Distribution Characteristics Of Elements Research Articles

Critical Raw Materials Supply: Challenges and Potentialities to Exploit Rare Earth Elements from Siliceous Stones and Extractive Waste

Critical raw materials (CRMs) supply is a challenge that EU countries have to face, with many thinking about domestic procurement from natural ore deposits and anthropogenic deposits (landfills and extractive waste facilities). The present research focuses on the possibilities linked to the supply of CRMs and the potential for exploiting rare earth elements (REEs), investigating a large variety of extractive waste and siliceous rocks in the Piedmont region (Northern Italy). Indeed, the recovery of REEs from the extractive waste (EW) of siliceous quarries and other siliceous ore deposits can be a valuable way to reduce supply chain risks. Starting with a review of the literature on mining activities in Piedmont and continuing with the sampling and geochemical, mineralogical, petrographic, and environmental characterization of EW facilities connected to siliceous dimension stones, of kaolinitic gneiss ore deposits, and of soils present near the investigated areas, this study shows that the degree of REEs enrichment differs depending on the sampling area (soil or EW) and lithology. The concentration of REEs in the EW at some sampling sites fulfils the indicators of industrial-grade and industrial recovery; the high cumulative production and potential market values of EW and the positive recovery effects through proven methodologies indicate a viable prospect of REE recovery from EW. However, REE recovery industrialization faces challenges such as the difficulty in achieving efficient large-scale recovery due to large regional differences in REE abundance, the mismatch between potential market value and waste annual production, etc. Nonetheless, in the future, EW from dimension stone quarries could be differentially studied and reused based on the enrichment and distribution characteristics of trace elements. The present paper shows investigation procedures undertaken to determine both CRMs potentialities and environmental issues (on the basis of literature data employed to select the more-promising areas and on sampling and characterization activities in the selected areas), together with procedures to determine the waste quantities and tentative economic values of REEs present in the investigated areas. This approach, tested on a large area (Piedmont region), is replicable and applicable to other similar case studies (at EU and non-EU levels) and offers decision makers the possibility to acquire a general overview of the potential available resources in order to decide whether and where to concentrate efforts (including economic ones) in a more detailed study to evaluate the exploitable anthropogenic deposits.

Study on the change of urban spatial structure in Three Northeast Provinces of China based on the coupling relationship between POI and nighttime light data

Identifying and measuring urban spatial structure is a prerequisite for understanding urban spatial characteristics, formulating urban development strategies and testing urban planning results. As important data sources that can visually reflect the spatial distribution characteristics of urban socio-economic and other physical elements, urban points of interest (POI) and nighttime light data play an important role in the study of urban spatial structure. In this study, the main urban areas of 36 cities of the Three Northeast Provinces (Heilongjiang Province, Jilin Province, Liaoning Province) were selected as the study area, the POI (6,553,294 points of interest) and nighttime light data from 2010, 2016, and 2022 were chosen as the basic research data, and the methods of point kernel density estimation, data griddedness, and multifactor combination mapping were used to analyze the developmental dynamics of the urban spatial structure. The study demonstrated: (1) The spatial coupling consistency of POI and nighttime light data in the main urban areas of the Three Northeast Provinces was high, and both had good applicability in urban spatial structure research; (2) POI and nighttime light values formed the spatial pattern of “axis + core − periphery” with Shenyang, Dalian, Changchun and Harbin as the core, while the coupling relationship between the POI and nighttime light data identified that the main urban areas in the Three Northeast Provinces presented a centralized agglomeration type, a decentralized grouping type, a belt combination type and a radial expansion type urban spatial structure; (3) From the perspective of changes in the coupling relationship between POI and nighttime light, most of the main urban areas of resource-mature cities, resource-regeneration cities and non-resource cities were affected by the regional development agglomeration and the “T” railway network, and the “high/medium–high/medium” area showed an expanding tendency; most of the main urban areas of resource-decline cities were affected by the lower development potential and the deprivation of economic factors by the surrounding core cities, while the “high/medium–high/medium” areas showed a contracting tendency. The results of the study can provide a scientific basis and theoretical reference for the future adjustment of urban spatial structure, planning and construction as well as resource allocation in the main urban areas of the cities in the Three Northeast Provinces.

Elements characteristics and potential environmental risk assessment of jarosite residue and arsenic sulfide residue based on geochemical and mineralogical analysis

The waste slag known as jarosite residue (JR) and arsenic sulfide residue (ASR) were produced following the creation of zinc by hydrometallurgical procedures. The increasing annual zinc mining has led to growing pressure to dispose of the resulting JR and ASR from zinc smelting, making it crucial to assess their environmental impact and feasibility for utilization. The main components, distribution characteristics of elements, and potential environmental risks of zinc smelting wastes are studied through toxicity leaching tests, sequential extraction procedures, and various characterization technologies such as XRF, XRD, and SEM-EDS. The mineral compositions of JR are natrojarosite, franklinite, and gunningite, and zinc mainly adheres to the crevices of the natrojarosite mineral. Meanwhile, the ASR of flocculent structures is composed of orpiment, greenockite, arsenic oxide, and calvertite, and As appears in the form of the S-As-O phase. The Zn, Cu, and Cd in JR were dominated by exchangeable bound (81.53–96.6 %), and the main form of As, Cd, Se, and Tl in ASR was organic matter bound (87.0–99.21 %). The Risk Assessment Code (RAC) method confirmed the risk of Cd, Cu, Zn, and Mo in JR is high, while the risk of Cd, Pb, and Cr in ASR is moderate. Compared to the standard value of “Identification Standard for Toxicity of Hazardous Waste Leaching (GB5085.3-2007)”, the leachate concentrations of Zn in JR as well as Cd and As in ASR were exceeded, suggesting that the JR and ASR were in the type of hazardous waste and posed an environmental risk. The study provides theoretical guidance for the future rational management and effective utilization of hazardous waste.

원전의 안전계통 설정치 불확도 평가에서의 중심극한정리 타당성 확인

In evaluating the uncertainty of nuclear power plant safety system setpoints, the central limit theorem(CLT) is often used when combining the uncertainties of each element. However, depending on the distribution characteristics of individual elements and the number of elements to be combined, there are cases where the central limit theorem cannot be applied. International standards are being revised to reflect this. In this paper, we describe various methodologies for calculating safety system setpoints and confirm whether the combined components follow the central limit theorem according to the distribution characteristics of the individual elements. The Monte Carlo simulation method is used as a basic tool to confirm this, and normality is verified using KS test in Python program library. Additionally, the variance characteristics of each distribution are examined and differences from the uniform distribution are analyzed. As a result of the analysis, in order for the combined component to follow the central limit theorem, if the distribution is concentrated on both sides compared to the uniform distribution, the number of input variables needs to be four or more. That is, when the number of input element uncertainty of the safety system setpoint exceeds 4, the combined uncertainty was evaluated to have normality regardless of the distribution of input element uncertainty. Therefore, it was confirmed that the method of applying CLT to calculate the coverage factor and then using it to obtain the expanded uncertainty was valid. In the case of a distribution concentrated toward the center compared to a uniform distribution, the number of variables less than 3 was required. The U type distribution, which is used to evaluate the uncertainty of wireless communication, showed characteristics closer to a uniform distribution than an inverted triangular distribution. Also, in the case of variance, it was found that the variance of the uniform distribution was larger than that of the linear distribution, confirming that this conformed to the maximum entropy principle.

Study on the distribution, enrichment and migration characteristics of trace elements in particulate matter during solid waste combustion

Trace element emissions caused by the entrainment of particulate matter (PM) has led to serious environmental pollution. This research focuses on the distribution, enrichment and migration characteristics of trace elements in different sizes of PM during the typical solid waste combustion. The results indicate that the mass concentration of trace elements in different PM is closely related to their volatility. Volatile trace elements such as Cu, In, Ag, Pb, and Cd tend to distribute in PM1. Higher temperatures facilitate the volatilization of trace elements, promoting their migration and enrichment in finer PM. The removal effect of Si–Al-based additives on trace elements in PM1 decreases with the increase of Si/Al ratio. Among them, the removal efficiency of 5% kaolin is the best. After the addition of Si–Al-additives, Zn and In mainly migrate to PM1-10, while Cu, V, Mo, As, Se, Cr, Ba, Mn, Co, Sr, and Ti mainly migrate to PM10+. Ag, Pb, and Cd migrate to both PM1-10 and PM10+ simultaneously.

Analysis of web design visual element attention based on user educational background

The evolution of Internet technology has led to an increase in online users. This study focuses on the pivotal role of visual elements in web content conveyance and their impact on user browsing behavior. Therefore, the use of visual elements in web design based on big data has aroused widespread concern among web designers, they apply visual elements to their web design works to make the web more attractive. This study examines the composition and distribution characteristics of key visual elements identified through user behavior data in a big data environment and discusses the use of visual elements in web design in the era of network economy. In addition, this paper issued 200 questionnaires to investigate the degree of attention to visual elements in web pages for users of different occupations and different educational backgrounds. Our survey indicated that visual elements captured the attention of 41% of corporate employees, whereas a mere 1% of social welfare workers focused on web content; 36% of undergraduates pay attention to visual elements of web pages, but only 5% and 4% of postgraduates and doctoral degrees and above. Therefore, the visual elements of the designed web page need to conform to the user's cultural background and professional background.

Optimizing Recharge Area Delineation for Small- to Medium-Sized Groundwater Systems through Coupling Methods and Numerical Modeling: A Case Study of Linfen City, China

In previous investigations, the demarcation of capture zones within a specific research area predominantly relied on a singular method, leading to pronounced limitations and uncertainties. To address this challenge, an extensive field survey was conducted, focusing on the systematic classification of water sources in the Linfen City region. Building upon this classification, an intricate fusion of a hydrogeological analysis and formulaic methodology was employed. This integrated approach, coupled with independent numerical simulation methods, was applied to delineate recharge areas for both alluvial fan pore water in piedmont regions and exposed karst water in small- to medium-sized water sources. Simultaneously, precise spatial interpolation was carried out on water quality monitoring data from supply wells within the water source area for the year 2020. This meticulous analysis facilitated the determination of the spatial distribution characteristics of hydrochemical elements. To assess the water quality within the capture zone, the class III groundwater quality standards of China were employed as a pivotal tool for validating the results of the delineation of water source recharge areas. In the final analysis, a comparative study between the integrated coupling method and numerical simulation outcomes revealed the successful delineation of the boundaries for the water supply areas of Tumen and Caojiapo in Linfen City, covering areas of 5.5 km2 and 22.29 km2, respectively. Simultaneously, the combination of the three methods accurately outlined the boundary of the Hexi water supply area, encompassing an area of 2.5224 km2. These results vividly illustrate that the amalgamation of various methodologies proves more beneficial for the precise delineation of capture zones, particularly in diverse types and scales of groundwater sources. The synergy exhibited by these three methods underscores their collective efficacy, providing a more comprehensive and intuitive delineation of the recharge areas for small- to medium-sized water sources. Consequently, these findings significantly enhance the practical application value of the study and hold promise in making substantial contributions to local groundwater security and management initiatives.

Insights into biogeochemistry and hot spots distribution characteristics of redox-sensitive elements in the hyporheic zone: Transformation mechanisms and contributing factors

Biogeochemical hot spots play a crucial role in the cycling and transport of redox-sensitive elements (RSEs) in the hyporheic zone (HZ). However, the transformation mechanisms of RSEs and patterns of RSEs hot spots in the HZ remain poorly understood. In this study, hydrochemistry and multi-isotope (N/C/S/O) datasets were collected to investigate the transformation mechanisms of RSEs, and explore the distribution characteristics of RSEs transformation hot spots. The results showed that spatial variability in key drivers was evident, while temporal change in RSEs concentration was not significant, except for dissolved organic carbon. Bacterial sulfate reduction (BSR) was the primary biogeochemical process for sulfate and occurred throughout the area. Ammonium enrichment was mainly caused by the mineralization of nitrogenous organic matter and anthropogenic inputs, with adsorption serving as the primary attenuation mechanism. Carbon dynamics were influenced by various biogeochemical processes, with dissolved organic carbon mainly derived from C3 plants and dissolved inorganic carbon from weathering of carbonate rocks and decomposition of organic matter. The peak contribution of dissolved organic carbon decomposition to the DIC pool was 46.44 %. The concentration thresholds for the ammonium enrichment and BSR hot spots were identified as 1.5 mg/L and 8.84 mg/L, respectively. The distribution pattern of RSEs hot spots was closely related to the hydrogeological conditions. Our findings reveal the complex evolution mechanisms and hot spots distribution characteristics of RSEs in the HZ, providing a basis for the safe utilization and protection of groundwater resources.

Corrosion behavior of 700 MPa grade weathering steel with 4.0 wt% Ni and 5.0 wt% Cr in simulated marine atmospheric environment

The dry-wet cycle corrosion behavior of low alloy steel (Q355B) and 700 MPa grade Ni, Cr composite weathering steel (4 wt% Ni-5 wt% Cr) in 2 wt% NaCl solutions was studied. The distribution characteristics of elements and phases in the corrosion products after 360 h corrosion cycle were analyzed by SEM and Raman spectroscopy. The formation mechanism of protective rust layer of Ni, Cr composite weathering steel in simulated marine environment was briefly described. The results show that the corrosion products of Q355B appear obvious stratification, and the rust layer of Ni, Cr composite weathering steel has no longer stratified. The Ni, Cr composite weathering steel forms a cationic selective rust layer during the corrosion process, which effectively prevents the penetration of Cl- and exhibits excellent corrosion resistance, the corrosion rate of Ni, Cr composite weathering steel after 72 h-360 h corrosion cycle is 1/8–1/3 of that of Q355B. The value of α/γ * increases with the extension of corrosion cycle, which is reach to 1.0 after 360 h corrosion cycle. The corrosion potential increases with the extension of corrosion cycle, the corrosion current density fluctuates slightly around 100 × 10−6 A/cm2.

Architectural Characteristics and Distribution Patterns of Gravity Flow Channels in Faulted Lake Basins: A Case Study of the Shahejie Formation in the Banqiao Oilfield, China

Internal depositional architecture and sand body distribution are the main challenges faced in the development of gravity flow channel deposits in China. Despite significant progress in the exploration and development of gravity flow deposits in recent years, our understanding of the internal architecture of composite sand bodies within gravity flow channels is still limited. Gravity flow channels represent a widely developed sedimentary type in the Shahejie Formation of the Banqiao Oilfield, Huanghua Depression. The lack of understanding of the spatial stacking relationship of gravity flow channel sand bodies hinders further development and remaining oil recovery within the oilfield. Through this study, we aimed to dissect the composite channels (5th architectural units) and single channels (4th architectural units) at the study area, using a combination of well logs and seismic data. We explored the identification criteria and spatial distribution characteristics of internal architectural elements within gravity flow channel reservoirs, based on abundant drilling data, well density grids, and 3D seismic data. By identifying and delineating single channels, we were able to summarize six identification criteria for single channels, including relative elevation differences, curve shapes, and the number of interbeds. We obtained the sand body scale and aspect ratio of single channels and established three depositional architectural patterns, i.e., isolated, lateral migration, and vertical accretion, thus revealing the differences in the spatial stacking relationships of sand bodies in different structural locations (blocks). This work provides new insights into the depositional architectural patterns of gravity flow channel deposits in the Banqiao Oilfield, Huanghua Depression.

The distribution and enrichment characteristics of rare earth elements between coals and coal ashes from four coal-fired power plants.

Coal and coal ash (slag and fly ash) have emerged as important potential sources for rare earth elements (REY). The distribution and enrichment of REY during coal combustion from coal-fired power plants are of great significance for the recovery of REY. In this study, the concentration of REY in coal and coal ash from four coal-fired power plants in China was determined using microwave digestion-inductively coupled plasma mass spectrometry. The distribution and enrichment characteristics of REY in coal and coal ash were studied. The coal ash contains 310-683 μg g-1 of REY, and the proportion of critical REY was greater than 30%, which is higher than the extraction concentration (300 μg g-1) recommended by the United States Department of Energy, indicating significant REY recovery potential. The concentration of REY in coal was positively correlated with ash yield, which could be explained by the fact that REY are mainly distributed in minerals. Coal and coal ash show similar REY distribution patterns, indicating that REY were not fractionated during the coal combustion. In addition, the enrichment coefficient of REY in fly ash was greater than that in slag, which revealed that REY were mainly enriched in fly ash. Therefore, the REY in fly ash has more recycling potential.

Ore genesis of the Bayanbaolege Ag-Pb-Zn deposit, NE China: Constraints on LA-ICP-MS studies of cadmium and related trace elements in sulfides

The newly discovered Bayanbaolege Ag-Pb-Zn deposit is located in the Southern Great Hinggan Range metallogenic belt, northeastern China, with 1440 t Ag, 380000 t Zn, 50000 t Pb, and a beneficial component of Cd (806 t Cd) and Ga (211 t Ga). The orebodies of this deposit occur as veins and are hosted mainly by a contact zone between the Permian silty slate and the granite intrusion, and have a closely spatio-temporal relationship with the early Cretaceous granodiorite porphyry intrusion.The mineralization process of the Bayanbaolege deposit can be divided into three mineralization stages including arsenopyrite-pyrite-quartz stage (stage I), pyrite-pyrrhotite-chalcopyrite stage (stage II) and galena-sphalerite-argentite -pyrite-calcite stage (stage III). LA-ICP-MS trace element mapping and spot analyses were conducted on the sphalerite and pyrite in stage III at the Bayanbaolege deposit.LA-ICP-MS trace element mapping and spot analyses were conducted on the stage III sphalerite and pyrite selected from the Bayanbaolege deposit in order to identify the occurrence form and distribution characteristics of critical metal elements, constrain the possible controls on the variation of trace elements, reveal the physicochemical condition of mineralization and provide new insights into the ore genesis. The results show that Ga, Ge, In, Cd, Mn, Cu, Ag and Co concentrations in sphalerite, and pyrite is the preferential host for Ge, As and Ni. The occurrence of Ga, Ge, In and Cd in sphalerite are mainly deposited in form of isomorphism. Physicochemical condition studies suggest that sphalerite precipitated from a medium-temperature hydrothermal system with the range from 190 °C to 291 °C (average at 230 °C) and accompanied with the intermediate fS2. Trace element concentrations of sphalerite are different from that of the MVT, VMS, SEDEX and skarn deposits. The results of this study, combined with the previous geological and physicochemical evidence, indicate that the Bayanbaolege Ag-Pb-Zn deposit deposit is an intrusion-related mesothermal hydrothermal vein-type deposit.

Role of placental barrier on trace element transfer in maternal fetal system and hypertensive disorders complicating pregnancy and gestational diabetes mellitus

BackgroundHypertensive disorders complicating pregnancy (HDCP) and gestational diabetes mellitus (GDM) can affect the placental barrier function to varying degrees. However, current studies show that the transfer and distribution characteristics of trace elements in the maternal-fetal system are still unclear. This study investigated the effect of the placental barrier on the transfer of trace elements from mother to fetus and its relationship with HDCP and GDM.MethodsA case-control method was used in this study. 140 pairs of samples were collected; 60 were from healthy pregnant women, and 80 were from patients with pregnancy complications. The contents of trace elements in paired samples were determined by inductively coupled plasma–mass spectrometry (ICP-MS). SPSS software was used to analyze the differences in trace element levels in matched samples of each group. The correlations were analyzed based on Pearson’s correlation factor (r).ResultsThe distribution characteristics of Fe content in the pathological group (HDCP group and GDM group) were the same as those in the normal group (umbilical cord blood > maternal blood > placenta), but there was no significant difference in the iron content in maternal blood and cord blood of pathological group. The distribution characteristics of Mn content in the pathological group (placenta > umbilical cord blood > maternal blood) were changed compared with those in the normal group (placenta > maternal blood > umbilical cord blood). In addition, the placental Cr content and cord blood Cr and Ni content of the pathological group were higher than those of the normal group. HDCP placental Cr and GDM placental Fe levels were significantly correlated with the Apgar score.ConclusionsThe transfer of Fe and Mn and the placental barrier function of Cr and Ni in the maternal-fetal system of HDCP and GDM are significantly altered, which directly or indirectly increases the maternal and fetal health risk.

Geochemical and Mineralogical Characteristics of Ion-Adsorption Type REE Mineralization in the Mosuoying Granite, Panxi Area, Southwest China

The ion-adsorption rare earth deposit developed on the Mosuoying granite in the Panxi area of southwestern China represents a significant advancement in the exploration of ion-adsorption rare earth deposits in Sichuan. Being the first and currently the sole ion-adsorption rare earth deposit in Sichuan, studying its rare earth mineralization characteristics holds great importance. This paper aims to investigate the geochemical properties of the Mosuoying granite and its overlying weathered crust using rock geochemical methods based on field geological investigations. The findings reveal that the deposit belongs to the light rare earth type, with the ore-forming parent rock attributed to the high-potassium calc-alkaline series. It exhibits a high rock REE content ranging from 419 to 578 ppm, indicating favorable mineralization potential. Hydrothermal alteration reduces the REE content of the parent rock, leading to a notable increase in the LREE/HREE ratio, thus impacting the partitioning of rare earth elements and subsequent ore formation. The distribution characteristics of rare earth elements in each layer of the weathered crust are controlled by the parent rock and exhibit a light rare earth distribution pattern. The completely weathered layer is the main enrichment zone for rare earth elements, and the migration and enrichment patterns of rare earth elements in the weathered crust are evident. From the semi-weathered layer to the completely weathered layer, all REEs were gained, with a higher degree of migration for LREE. From the completely weathered layer to the clay layer, all REEs were lost, and the vertical distribution of rare earth content shows a “low-high-low” pattern.

Effects of seasonal temperature regimes: Does Cyprinus carpio act as a health hazard during the construction of Suki Kinari hydropower project on Kunhar River in Pakistan?

The main purpose of the current study was to assess the levels of trace elements (iron, lead, zinc, copper, and manganese) in both water and fish muscles of common carp (Cyprinus carpio) in the Kunhar River during the development of the Suki Kinari hydropower project (SKHPP). Additionally, the aim was to shed light on the potential health hazards associated with the consumption of fish by residents. Surface water and fish (muscle and liver) from ten specific sampling locations in the Mansehra district (affected by an SKHPP) along the river were examined to determine the levels of trace elements. The findings divulged that the water at all locations exhibited concentration levels of iron (Fe), lead (Pb), and manganese (Mn) that surpassed the benchmarks established by the World Health Organization in 2011. Conversely, the concentration levels of copper (Cu) and zinc (Zn) fell beneath the stipulated standards. Moreover, the concentrations of Mn, Zn, and Pb were found to be excessively high. The findings presented in the present study offer a comprehensive comprehension of the spatial and distribution characteristics of trace elements in both water and fish species along the Kunhar River, taking into consideration the impact of the SKHPP. Additionally, our data emphasize the potential health hazards that may arise from the prolonged consumption of fish by the local population.

Distribution characteristics of Sulfur, phosphorus and trace elements in crude oil and source rock chloroform asphaltenes “a” and description of an oil-bearing system in the Ordos Basin

The multiple sets of source rocks and crude oil biomarkers in the Yanchang Formation have no clear results of oil-source correlation. Chloroform asphaltenes “A” was extracted from the source rocks and crude oils and microwave digested, and its elemental composition analyzed by ICP–MS for oil-source correlation. The S/P and the ratio of light and heavy rare earth elements are oil-source correlation indices. The total amount of transition metals may be useful for oil-oil and oil-source correlation using cluster analysis techniques, but redox parameters are not effective for oil-oil and oil-source correlation in lacustrine oil. It is proposed that the oils in the Longdong area and Jiyuan area all come from the Chang 7 source rocks. The oils in the Shanbei area are derived from the Chang 9 source rocks in the area and the Chang 7 source rocks in Longdong. The Chang 10 oils in the Shanbei area and Chang 9 oils in the middle Lake Basin appear to come from other sources. Trace elements can provide valuable clue on the hydrocarbon sources and oil migration patterns of the Yanchang Formation, which is of great significance in the search for possible deep oil-bearing systems in the Shanbei area.

Distribution characteristics of selenium and heavy metal elements in soil-crop system in ankang, shaanxi, china

A total of 229 groups of root vegetables, rice, corn and their root soils were collected in Ankang, Shaanxi, to analyze the characteristics of element migration and transformation in crops and root soil, to compare the migration and enrichment capabilities of various elements in different crops, to explain the characteristics of root soil pH and element correlation, and provide a theoretical basis for agricultural development. Results showed that there were differences in the ability of crops to accumulate various elements in the soil. The absorption capacity of Se, Cd and Zn elements was strong, while the bioaccumulation ability of As, Pb and Cr elements was weak. The contents of Cr, As and Hg were the highest in rice, which were significantly higher than those in root vegetables and corn. The contents of Cd, Cu and Pb in root vegetables were the highest, significantly higher than those in rice and corn. The content of various elements in crops and root soil had a different intensity correlation. Generally speaking, the content of various elements in crops increased with the increase of root soil element content to a certain extent. There was a negative correlation between pH and soil elements, and there was a significant positive correlation between the elements in the root soil of different crops. Bangladesh J. Bot. 52(2): 649-657, 2023 (June) Special

Distribution characteristics of selenium and heavy metal elements in soil-crop system in ankang, shaanxi, china

A total of 229 groups of root vegetables, rice, corn and their root soils were collected in Ankang, Shaanxi, to analyze the characteristics of element migration and transformation in crops and root soil, to compare the migration and enrichment capabilities of various elements in different crops, to explain the characteristics of root soil pH and element correlation, and provide a theoretical basis for agricultural development. Results showed that there were differences in the ability of crops to accumulate various elements in the soil. The absorption capacity of Se, Cd and Zn elements was strong, while the bioaccumulation ability of As, Pb and Cr elements was weak. The contents of Cr, As and Hg were the highest in rice, which were significantly higher than those in root vegetables and corn. The contents of Cd, Cu and Pb in root vegetables were the highest, significantly higher than those in rice and corn. The content of various elements in crops and root soil had a different intensity correlation. Generally speaking, the content of various elements in crops increased with the increase of root soil element content to a certain extent. There was a negative correlation between pH and soil elements, and there was a significant positive correlation between the elements in the root soil of different crops. Bangladesh J. Bot. 52(2): 649-657, 2023 (June) Special

Spatial Distribution, Source Analysis, and Health Risk Assessment of Metal Elements in Karst Water in Southeastern Chongqing

Dispersed karst water is an important water supply source, or even the only water supply source, for some districts and counties in Chongqing City. It is particularly necessary to understand the distribution characteristics of metal elements in karst water and the health risks exposed. In this study, the scattered karst water in the southeastern part of Chongqing was taken as the main research object, and the concentrations of Al, Cu, Pb, Zn, Cr, Cd, Ni, Mn, As, and Hg in 42 groups of karst spring water samples were determined. The spatial distribution of metal elements with a high detection rate was revealed using the ordinary kriging interpolation method, and the spatial distribution characteristics, sources, and health risks of metal elements were analyzed using multivariate statistical methods and health risk models. The results showed that the quality of dispersed karst water in southeastern Chongqing was generally good, and the spatial scale variability in the occurrence of metal elements in karst water was strong, especially for Ni and As. The sources of Cu, Pb, As, Zn, and Cr were mainly affected by the regional geological background; Al and Mn were mainly affected by human industrial, agricultural, and mining activities; and Ni was affected by both the natural background and human activities. The total health risk of exposure through the drinking route was higher than that of the skin infiltration route, which was the main exposure route of the human body. The total health risk of children exposed through the drinking route was higher than that of adults, and the total health risk of adults exposed through the skin infiltration route was higher than that of children. It is worth noting that Cr was the determinant of total health risk. From the perspective of drinking water safety, local residents need to pay certain attention to water quality when drinking distributed karst groundwater, in order to reduce the health risk of the population.

Spatial Heterogeneity of Rare Earth Elements: Implications for the Topsoil of Regional Ion-Adsorption Type Rare Earth Deposit Areas in Southern China

The migration and spatial distribution characteristics of topsoil rare earth elements (REEs) are significant for the risk assessment of the external environment. However, the spatial distribution of REEs in the topsoil of ion-adsorption type rare earth element (REE) mining areas is poorly studied. We aimed to determine the differences and control factors of the spatial distribution of REEs in the topsoil of typical rare earth mines in South Jiangxi, South China. Sixty-five topsoil samples and eighteen profile samples were collected and analyzed for their rare earth content to elucidate spatial autocorrelation and heterogeneity using statistical analysis software (IBM SPSS Statistics 26.0.0.0, GS+9.0, and Arcgis10.2.0.3348). Moran index analysis showed that the positive correlation between sampling points was significant within the range of 0–500 m. The best fitting models of the semi-variance variogram were the exponential model, Gaussian model, and spherical model. The sequence of the spatial structure (C0 + C) was Ho > Tb > La > Pr > Nd > Sm > Gd > Tm > Lu > Dy > Er > Yb > Ce > Eu. The spatial fractal distribution pattern was Ho > Tb > Lu > Er > Dy > Yb > Tm > Gd > Ce > La > Eu > Sm > Pr > Nd. This indicated that the light rare earth elements (LREEs) and heavy rare earth elements (HREEs) in the topsoil were significantly different from the other sediments. This study provides new evidence for the environmental quality assessment of the in situ leaching of ionic rare earth ores into the topsoil layer.