasons (April to September) and winter monsoon seasons (October to February) in this region. Cd was classified as an extremely strong potential ecological risk based on solubility and the Hakanson ecological risk index. Source contributions to wet deposition were calculated by PMF, suggesting that dust, biomass burning, industries, vehicles, long-range transport and marine aerosol sources in Guangzhou, and Zn fertilizers, marine aerosol sources, agriculture, incense burning, biomass burning, vehicles and the ceramics industry in Dinghushan, were the potential sources of heavy metals.

Investigation of Corrosion Characteristics of High-Sodium High-Chlorine Lignite during Circulating Fluidized Bed Combustion

Corrosion experiments were conducted in a 0.4 T/D circulating fluidized bed (CFB) test rig with the high-sodium high-chlorine lignite as fuel to investigate the corrosion phenomena and mechanisms through the air-cooled probes in furnace and tails, respectively. Three alloy materials involving four metal elements (Al, Cr, Ni and Fe) were used to compare their anticorrosion characteristics with the thermodynamic equilibrium calculation software Factsage 6.1 as an auxiliary tool. Experimental results indicate that the probes exposed to the high-temperature flue gas in furnace suffered severe corrosion, which was primarily caused by gaseous corrosive media including HCl (g), NaCl (g) and Cl2 (g), while the probes in tails underwent the almost negligible corrosion arising from the deposited NaCl crystal on the top surface of the probe. The protective oxidation scale formed on the outer surface of alloy was the key to corrosion resistance rather than the internal metal with high quality. Despite different alloy...