Distribution Of Zn Research Articles

Visualizing the gas-sensitive structure of the CuZn surface in methanol synthesis catalysis

Methanol formation over Cu/ZnO catalysts is linked with a catalytically active phase created by contact between Cu nanoparticles and Zn species whose chemical and structural state depends on reaction conditions. Herein, we use variable-temperature scanning tunneling microscopy at elevated pressure conditions combined with X-ray photoelectron spectroscopy measurements to investigate the surface structures and chemical states that evolve when a CuZn/Cu(111) surface alloy is exposed to reaction gas mixtures. In CO2 hydrogenation conditions, Zn stays embedded in the CuZn surface, but once CO gas is added to the mixture, the Zn segregates onto the Cu surface. The Zn segregation is CO-induced, and establishes a new dynamic state of the catalyst surface where Zn is continually exchanged at the Cu surface. Candidates for the migrating few-atom Zn clusters are further identified in time-resolved imaging series. The findings point to a significant role of CO affecting the distribution of Zn in the multiphasic ZnO/CuZn/Cu catalysts.

Reconstruction of Electric Double Layer on the Anode Interface by Localized Electronic Structure Engineering for Aqueous Zn Ion Batteries

AbstractThe electric double layer (EDL) at the electrode/electrolyte interface plays a crucial role to the electrochemical reactions of zinc ion batteries. For Zn anode, the EDL consists of H2O dipoles, which can cause Zn corrosion and passivation. Herein, the localized electronic‐rich (LER) structure performing as soild electrolyte interphase (SEI) changes the electron distribution, leading to the rapid capture of Zn2+, thus promoting the desolvation of the cH2O shell. Moreover, the LER generates an electrostatic repulsion effect to SO42−. Consequently, a unique H2O‐poor EDL is reconstructed with the distribution of Zn2+‐H2O‐SO42−, which inhibits side reactions and improves the deposition kinetics of Zn2+. In situ Raman intuitively confirms that the zinc‐ion‐flux is uniform during the whole electroplating process. LER as regulator for EDL structure, leads to smooth and fast Zn2+ deposition. The performance enhancement is demonstrated by LER@Zn//LER@Zn cells, which exhibit exceptional lifespan for 4800 h. Furthermore, the LER@Zn///MnO2 cell shows improved cycling stability over 1500 cycles, with a high capacity of 124 mAh g−1 at 5 C.

Enhancing the growth and zinc efficiency of cherry tomatoes by inoculating endophytic bacteria from zinc hyperaccumulator, Sedum alfredi Hance

Microbial biofertilizers, an innovative and eco-friendly strategy for nutritional improvement, could be utilized for zinc (Zn) efficiency and biofortification. Endophytic bacteria with Zn solubilizing and plant growth-promoting capacities were isolated from hyperaccumulator S. alfredi, and their impacts on the growth and Zn efficiency of cherry tomatoes under Zn-deficiency conditions were investigated. The results showed that most endophytic bacteria promoted the growth of tomato seedlings, while only specific endophytic bacteria played a role in Zn accumulation. Among them, inoculation with SaBA1, SaPS2, SaEN1, and SaPA1 not only significantly increased the fresh weight (FW) of tomato's young leaves by 3.1 to 3.6 times, but also raised the soil available Zn concentration by 0.58–0.92 mg/kg and improved the Zn accumulation in young leaves by 18 % to 30 %. The results indicated that these four bacteria could activate the availability of soil Zn, regulate the distribution of Zn in plants, and enable tomatoes to maintain healthy growth and development under Zn-deficiency conditions. This revealed their immense potential in enhancing crop yield, improving crop Zn nutrition, and boosting crop Zn efficiency.

Novel cow dung-doped sludge biochar as an efficient ozone catalyst: Synergy between graphitic structure and defects induces free radical pathways

A composite material, cow dung-doped sludge biochar (Zn@SBC-CD), was synthesized by one-step pyrolysis using ZnCl2 as an activating agent and applied to a catalytic ozonation process (COP) for methylene blue (MB) removal. SEM, XRD, FTIR, XPS and BET analyses were performed to characterize the biochar (BC) catalysts. Zn@SBC-CD had high graphitization degree, abundant active sites and uniform distribution of Zn on its surface. Complete removal of MB was achieved within 10 min, with a removal rate much higher than that of ozone alone (32.4%), implying the excellent ozone activation performance of Zn@SBC-CD. The influence of experimental parameters on MB removal efficiency was examined. Under the optimum conditions in terms of ozone dose 0.04 mg/mL, catalyst dose 400 mg/L and pH 6.0, COD was completely removed after 20 min. Electron paramagnetic resonance (EPR) analysis revealed radical and non-radical pathways were involved in MB degradation. The Zn@SBC-CD/O3 system generated superoxide anion radicals (•O2−), which were the main active species for MB removal, through adsorption, transformation, and transfer, Furthermore, Zn@SBC-CD exhibited good reusability and stability in cycling experiments. This study provides a novel approach for the utilization of cow dung and sludge in synthesis of functional biocatalysts and application in organic wastewater treatment.

Biochemical properties of winter wheat (Triticum vulgare L.) under Zn and Cu balance in the soil-culture system

The role of trace elements as a factor in the formation of biochemical features of grain crops is a debatable and extremely understudied issue. At the same time, the ecological importance of the balance of nutritional elements for the normal functioning of plants is widely highlighted in biology and agronomy. The purpose of the study was to determine the interdependence of biochemical and biogeochemical features and to determine the influence of the biogeochemical balance of Zn and Cu on the biochemical parameters of wheat in various agrolandscapes of the forest-steppe of Ukraine. We has been developed an original method of regional spatial correlation between the balance of micronutrients in the soil-crop system and biochemical indicators of the quality of plant products. Spatial correlation was implemented in wheat growing areas in two agrolandscapes, namely, with dark gray podzolized soils in the Kyiv region and gray podzolized soils in the Vinnytsia region. Regional features of the distribution of Zn and Cu in the agricultural landscape are summarized by their biogeochemical formulas, which highlight 5 evaluation characteristics of the soil-culture system in subsoil rocks, soils, and grain crops. Features of the quality of wheat in the territory of agrolandscapes are determined by statistical data on the content of protein, gluten, and vitreousness. The result of the spatial correlation of the specified characteristics is the determination of the interdependencies of the biochemical parameters of the nutritional quality of wheat and the balance of Zn, Cu in the investigated agrolandscapes. The determined differences between the features of the links of the biogeochemical chains of zinc and copper indicate the possibility of a decrease in the vitreousness and protein in wheat grains as a result of the lack of this nutrient microelement, even under the conditions of their natural and agrogenic accumulation in the soil. The inconsistency of the processes in the soil and the agrocenosis of the agrolandscape indicates the expediency of changes in soil protection and agrochemical melioration systems. Special attention needs to be paid to research on foliar nutrition of wheat culture, as a factor in increasing the biophilicity of nutrient microelements and the corresponding increase in the protein content and vitrification of wheat grain.

Migration and morphological transformation patterns of heavy metals on sludge cells and extracellular polymeric substances (EPS) under the influence of different treatments.

The impediment of sludge resource utilization stems from the presence of heavy metals within the sludge matrix. To optimize heavy metal removal techniques from undried sludge, it is essential to study the distribution of heavy metals in the sludge flocs structure and the changes in morphology in the sludge cells after different treatments. In this study, the sludge was subjected to chemical treatments using citric acid (CA), EDTA, and saponin, as well as electrokinetic treatment at 2 V/cm. The distribution and migration of Cu, Ni, and Zn in sludge flocs after various treatment methods were analyzed. The heavy metals were found to migrate from intracellular to extracellular polymeric substances (EPS) without causing extensive sludge cell lysis. They gradually diffused outward with the dispersion of the EPS layer. The migration efficiency of the three heavy metals in the sludge flocs was Zn, Ni, and Cu. This was mainly related to the initial distribution and morphology of the heavy metals. Under the influence of chemicals and an electric field, the acid-soluble and reducible heavy metals in the cells partially migrated to the EPS, while the stable heavy metals transformed into an unstable state. Furthermore, the order of chemical reagents in terms of their effect on the migration efficiency of heavy metals was CA > EDTA > Saponin, owing to the varying binding strengths of heavy metals and their impact on the degree of loosening of the EPS. Especially after CA treatment a greater proportion of Cu, Ni, and Zn were transferred from the cells to the EPS. The acidification effect near the anode during electrokinetic treatment intensifies the migration of heavy metals. This study provides basic research for subsequent engineering optimization aimed at removing heavy metals from sludge.

Polyethylene microplastic and nano ZnO Co-exposure: Effects on peanut (Arachis hypogaea L.) growth and rhizosphere bacterial community

Microand nano-pollutants are receiving increased research attention. However, the effects of the interactions and co-exposure to these pollutants in soil are yet to be fully elucidated. This work aimed to investigate the effects of co-exposure to polyethylene microplastics (PEMPs) and nano-ZnO (nZnO) in soil on the growth, nutrient uptake, and distribution of the peanut (Arachis hypogaea L.) and soil microbial community. Results revealed that 500 mg kg−1 nZnO significantly decreased the dry weight of peanut root, stem, leaf, and fruit by 84.4%, 79.1%, 87.3%, and 95.8%, respectively, compared with the control. Co-exposure treatments significantly alleviated this trend. Co-exposure treatments further decreased Zn concentration in peanuts by 30.3%–58.9% compared with nZnO single exposure. The distribution of Zn in peanut stems also maintained a consistent trend with the concentration and primarily occurred in the vascular bundles near the epidermis. Co-exposure and PE treatments increased the abundance of soil bacteria primarily because many PE particles entered the soil to build more living space for bacteria. These findings showed that composite pollution had a robust disturbing effect on the soil–peanut system, and the two pollutants were primarily physically adsorbed. PE particles can adsorb nZnO and then become the carrier of nanoparticles.

Influence of Swine Wastewater Irrigation and Straw Return on the Accumulation of Selected Metallic Elements in Soil and Plants

Treated livestock wastewater reuse for irrigation and straw return in arid regions have become common practices worldwide. However, many uncertainties still exist regarding the effects of the returning straw sizes on heavy metal accumulation in soil and plants under treated livestock wastewater irrigation. In a pot experiment growing maize and soybean, large (5–10 cm), medium (1–5 cm), and small (<1 cm) sizes of wheat straw were amended to assess the changes in Cu and Zn distribution in the rhizosphere, bulk soils, and plants. Groundwater and swine wastewater were used as irrigation water resources. The results showed that irrigation with swine wastewater significantly reduced soil pH and increased the concentration of soil-available potassium. Concentrations of Cu in soil were more sensitive to swine wastewater and straw application than those of Zn in soil. Swine wastewater irrigation increased the accumulation of Cu and Zn in plants with higher concentrations of Zn, while straw return tended to inhibit this increase, especially when a small size of straw was employed. In addition to providing a reference for revealing the interaction mechanism between swine wastewater irrigation and straw return, this study proposes feasible solutions to improve the efficiency of agricultural waste recycling and realize sustainable agricultural development.

Spatial distribution of Pb and Zn in soils under native vegetation in Southeast Brazil.

Heavy metals can play an important biological role as micronutrients but also as potentially toxic elements (PTEs). Understanding the natural concentrations of PTEs-Pb and Zn included-in soils allows for the identification and monitoring of contaminated areas and their role in environmental risk assessment. In this study, we aim to determine semi-total or natural and available concentrations of Pb and Zn in topsoils (0-20 cm depth) from 337 samples under native vegetation in the State of Minas Gerais, Brazil. Additionally, we sought to interpret the spatial geochemical variability using geostatistical techniques and quality reference values for these elements in soils were established. The semi-total concentrations were determined by flame and graphite furnace atomic absorption after microwave-assisted nitric acid digestion method. The available concentrations were extracted using the Mehlich-I extractor and determined by atomic absorption spectrometer. Spatial variability was modeled using semivariance estimators: Matheron's classic, Cressie and Hawkins' robust, and Cressie median estimators, the last two being less sensitive to extreme values. This allowed the construction of digital maps through kriging of semi-total Pb and Zn contents using the median estimator, as well as other soil properties by the robust estimator. The dominance of acidic pH and low CEC values reflects highly weathered low-fertility soils. Semi-total Pb contents ranged from 2.1 to 278 mg kg-1 (median: 9.35 mg kg-1) whereas semi-total Zn contents ranged from 2.7 to 495 mg kg-1 (median: 7.7 mg kg-1). The available Pb contents ranged from 0.1 to 6.92 mg kg-1 (median: 0.54 mg kg-1) whereas available Zn contents ranged from 0.1 to 78.2 mg kg-1 (median: 0.32 mg kg-1). The highest Pb and Zn concentrations were observed near Januária, in the northern part of the territory, probably on limestone rocks from the Bambuí group. Finally, the QRVs for Pb and Zn in natural soils were lower than their background values from other Brazilian region and below the prevention values suggested by Brazilian environmental regulations.

Trace Metals Distribution in Tissues of 10 Different Shark Species from the Eastern Mediterranean Sea

As long-living apex predators, sharks tend to bioaccumulate trace metals through their diet. The distribution of Al, As, Cd, Co, Cr, Cs, Cu, Fe, Mn, Ni, Pb, V, Zn and Hg in different tissues (muscle, liver, heart, gills and gonads) of large-size (58–390 cm) sharks, some of which rare, of the eastern Mediterranean Sea was studied. Trace metals analyses in samples originating from ten different Chondrichthyes species were performed by inductively coupled plasma–mass spectrometry (ICP-MS) and Cold Vapor Atomic Absorption Spectrometry (CVAAS) for Hg. Data on trace metal levels are for the first time reported herewith for the species O. ferox and H. nakamurai. Higher median concentrations of trace metals were generally determined in the liver. The concentrations of Hg, Cs and As in the muscle increased proportionally with body length. Statistically significant differences between sexes were recorded for Hg, Cr, Ni and As (p = 0.015) in the muscle tissues of P. glauca. Muscle tissue Hg concentrations exceeded the EU maximum limit (1 μg g−1 wet weight) in 67% of the individuals sampled, with the highest concentrations detected in O. ferox and S. zygaena, whereas regarding Pb (limit 0.30 μg g−1 ww), the corresponding percentage was 15%. Arsenic concentrations were also of concern in almost all shark tissues examined.

Heavy metals concentration in soils across the conterminous USA: Spatial prediction, model uncertainty, and influencing factors

Assessment and proper management of sites contaminated with heavy metals require precise information on the spatial distribution of these metals. This study aimed to predict and map the distribution of Cd, Cu, Ni, Pb, and Zn across the conterminous USA using point observations, environmental variables, and Histogram-based Gradient Boosting (HGB) modeling. Over 9180 surficial soil observations from the Soil Geochemistry Spatial Database (SGSD) (n = 1150), the Geochemical and Mineralogical Survey of Soils (GMSS) (n = 4857), and the Holmgren Dataset (HD) (n = 3400), and 28 covariates (100 m × 100 m grid) representing climate, topography, vegetation, soils, and anthropic activity were compiled. Model performance was evaluated on 20 % of the data not used in calibration using the coefficient of determination (R2), concordance correlation coefficient (ρc), and root mean square error (RMSE) indices. Uncertainty of predictions was calculated as the difference between the estimated 95 and 5 % quantiles provided by HGB. The model explained up to 50 % of the variance in the data with RMSE ranging between 0.16 (mg kg−1) for Cu and 23.4 (mg kg−1) for Zn, respectively. Likewise, ρc ranged between 0.55 (Cu) and 0.68 (Zn), respectively, and Zn had the highest R2 (0.50) among all predictions. We observed high Pb concentrations near urban areas. Peak concentrations of all studied metals were found in the Lower Mississippi River Valley. Cu, Ni, and Zn concentrations were higher on the West Coast; Cd concentrations were higher in the central USA. Clay, pH, potential evapotranspiration, temperature, and precipitation were among the model's top five important covariates for spatial predictions of heavy metals. The combined use of point observations and environmental covariates coupled with machine learning provided a reliable prediction of heavy metals distribution in the soils of the conterminous USA. The updated maps could support environmental assessments, monitoring, and decision-making with this methodology applicable to other soil databases, worldwide.

A Fine Analysis of Zn Species Structure and Distribution in Zn/ZSM-5 Catalysts by Linear Combination Fitting Analysis of XANES Spectra

Investigating the distribution of different Zn species on Zn-containing zeolite catalysts is crucial for identifying the active sites and establishing the relationship between the catalyst’s structure and its activity in the process of ethylene aromatization. By utilizing X-ray absorption near edge spectra (XANES) of various reference samples, this study employed linear combination fitting (LCF) analysis on XANES spectra of real samples to accurately measure the changes in the distribution of Zn species in Zn-containing HZSM-5 zeolites under different Zn sources and loadings. The results showed that ZnOH+, ZnO clusters, and ZnO crystalline structures coexist in Zn/HZSM-5 catalysts prepared through physical mixing and incipient wet impregnation methods. A similar trend was observed for catalysts prepared using different methods, with an increase in Zn content resulting in a decrease in the proportion of ZnOH+ and a significant increase in the amount of larger ZnO crystals. Furthermore, ZnO clusters were confined within the zeolite pores. The findings of this study established a direct correlation between the amount of ZnOH+ determined through LCF analysis and both the rate of hydrogen production and the rate of aromatics formation, providing strong evidence for the catalytic role of ZnOH+ as an active center for dehydrogenation, which plays a key role in promoting the formation of aromatics. The method of LCF analysis on XANES spectra allows for the determination of the local structure of Zn species, facilitating a more precise analysis based on the distribution of these species. This method not only provides detailed information about the Zn species but also enhances the accuracy of the overall analysis.

Mass spectrometric analysis of transition metal complexes formed through contact of artificial sweat with circulating Euro coins

AbstractIt is well‐known that some metals/alloys sensitize the skin of susceptible individuals. Trace amounts of metals and chemical compounds containing metal ions can affect human health, i. e., cause allergy or inflammation. However, the details of this metal‐induced allergic reaction are not well understood. Complexes of nickel, copper, and zinc are known to be easily formed through contact of metal alloys with ubiquitously available organic compounds such as triacylglycerols, amino acids, urea, and fatty acids found in skin secretions or skin care products. Thus, an analytical technique is required to characterize and identify metal complexes formed on metallic everyday products, ideally offering a chemically specific, laterally resolved view of allergy‐causing processes. Here we present a mass‐spectrometry‐based analytical workflow to characterize metal‐containing compounds formed on the surface of 1‐euro coins when in contact with artificial sweat. This study identified different metal complexes by using tandem mass spectrometry (MS/MS). Surface imaging of 1‐Euro coins employing laser‐based mass spectrometry revealed the lateral distribution of Zn, Cu, and Ni complexes with low‐micrometer resolution.

Micronutrient Status and Distribution of Some Community Lands Earmarked for Agricultural Intensification in Bayelsa State for Food Security

Improved agricultural production requires balanced nutrients. In spite of Bayelsa State’s intention to increase its’ agricultural base, little or no information is available on the soils micronutrient status. This study evaluated the status and distribution of Fe, Mn, Zn and Cu in some communities earmarked for agricultural intensification. Sample collection was guided by horizon differentiation. Micronutrients distribution variation was evaluated using coefficient of variation. Iron concentration varied from 41-91 mg/kg in Elemebiri (ELM) soils with moderate %CV (16, 17 and 28 for ELM1, ELM2 and ELM3) and 34-92 mg/kg in Trofani (TFN) soils with moderate to high %CV (30, 20 and 33 for TFN1, TFN2 and TFN3), respectively. The Mn values varied from 1.3 – 4.25 mg/kg for Elemebiri soils and 0.34 – 3.8 mg/kg for Trofani soils. The %CV of Mn was high as ELM1, ELM2 and ELM3 recorded 36, 31 and 38 %CV and TFN1, TFN2 and TFN3 87, 56 and 63, respectively. Available Zn varied between 3.48 – 16.56 mg/kg and 0.87 – 18.56 mg/kg in the Elemebiri and Trofani soils, respectively. The %CV for Zn was 32, 26, and 53 for ELM1, ELM2 and ELM3 and 41, 24 and 56 for TFN1, TFN2 and TFN3, respectively. Copper concentration varied between 1.24 – 5.3 mg/kg for Elemebiri soils and 0.75 – 5.7 mg/kg for Trofani soils. The %CV for Cu was 28, 33 and 25 for ELM1, ELM2 and ELM3 and 36, 53 and 43 for TFN1, TFN2 and TFN3, respectively. Though micronutrient status of the soils looks promising, there is need for close monitoring.

Iron powder in-situ catalytic pyrolysis on coated wooden board: Kinetic, products, and recovery

Catalytic pyrolysis is a promising method for the resource utilization of wooden waste, and in-situ catalysis enhances the process and reduces treatment costs. The selection of catalysts is crucial, as their catalytic effect and service life directly impact treatment effectiveness and economic benefits. In this study, iron powder was utilized to examine its potential in in-situ catalytic pyrolysis of coated wooden boards. The results showed that some of the iron powder could compete for oxygen from lignin/ hemicellulose during the early pyrolysis stage, resulting in the formation of FeO and a decrease in CO2. The formed FeO then promoted cellulose decomposition, reducing the pyrolysis activation energy by 26% ∼ 48%. Despite the addition of iron powder, no obvious impact was observed on the distribution of product yields. However, there are differences in the specific composition: the gas products showed a decrease of CO2 by 26% and CH4 by 13%, while the bio-oil showed an increase of phenol by 8%. This revealed that the iron powder primarily changed the energy barrier of the pyrolysis reaction. There was magnetic separation followed by particle size screening for the recovery of solid products. After separation, the recovery rate of iron powder was determined to be only 65.39%. Two kinds of char particles appeared in the separated products: magnetic (M3) and non-magnetic (NM). Approximately 44.45% of total Fe (from Fe powder and coating materials) contents and 73.62% of total Ti (main metal in the primary coating) were found in M3, while only 1.32% and 10.90% in NM, respectively. Interestingly, the distribution of elements Zn, Ba, and Mg was found to be opposite to that of Fe, which mainly distributed in NM and M2. It might be attributed to the primary coating on the M3 surface, which likely to help facilitated the adsorption of iron particles according to the combination of SEM/EDS and ICP-MS results. The adsorption competition effect of Fe and other metals resulted in significant differences in the distribution of metals on several char particles.

Long cycle‐life aqueous Zn battery enabled by facile carbon nanotube coating on Cu current collector

AbstractAs an alternative to Li‐ion batteries, aqueous Zn batteries have gained attention due to the abundance of Zn metal, low reduction potential (–0.76 V vs. standard hydrogen electrode), and high theoretical capacity (820 mAh g–1) of multivalent Zn2+ ion. However, the growth of Zn dendrites and the formation of irreversible surface reaction byproducts pose challenges for ensuring a long battery lifespan and commercialization. Herein, the Cu foil coated with a single‐walled carbon nanotube (SWCNT) layer using a facile doctor blade casting method is utilized. The SWCNT‐coated Cu foil demonstrates a significantly longer battery lifespan compared to the bare Cu in the half‐cell tests. Through operando optical microscopy imaging, we are able to provide intuitive evidence that Zn deposition occurs between the carbon nanotube (CNT) coating and Cu substrate, in agreement with the computational results. Also, with various imaging techniques, the flat morphology and homogeneous distribution of Zn beneath the SWCNT layer are demonstrated. In addition, the full‐cell using CNT‐coated Cu exhibits a long cycle life compared to the control group, thereby demonstrating improved electrochemical performance with limited Zn for the cycling process.

Prediction of heavy metal ion distribution and Pb and Zn ion concentrations in the tailing pond area.

The pollution caused by tailings ponds has resulted in ecological damage, with soil contamination significantly impacting the daily lives of residents in the vicinity of mining areas and the future development of mining areas. This study assesses the transport status of heavy metal pollution in tailings areas and predicts its impact on future pollution levels. This study focused on lead-zinc tailing ponds, exploring the spatial and chemical distribution characteristics of heavy metals based on the distributions of Pb, Zn, As, Cu, Cr, Cd, Hg, and Ge ions. The concentrations of the major heavy metal ions Pb and Zn in tailings ponds were predicted via the exponential smoothing method. ① The total accumulation of Pb and Zn in the mine tailings ranges from 936.74~1212.61 mg/kg and 1611.85~2191.47 mg/kg, much greater than the total accumulation of the remaining six heavy metals. The total accumulation of associated heavy metal Cu was high, and the lowest total heavy metals were Hg and Ge at only 0.19 mg/kg and 1.05 mg/kg. ② The analyses of soil heavy metal chemical forms reveal that the heavy metals Pb and Zn had the highest exchangeable state content and state ratio and the strongest transport activity in the industrial plaza and village soils. Pb and Zn are the heavy metals with the greatest eco-environmental impacts in the mining area. ③ The predicted results show that the soil concentrations of the heavy metals Pb and Zn around the tailings area in 2026 are 1.335 and 1.191 times the predicted time starting values. The concentrations of the heavy metals Pb and Zn at the starting point of the forecast are already 3.34 and 3.02 times the upper limits of the environmental standard (according to environmental standards for gravelly grey calcium soils). These results have significant implications for heavy metal pollution risk management.

Nehézfémek elosztása a szénbányák hulladéklerakóiban statisztikai elemzés alapján

At the UN Climate Change Conference in Glasgow in autumn 2021 (COP26), world leaders and participants decided to phase out coal energy and gradually replace fossil fuels. At COP26, Ukraine has committed to shutting down state-owned coal-fired power plants by 2035, reducing methane emissions by 30% by 2030 and halting deforestation. The waste dumps are also a detrimental factor in coal mining. The determination of the heavy metals content in the waste dumps of coal mines is a topical issue today, as the results of such studies are part of the monitoring of the environmental safety of mining regions. This scientific article considers the results of research on the heavy metals content in the waste dumps and their distribution in one of the largest coal mines in the Lviv-Volyn coal basin – ‘Chervonohradska’ (Ukraine). 2.9 million m3 of rock have accumulated in the dump since 1971. Every year, 40,000 m3 of fresh rock is dumped. Samples were taken uniformly from all sides of the dump in places with no vegetation cover. Note that exceeding the maximum allowable concentrations of the studied heavy metals is observed in all areas except for Zn. Statistical analysis of the results of semi-quantitative spectral studies of waste dumps rock at the Chervonohradska mine site was performed using the Statistica 8 applied statistics package. According to the results of more than 50 samples taken at a depth of 0.3 m, the statistical distribution of heavy metals Mn, Pb, Ni, Cu, Zn and Co in the mine dumps was determined, and a correlation analysis was performed. It was found that the distributions of Cu and Zn in dumps are closest to normal. The nonparametric Spearman coefficient (rs) revealed the average level of correlation of the content of heavy metals in the pairs Mn and Ni (rs = 0.46), Mn and Zn (rs = 0.52), Ni and Zn (rs = 0.57), Cu and Zn (rs = 0.49). Chaotic and uneven discharge of rock onto the open area caused uneven substrate deposition of certain chemical elements in the profile of the dump.

Speciation, distribution and relationship of zinc and cadmium in summer coastal seawater of northern China

Considering that zinc (Zn) is essential for marine phytoplankton growth and cadmium (Cd) can replace Zn as a cofactor of mutual conversion and regulate the effect of carbonic anhydrase, we here presented the concentration, chemical speciation and relationship of Zn and Cd collected from three consecutive voyages (2019–2021) in summer coastal seawater of northern China. Dissolved Zn and Cd concentrations were determined using inductively coupled plasma mass–spectrometry (ICP–MS) and ranged from 0.37 to 3.09 μM and 1.88–13.66 nM, respectively. Natural labile Zn and Cd were determined using a highly automated electrochemical detection system and ranged from below detection limit-1.11 μM and below detection limit-5.23 nM, respectively. The speciation, distribution and interrelationships of Zn and Cd were compared with the distribution of the diatoms community, and studied by the correlation with pH and dissolved inorganic carbon (DIC). Finally, the Zn and Cd labile and inert chemical species concentrations were compared with those of the open sea and the coast. The results indicated that the dissolved Zn and Cd concentrations in surface seawater were higher than those in bottom seawater, possibly due to the dominance of exogenous inputs compared to phytoplankton uptake. Higher phytoplankton abundance was associated with lower natural labile Zn and Cd concentrations, but this was not the main factor affecting the distribution of natural labile Zn and Cd. Unlike the open ocean, there was no potential for Zn limitation of certain phytoplankton groups in this region, but both Zn and Cd played important roles in the fixation of carbon dioxide, and Cd might result in mitigating Zn uptake. Activities such as ocean currents, which bring limiting nutrient trace metals (e.g., Zn) from the coast into the open ocean, could regulate the structure of primary producers. This study has great potential for the investigation of the biogeochemical cycling of Zn and Cd and their role in marine carbon fixation in coastal seawater.

Health risk assessment of heavy metals in soils and crops in a mining area (Au-Ag-Cu-trona-oil et al.) of the Nanyang Basin, Henan Province, China

Heavy metal distribution in mining areas has always been a hot research topic due to the special environment of these areas. This study aims to explore the impact of heavy metal pollution on soils and crops in the study area, ensure the safety of local crops and the health of local residents, and provide a basis for the subsequent environmental restoration and the prevention and control of environmental pollution. Based on the analysis of the heavy metal concentrations in local soils and crops, the study investigated the spatial distribution, pollution degrees, and potential ecological risks of heavy metals in the farmland of a mining area in the southeastern Nanyang Basin, Henan province, China explored the sources of heavy metals and assessed the health risks caused by crop intake. The results of this study are as follows. The root soils of crops in the study area suffered heavy metal pollution to varying degrees. The degree of heavy metal pollution in maize fields is higher than that in wheat fields, and both types of fields suffer the most severe Cd pollution. Moreover, the root soils of different crops suffer compound pollution. The root soils in the maize fields suffer severe compound pollution at some sampling positions, whose distribution is similar to that of the mining area. Cd poses the highest potential ecological risks among all heavy metals, and the study area mainly suffers low and moderate comprehensive potential ecological risks. The principal component analysis (PCA) shows that the distribution of Zn, Cd, Pb, and As in soils of the study area is mainly affected by anthropogenic factors such as local mining activities; the distribution of Cr and Ni is primarily controlled by the local geological background; the distribution of Hg is mainly affected by local vehicle exhaust emissions, and the distribution of Cu is influenced by both human activities and the geological background. Different cereal crops in the study area are polluted with heavy metals dominated by Cd and Ni to varying degrees, especially wheat. As indicated by the health risk assessment results, the intake of maize in the study area does not pose significant human health risks; however, Cu has high risks to human health, and the compound heavy metal pollution caused by the intake of wheat in the study area poses risks to the health of both adults and children. Overall, the soils and crops in the study area suffer a high degree of heavy metal pollution, for which mining activities may be the main reason.©2023 China Geology Editorial Office.