Distribution Of Heavy Elements Research Articles

Comparing the three-dimensional morphological asymmetries in the ejecta of Kepler and Tycho in X-rays

Aims. Recent simulations have shown that asymmetries in the ejecta distribution of supernova remnants (SNRs) may be a reflection of asymmetries left over from the initial supernova explosion. Thus, SNR studies provide a vital means for testing and constraining model predictions in relation to the distribution of heavy elements, which are key to improving our understanding of the explosion mechanisms in Type Ia supernovae. Methods. The use of a novel blind source separation method applied to the megasecond X-ray observations of the historic Kepler and Tycho supernova remnants has revealed maps of the ejecta distribution. These maps are endowed with an unprecedented level of detail and clear separations from the continuum emission. Our method also provides a three-dimensional (3D) view of the ejecta by individually disentangling red- and blueshifted spectral components associated with images of the Si, S, Ar, Ca, and Fe emission. This approach provides insights into the morphology of the ejecta distribution in those two remnants. Results. Those mappings have allowed us to thoroughly investigate the asymmetries in the intermediate-mass elements and Fe distribution in two Type Ia supernova remnants. We also compared the results with the core-collapse Cassiopeia A remnant, which we had studied previously. The images obtained confirm, as expected for Type Ia SNRs, that the Fe distribution is mostly closer to the core than that of intermediate-mass elements. They also highlight peculiar features in the ejecta distribution, such as the Fe-rich southeastern knot in Tycho.

Two‐stage soil core sampler to collect a less‐compressed core from forested areas

AbstractA two‐stage sampler was designed to investigate the vertical distribution of heavy metals and trace elements that contaminate forest soils through atmospheric deposition. The hand‐corer consisted of two L‐shaped aluminum angles that were driven separately into the soil to reduce friction between the corer wall and the soil. This allowed for soil cores to be collected with less compression than with traditional corers. The corer is easily made, inexpensive, lightweight, and easy to carry. The degree of compression of soil cores collected at a depth of 20 cm from various montane forests in Japan was usually less than 10% (collected core length >18 cm); although, more compression occurred in soil with a higher air content. The degree of compression of soil cores collected from urban forests was lower than that in montane forests. When the two‐stage sampler was compared with a tube‐type sampler in a Japanese cedar (Cryptomeria japonica) forest, the compression degree of a soil core collected with the two‐stage sampler was a quarter that of the tube‐type sampler. The collection of less‐compressed soil cores will allow for reconstruction of a more accurate linear depth distribution of contaminants. To demonstrate this, we investigated the vertical distribution of Pb, Sb, and radioactive 137Cs in soil cores collected from conifer plantations on Mount Tsukuba, Japan, in April 2011. The migration centers of anthropogenic Pb, Sb, and 137Cs were positioned at 7.9, 7.5, and 3.3 cm from the ground surface, respectively. These distances probably reflect differences in the history of atmospheric pollution.

Utility and influence mechanism of densification modulation on grain boundary diffusion in NdFeB magnets

Grain boundary diffusion technology is pivotal in the preparation of high-performance NdFeB magnets. This study investigates the factors that affect the efficiency of grain boundary diffusion, starting from the properties of the diffusion matrix. Through the adjustment of the sintering process, we effectively prepared magnets with varied densities that serve as the matrix for grain boundary diffusion with TbHx diffusion. The mobility characteristics of the Nd-rich phase during the densification stage are leveraged to ensure a more extensive distribution of heavy rare earth elements within the magnets. According to the experimental results, the increase in coercivity of low-density magnets after diffusion is significantly greater than that of relatively high-density magnets. The coercivity values measured are 805.32 kA/m for low-density magnets and 470.3 kA/m for high-density magnets. Additionally, grain boundary diffusion notably enhances the density of initial low-density magnets, addressing the issue of low density during the sintering stage. Before the diffusion treatment, the Nd-rich phases primarily concentrate at the triangular grain boundaries, resulting in an increased number of cavity defects in the magnets. These cavity defects contain atoms in a higher energy state, making them more prone to transition. Consequently, the diffusion activation energy at the void defects is lower than the intracrystalline diffusion activation energy, accelerating atom diffusion. The presence of larger cavities also provides more space for atom migration, thereby promoting the diffusion process. After the diffusion treatment, the proportion of bulk Nd-rich phases significantly decreases, and they infiltrate between the grains to fill the cavity defects, forming continuous fine grain boundaries. Based on these observations, the study aims to explore how to utilize this information to develop an efficient technique for grain boundary diffusion.

Source apportionment of soil heavy metals based on multivariate statistical analysis and the PMF model: A case study of the Nanyang Basin, China

Analyzing the spatial variation characteristics of heavy metals in soil and identifying their sources is crucial for preventing, controlling, and managing regional environmental pollution. In this study, 5778 surface soil samples were collected from the Nanyang Basin. The content characteristics of five heavy metals (As, Cr, Cd, Hg, and Pb) were determined and analyzed. The spatial distribution characteristics of these heavy metals in the soil were investigated using inverse distance interpolation and spatial autocorrelation analysis. Additionally, the sources of heavy metals in the soil were qualitatively and quantitatively explored through PCA and PMF models. The results revealed that the mean values of all elements, except As and Hg, exceeded the country soil background values. Spatially, the distribution of soil heavy metal elements showed evident heterogeneity and autocorrelation, with obvious differences between the western and eastern regions, where heavy metal concentrations were generally higher in the west and lower in the east. Four sources of heavy metals were identified in the study area: mining sources, natural sources, transportation sources, and a combined source of atmospheric deposition and agricultural activities. The element As was primarily derived from natural sources (80.90%). The element Cr was influenced by multiple factors, mainly from mining sources (66.20%) and natural sources (31.80%). Transportation sources (46.30%) and mining sources (44.80%) were the primary influences on the element Cd. The element Pb was influenced by transportation sources (64.70%) and natural sources (18.11%). The element Hg was mainly influenced by both atmospheric deposition from coal combustion and agricultural activities (90.50%).

Observational Studies of r- and s-Process Elements for Milky Way Stars

Elements heavier than iron-group are produced by rapid and slow neutron-capture processes (r-process and s-process) in the universe. The site of the processes and history of the enrichment in the Milky Way Galaxy have been studied by spectroscopic observations of stars with different ages and population (Galactic disks, halo etc.). The abundance studies of neutron-capture elements for Milky Way stars, including our long-term observational efforts using the spectroscopic survey telescope LAMOST and the 8.2m Subaru Telescope are reviewed. This article covers the observational results on the abundance distributions of heavy elements (Sr, Ba and Eu), and elemental abundance patterns of r- and s-process enhanced stars.

A high sensitivity microbeam RBS setup for heavy elements implantation profiles analysis

This work presents a new setup that integrates heavy ion RBS with microbeam technology combined with high detection solid angle for the measurement of the depth profile and areal distribution of heavy elements in silicon using a Si microbeam. Focussed 2.4 MeV Si2+ ions were scanned over the frontal or lateral surface of silicon wafers to measure both the areal concentrations and depth profiles of all elements heavier than silicon. Tests were done on samples with Pt concentration range of 4 × 10 12–2 × 10 14 at/cm 3 that was diffused via the Pt-Silicide surface layer process from one lateral surface into the 400 µm thick Si wafers. It is important to note that employing a Si ion beam instead of the conventional He ion beam serves the purpose of not only increasing the backscattering cross section, as in well-established heavy element RBS, but also reducing pileup by eliminating scattering from the Si substrate, which is essential for sensitive analysis. This allows a significant increase in microbeam currents without increasing the count rate in large area detectors. A set of two large area PIN diodes (10x10 mm) were used in an optimized configuration resulting in 1,04 sr detection solid angle. Additionally, an appropriate microbeam collimator was used to shield the PIN diodes from events caused by forward scattering and scattering of the Si ion beam halo from different components in the reaction chamber. Lateral scans of the silicon wafer were performed by focussed Si ions, with ∼10 µm spot size and of the nA range beam currents. The RBS intensity maps containing the Pt depth profile were obtained with a sensitivity of 6.7 × 109 at/cm2.

The updated BaSTI stellar evolution models and isochrones – IV. α-Depleted calculations

ABSTRACT This is the fourth paper of our new release of the BaSTI (a Bag of Stellar Tracks and Isochrones) stellar model and isochrone library. Following the updated solar-scaled, α-enhanced, and white dwarf model libraries, we present here α-depleted ([α/Fe] = −0.2) evolutionary tracks and isochrones, suitable to study the α-depleted stars discovered in Local Group dwarf galaxies and in the Milky Way. These calculations include all improvements and updates of the solar-scaled and α-enhanced models, and span a mass range between 0.1 and 15 M⊙, and 21 metallicities between [Fe/H] = −3.20 and +0.45 with a helium-to-metal enrichment ratio ΔY/ΔZ = 1.31, homogeneous with the solar-scaled and α-enhanced models. The isochrones – available in several photometric filters – cover an age range between ∼20 Myr and 14.5 Gyr, including the pre-main-sequence phase. We have compared our isochrones with independent calculations of α-depleted stellar models, available for the same α-element depletion adopted in the present investigation. We have also discussed the effect of an α-depleted heavy element distribution on the bolometric corrections in different wavelength regimes. Our α-depleted evolutionary tracks and isochrones are publicly available at our BaSTI website.

Determination of heavy metals and rare earth elements in sediment and river water of the Citarum Watershed

Citarum River and its tributary rivers flows through Bandung Regency, with the watershed area about 6080 km2. These rivers play important role for local people in various field. Unfortunately, the anthropogenic activities in Citarum watershed have caused some environmental problems such as erosion, sedimentation, and water quality deterioration. Many various elements and heavy metals enter into the river from industrial waste, domestic waste, and some lithogenic materials where they will be distributed to aquatic ecosystem components such as sediment and aquatic biota. The aim of this research is to determine the distribution of heavy metals and rare earth elements in water and sediment river in Citarum River and its tributary river. The heavy metals and rare earth elements were measured using neutron activation analysis technique that can determine many elements simultaneously. The samples were collected from 10 sampling stations, from Situ Cisanti (upper segment) to Saguling Reservoir inlet, in March 2022. The result indicated that there were 13 elements detected in river water that consist of Na, K, Ca, Al, Mg, Ti, Co, Zn, Rb, Rb, Sb, Cs, La, V. In river sediment, 25 elements were detected that consist of 9 major elements (Na, K, Ca, Fe, Al, Mg, Ti, V, Mn), 10 minor elements (Co, Zn, Rb, Sb, Cs, Ba, Ta, Cs, Th, U, Hf) and 6 rare earth elements (La, Sc, Ce, Sm, Eu, Yb).

Spatial distribution and ecological risk assessment of heavy metal elements in rock‐soil in the mountainous areas of Southwest China: A case study of Xichang

This study employs the Muller geological accumulation index method and the Hakanson risk assessment method in combination with ArcGIS technology to assess the potential heavy metal pollution in soil. The study aims to investigate the geochemical characteristics, pollution degree, and potential ecological risks associated with soil heavy metal element content and distribution across various geological formations. The concentrations of eight heavy metals, namely Cu, Cd, Ni, Pb, Zn, Hg, As, and Cr, were analysed by collecting samples of the soil layer, parent material layer, and parent rock layer. The proportions of samples with different risk levels are accurately calculated to locate areas with high pollution risks. The findings are as follows: Firstly, the soil pH value in the study area is low, and the Cd and Cr concentrations are 1.38 and 1.20 times the background concentrations in soil in Sichuan Province, respectively. Moreover, Cu, Cd, Ni, Zn, and Cr concentrations are 1.23, 1.10, 1.20, 1.10, and 1.55 times the background concentrations in soil in China. Secondly, the distribution of heavy metal elements varies across different geological formation units, and the heavy metal contents of different samples from the same formation also varies significantly. The concentrations of heavy metal elements are influenced by different geological formations, with the pedogenic parent rock in the soil determining the initial concentrations of heavy metal elements. Thirdly, the spatial distribution of heavy metal elements indicates a good spatial distribution coupling relationship among the soil layer, parent material layer, and rock layer. The study suggests that the contents of the eight heavy metal elements in the soil inherited the characteristics of the parent material to a large extent and are influenced and controlled by the pedogenic parent rock (geological formation). Finally, the evaluation results reveal that all eight heavy metal elements exhibit moderate pollution, with a relatively large distribution area exhibiting moderate Cd, Hg, and As pollution and above. The overall study area exhibits a mild potential ecological risk level, with some areas at a moderate potential ecological risk level, distributed in patches across the study area. Cd and Hg exhibit relatively high potential ecological risks. The potential ecological risks of heavy metals are relatively high in the JKms and Tss units. While the overall quality of the soil in the study area is good, heavy metal pollution and potential ecological risks of some elements are still above ideal levels.

Spatial Distribution of Heavy Metals in the Soil of Different Area at Right Bank in Mosul City, Northern Iraq, Part 1

The present study focuses on how to assess the reality of soil pollution by heavy elements on the right bank of Mosul City after 2017. Seventy samples are collected from the right-bank soils depending on the random system. Chemical analysis is conducted using the ICP-MS technique to determine the concentrations of the heavy elements (As, Cd, Cr, Ni, Pb, Zn) in these samples, and then to calculate the pollution factors: Geoaccumulation Index, Enrichment Factor, and Contamination Factor. The average crust is adopted for the comparison and definition of the permissible limits for calculating the pollution factors. The results of the chemical analysis show that the concentrations of the elements (As, Cd, Cr, Ni, Pb, Zn) are higher than the average crust by a ratio of 100%, 85.3%, 44.29%, 100%, 37.14%, 24.28% respectively, which have an effect on the results of the pollution factors, and this refers to an addition of heavy elements to soil of the right bank of Mosul City as a result of human activity (anthropogenic). These activities are the military operations and the use of different types of weapons such as bombs, missiles, ammunition and the remnants thereof, which contain many heavy metals as well as fumes and gases emitted from burning waste, vehicle exhaust, electricity generators, liquid waste in urban and industrial areas, sewage water, fertilizers and pesticides. To know the role of physicochemical characteristics and their contribution to the distribution of heavy elements in the soil, pH and electrical conductivity are measured and the organic matter content is determined. The results show a rate of 7.8, 27.8, and 4.6, respectively.

Dramatic relativistic effects on the ns dipole angular distribution asymmetry parameter, βns , of heavy and superheavy elements

A theoretical study of the dipole photoelectron angular distribution asymmetry parameter, β, of the 6s, 5s and 4s subshells has been conducted for a range of closed-shell heavy, Hg (Z = 80), Rn (Z = 86), Ra (Z = 88) and superheavy, No (Z = 102), Cn (Z = 112), Og (Z = 118), Ubn (Z = 120) elements to understand the deviation of β from the nonrelativistic value of 2 owing to relativistic effects. It was found that the deviation, strongest in Cooper minimum regions, persists over all energy for all ns subshells, and the deviations increase with Z. Three levels of relativistic calculations were performed in order to pinpoint the particular interactions responsible for the details of the behavior of the ns β’s as functions of energy, n, and Z and, in addition to the effects of the (relativistic) spin–orbit interaction, interchannel coupling was found to be of crucial importance in the determination of the β parameter in most of the situations studied.

Measurement of the 86Kr(α,n)89Sr cross section at energies relevant for the weak r-process

The r-process has been shown to be robust in reproducing the abundance distributions of heavy elements, such as europium, seen in ultra-metal poor stars. In contrast, observations of elements 26 < Z < 47 display overabundances relative to r-process model predictions. A proposed additional source of early nucleosynthesis is the weak r-process in neutrino-driven winds of core-collapse supernovae. It has been shown that in this site (α,n) reactions are both crucial to nucleosynthesis and the main source of uncertainty in model-based abundance predictions. Aiming to improve the certainty of nucleosynthesis predictions, the cross section of the important reaction 86Kr(α,n)89Sr has been measured at an energy relevant to the weak r-process. This experiment was conducted in inverse kinematics at TRIUMF with the EMMA recoil mass spectrometer and the TIGRESS gamma-ray spectrometer. A novel type of solid helium target was used.

Determination of heavy metals amount in raw milk of Bangladesh

Milk is an indispensable part of the human food regimen that serves several nutritional benefits. Although milk is rich in micronutrients and macronutrients, heavy metal contamination of milk and dairy products is a serious concern. The distribution and deposition of heavy metals and trace elements including Fe, Cu, Zn, Mn, Cd, Cr, Pb, As, etc in different administrative areas of Bangladesh were investigated in this study. All transition metals, regardless of whether they are considered essential or potentially harmful, can have a negative effect on humans and animals if added to the diet in excessive amounts. The samples were prepared for examination by ashing, and after acid digestion, the heavy metals were detected using atomic absorption spectrophotometry. The concentrations obtained in mg/kg were in the range of (0.447 ± 0.043), (0.314 ± 0.077), (0.152 ± 0.025), (0.065 ± 0.022), (0.008 ± 0.002), (0.026 ± 0.003), (0.158 ± 0.027), (0.007 ± 0.001) for iron, copper, zinc, manganese, lead, cadmium, chromium and arsenic respectively. The study was implemented to assess the concentration of heavy metals and if these heavy metals fell below the World Health Organization's permissible standards (WHO). The investigation disclosed high quantities of iron and other metals that were above WHO guidelines. Iron (Fe) concentrations were higher compared to WHO standards (0.5 mg/kg) in raw milk from all divisions except Chittagong. As heavy metal contamination has been a public health concern in recent years, additional research is needed to ascertain the precise origins of heavy metals in raw milk.

Jupiter’s inhomogeneous envelope

Context.While Jupiter’s massive gas envelope consists mainly of hydrogen and helium, the key to understanding Jupiter’s formation and evolution lies in the distribution of the remaining (heavy) elements. Before the Juno mission, the lack of high-precision gravity harmonics precluded the use of statistical analyses in a robust determination of the heavy-element distribution in Jupiter’s envelope.Aims.In this paper, we assemble the most comprehensive and diverse collection of Jupiter interior models to date and use it to study the distribution of heavy elements in the planet’s envelope.Methods.We apply a Bayesian statistical approach to our interior model calculations, reproducing the Juno gravitational and atmospheric measurements and constraints from the deep zonal flows.Results.Our results show that the gravity constraints lead to a deep entropy of Jupiter corresponding to a 1 bar temperature that is 515 K higher than traditionally assumed. We also find that uncertainties in the equation of state are crucial when determining the amount of heavy elements in Jupiter’s interior. Our models put an upper limit to the inner compact core of Jupiter of 7MEarth, independently of the structure model (with or without a dilute core) and the equation of state considered. Furthermore, we robustly demonstrate that Jupiter’s envelope is inhomogeneous, with a heavy-element enrichment in the interior relative to the outer envelope. This implies that heavy-element enrichment continued through the gas accretion phase, with important implications for the formation of giant planets in our Solar System and beyond.

Distribution of trace metals in a soil-tea leaves-tea infusion system: characteristics, translocation and health risk assessment.

The effects of metal pollution on tea are of great concern to consumers. We apply Geographic information systems technology to study the distribution of heavy metal elements in tea plantation ecosystems in Jiangsu Province, explore the relationships among metals in the soil, tea leaves and tea infusions, and assess the human safety risks of metals. The concentrations of nine metals in a soil-tea leaves-tea infusion system were studied at 100 randomly selected tea plantations in Jiangsu Province, China. Concentrations of selected metals, zinc (Zn), nickel (Ni), manganese (Mn), chromium (Cr) and copper (Cu), were quantified using an inductively coupled plasma-optical emission spectrometer (ICP-OES), and cadmium (Cd), arsenic (As), plumbum (Pb) and mercury (Hg) were quantified using inductively coupled plasma-mass spectrometry (ICP-MS). Arc-Map 10.3 was used for the spatial analysis of metals in soil, tea leaves and tea infusions. We found that the contents of Mn, Ni and Zn are high level in soil, tea leaves and tea infusions. The Mn level showed a spatial distribution pattern with greater concentrations at the junction of Nanjing and Yangzhou, southwest of Changzhou and west of Suzhou. The hazard index (HI) values in north-central Nanjing, southern Suzhou, southwestern Changzhou and northern Lianyungang were relatively greater. The Zn, Ni, Mn, Cr and Cu levels in the soil-tea infusion system were 17.3, 45.5, 54.5, 1.5 and 14.3%, respectively. The order of the leaching rates of the elements was Ni > Cr > Zn > Mn > Cu. The relative contribution ratios of HI were in the order of Mn > Ni > Cu > Zn > Cr > Pb > Cd > As > Hg. In tea infusions, the Mn level has the greatest potential health risks to consumers. Moreover, using Csoil it was inferred that the safety thresholds of Zn, Ni, Mn, Cr and Cu in soil were 27,700, 50, 1230, 493,000 and 16,800mgL-1, respectively. The content of heavy metals in soil and tea varies greatly in different regions of Jiangsu Province, 92% of the soil has heavy metal content that meets the requirements of pollution-free tea gardens, 91% of tea samples met the requirements of green food tea. The thresholds for Ni (50mgL-1) and Mn (1230mgL-1) can be used as maximum limits in tea plantation soils. The consumption of tea infusions did not pose metal-related risks to human health.

Assessment of toxic heavy metals and trace elements in poultry feeds, consumer chickens and eggs in Bangladesh

Considering the potential health hazardous effects, the distribution and deposition of heavy metals and trace elements including Mn, Fe, Cu, Zn, Cd, Cr, and Pb in different tissues (skin, brain, liver, meat, and bone) of broiler and layer chickens, their feeds, litter, and eggs were analyzed using atomic absorption spectrophotometer (AAS) after nitric/perchloric acid digestion. The samples for this study were taken from four poultry industries located at Sreepur upazila of Gazipur district of Bangladesh. The observed levels of heavy metals and trace element contents in different studied samples were to be in the range of 0.143±0.001 to 7.324±0.004 mg/kg for Mn, below the detection limit (BDL) to 324.43±0.003 mg/kg for Fe, 0.451±0.002 to 4.329±0.005 mg/kg for Cu, 0.014±0.001 to 7.413±0.003 mg/kg for Zn, 0.082±0.002 to 7.806±0.002 mg/kg for Cr, 0.112±0.002 to 1.581±0.002 mg/kg for Cd, and BDL to 34.775±0.004 mg/kg for Pb. Although some elements were found at a lower concentration in feed samples, they were found at a higher level in various parts of the examined chickens, eggs, and litter which may be resulted from other sources such as drinking water, soil, and the surrounding environment of the poultry industries. The brain contained a maximum amount of Cd, Cr, and Pb in comparison to other studied tissues of poultry. Most of the chicken body parts showed an excess level of Cr than the recommended guidelines. The Cu and Zn contents were usual in studied egg samples, whereas Mn, Fe, Cd, Cr, and Pb were found higher than their tolerance limits which are highly alarming for public health and demand regular governance and monitoring. Asian Australas. J. Biosci. Biotechnol. 2021, 6 (3), 128-141

Controlling factors of groundwater chemistry and statistical analysis of the samples related to ophiolite of Nourabad-Harsin, West of Iran.

Recognizing controlling factors of groundwater chemistry in the ophiolite region of the southeastern area of Kermanshah is the aim of this study. The findings reveal that some samples' calcium, magnesium, and sodium absorption risk is higher than the standard range. Besides, statistical relationships of the data were investigated to recognize the key factors controlling water chemistry. Pearson's correlation was used to determine the elements with the same source. Saturation index (SI) and water-rock interaction helped us find the important minerals in reaction with water. Besides, the map of the spatial distribution of heavy elements was applied to prove the elements with a common source. According to these ties, the important factors controlling groundwater chemistry of the region are dissolution of gypsum as the common source of Ca, Sr, and S; dissolution and weathering of Cr-spinel mineral in peridotites as the common source of Si, Mg, and Cr; dissolution of existing Fe-Mg olivine and pyroxene in peridotite silicates as the common source of Mg and Ni, and dissolution of chalcedony, barite, and calcite as three minerals with the highest dissolution in water-rock interactionof groundwater samples.

Evaluate the Distribution of Heavy Elements that Dissolved in Ground Water Using IDW in AL-Wafa City, Al-Ramadi,Iraq

Groundwater can be assessed by studying water wells. This study was conducted in Al-Wafa District, Anbar Governorate, Iraq. The water samples were collected from 24 different wells in the study area, in January 2021. A laboratory examination of the samples was conducted. Geographical information systems technique was relied on to determine the values of polluting elements in the wells. The chemical elements that were measured were [cadmium, lead, cobalt and chromium]. The output of this research were planned to be spatial maps that show the distribution of the elements with respect to their concentrations. The results show a variation in the heavy elements concentrations at the studied area groundwater. The samples show different values of concentrations; for Cadmium (0.218-1.624) ppm, Lead (0.217-1.157) ppm, Cobalt (0.014-0156) ppm, and for Chromium (0.045-0263) ppm. The distribution of the materials concentrations differs for each element which is refer to the sources of pollution are not relate to industry, but it could be relate to fertilization.

Pollution Characteristics and Risk Assessment of Heavy Metal Elements in Sediment in the West Lake of Hengshui Lake

21 sampling points were set in the West Lake of Hengshui Lake including 20 fish ponds and 1 natural pond to analyze the contents distribution of heavy metal elements including Cr, Zn, Pb, Cu, Cd, Hg, As, and Sb in sediment. The degree of heavy metal pollution was evaluated by the geoaccumulation index (Igeo) method. The results showed that the concentrations of Cr, Zn, Pb, Cu, Cd, and Hg at in all sampling points of the fish ponds were lower than soil risk screening values of agricultural land in soil environmental quality: risk control standard for soil contamination of agricultural land (trial) (GB 15618-2018). The concentrations of As at 5 sampling points were higher than soil risk screening values and lower than soil risk control values of agricultural land in GB 15618-2018. The concentrations of Sb were lower than soil risk screening values of construction land in soil environmental quality: risk control standard for soil contamination of development land (trial) (GB 36600-2018). The evaluation results of the geoaccumulation index method showed that the pollution degrees of Cd, Pb, and Hg were moderately contaminated in general, the pollution degree of Cu was uncontaminated to moderately contaminated in general, the pollution degrees of Cr and As were uncontaminated to moderately contaminated in some sampling points, and Zn and Sb could be regarded as uncontaminated in sediment of the fish ponds in the West Lake of Hengshui Lake. Otherwise, the average contents of other heavy metal elements in sediment of the fish ponds in the West Lake of Hengshui Lake were higher than the background value of soil in Hebei Province (BVSH) except for Zn and Sb. The average contents of seven heavy metal elements in sediment of the natural pond in the West Lake of Hengshui Lake were lower than BVSH except for Cr. The result can be regarded as no pollution in the natural pond because the values of Igeo were all lower than 0. The heavy metal pollution in the sediment of the West Lake of Hengshui Lake may be due to the introduction of feeding. The water environment of the West Lake of Hengshui Lake can be effectively improved by cleaning up the sediment of fish ponds and “returning fishing to wetland.”

A diffuse core in Saturn revealed by ring seismology

The best constraints on the internal structures of giant planets have historically originated from measurements of their gravity fields1,2,3. These data are inherently mostly sensitive to a planet’s outer regions, stymieing efforts to measure the mass and compactness of the cores of Jupiter2,4,5 and Saturn6,7. However, studies of Saturn’s rings have detected waves driven by pulsation modes within the planet8,9,10,11, offering independent seismic probes of Saturn’s interior12,13,14. The observations reveal gravity-mode pulsations, which indicate that part of Saturn’s deep interior is stable against convection13. Here, we compare structural models with gravity and seismic measurements from Cassini to show that the data can only be explained by a diffuse, stably stratified core–envelope transition region in Saturn extending to approximately 60% of the planet’s radius and containing approximately 17 Earth masses of ice and rock. This gradual distribution of heavy elements constrains mixing processes at work in Saturn, and it may reflect the planet’s primordial structure and accretion history.