Source Of Cr Research Articles

Heavy metal pollution of street dust in the largest city of Mexico, sources and health risk assessment

In large industrialized cities, tons of particles containing heavy metals are released into the environment and accumulate on street surfaces. Such particles cause a potential risk to human health due to their composition and size. The heavy metal contamination levels, main emission sources, and human health risks were identified in 482 samples of street dust. Heavy metal concentrations were obtained by microwave-assisted acid digestion and ICP-OES. The results indicated that street dust in Mexico City is contaminated mainly with Pb, Zn, and Cu, according to the contamination factor and the geoaccumulation index. The pollution load index of the street dust was made with the concentrations of Pb, Zn, Cu, Cr, and Ni. The main sources of Pb, Zn, Cu, and Cr are anthropic, probably due to vehicular traffic. The highest levels of Cr and Pb in urban dust represent a health risk for children. Contamination limits were proposed for heavy metals in street dust of Mexico City. These limits might be useful to generate and apply public policies to decrease anthropic emissions of the heavy metals studied, particularly Cr and Pb.

Chemical Fractionation and Risk Assessment of Some Heavy Metals in Soils, Assiut Governorate, Egypt

Toxic elements behavior in Egyptian soil need more studies for the enhancement of soil quality and human health protection. The current study focuses on the mobility assessment of chemical species of As, Pb, Cr, Ni, Cu and Co in soils due to anthropogenic emission using sequential extraction (SE) and risk assessment code (RAC). Generally, the studied soils are alkaline calcareous loam soil. It has a low organic matter (OM) that ranges from 1 to 3.8% and is enriched with As, Pb, Cr, Ni, Cu and Co, which preferentially accumulate in soil clay and silt fraction. SE revealed that the non-residual (bioaccessible) fraction contains about (70.7%) As, (65.2%) Co, (58.8%) Cr, (28.4%) Cu, (6.8%) Ni and (64.5%) Pb, indicates the risk of pollution with As, Co, Cr, and Pb. RAC values indicated a high risk of soil pollution with As, medium risk of Co and Pb, low risk of Cu and Ni, and no risk of Cr. The results pointed out the geogenic source of Cr, mixed source of Co, Cu, and Ni and the anthropogenic source of As and Pb. The spatial distribution analyses of these metals indicated the role of urbanization, traffic, and industry on the releasing of toxic metals into the environment.

Replacement of the Common Chromium Source CrCl3(thf)3 with Well-Defined [CrCl2(μ-Cl)(thf)2]2.

CrCl3(thf)3 is a common starting material in the synthesis of organometallic and coordination compounds of Cr. Deposited as an irregular solid with no possibility of recrystallization, it is not a purity guaranteed chemical, causing problems in some cases. In this work, we disclose a well-defined form of the THF adduct of CrCl3 ([CrCl2(μ-Cl)(thf)2]2), a crystalline solid, that enables structure determination by X-ray crystallography. The EA data and XRD pattern of the bulk agreed with the revealed structure. Moreover, its preparation procedure is facile: evacuation of CrCl3·6H2O at 100 °C, treatment with 6 equivalents of Me3SiCl in a minimal amount of THF, and crystallization from CH2Cl2. The ethylene tetramerization catalyst [iPrN{P(C6H4-p-Si(nBu)3)2}2CrCl2]+[B(C6F5)4]− prepared using well-defined [CrCl2(μ-Cl)(thf)2]2 as a starting material exhibited a reliably high activity (6600 kg/g-Cr/h; 1-octene selectivity at 40 °C, 75%), while that of the one prepared using the impure CrCl3(thf)3 was inconsistent and relatively low (~3000 kg/g-Cr/h). By using well-defined [CrCl2(μ-Cl)(thf)2]2 as a Cr source, single crystals of [(CH3CN)4CrCl2]+[B(C6F5)4]− and [{Et(Cl)Al(N(iPr)2)2}Cr(μ-Cl)]2 were obtained, allowing structure determination by X-ray crystallography, which had been unsuccessful when the previously known CrCl3(thf)3 was used as the Cr source.

Microbial Mechanisms for Remediation of Hexavalent Chromium and their Large-Scale Applications; Current Research and Future Directions

The increase of anthropogenic activities has led to the pollution of the environment by heavy metals, including chromium (Cr). There are two common oxidative states of Cr that can be found in industrial effluents the trivalent chromium Cr(III) and the hexavalent chromium Cr(VI). While the hexavalent chromium Cr(VI) is highly toxic and can trigger serious human health issues, its reduced form, the trivalent chromium Cr(III), is less toxic and insoluble. Leather tanning is an important industry in many developing countries and serves as a major source of Cr(VI) contamination. Globally, tannery factories generate approximately 40 million m3 of Cr-containing wastewater annually. While the physico-chemical treatments of tannery wastewater are not safe, produce toxic chemicals and require large amounts of chemical inputs, bioremediation using chromium-resistant bacteria (CRB) is safer, efficient and does not produce toxic intermediates. Chromium-resistant bacteria (CRB) utilise three mechanisms for Cr(VI) removal: biotransformation, biosorption and bioaccumulation. This review will evaluate the three Cr(VI) detoxification mechanisms used by bacteria, their limitations and assess their applications for large-scale remediation of Cr(VI). This can be helpful for understanding the nature of Cr(VI) remediation mechanisms used by bacteria, therefore, bridging the gap between laboratory findings and industrial application of microorganisms for Cr(VI) removal.

Tailoring the thermal and mechanical properties of diamond/Cu composites by interface regulation of Cr alloying

Copper matrix composites reinforced with 60 vol% diamond particles were prepared by pressure infiltration using Cu-Cr alloy with 0.3–1.0 wt% Cr. The x-ray diffraction, scanning electron microscopy, and transmission electron microscopy were conducted to characterize the Diamond/Cu composites interface. The interface structure evolves from the discontinuous point contact to continuous strip carbides depending on the availability of Cr source. With Cr content increasing, the thermal conductivity of the Diamond/Cu-Cr composites increases first and then decreases. The highest thermal conductivity of 696 W/mK was achieved at 0.5 wt% Cr addition, while the highest tensile strength and bending strength of 252 MPa and 523 MPa were achieved at 0.7 wt% Cr addition. By optimizing the interface thermal resistance and interface bonding strength, Diamond/Cu composites with excellent comprehensive properties can be obtained.

Tribological properties of CrAlSiC coatings fabricated under various conditions for generating carbon plasma

There were investigated tribological properties of CrAlSiC coatings deposited by two techniques. In both techniques a plasma source of a cathode-arc discharge with Cr-Al-Si composite target served the source of Cr, Al, and Si atoms during coating deposition. A plasma source of a pulsed cathode-arc discharge with graphite cathode and a gas discharge device to generate a non-self-sustained discharge in argon-acetylene mixture have been used for generating carbon plasma in first and second techniques, correspondingly. First coating has a low coefficient of friction. Under frictional action, coating wears out uniformity without chipping. Second coating is less resistant to frictional action.

A New Cosmic-Ray-driven Instability

Abstract Cosmic-ray-driven (CR-driven) instabilities play a decisive role during particle acceleration at shocks and CR propagation in galaxies and galaxy clusters. These instabilities amplify magnetic fields and modulate CR transport so that the intrinsically collisionless CR population is tightly coupled to the thermal plasma and provides dynamical feedback. Here, we show that CRs with a finite pitch angle drive electromagnetic waves (along the background magnetic field) unstable on intermediate scales between the gyroradii of CR ions and electrons as long as CRs are drifting with a velocity less than half of the Alfvén speed of electrons. By solving the linear dispersion relation, we show that this new instability typically grows faster by more than an order of magnitude in comparison to the commonly discussed resonant instability at the ion gyroscale. We find the growth rate for this intermediate-scale instability and identify the growing modes as background ion-cyclotron modes in the frame that is comoving with the CRs. We confirm the theoretical growth rate with a particle-in-cell simulation and study the nonlinear saturation of this instability. We identify three important astrophysical applications of this intermediate-scale instability, which is expected to (1) modulate CR transport and strengthen CR feedback in galaxies and galaxy clusters, (2) enable electron injection into the diffusive shock acceleration process, and (3) decelerate CR escape from the sites of particle acceleration, which would generate gamma-ray halos surrounding CR sources such as supernova remnants.

Effects of organic chromium sources on growth performance, lipid metabolism, antioxidant status, breast amino acid and fatty acid profiles in broilers.

BACKGROUNDTrivalent chromium (Cr) is involved in carbohydrate, lipid, protein and nucleic acid metabolism in animals. This study evaluated the effects of different organic Cr forms with Cr methionine (CrMet), Cr picolinate (CrPic), Cr nicotinate (CrNic), and Cr yeast (Cr‐yeast) at the level of 400 μg kg−1 Cr, on growth performance, lipid metabolism, antioxidant status, breast amino acid and fatty acid profiles of broilers. In total, 540 one‐day‐old Arbor Acres male broilers were randomly assigned to five treatments with six replicates (18 broilers per replicate) until day 42.RESULTSThe results showed growth performance was not affected by Cr sources. The Cr‐yeast group had lower serum cortisol levels than the CrNic group (P < 0.05). Besides, Cr‐yeast increased methionine and cysteine content in breast compared with the control group. Liver malondialdehyde content was lower in the CrMet group than the CrPic group on day 42 (P < 0.05). The n‐3 polyunsaturated fatty acid (PUFA) values were increased, but the n‐6/n‐3 PUFA ratio was decreased in both CrMet and CrNic groups (P < 0.05). There were no significant effects on broilers’ serum antioxidant status and breast total essential amino acid content among all treatments.CONCLUSIONSDiets supplemented with organic Cr could regulate lipid metabolism, and improve amino acid and fatty acid profiles in broiler breast. Moreover, Cr‐yeast was the most effective source in improving methionine and cysteine content, whereas CrMet was more effective than CrNic in increasing n‐3 PUFA value and decreasing n‐6/n‐3 PUFA ratio in breast meat and effectively strengthened liver antioxidant ability than CrPic. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Sustainable biorefinery associated with wastewater treatment of Cr (III) using a native microalgae consortium

Microalgae have emerged as renewable and sustainable candidates for biorefineries since they can generate bioproducts and bioenergy through the removal of contaminants contained in wastewater. In the present study, a native microalgae consortium (NMC) is isolated from a wastewater treatment plant, and used to remove 100 mgL−1 Cr(III). The native microalgae consortium is enriched in a photobioreactor with the following conditions: Bold’s Basal Medium (BBM), pH 8, room temperature and 20 µmolm−2s−1 light intensity. The molecular characterization reveals the presence of the following species: Tetradesmus sp., Scenedesmus sp and Ascomycota sp. The development of microalgae is evaluated through the production of biomass, pH, protein, lipid and carbohydrate, while the consortium presents the potential to obtain biofuels. The ability of the consortium to absorb two different sources of Cr (III) was determined using real tannery wastewater and synthetic water prepared with Cr2(SO4)3. The adsorption efficiency of the microalgae is analyzed using adsorption isotherms of Langmuir model, indicating 99% adsorption efficiency of 100 mgL−1 Cr(III). FT-IR and SEM analyses enable to identify the presence of Cr(III) in the native microalgae consortium. The promising features of this NMC underpin the idea of establishing a sustainable biorefinery to generate different bioproducts, in order to achieve a resource-efficient biomass use for a circular bioeconomy.

Spatial distribution and eco-environmental risk assessment of heavy metals in surface sediments from a crater lake (Bosomtwe/Bosumtwi).

Thirty samples of sediments were taken from Bosumtwi Lake (also called Bosomtwe Lake) in Ghana and analyzed for the contents of Fe, As, Hg, Co, Cr, Ni, Cd, and Pb. Several pollution indices (enrichment factor (EF), contamination factor (CF), geoaccumulation (Igeo), and pollution load index (PLI)) were used to determine sedimentary pollution levels, and the risk of environmental exposure was calculated using Hakanson's potential ecological risk (PER) indices. The results from PER assessments have indicated that sediments from the Bosumtwi Lake present a moderate environmental risk. According to EF calculations, Hg in Bosumtwi lake sediments is the element of concern that is being severely enriched. Hg was the largest contributor to PER with a 97% risk contribution. Multivariate statistical analysis revealed that the main sources of Hg were agrochemicals and atmospheric deposition, whereas the sources of Fe, As, Co, Cr, and Ni to Bosumtwi Lake were natural processes and are derived from the local lithology. There was no strong significant correlation among the contents of the heavy metals, sediment grain sizes, and total organic carbon (TOC), suggesting their lack of control in the distribution of heavy metals, the source, and the transport pathway. Finally, it is strongly recommended to do a study on Hg bioavailability in Bosumtwi Lake sediments. These findings will be relevant to Bosumtwi Lake's profiling and historical development of heavy metal loads.

BIOMONITORING OF CHEMICAL ELEMENT AIR POLLUTION IN HANOI USING Barbula indica MOSS

Atmospheric deposition of chemical elements in the Hanoi region has been investigated in this study based on moss biomonitoring. Twenty-seven Barbula indica moss samples were collected from the end of 2016 to the beginning of 2017, and the concentrations of 33 chemical elements in the samples were determined by instrumental neutron activation analysis. The results show that Hanoi s air is highly polluted with Zn, Ba and Ta, and slightly polluted with Al, Cl, Sc, Ti, V, Cr, Mn, Fe, Ni, Co, As, Cd, Sb, La, Ce, Sm, Gd, Tb, Yb, Hf, Th and U. A determination of the possible pollution sources has been made for the analyzed elements; namely: coal and oil combustion are the main sources of V, Ni, Co and As; vehicle exhaust and non-exhaust sources, as well as industrial emissions, are the main sources of Mn, Co, Cd and Ba; construction dust is the source of Ca, Mg and Sb; various industries are the sources of Cr and Ni; the dust from cement kilns and ash from biomass burning is responsible for K and Cl; two-stroke motor vehicles, galvanizing factories and tire wear are the sources of Zn; and Br may be emitted from burning wastes.

Dietary supplementation of chromium for finishing pigs

ABSTRACT: Increasing fat deposition and feed conversion ratio over the days in finishing phase directly influence pork quality and productive profitability. Nonetheless, the slaughter of heavier pigs can result in benefits for the slaughterhouse due to dilution of production and processing costs, as well as economic benefits for the pig producer resulting from the dilution of production costs. Therefore, dietary supplementation of chromium for finishing pigs of high lean-genotypes is a strategy to increase lean tissue accretion and minimize fat deposition, reflecting positively on growth performance. This review discussed recent studies results and mechanisms of action of this modifier of performance and carcass a traits in finishing pigs. Chromium increases the insulin action, facilitating insulin binding to the receptors on cell membrane. As a result, insulin-sensitive cells uptake more glucose, which will be later converted into energy. This additional energy is use to increase protein synthesis, thereby increasing the amount of lean tissue and reducing fat content in the carcass, without altering protein intake by pigs. Chromium also reduces lipid oxidation rate maintaining meat quality for longer period. In conclusion, dietary Cr supplementation for finishing pigs have shown that 0.2 mg/kg of organic Cr sources for pigs from ~60 kg until the slaughter can improve growth performance, lean gain and reduce fat content in carcass. However, the development of nanotechnology has allowed the use of inorganic Cr source at 0.2 mg/kg of inclusion, leading to improve the growth performance and carcass traits of finishing pigs.

Hydrogeochemical investigation of Cr in the ultramafic rock-related water bodies of Loutraki basin, Northeast Peloponnese, Greece

This research aims to determine the hydrogeochemical characteristics, origin, and geochemical evolution of the Cr enriched alkaline waters in the ultramafic rock-related water bodies of Loutraki basin in Northeast Peloponnese, Greece. The significance of the particular research lies in the fact that Cr occurrence raises concerns with respect to health risks associated with the utilization of such aquifers for drinking water supply. Therefore, the investigation of water–rock interaction processes leading to Cr mobilization in such environments is of great importance. A total of 41 water samples including groundwater from the alluvial and fractured aquifers as well as surface water were collected and analyzed for major and trace elements during the wet and dry seasons of 2015. Solid samples including soils, sediments and rocks were also collected to provide evidence of elemental mobilization due to water–rock interaction, with special focus on Cr. Τhe main Cr-bearing minerals identified were Cr-spinel, ferrichromite, magnetite, clinopyroxene, chlorite and serpentine. The observed dissolution textures within the magnetite rim and across the magnetite–chromite boundary indicate that these latter can be also active sources of Cr(III). Both groundwater and surface waters are of Mg–HCO3 type due to CO2-driven dissolution of serpentine minerals and Mg-carbonates/hydroxides. The formation of hydromagnesite aggregates is attributed to precipitation from Mg2+-rich alkaline waters. The highest Cr(VI) concentrations were measured in the alluvial aquifer (6.7–74.3 μg L−1) and the lowest in the fractured ophiolitic aquifer (1.9–14.3 μg L−1); while in surface water, the maximum measured Cr(VI) concentration was up to 3.9 μg L−1. Finally, the identification of Mn-rich hematite indicates that the oxidation of Cr(III) to Cr(VI) is probably performed by manganese–iron oxides.

Chromium and Zinc Speciation in Airborne Particulate Matter Collected in Ulaanbaatar, Mongolia, by X-Ray Absorption Near-edge Structure Spectroscopy

ABSTRACT This study examined the chemical speciation of atmospheric particulate matter (PM) samples collected in Ulaanbaatar, Mongolia. The health effects of atmospheric aerosol depend on the particles’ size distribution, elemental composition and chemical species as well as other factors, which vary according to the pollution sources and meteorological conditions. Employing the International Atomic Energy Agency (IAEA) supported X-ray fluorescence (XRF) beamline at Elettra Sincrotrone Trieste, Italy, we used a small incidence angle for the synchrotron emission radiation in this ultra-high-vacuum environment to analyze the fine and the coarse mode (PM2.5 and PM2.5-10, respectively) through X-ray absorption near-edge structure (XANES) spectroscopy, which was applied to the K-edges of the chromium (Cr) and zinc (Zn) in PM samples selected via energy-dispersive XRF (EDXRF) analysis for their high concentrations of these transition metals. The spectroscopic results identified trivalent chromium sulfate [Cr2(SO4)3] and chromium oxide (Cr2O3) compounds as the major chemical forms of Cr in both the coarse and the fine PM fraction. Furthermore, both fractions contained abundances of sulfate (ZnSO4) and silicate (Zn2SiO4) compounds, but only the fine mode contained Zn oxalate (ZnC2O4), whereas only the coarse mode contained Zn chloride (ZnCl2). These Cr and Zn species seemed to originate from local anthropogenic sources, e.g., combustion products or traffic-related resuspended road dust. Our findings, which are based on the first chemical speciation analysis from Ulaanbaatar, provide insight into the physiochemical characteristics of atmospheric aerosols as well as information on the potential sources of Cr and Zn species bound to fine and coarse PM.

Red mud based binder: A sustainable material for removal of chromium (VI) from water

Presence of chromium (VI) or Cr (VI) in the environment leads to its bioaccumulation and disruption of metabolic activity in living beings. Contaminated water is one of the main source of Cr (VI) into the living systems. Though different approaches for its removal have been investigated, a sustainable, cost effective and efficient method still remains a challenge. Red mud is an industrial waste from aluminum extraction process and is found to contain 40% of iron. According to past investigations, naturally occurring materials rich in iron have shown affinity to heavy metals and high binding stability. In the present study we have investigated red mud based geopolymer binder for removal of Cr (VI) from water. According to past studies, red mud geopolymer binder is difficult to cure at ambient temperature. Hence GGBS (ground granulated blast furnace slag) was added to the red mud in the geopolymer binder. The percentage of red mud in the binder was taken as 40%. In order to be used for practical applications, any material used for water purification should have a good strength and durability. Compression test of the geopolymer binder using processed red mud has shown an improvement in its mechanical property which includes strength. Investigation on removal of Cr (VI) as dichromate salt by adsorption by the red mud based binder was done by spectral analysis using UV–Vis spectrophotometer. 1,5-diphenylcarbazide was used to observe change in concentration of Cr (VI) as it forms a red violet colored complex with Cr (VI). A decrease in intensity with increase in time of contact between the red mud binder and dichromate solution was observed. The developed material has a potential to be used for removal of Cr (VI) from water.

Evaluation of CO2 and CH4 adsorption using a novel amine modified MIL-101-derived nanoporous carbon/polysaccharides nanocomposites: Isotherms and thermodynamics

The high efficiency organic-inorganic nanocomposites were fabricated by the simple impregnation of polysaccharides such as alginate, cellulose and chitosan on the MIL-101-derived nanoporous carbon (MDC) for gas adsorption from natural gas. The volumetric method was employed to investigate CO2 and CH4 uptake at the different temperatures and P < 21 bar. The incorporation of polysaccharides can enhance the CO2 binding affinity and lead to improved CO2 adsorption capacity. Structural analyses of the samples were characterized by N2 isotherms, FT-IR, TEM, TGA, XRD, FESEM and EDS with mapping analysis. Despite promising advances in the synthesis of MIL-101 as an excellent adsorbent in recent decades, this adsorbent has not yet been commercialized due to the toxic and expensive synthesis procedure of MIL-101. In this work, MIL-101 was synthesized from waste Cr source and without using hydrofluoric acid as a mineral agent. The highest uptake was observed for the nanocomposites of chitosan-MDC (MDC@CT). This behavior of MDC@CT can be explained by the presence of surface NH2-groups which act as primary adsorption sites for CO2. This study also assesses the potential effect of amine-based nitrogen-rich surface functional group loads on MDC@CT on gas adsorption properties. Tris(3-aminoethyl)amine was selected as the amine source in the preparation of amine-modified MDC@CT. The CO2 adsorption was best fitted by Langmuir model, while the CH4 adsorption followed the Freundlich models. The respective negative values of ΔG and ΔH revealed that the adsorption of both the gases were spontaneous and exothermic.

PSVI-7 Effects of feeding chromium- and zinc- amino acid complexes on growth performance and carcass characteristics of finishing bulls fed zilpaterol hydrochloride for the last 30 days in the feedlot

Abstract A 2 x 2 factorial study was conducted to evaluate main and interaction effects of feeding amino acid complexed sources of Zn (Zn-AAC; 40 mg /kg DM from Availa® Zn; Zinpro Corp., Eden Prairie, MN) and Cr (chromium methionine; Cr-Met; 0.20 mg / kg DM from Availa® Cr; Zinpro Corp., Eden Prairie, MN) fed in combination or separately, compared to an iso-Zn level Control (CON) group that provided Zn from ZnSO4 (80 mg Zn∙kg-1DM) with no supplemental source of Cr. Treatments were replicated into 4 pens with 5 finishing Bos taurus x Bos indicus bullocks/pen (80 bullocks; BW= 421 kg). Treatment diets were initiated 28 d prior to starting zilpaterol hydrochloride (ZIL; 15 mg/kg BW) with ZIL fed daily for 33 d followed by a 4 d withdrawal before harvest. During the ZIL-feeding Zn-ACC x Cr-Met interactions were present for ADG and Gain:Feed (G:F) where Zn-ACC improved ADG (P≤ 0.05) and Cr-Met improved G:F vs. CON. Effects may have been mediated by differences in DM intake (DMI), where DMI was numerically increased by Zn-ACC and decreased (P ≤ 0.01) by Cr-Met. Overall, feeding Cr-Met moderated DMI and improved G:F (P ≤ 0.05). Measures of carcass composition were not affected by Zn-ACC or Cr-Met. Hot carcass weight was increased (P ≤ 0.05) by feeding Zn-ACC and tended to increase with Cr-Met. Daily carcass gain increased from feeding either Zn-ACC or Cr-Met during the ZIL phase and overall study. Feeding Zn-ACC was a primary driver during the ZIL period and overall trial for increasing growth rate, with little or no influence on DM intake while feeding Cr-Met moderated DM intake to improve dietary and energetic efficiency. Balancing the feeding levels of Zn-ACC and Cr-Met will be key to optimizing the overall biological response and net return.

Investigation of Soil Cr and Ni Contamination in Different Land Uses and Tracing the Source of Contamination

Chromium (Cr) and nickel (Ni) are commonly used heavy metals in alloy manufacture. In Korea, most research on heavy metal(loid)s focused on As, Cd, Cu, Pb, and Zn, and little attention has been paid to Cr and Ni. However, recent studies showed that they were gradually increasing in the soils, especially when the soils were influenced by human activities. Thus, this study aims to investigate soil Cr and Ni concentrations in different land uses and trace the source of Cr and Ni contamination. Cr and Ni concentrations in different use of soil were obtained from literature and soil analysis. Also, to identify the impact of dust deposition on the soil Cr and Ni, Cr and Ni levels in air dust from various areas were studied by literature review and air dust analysis. Soil Cr and Ni concentrations were higher near roadsides and industrial complexes, and their concentrations had a strong linear correlation. This indicates that Cr and Ni could have a common source of contamination such as vehicles. Similarly, Cr and Ni concentrations in air dust were also higher near roadsides, urban areas, and industrial areas. Therefore, Cr and Ni loads on soils are highly related to traffic and industrial activities. Averaged Cr and Ni concentrations in different soil uses compared to Korean natural background levels..

Behaviour of Cr in runoff from two catchments underlain by felsic bedrock

ABSTRACT Chromium isotope and chemical compositions in runoff from two felsic rock catchments, the Lysina (LYS; Czech Republic) and the Neglinka (NEG; northwest Russia), were studied. Three types of water were identified: Na-Ca-SO4 type for the LYS, Mg-Ca-Cl-HCO3 type for the NEG downstream, and Mg-Ca-Cl to Mg-Ca-HCO3 type for the NEG upstream. The Cr (III) liberated during soil/bedrock weathering oxidized to Cr (VI), which was the main dissolved Cr species in both catchments. Variations in δ53Cr values for LYS runoff (–0.07‰ to +0.37‰) reflected a sole Cr source, seasonality of weathering and hydrologically controlled leaching/export processes. In the NEG catchment, back-reduction of Cr (VI) to Cr (III) during riverine transport resulted in a decrease in Cr concentrations (to 10–30%) and in an increase of δ53Cr values (+0.09 to +0.42‰ for the upstream to +0.72 to +1.73‰ for the downstream). Groundwater discharge could have influenced the chemical composition of the downstream NEG runoff to some extent.

Heavy metals in different moss species in alpine ecosystems of Mountain Gongga, China: Geochemical characteristics and controlling factors.

Terrestrial mosses are promising tracers for research concerning metal atmospheric deposition and pollution. Concentrations of Cr, Co, Ni, Zn, Sr, Cd, Ba, and Pb in different moss species from Mountain Gongga, China were analyzed to investigate the effects of growth substrates, geographic elevation, and type of moss species on the accumulation characteristics of heavy metals, as well as to identify heavy metal sources. The ability of heavy metals to accumulate in moss varied significantly, with low concentrations of Cd and Co; medium concentrations of Cr, Ni, and Pb; and high concentrations of Zn, Sr, and Ba. Elevation significantly influenced the accumulation characteristics of heavy metals, with high concentrations found at lower elevations due to proximal pollution. Growth substrate and moss species were found to have certain influence on the bioconcentration capacities of heavy metals in moss in this study. Correlation analysis showed similar sources for Sr, Zn, and Ba, as well as for Ni, Co, and Cr. The positive matrix factorization (PMF) model was consistent with atmospheric deposition of Pb and Cd; substrate sources of Cr, Co, and Ni; and anthropogenic sources of Ba, Sr, and Zn. This research characterized the accumulation characteristics of heavy metals and their influence factors in different mosses found in alpine ecosystems and provides a reference for future studies in similar areas.