Chromium Content Research Articles

ANALYZING THE EXTENT OF LEACHATE FROM A MAJOR DUMPSITE WITHIN THE CRETACEOUS SEDIMENTS OF IKOM-MAMFE EMBAYMENT, SOUTHEAST NIGERIA

Groundwater resources in the region serve as a vital source of potable water for local communities and are essential for supporting various socio-economic activities. Unfortunately, the infiltration of leachate from dumpsite contributes to the dispersion of contaminants within the cretaceous sediments, posing a potential threat to groundwater quality. This study presents an exhaustive examination of leachate extent emanating from a prominent dumpsite situated within the Cretaceous sediments of the Ikom-Mamfe Embayment, Southeast Nigeria. Employing meticulous soil sampling methodologies and water collection from strategically positioned boreholes near the Ikom dumpsite, advanced techniques such as Electrical Resistivity Tomography (ERT) and Vertical Electric Sounding (VES) were utilized to scrutinize the infiltration of leachate within the site. Laboratory analyses were conducted to evaluate the concentrations of heavy metals, including Lead, Mercury, Arsenic, Nickel, Chromium, and Cadmium, in both soil and borehole water samples. The findings unveiled alarming levels of Lead and Cadmium concentrations in the soil, exceeding established regulatory thresholds, with recorded values ranging from 552.34 to 556.93 mg/kg and 11.88 to 7.46 mg/kg, respectively. Similarly, borehole water analyses in the vicinity of the Ikom dumpsite revealed elevated concentrations of Arsenic, Lead, Cadmium, and Nickel, surpassing WHO limits in specific boreholes (BH2 and BH3), indicative of potential soil porosity issues and unfavorable geological conditions prevalent in the study area. Notably, the use of ERT delineated an inverse resistivity of 5.99 Ωm at a depth of 9.26 m, pinpointing the leachate-infiltrated cretaceous sediments zone, extending laterally from 10m to 40m along the profile. The observed infiltration of leachate at 9.26 m depth underscores its penetration into the sandstone, shale, and dark gray shale strata within the dumpsite. Furthermore, the quantified thickness layer ranging from 1.41 to 4.37 affirmed leachate infiltration within the sandstone, shale, and dark gray shale strata, with implications for its movement and containment dynamics. This study underscores the critical role of layer thickness in influencing the migration and containment of leachate, with thicker layers potentially acting as barriers to its movement, while thinner layers may facilitate more rapid migration. Additionally, the assessment of aquifer protective capacity, denoted by ratings below (<0.1), underscores the poor protective capacity of the aquifer system in the study area. In light of these findings, strategic management, remediation, and vigilant monitoring measures are advocated to mitigate contamination risks and safeguard water quality.

Determination of Essential Minerals in the Indigenous Vegetables Solanum nigrum (Stout Shade) and Gynandropsis gynandra (Spider Plant) from Two Agroecological Zones in Kisii County, Kenya.

Vegetables are good sources of essential mineral elements that promote good health and immunity. Information on the nutritional contents of indigenous vegetables is scarce. Therefore, this study sought to ascertain the concentrations of magnesium, manganese, chrome, zinc, copper, and iron in Solanum nigrum and Gynandropsis gynandra indigenous vegetables from two agroecological zones (upper midland and lower highland) of Kisii County, Kenya, using inductively coupled plasma optical emission spectroscopy (ICP‒OES). For Gnandropsis gynandra, the most abundant erythrocytic synthesis element was Fe (1856.67 ± 15.28mg/kg DW) for plants harvested from Nyanchwa (UM), and the least was Cu (8.90 ± 0.44mg/kg DW) in plants harvested from Kari (LH). In addition, Mg was the hypoglycemic element with the highest concentration (5975.00 ± 10.00mg/kg DW), and Cr lowest (3.16 ± 0.45mg/kg DW) in samples harvested from Matongo (UM). For Solanum nigrum, the most erythrocytic synthesis element was Fe (1280.00 ± 10.00mg/kg DW for samples collected from Kiamabundu (UM), and the least was Cu (9.08 ± 0.15mg/kg DW) in the samples from Nyanchwa (UM), whereas Mg in samples from Nyabioto (UM) was the hypoglycemic element with the highest concentration (4920.00 ± 10.00mg/kg DW) and Cr in samples from Mariba (LH had the lowest concentration) (3.95 ± 1.63mg/kg DW). The concentrations of elements in the two indigenous vegetables from the UM agroecological zone were slightly greater than those in the LH agroecological zone. Nonetheless, the variations observed were not statistically significant (P < 0.05). Enzymatically bio accessed concentrations of iron, zinc, chromium, magnesium, manganese, and copper were higher than those obtained aquatically. The indigenous vegetable bio avails substantial amounts of iron and copper to enable them be used in the management pernicious anaemia; on the other hand, the substantial bio availed levels of zinc, manganese, magnesium, and chromium enables the vegetable to be used in the management of diabetes.

Prenatal Parental Exposure to Metals and Birth Defects: A Prospective Birth Cohort Study.

While maternal exposure to high metal levels during pregnancy is an established risk factor for birth defects, the role of paternal exposure remains largely unknown. We aimed to assess the associations of prenatal paternal and maternal metal exposure and parental coexposure with birth defects in singletons. This study conducted within the Jiangsu Birth Cohort recruited couples in early pregnancy. We measured their urinary concentrations for 25 metals. A total of 1675 parent-offspring trios were included. The prevalence of any birth defects among infants by one year of age was 7.82%. Paternal-specific gravity-corrected urinary concentrations of titanium, vanadium, chromium, manganese, cobalt, nickel, copper, and selenium and maternal vanadium, chromium, nickel, copper, selenium, and antimony were associated with a 21-91% increased risk of birth defects after adjusting for covariates. These effects persisted after mutual adjustment for the spouse's exposure. Notably, when assessing the parental mixture effect by Bayesian kernel machine regression, paternal and maternal chromium exposure ranked the highest in relative importance. Parental coexposure to metal mixture showed a pronounced joint effect on the risk of overall birth defects, as well as for some specific subtypes. Our findings suggested a couple-based prevention strategy for metal exposure to reduce birth defects in offspring.

Mineral and Organic Materials as Factors Reducing the Effect of Petrol on Heavy Metal Content in Soil.

As industrial production increases worldwide, so does the demand for fuels. The transport of fuels from the point of production to the end user poses a risk of environmental pollution, both during transport and during combustion in internal combustion engines. The soil is a part of the environment which is particularly sensitive to contamination by petroleum substances. For this reason, research has been carried out into the possibility of reducing the impact of petrol on the content of heavy metals in the soil using various materials, both mineral (bentonite, calcium oxide) and organic (compost). These played an important role in the in situ remediation of contaminated soils. Petrol contamination increased the content of some heavy metals (Pb, Cd, or Ni), while it decreased the content of other metals (Cr, Zn, Co, and Cu) in the soil. The materials used in this study significantly altered the levels of heavy metals in the soil. The strength of the effect varied and the direction of the effect depended on the element. Bentonite was the most effective, while calcium oxide and especially compost were less effective. The most beneficial (limiting) effect of calcium oxide was shown on the soil content of cadmium, cobalt, and chromium, while the bentonite effects were on the content of chromium. The application of the abovementioned materials seems to be effective in reducing low level soil contamination by petrol.

Application of modified pumice particles with a metal-organic composite prepared by m-phenylenediamine an Iron (II) for photoreduction of Cr(VI) under visible light

Discharging heavy metals into water bodies results in global environmental risks. Hexavalent chromium (Cr(VI)) is known as a harmful substance that poses substantial health hazards to humans. This study aimed to modify the pumice beads using a metal-organic composite synthesized by m-Phenylenediamine (mPD) and Iron (II) (FeCl2·4H2O) via a solvent-free method for photoreduction of the Cr(VI) to Cr(III) in wastewater. In the proposed method, iron (II) ions serve both as an electron generator and as a linker for the polymerization of mPD on the pumice surface in the high-temperature pyrolysis process. The optimum molar ratio of FeCl2·4H2O/mPD and the pyrolysis temperature were determined to be 1 and 700 °C. Moreover, the operative parameters such as pH, hole scavenger (formic acid) dosage, photocatalyst mass, Cr(VI) initial concentration, and reaction time were studied and the optimum condition was obtained as pH of 2.0, hole scavenger dosage of 20 mL L−1, photocatalyst mass of 2 g, chromium concentration of 100 mg L−1 and 13 min for irradiation time. The ability of the photocatalyst to reduce Cr(VI) at a concentration of 50 and 100 mg L−1 under natural sunlight irradiation was also examined and a reduction efficacy of 100 % was achieved under optimum conditions within 40 and 60 min; respectively. Finally, the reusability test was conducted up to 10 cycles, and the results proved the durability and practicality of the prepared photocatalyst. The easy separation, short reaction time, and functioning under natural sunlight exhibited a promising application of the proposed photocatalyst for Cr(VI) reduction.

Development of a surfactant-assisted lanthanum anchored hydroxyapatite@polyaniline hybrid composite for the elimination of chromium ions from aqueous solution

The predominant cause of the global clean water deficit is water contamination caused by heavy metals discharged from various industrial effluents. Innovating low-cost adsorbents that can eliminate heavy metals from polluted water is essential to address this challenge. Human health can be negatively impacted by water contamination caused by the increased levels of carcinogenic heavy metals, such as chromium (Cr), found in wastewater. The main goal of this research is to remove chromium ions from an aqueous environment by utilizing the surfactant-assisted lanthanum anchored hydroxyapatite@polyaniline (CTAB-LaHAp@PANI) hybrid composite. Various analytical techniques including FTIR, XRD, SEM, EDX, TEM, TGA, and XPS analysis were utilized for the characterization of the prepared adsorbents. Different influencing factors such as contact time, solution pH, adsorbent dosage, and initial chromium concentration were systematically optimized through the batch method to achieve maximum removal efficiency of the CTAB-LaHAp@PANI hybrid composite. Remarkably, the CTAB-LaHAp@PANI demonstrated a maximal adsorption capacity of 98.2 mg/g, with an optimal contact time of 120 min at pH 3. The isotherm and kinetic analyses indicated that chromium adsorption onto the CTAB-LaHAp@PANI hybrid composite followed the Langmuir and pseudo-second-order kinetic models, supported by high correlation coefficient values. Moreover, the possible removal mechanism of chromium ions on the prepared hybrid composite was explained based on the results obtained from various analytical techniques. The as-prepared CTAB-LaHAp@PANI hybrid composite demonstrates a superior adsorption capacity, exceptional water stability, cost-effectiveness, and various other characteristics that render it an attractive choice for removing chromium ions from the aqueous phase.

Simulation of hexavalent chromium removal by electrocoagulation using iron anode in flow-through reactor

An electrocoagulation (EC) model is developed for hexavalent chromium reduction and precipitation, using iron electrodes. Parallel removal mechanisms such as adsorption of chromium on ferrihydrite and direct reduction at the cathode is assumed negligible due to low concentration of Cr(VI). The reaction model presented for batch system represents species complexation, precipitation/dissolution, acid/base, and oxidation-reduction reactions. Batch reactor simulation is verified using experimental data obtained by Sarahney et al. (2012), where the effect of initial chromium concentration, pH, volumetric current density, and ionic strength is considered (Sarahney et al., 2012). The model couples multicomponent ionic transport in MATLAB with chemical reaction model in PHREEQC, as a widely used computational programming tool and a geochemical reaction simulator with comprehensive geochemistry databases. The suggested current density is 0.05−0.3mA/cm2 and the surface to volume ratio in batch reactor is considered 0.017 1/cm. Design parameters are presented for operation of a flow-through hexavalent chromium removal using electrocoagulation by iron electrode to treat Cr(VI) in range of 10–50 mg/L. The operational parameters for a flow-through EC reactor for Cr(VI) removal is suggested to follow 0.05mA/cm2≤3nFeQcCrVIinlet≤0.3mA/cm2.

Control of paleoclimate and paleoweathering on chromium contents in a non-ultramafic aquifer hosting high chromium groundwater.

Cr(VI) is a carcinogen with proven mutagenic and genotoxic effects. The effects of the depositional environment (e.g., paleoweathering, paleoclimate, and paleoredox condition) on Crenrichment in non-ultramafic aquifer solids are unclear. In this study, we presented the sedimentary characteristics of a borehole from a typical non-ultramafic aquifer with high Cr groundwater in Jingbian, central Ordos Basin, China. Chromium was enriched in the K1h sandstone aquifer, especially at depths of 400-500m, with the highest value of mass transport coefficient (τAl,Cr) up to 92.13% and τAl,Fe up to 33.5%. The provenance of aquifer Cr was predominantly intermediate and felsic igneous rocks with a mafic rock mixture. This mafic source was inferred from Cr-rich granodiorite and mafic/ultramafic rocks in the Yinshan (Daqingshan-Wulashan) Block, northern Ordos Basin. The Cr-rich aquifer in K1h was developed due to a moderate chemical index of alteration (CIA) (mean, 56.7) under relatively warm and humid paleoclimate, as evidenced by high CIA-temperature (CIA-Temp) (mean, 6.79°C) and paleoclimatic index values (mean, 0.40). Fe-Mn redox cycling in the oxic to suboxic environments contributed to aquifer Cr accumulation. Using path analysis, we identified that paleoclimate created favorable weathering conditions and enrichment of Fe contributed to the formation of high-Cr aquifers. The study reveals the formation of positive Cr anomalies in non-ultramafic aquifers, which is the potential source of groundwater Cr, and highlights the effects of depositional factors on Cr accumulation during aquifer deposition or early diagenesis. It can provide new insights into the natural processes of high-Cr sediments occurring in non-ultramafic aquifers.

Distribution and transformation of potentially toxic elements in cracks under coal mining disturbance in farmland.

The ground cracks resulting from coal mining activities induce alterations in the physical and chemical characteristics of soil. However, limited knowledge exists regarding the impact of subsidence caused by coal mining on the distribution of potentially toxic elements (PTEs) fractions in farmland soil. In this study, we collected 19 soil profiles at varying depths from the soil surface and at horizontal distances of 0, 1, 2, and 5m from the vertical crack. Using BCR extraction fractionation, we determined the geochemical fractions and total concentrations of Chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb) to investigate their ecological risk, spatial fraction distribution, and main influencing factors. Results showed that the values of Cd appearing in 68.7% of the samples were higher than 40 and less than 80, presented a moderate ecological risk. Chromium (Cr), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), and lead (Pb) were mainly bound to residual fractions (> 60%) with lower mobility and Cd was dominated by F1 (acid-soluble fractions, 50%) and F2 (reducible fractions, 29%) in surface soil (0-20cm). The geochemical fractionation revealed that the mobile fractions (F1-acid-soluble and F2-reducible) of PTEs were primarily located near the crack, influenced by available potassium. In contrast, the less mobile fractions (F3-oxidizable and F4-residual) exhibited higher concentrations at distances of 2 and 5m from the crack, except for arsenic, influenced by the presence of clay particles and available phosphorus.

Treatment of greywater using a non-aerated combined horizontal and vertical flow constructed wetland

ABSTRACT Human, animal, and plant health is universally paramount, yet the release of poorly treated wastewater into the environment poses a significant risk to all life forms. Hence the need to employ wastewater treatment technologies to curb these health risks. Due to the need to adopt sustainable wastewater treatment technologies, this study investigated the use of a non-aerated hybrid horizontal and vertical flow constructed wetland for the removal of heavy metals and microorganisms from greywater. This was done at six different hydraulic retention times. Results showed significant reductions (p &amp;lt; 0.05) in heavy metal (manganese, zinc, cadmium, magnesium, chromium, and iron) concentrations, with some showing compliance to Ghana's Environmental Protection Agency and the United Kingdom National Environment Regulation recommended discharge limits. Heavy metal concentrations in effluent samples ranged from as low as 0.00 ± 0.15–0.23 ± 0.06 mg/L. Furthermore, there were significant reductions in Escherichia coli and Salmonella typhi (p &amp;lt; 0.05), which also showed compliance to Ghana's Environmental Protection Agency effluent discharge standards. The effluents from the system at HRT 3 days showed high removal efficiency ranges of 82–90% of bacteria. It is recommended that hybrid constructed wetlands should be incorporated in the treatment of greywater.

Analysis of Tribological Properties of Hardfaced High-Chromium Layers Subjected to Wear in Abrasive Soil Mass.

This article presents the results of abrasion wear resistance tests of wear-resistant steel and surfacing under laboratory conditions and natural operation. Abrasion wear resistance determined on the basis of the study by determining geometrical characteristics of the alloying additives using computer image analysis methods, as well as examining the changes occurring on the surface of the workpieces and their wear intensity. Based on the results obtained from laboratory tests, it was noted that AR steel exhibited 14 times greater wear than the padding weld. This wear is affected by alloy additives, which, for the padding weld, are chromium additives. The microstructure image shows that soil mass had a destructive effect mainly on the matrix of the material, whereas in the areas with high concentrations of chromium precipitates, this effect was significantly weaker. The operational test results showed that within the area of the tine subjected to hardfacing, the material loss was lower than that for the same area of the tine in the as-delivered state. For the hardfaced tine, a 7% loss of volume was noted in relation to the operating part before testing and following the friction process. However, for the operating part in the as-delivered state, this difference amounted to 12%.

Corrosion Behavior of Ferritic 12Cr ODS and Martensitic X46Cr13 Steels in Nitric Acid and Sodium Chloride Solutions.

This paper presents corrosion resistance results of a 12Cr ferritic ODS steel (Fe-12Cr-2W-0.5Zr-0.3Y2O3) fabricated via a powder metallurgy route as a prospective applicant for fuel cladding materials. In a spent nuclear fuel reprocessing facility, nitric acid serves as the primary solvent in the PUREX method. Therefore, fundamental immersion and electrochemical tests were conducted in various nitric acid solutions to evaluate corrosion degradation behavior. Additionally, polarization tests were also performed in 0.61 M of sodium chloride solutions (seawater-like atmosphere) as a more general, all-purpose procedure that produces valid comparisons for most metal alloys. For comparison, martensitic X46Cr13 steel was also examined under the same conditions. In general, the corrosion resistance of the 12Cr ODS steel was better than its martensitic counterpart despite a lower nominal chromium content. Potentiodynamic polarization plots exhibited a lower corrosion current and higher breakdown potentials in chloride solution in the case of the ODS steel. It was found that the corrosion rate during immersion tests was exceptionally high in diluted (0.1-3 M) boiling nitric acid media, followed by its sharp decrease in more concentrated solutions (>4 M). The results of the polarization plots also exhibited a shift toward more noble corrosion potential as the concentrations increased from 1 M to 4 M of HNO3. The results on corrosion resistance were supported by LSCM and SEM observations of surface topology and corrosion products.

Processing of Ilmenite Concentrate with High Chromium Content

The results of research on the processing of ilmenite concentrate from the Obukhovskoye deposit are presented in this article. As the concentrate has a high chromium content, the study involved converting the iron into metal and the titanium into slag through the addition of soda. Positive results were obtained during the smelting of the ilmenite concentrate, and a one-stage smelting mode was established. This mode involved an increase in the temperature up to 1700 °C, with a heating step of 10 °C/min and using an argon supply. The holding time at this temperature was 30 min, followed by cooling to 700 °C in argon. The optimal parameters for sintering the non-magnetic fraction with soda and leaching the sinter with water and hydrochloric acid solution were also determined.

Bio-availability of potential trace elements in urban dust, soil, and plants in arid northwest China

Potential trace elements pollution in cities poses a threat to the environment and human health. Bio-availability affects toxicity levels of potential trace elementss on organisms. This study focused on exploring the relationship between soil, plant, and atmospheric dust pollution in Urumqi, a typical city in western China. It aims to help reduce pollution and protect residents’ health. The following conclusions were drawn: 1) potential trace elementss like Cr, Pb, As, and Ni are more prevalent in atmospheric dust and soil than in plants. Chromium was in the first group, Cadmium and Mercury were in the second, and Plumb, Arsenic, and Nickel were in the third. Atmospheric dust and soil exhibit a significantly higher heavy metal content than plants. For example, The atmospheric dust summary Chromium content was up to 88 mg/kg. 2) Soil, atmospheric dust, and plants have the highest amount of residual form. Residual form had the highest percentage average of 53.3%, whereas Organic matter bound form had the lowest percentage of just 7.7%. The plants contained less residual heavy metal than the soil and atmospheric dust. 3) The correlation coefficient between the carbonated form content of Cd of soil and atmospheric dust is 0.95, which is closely related. Other potential trace elements show similar correlations in their bio-available contents in soil, plants, and atmospheric dust. This study suggests that in urban area, the focus should be on converting potential trace elements into residual form instead of increasing plants’ absorption of potential trace elements.

Distribution Characteristics, Risk Assessment, and Source Analysis of Heavy Metals in Farmland Soil of a Karst Area in Southwest China

Soil environmental quality related to the residents’ life, health, and safety, has been the hotspot issues in science of ecological environment protection. Evaluating the distribution characteristics, ecological risk, and source of heavy metals in farmland is important for protecting soil resources. The agricultural area of Lianhua town, Gongcheng County, Guilin is a typical karst landform. In response to the problem of heavy metal pollution and complex sources in the soil of this area, the characteristics and sources of heavy metal pollution in the soil profiles from farmland, abandoned land, and forest were studied using the single-factor index method, the geoaccumulation index (Igeo) principal component analysis (PCA) and positive matrix factorization (PMF) model. The results showed that: (1) that the contents of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in the soil profile of the study area were higher than that of the soil elements background values in Guangxi. The total and available forms contents of all heavy metal elements exhibited the characteristics of accumulation in the surface profile; (2) among the six heavy elements, the contents of Cd were in a moderately to heavily polluted state. The contents of Cd in some soil profiles exceeded the control standard for agricultural land soil pollution. The contents of Zn and Ni were from slightly to moderately polluted in areas with frequent agricultural activities; (3) according to the PCA and PMF model, there were three main sources of heavy metals in the study area. Among them, Cd, Cu, Ni, and Zn are related to agricultural activities; the elements As, Cd, Cr, and Hg are closely related to geological background; Pb and Zn are mainly affected by atmospheric sedimentation of transportation. Agricultural activities and natural geological background are the main contribution sources of heavy metals in soil. Human activities are the main factors that cause the accumulation of heavy metals in soil. This research has theoretical guidance and practical significance for the prevention and control of soil heavy metal pollution and the protection of farmland environmental quality in the region.

Chromium removal by microbial mats: understanding the effect of salinity and pH.

Environmental contamination by chromium represents a serious public health problem. Therefore, it is crucial to develop and optimize remediation technologies to reduce its concentration in the environment. The aims of this study were to evaluate the uptake of chromium by live and complete microbial mats in experimental mesocosms under different pH and salinity conditions to understand how these factors affect the microphytobenthic community and, consequently, how chromium removal process is influenced. Microbial mats from the estuarine environment were exposed to 15mg Cr/L under different pH (2, 4, and 8) and salinity (2, 15, and 33) conditions. Salinity, redox potential, and pH were measured throughout the trial in solutions and in microbial mats, while total Cr determinations were performed at the end of the assay. The results demonstrated that the removal efficiency of Cr by microbial mats was significantly improved in solutions at pH 2, remaining unaffected by variations in salinity. Notably, both cyanobacteria and diatoms showed remarkable resistance to Cr exposure under all conditions tested, highlighting their exceptional adaptability. Microbial mats have proved to be effective filters for reducing the concentration of chromium in aqueous solutions with varying pH and salinity levels.

Date estimation of fabrication and repair of Color garments encouragement banner

The Color Garments Encouragement Banner was designated a Korean Heritage in 2014 to recognize it as the most significant object of the color garments encouragement campaign. However, despite its significance, nothing is known about its manufacture. Therefore, this study attempted to analyze the materials of the banners to estimate when they were manufactured and repaired. The investigation of materials on the banner involved visual examination, literature review, microscopy, SEM–EDS, FT-IR, Py-GC–MS, ICP-MS, and LC–MS. The fabric, patch, and threads comprising the artifact were identified as cotton. FT-IR and Py-GC–MS confirmed that the repair patch was a woven blend of polyester and cotton yarns. EDS analysis indicated that the polyester was treated with titanium delustering. ICP-MS detected high concentrations of chromium that were not used in traditional dyeing techniques. The azo and sulfur compounds were identified by LC–MS analysis. The material layered on the grommet patch was thought to be a mixture of Pb, Ti with CaCO3 and BaSO4. Based on the overall results, the production date of the banner was narrowed down to the late 1920s, and the repair date to the mid-1950s. Although the materials used could not be identified owing to the limitations of the applicable analysis. Nonetheless, it is hoped that the analyses conducted in this study can serve as a scientific foundation for dating modern cultural heritage objects with limited handed-down record and historical documentation.

Analysis of Heavy Metal Characteristics and Health Risk Assessment of Dried Fish Marketed in Guangzhou, China.

This study investigated heavy metal contamination in dried fish sold in Guangzhou, China, and evaluated the resultant non-carcinogenic and carcinogenic health risks. Dried fish samples were purchased from Baiyun, Tianhe, Panyu, and Yuexiu districts in Guangzhou, where the population is substantial. They were randomly acquired in bustling supermarkets and farmers' markets, targeting the most popular dried fish in these areas. Sixty samples from five dried fish types (Stolephorus chinensis, Thamnaconus modestus, Nemipterus-virgatus, river fish, Ctenopharyngodon idella) were analyzed for chromium (Cr), arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg) content. Quantification of the heavy metals were carried out by inductively coupled plasma mass spectrometry (ICP-MS) for Cr, As, Cd, and Pb, and an automatic mercury analyzer for Hg. The median concentration of these heavy metals in dried fish were 0.358mg/kg, 2.653mg/kg, 0.032mg/kg, 0.083mg/kg, and 0.042mg/kg, respectively. Pollution severity was ranked as dried Nemipterus-virgatus > dried Stolephorus chinensis > dried Thamnaconus modestus > dried river fish > dried Ctenopharyngodon idella, with As being the most predominant pollutant. All fish types showed severe As pollution. Non-carcinogenic risks were identified in the consumption of dried Nemipterus-virgatus and dried Stolephorus chinensis for both genders, while potential carcinogenic risks were associated with four of the fish types. Women faced higher health risks than men from dried fish consumption. Consequently, we advise consumers to minimize their intake of dried fish and regulatory agencies conduct regular monitoring of heavy metal levels in commercially available dried fish to avert potential health risks.

Serum metabolic changes link metal mixture exposures to vascular endothelial inflammation in residents living surrounding rivers near abandoned lead–zinc mines

Metal exposure is associated with vascular endothelial inflammation, an early pathological phenotype of atherosclerotic cardiovascular events. However, the underlying mechanism linking exposure, metabolic changes, and outcomes remains unclear. We aimed to investigate the metabolic changes underlying the associations of chronic exposure to metal mixtures with vascular endothelial inflammation. We recruited 960 adults aged 20–75 years from residential areas surrounding rivers near abandoned lead–zinc mine and classified them into river area and non-river area exposure groups. Urine levels of 25 metals, Framingham risk score (FRS), and serum concentrations of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), as biomarkers of vascular endothelial inflammation, were assessed. A “meet-in-the-middle” approach was applied to identify causal intermediate metabolites and metabolic pathways linking metal exposure to vascular endothelial inflammation in representative metabolic samples from 64 participants. Compared to the non-river area exposure group, the river area exposure group had significantly greater urine concentrations of chromium, copper, cadmium, and lead; lower urine concentrations of selenium; elevated FRS; and increased concentrations of ICAM-1 and VCAM-1. In total, 38 differentially abundant metabolites were identified between the river area and non-river area exposure groups. Among them, 25 metabolites were significantly associated with FRS, 8 metabolites with ICAM-1 expression, and 10 metabolites with VCAM-1 expression. Furthermore, fructose, ornithine, alpha-ketoglutaric acid, urea, and cytidine monophosphate, are potential mediators of the relationship between metal exposure and vascular endothelial inflammation. Additionally, the metabolic changes underlying these effects included changes in arginine and proline metabolism, pyrimidine metabolism, starch and sucrose metabolism, galactose metabolism, arginine biosynthesis, and alanine, aspartate, and glutamate metabolism, suggesting the disturbance of amino acid metabolism, the tricarboxylic acid cycle, nucleotide metabolism, and glycolysis. Overall, our results reveal biomechanisms that may link chronic exposure to multiple metals with vascular endothelial inflammation and elevated cardiovascular risk.

Influence of thermal conductivity on evolution of grain morphology during laser-based directed energy deposition of CoCrxFeNi high entropy alloys

A model CoCrxFeNi high entropy alloy system was chosen to investigate the effect of thermal conductivity on the evolution of spatial orientation of columnar grain morphology during laser directed energy deposition. The thermal conductivity of the alloy was varied by tuning the chromium content in CoCrxFeNi alloys. CoCrxFeNi alloys with chromium content ranging between 0 and 24 at% were produced under identical processing conditions of laser direct energy deposition method. Electron back scattered diffraction images of the cross-sections revealed that the spatial orientation of grain morphology transitioned from zigzag columnar grains from layer-to-layer to near-continuous columnar grains across multiple layers with increased content of chromium in CoCrxFeNi. A multi-scale multi-physics finite element based thermo-kinetic model with consideration to multi-track multi-layer nature of the laser direct energy deposition technique was adopted to correlate the process thermo-kinetics with the evolution of microstructure. The computation calculations revealed that the decrease in thermal conductivity from 36 W/m.K (CoFeNi) to 26 W/m.K (CoCr24FeNi) at the melting point reduced the cooling rate from 3.3 ×104 °C/s to 1.3 ×104 °C/s in CoFeNi and CoCr24FeNi alloys, respectively. This subsequently evolved into increased degree of remelting of previously deposited layers and caused the direction of resultant thermal gradient to reorient towards the build direction. Such reorientation in resultant thermal gradient contributed to transition of spatial orientation of grain morphology from columnar zigzag microstructures from layer-to-layer to near continuous columnar grains across multiple layers. The present observation was verified compared with other reported metallic systems exhibiting zigzag and continuous columnar grains, and a unified mechanism underlining the role of thermal conductivity on microstructure evolution was proposed.