Distribution Characteristics Of Metals Research Articles

Distribution, contamination assessment, and sources of heavy metals in surface sediments from the south of the North Yellow Sea, China

This paper reports the contents of six heavy metals and particle sizes in the surface sediments of 120 sampling stations in the southern North Yellow Sea to reveal heavy metal distribution characteristics, contamination assessment, and sources. Cu and Cr enrichments were mainly found in coastal areas with high mud content (silt and clay). However, Zn, Cd, Pb, and Hg were enriched in Weihai Bay and Dongpu Bay, which have denser populations, estuaries, and shipyards. The geoaccumulation index and principal component analysis showed that Cu and Cr contamination was low, and the sources were mainly natural processes. In addition, Zn and Cd pollution in the nearshore area was moderate, and its provenance was natural processes and human activity. However, most areas exhibited Pb and Hg contamination due to waterborne traffic and industries, including shipbuilding and gold mining.

Heavy Metal Distribution Characteristics, Water Quality Evaluation, and Health Risk Evaluation of Surface Water in Abandoned Multi-Year Pyrite Mine Area

Acid mine drainage (AMD) is a major anthropogenic source of heavy metal discharge worldwide. However, little research has been carried out on the development of AMD in abandoned pyrite mines and the heavy metal contamination of mine surface water. The aim of this study was to investigate and assess heavy metal pollution in three streams within an abandoned pyrite mine area in southeastern Shaanxi Province, China. Surface water pollution was assessed using the pollution index assessment method and the health risk assessment model. The results showed that the combined heavy metal pollution indices of the surveyed rivers were Tielu Creek (4699.227), Jiancao Creek (228.840), and Daoban Creek (68.106). After multivariate statistical analysis, it was found that the tailings slag and mine chamber in the abandoned mine area were the main causes of AMD, and AMD posed a serious risk of heavy metal pollution to the surrounding waters. The risk of carcinogenicity of heavy metals is also quite high in the surface water of mining area. Therefore, there is an urgent need to ecologically manage heavy metal pollution from abandoned mine sites, and this study provides insights into understanding heavy metal pollution in the aquatic environment of abandoned mine sites.

Biomonitoring trace metal contamination in Guangzhou urban parks using Asian tramp snails (Bradybaena similaris)

Anthropogenic activities have caused environmental metal contamination in urban areas. Biomonitoring using organisms such as invertebrates can evaluate metal pollution, supplementing chemical monitoring, which cannot comprehensively reflect how metals influence organisms in the urban environment. To assess metal contamination in Guangzhou urban parks and its source, Asian tramp snails (Bradybaena similaris) were collected from ten parks in Guangzhou in 2021. The metal concentrations (Al, Cd, Cu, Fe, Mn, Pb, and Zn) were measured by ICP–AES and ICP–MS. We evaluated the metal distribution characteristics and correlations among metals. The probable sources of metals were determined by the positive matrix factorization (PMF) model. The metal pollution levels were analysed using the pollution index and the Nemerow comprehensive pollution index. The mean metal concentrations were ranked Al > Fe > Zn > Cu > Mn > Cd > Pb; metal pollution level in the snails was ranked Al > Mn > CuFe > Cd > Zn > Pb. Pb–Zn–Al–Fe–Mn and Cd–Cu–Zn were positively correlated in all samples. Six major metal sources were identified: an Al–Fe factor corresponding to crustal rock and dust, an Al factor related to Al-containing products, a Pb factor indicative of traffic and industries, a Cu–Zn–Cd factor dominated by the electroplating industry and vehicle sources, an Mn factor reflecting fossil fuel combustion, and a Cd–Zn factor related to agricultural product use. The pollution evaluation suggested heavy Al pollution, moderate Mn pollution, and light Cd, Cu, Fe, Pb, and Zn pollution in the snails. Dafushan Forest Park was heavily polluted; Chentian Garden and Huadu Lake National Wetland Park were not widely contaminated. The results indicated that B. similaris snails can be used as effective biomarkers for monitoring and evaluating environmental metal pollution in megacity urban areas. The findings show that snail biomonitoring provides a valuable understanding of the migration and accumulation pathways of anthropogenic metal pollutants in soil‒plant–snail food chains.

Comparative analysis of Cd fractional composition in soils under anthropogenic and artificial pollution

The composition of cadmium (Cd) compounds in soils of both technogenic landscapes and a model experiment were studied using the sequential fractionation method. A model experiment was conducted with artificial soil contamination by easily soluble Cd compounds. Pollution doses simulated the level of pollutant content in the studied soils of the impact zones and corresponded to low, high, and very high pollution. Fractions revealed both general features and specific metal distribution characteristics in anthropogenically polluted soil and soil under artificial pollution. The largest amount of Cd in the soils was concentrated in the residual fraction (up to 60%). With increasing pollution level, the proportion of the residual fraction decreases and the proportion of mobile compounds (exchangeable fraction and carbonate fraction) of the metal increases (up to 22% and 18%, respectively). In contaminated soil, carbonates and Fe-Mn oxides play the main role in the Cd fractional distribution. Fractional distribution of Cd shows general regularities both under anthropogenic pollution and under artificial contamination; however, metal demonstrated high mobility at artificially contamination.

Spatial variability of soil Cd content based on IDW and RBF in Fujiang River, Mianyang, China

Establishing the spatial distribution of soil properties in agro-ecosystems is critical to increasing the productivity of intensive tillage soils and reducing environmental pressure. Thus, a comprehensive understanding of soil’s heavy metal distribution characteristics is important for optimal management. The goal of this study was to determine the most accurate soil Cd interpolation method for the study area and analyze the variation and spatial distribution of Cd content with depth. In this work, we employed two common spatial interpolation methods—inverse distance weighting (IDW) and radial basis function (RBF)—in conjunction with a geographic information system (GIS) to interpolate sampling data of the heavy metal cadmium (Cd) throughout Santai County; a locale in the lower part of Fujiang River, Mianyang, in the northeast of Sichuan Province. The results of our investigation are as follows. (1) At depths of 0–50 cm, the Cd content decreased with depth while the coefficient of variation (Cv) increased with depth. The exponential model and the Gauss model adequately described the Cd content’s spatial autocorrelation and the determination coefficient (R2) varied within 0.747–0.962, indicating that the model had high precision. (2) With respect to the accuracy of the IDW and RBF methods, IDW was more accurate than the RBF in the 0–20 cm soil layer, yet the reverse was found in the 20–50 cm soil layer. (3) Three-dimensional spatial distribution maps—constructed using the RBF and IDW methods at different soil depths—showed that the RBF method provided a greater smoothing effect than the IDW method. The spatial variability of soil Cd content shows that: (1) the Cd content’s spatial autocorrelation was strong in the 0–50 cm soil layer. (2) The IDW method is suitable for areas that are greatly influenced by human or farming activities while the RBF method is appropriate for areas that are greatly influenced by internal soil factors. The RBF is superior for evaluating the spatial distribution of soil Cd content in this area.

Ecological Risk Assessment of Heavy Metals in the Vicinity of Tungsten Mining Areas, Southern Jiangxi Province

ABSTRACT A field survey was performed to investigate the metals contamination in the vicinity of tungsten mining areas. Ten sampling sites alongside perennial wind direction were selected for soil collection and heavy metal contents determination, include Cr, Cu, Zn, Pb, As, Cd, and W. Horizontal and vertical distribution characteristics of metals were performed. Geo-accumulation and potential ecological risk of soil samples were discussed for a description of risk assessment. The results showed that the mean concentrations of all metals in soil samples exceeded the background value of Jiangxi background. The heavy metal contents in vertical profiles revealed the surface accumulation of Cd, W, and Pb, while, As increased as soil depth increased. The geo-accumulation index shown the highest pollution level of W and followed by Cd. Single ecological risk factor () figured out that the contamination degree followed the sequence of Cd>As>W>Zn>Pb>Cr>Cu. Furthermore, the potential ecological risk index () was calculated for risk level assessment, and Cd takes account the most contribution in surface soil, followed by W and As.

Evaluation of heavy metal distribution characteristics of agricultural soil-rice system in a high geological background area according to the influence index of comprehensive quality (IICQ).

Heavy metal pollution is a global ecological safety issue, especially in crops, where it directly threatens regional ecological security and human health. Selecting scientific evaluation methods is an important prerequisite for understanding the distribution of heavy metals in a region. To evaluate the distribution characteristics of arsenic (As), cadmium (Cd), copper (Cu), and zinc (Zn) in farmland soil-rice system in Doumen District of Zhuhai City, Pearl River Delta, we analyzed the high geological background area and heavy metal contents in soil by inverse distance-weighted interpolation and single-factor pollution index. Bioconcentration factor (BCF) was used to study the migration and accumulation characteristics of heavy metals. Then, the soil-rice system was evaluated comprehensively with a novel evaluation method, i.e., the influence index of comprehensive quality (IICQ). Results showed that As, Cd, Cu, and Zn in the soil of the study area followed normal distribution. Cd and Cu were the main pollutants whose point contamination rates were 50% and 22.86%, respectively. A total of 2.86% of the soil were contaminated by As, and no Zn contamination was observed in the soil. At the same time, As and Cd in rice were partially polluted, and the Cu and Zn were not polluted. The order of bioaccumulation coefficient was Cd > Zn > Cu > As, and no evident enrichment was observed. According to the impact index of IICQ to evaluate the pollution of heavy metals in the soil-rice system, 96.98% of the soil in study area was in a state of moderate, heavy, and extreme pollution, which were concentrated in the northern and central parts of the study area. The soil-rice system in the high geological background area was in a subhealthy state. A total of 90.69% of the soil were polluted, but the rice met the national food safety standards.

Drying of supported catalysts for high metal concentrations: A reduced parameter model

Supported catalysts are widely used in many industries. Manufacturing these catalysts is complex and manufacturing processes are influenced by many interdependent parameters. Although the performance and activity of catalysts are the most critical properties, their structures and design are also critical to their effectiveness. Previous work has shown that drying of catalysts can lead to the redistribution of metal and this in turn can affect the performance of the catalyst. At the same time, drying processes are often designed and scaled up by trial-and-error so it is desirable to have predictive models of the drying process. Previous experimental and modeling work has shown how the adsorption (of metal on the catalyst support) can significantly influence metal distributions at lower concentrations. It was also observed that at higher concentrations, adsorption was no longer the controlling factor, and solution properties began to control the metal distribution characteristics. Solution properties like density, viscosity, surface tension and volume ratio of metal all change as the metal concentration increases and these properties can in turn affect the distribution of metal during drying. In previous work, a drying model was developed that takes into account six different parameters to account for changes in solution properties as the concentration of metal increased. In this work, we carry out a parametric analysis, for nickel nitrate hexahydrate on a γ-alumina support, to investigate the relative importance of these parameters in accounting for metal redistribution during drying at high concentrations. A detailed analysis on each of the solution parameters, in terms of the drying rate and redistribution of metal, showed that only three of the parameters were important: the volume ratio of metal, the vapor pressure, and the solubility of the metal in the solution. Based on this, we have created a reduced parameter model with fewer parameters. This model can be used for different metal precursors without doing multiple expensive and time-consuming experiments. We tested this reduced parameter model using a new metal precursor (cobalt nitrate hexahydrate) on the same support, and modeling and experimental results for the new metal precursor are presented in this paper. We show that the reduced parameter model does not show appreciably different results from the more complex drying model and the results are in qualitative agreement with the experimental results.

Distribution characteristics of heavy metals in surface soils from the western area of Nansi Lake, China.

Surface soil samples collected from the western area of Nansi Lake, China, were analyzed for selected heavy metals including As, Cd, Pb, and Zn, to determine their spatial distributions and environmental effects. The average concentrations of As, Cd, Pb, and Zn in soil were 13.21mg/kg, 0.20mg/kg, 23.94mg/kg, and 79.95mg/kg, respectively. The concentration of As, Cd, and Zn was approximately 1.44-, 2.33-, and 1.25-fold higher than its background values in study area, respectively. Meanwhile, the concentrations of heavy metals progressively decreased from east to west within the study area, in a step-function distribution. The differences in the heavy metal distribution characteristics might be caused by the lake water irrigation and agricultural activities such as fertilizer and pesticide use. There were significant positive correlations between the values of OrgC, Al2O3, and Fe2O3 and concentrations of heavy metals. According to the Geo-accumulation index (Igeo) and the potential ecological risk index (PERI), Cd posed higher potential ecological risk in surface soil when compared with As, Pb, and Zn. These results could provide the scientific basis on which to evaluate the distribution of heavy metals under natural and anthropogenic influences in the surface soil near Nansi Lake, China.

Metal (loid)s pollution characteristics and ecotoxicity evaluation in soil nearby a silver smelting yard

The spatial distribution characteristics of metal(loid)s (Cu, Zn, Cd, As, and Pb) in the soil of a silver smelting zone located in Chenzhou, Hunan province, China and their ecological toxicity were studied in this paper. The results showed that the average concentration of these metal(loid)s in the soil of the silver smelting yard and surroundings decreased in the order: Pb > Cu > Zn > As > Cd, and all of these metal(loid)s greatly surpassed the local background. In general, the concentration of metal(loid)s in soil decreased with the increase in distance from the pollution source in the horizontal direction. In addition, the metal concentration decreased with an increase of depth. The geo-accumulation index and toxic unit analysis revealed that the smelting yard was extremely contaminated and Cu, Cd, and As exhibited the most toxic effects in this area. Furthermore, in soils nearby smelting yard, higher contamination was found in the lower geographical forms than in the higher parts of the terrain.

Assessment of metal contamination in water and sediments from major rivers in South Korea from 2008 to 2015

This study is the first report to evaluate (8 years data) the contamination degree and distribution characteristics of metals in the surface water and sediments of four Korean rivers (Nakdong, Yeongsan, Geum, and Han). Eight years of data were evaluated, and metal concentrations in the river water were found to be below permissible limits but high enough to cause detrimental effects (under chronic exposure) to aquatic organisms. The analysis of metals in the river sediments showed the following trend: Zn > Cu > Cd > Pb > Ni > As > Cr > Hg. The concentrations of metals in sediments (especially in the Geum and Han rivers) were above the permissible limits reported by international agencies. Concentrations of Cu, Ni, and Zn were high enough to pose risks to aquatic communities. In sediments, metals pollution was also evaluated using different indices, such as enrichment factor (EF), geoaccumulation index (Igeo), contamination factor (CF), degree of contamination (Cd), modified degree of contamination (mCd), and pollution load index (PLI). The CF, EF, and Igeo indices demonstrated that most of the river sediment samples were moderately to heavily contaminated by Cd, Cu, Pb, and Zn. The PLI values were above one in the Geum and Han river sediments, which indicated polluted conditions. Similarly, Cd indicated a considerable to very high degree of contamination, while mCd indicated a low to moderate degree of contamination in all four river sediments. Finally, it was found that the extent of metals pollution in the Korean rivers reached a critical condition, which could be detrimental to the biota of the rivers, as well as to humans in the long term.

Analysis of metal content and vertical stratification of epiphytic mosses along a Karst Mountain highway.

Road-based transport emissions are a major source of atmospheric metal pollution. However, there have been few studies on emissions from road traffic in mountainous areas. In this study, epiphytic mosses from trees at different elevations of a highway, a typical road with extraordinary elevation change in a mountainous area of karst in Guizhou, China, were analyzed for metal content as well as the spatial distribution pattern of metals. Mosses were sampled from three sections of highway at different elevations, from 1292-1357, 1394-1441, to 1481-1548m. Principal component analysis and heat-map clustering were used to identify the principal factors affecting metal deposition. The results show that the metals of mosses from different elevations were divided into four factors. Group 1 which included Ni, Fe, Mg, Ba, and Al was attributed to a dominantly geogenic source. Group 2 included Zn, Cu, Mn, and Cr, from vehicle-related materials including tires and brakes. Group 3, Cd, can be attributed to high Cd background levels from local origins and traffic emissions, particularly tire wear. Group 4, Pb, is associated with brake wear and historical deposition. The epiphytic moss widely distributed in the study area, Ectropothecium aneitense Broth. & Watts, was used to analyze the spatial distribution pattern of the metals. Metal content gradually decreased with increase in elevation. Levels of Ni, Fe, Mn, Ba, and Cd were all significantly correlated with elevation (p < 0.05), simultaneously affected by terrain and vertically stratified. We highlighted the vertical distribution characteristics of metal in epiphytic mosses in this study, which could improve moss application for ecological monitoring due to road-based transport emissions with elevation changes.

Study on the Pollution Characteristics of Heavy Metals in Seawater of Jinzhou Bay

Abstract The Jinzhou Bay is one of the bays polluted heavily by the heavy metals. Twenty surface seawater samples were collected to analyze the dissolved and particulate concentrations of Cu, Pb, Zn, Cd, Hg and As using the methods of Atomic Absorption and Atomic Fluorescence. The heavy metal distribution characteristics, influencing mechanism and the distribution ratio between particulate and dissolved state were analyzed. The results showed that the concentration of Cd in 25% stations was higher than the first standard value of sea water quality. The concentration of As was lower than the standard value in all stations. The concentration of dissolved heavy metal was highest in west closer to the land and Wuli River estuary, and decreased from west to east. There was lower value area of heavy metals like tongue caused by the tidal. The particulate Pb concentration accounted for 83.00% in total concentration, and the other heavy metals in particulate state were lower than that in the dissolved state. The pollution of the particulate heavy metals was becoming more and more serious from open sea to offshore marine areas. Therefore the heavy metals distribution in the Bay was affected not only by the coastal pollutants but also by the hydrodynamic factors.

Study of quality control and metal distribution in urban airborne particulates

In this investigation, results of 33 elements in airborne samples collected continuously over nine urban locations are discussed. Inductively coupled plasma-atomic emission spectrometry technique was used for determining concentration of metals. Quality control was established prior to analysis of real air samples. The guidelines followed are based on USEPA Compendium Method IO-3.4. Uncertainty in analysis was also established. Based on the concentration of metals in airborne particulates, we attempted to study the metal distribution characteristics in ambient air at various urban locations. Metals such as Al, Ca, Fe were comparatively at higher concentrations than the other elements under study at most of the locations. The city vehicles operate on lead-free fuels; however, concentration of lead in urban dust was observed in the concentration range of 0.33–6.24 μg/m3. Soil samples were also collected from sites close to the air sampling locations. Soil samples were also analysed for metal content. Enrichment factor was determined for elements measured at nine urban locations. The data supports interpretation of results in terms of contribution of metals in airborne particulates from anthropogenic and noncrustal origin.

Characterization, Source Identification and Apportionment of Selected Metals in TSP in an Urban Atmosphere

To understand the metal distribution characteristics in the atmosphere of urban Islamabad, total suspended particulate (TSP) samples were collected on daily 12 h basis, at Quaid-i-Azam University campus, using high volume sampler. The TSP samples were treated with HNO(3)/HClO(4) based wet digestion method for the quantification of eight selected metals; Fe, Zn, Pb, Mn, Cr, Co, Ni and Cd by FAAS method. The monitoring period ran from June 2001 to January 2002, with a total of 194 samples collected on cellulose filters. Effects of different meteorological conditions such as temperature, relative humidity, wind speed and wind direction on selected metal levels were interpreted by means of multivariate statistical approach. Enhanced metal levels for Fe (930 ng/m(3)), Zn (542 ng/m(3)) and Pb (210 ng/m(3)) were found on the mean scale while Mn, Cr, Co and Ni emerged as minor contributors. Statistical correlation study was also conducted and a strong correlation was observed between Pb-Cr (r=0.611). The relative humidity showed some significant influence on atmospheric metal distribution while other meteorological parameters showed weak relationship with TSP metal levels. Regarding the origin of sources of heavy metals in TSP, the statistical procedure identified three source profiles; automobile emissions, industrial/metallurgical units, and natural soil dust. The metal levels were also compared with those reported for other parts of the world which showed that the metal levels in urban atmosphere of Islamabad are in exceedence than those of European industrial and urban sites while comparable with some Asian sites.

Studies of spatial and temporal distribution characteristics of TSP-bound trace metals in Seoul, Korea

In the present study, TSP-bound metal concentrations were measured from seven different urbanized locations in Seoul, Korea for the period from March 2001 through May 2002. Our measurement data were analyzed to explore the possible influences of spatial and temporal factors on metal distribution characteristics. To determine the importance of those aspects, the measured concentrations were compared between different metals and between different sites in terms of several criteria: (1) absolute concentrations and enrichment factor (EF) values; (2) coefficient of variation (CV) values of metal concentrations; (3) relative patterns of temporal variations; and (4) relative abundance of strong correlations. According to our analysis of metal distribution characteristics in the study area, the main results of our study can be summarized as follows: (1) a number of metals (e.g., Cd, Cu, and Pb) are highly enriched relative to the average crustal ratios (to Fe); (2) the behavior of Cu is found to vary irregularly, while Fe, Mn, and Pb are tightly coupled both spatially and temporally in the study area; (3) for most elements except Cu and Cd, seasonal variations are observed in a systematic manner; and (4) when compared against those observed in other parts of the world, our Cu and Cd concentrations observed in many locations of Seoul are notably high. The overall results of our study suggest that the distribution characteristics of metals can be regulated strongly by spatial and temporal factors and that such controls are distinguished very clearly between different metal types.

Relationships between spatial and temporal variabilities in airborne metal distributions in Won Ju City, Korea

The relationship between temporal and spatial factors in controlling the metal distribution characteristics was investigated using the monthly metal concentration data collected from four distinctive sampling sites (grassland, residential, commercial, and industrial site) of Won Ju City, Kang Won province for approximately 4-year periods between 1991 and 1995. In order to compare the relative role of spatial and temporal factors, two-factor analysis of variance (ANOVA) was applied to these data sets. For the application of this method, temporal factors were investigated in terms of both annual and seasonal basis. The results of our data analysis indicated several interesting aspects of metal-to-metal distribution behavior such that: (1) Pb, Fe, and Cu tend to exhibit strong variabilities in both spatial and temporal scale, (2) the distribution variabilities for Mn are almost negligible in both temporal and spatial scale, (3) Cd is more variable in temporal, rather than spatial, sense, and (4) Cr and Ni can exhibit more variable patterns depending on temporal scale selected for data analysis. On the basis of this study, the relative roles of spatial and temporal factors are described in relation to each other and to different metal species.

Metals in airborne particulate matter from the first and second industrial complex area of Taejon city, Korea

To understand the metal distribution characteristics in a rapidly urbanized area, we collected and analyzed particulate matter (PM) samples for the metal concentrations. Using our measurement data for various metal species, we examined both the extent of metal pollution in the study area and the seasonality in their distribution characteristics. Results showed that each metal exhibited their occurrences in diverse concentration ranges over several orders of magnitude such as the mean values ranging from minimum value of 0.07 (Be) to maximum value of 1633 ng m −3 (Fe). In addition, the extent of metal pollution in the study area was in general comparable with those typically observed from a strongly polluted urban area, if comparison was made with the results of previous studies. Examinations of their temporal distribution patterns indicated that most of metals tend to exhibit seasonal peaks during winter (or spring) seasons, similarly to the observed pattern for PMs. Moreover to explain the factors regulating their mobilization properties, the data were analyzed through the application of correlation analysis. Results of our correlation analysis showed that most metals can exhibit strong positive correlations each other, while they tend to be inversely correlated with most of important meteorological parameters (including air temperature and precipitation). Based on the overall results of our study, we conclude that the site may be strongly impacted by man-made sources but that many characteristics of their cycling are not significantly different from those generally observed from natural environments.