Distribution Patterns Of Pb Research Articles

Dissolved Pb and Cd Distribution in Cengkok Nearshore of Banten Bay, Indonesia: Processes and Mechanisms

The onshore of Banten Bay has been an active zone with settlements, industries, and ports that potentially release heavy-metal containing waste. This study aims to explain the extent to which Pb and Cd may disperse in the Cengkok nearshore of Banten Bay, Indonesia. Water samples were collected monthly from April to September 2019. Analysis of dissolved heavy metals followed the APHA 2012 procedure. The water quality conditions of the Cengkok nearshore varied during the study period. The distribution of dissolved Pb and Cd in April, June, July, and August are generally undetected although they were found in May ranging <0.002 - 0.011 mg/L Cd and <0.002 - 0.008 mg/L Pb. In September, Cd and Pb were found at all locations varying 0.007 - 0.014 mg/L and 0.004 - 0.042 mg/L, respectively. Cd and Pb distribution patterns varied and could indicate both the riverine effect and coastal processes. Cd and Pb were found discontinuously and disperse differently, indicating the effect of monthly seasons and coastal dynamics.

Accumulation and Transport Characteristics of Cd, Pb, Zn, and As in Different Maize Varieties

The enrichment and translocation characteristics of Cd, Pb, Zn, and As by various parts of maize plants were investigated using field experiments in 22 maize varieties simultaneously under uncontaminated, low, middle, and serious heavy metal Cd, Pb, Zn, and As complex-contaminated farmland soil conditions. The relationship between the uptake of Cd, Pb, Zn, and As by maize plants and the morphological content of heavy metals in the soil was also discussed through principal component analysis and correlation analysis of the concentrations of eight heavy metals, including Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn. The results showed that:① the distribution pattern of Cd and Zn contents in different parts of the maize plant was as follows:upper stalk>lower stalk>root>seed, the distribution pattern of Pb was As follows:root>lower stalk>upper stalk>seed, and the As distribution pattern was:root>upper stalk>lower stalk>seed. The different distribution patterns were closely related to the accumulation characteristics of the crop itself and the environmental activity of Cd, Pb, Zn, and As in the soil of the study area. ② There were significant differences in Cd and Pb accumulation among 22 maize cultivars due to their genetic background (P<0.05), which showed four trends:Cd and Pb compound high-accumulation varieties, single Cd or Pb low-accumulation varieties (low Cd and high Pb, low Pb and high Cd), and Cd and Pb compound low-accumulation varieties. Among them, the content of Cd in the grain of the three varieties exceeded the national food safety standard, and the content of Cd in the stem and leaf of 14 varieties exceeded the national food health standard. The Pb content in stems, leaves, and grains of all cultivars did not exceed the standard, but the Pb content in grains of some cultivars was close to the limit and had the risk of exceeding the standard. The content of As in the stem, leaf, and grain of different maize varieties was much lower than the standard limit value, showing a stable low-accumulation characteristic. The content of Zn in the stem and leaf of different maize varieties increased with the increase in the content of Zn in soil, but the content of Zn in grain remained within the threshold of normal plant growth. ③ Cd, Pb, Zn, and As in maize plants in the study area had a certain homology and were mainly affected by the excessive levels of Cd, Pb, Zn, and As pollutants in the soil. This showed that anthropogenic sources were brought about by mine extraction and tailings stockpiles, whereas Cu elements in maize plants were affected by certain anthropogenic pollution sources, though to a limited extent. Hg, Ni, and Cr in maize plants had a certain homology; this showed the natural source of soil parent material and weathering product accumulation. ④ The contents of Cd, Pb, Zn, and As elements in various parts of the corn plant, as well as the contents of Cr and Ni elements all had a very significant positive correlation (P<0.01). The transport mechanisms of Cd, Pb, Zn, and As elements in the plant may have a common. However, there was a synergistic effect in the migration from the root of the corn to the upper part of the ground, and the same was true for the elements of Cr and Ni. The elements of Hg and Cd, Pb, Zn, and As in the corn stems and leaves and Hg and Cd, Hg, As, Pb, Cr, Ni, and Zn in grains all showed certain antagonistic effects. ⑤ The comparison method simultaneously satisfied the following requirements:the contents of Cd, Pb, and As in stems and leaves did not exceed the national food hygiene standards, and the contents of Cd, Pb, and As in the grains did not exceed the national food safety standards. The cluster analysis of Cd, Pb, and As in grains was a low-accumulation group, and the enrichment and transport coefficients of Cd, Pb, and As in the stems and leaves and grains were low as the optimal conditions. C18 (Xianyu 335) could be selected as the optimal maize variety with low accumulation of Cd, Pb, and As and normal Zn content in grain, which is suitable for promoting and applying in the heavy metal complex-polluted farmland around industrial and mining enterprises in north China.

Low-molecular-weight organic acid-mediated tolerance and Pb accumulation in centipedegrass under Pb stress

Lead (Pb) is one of the most harmful, toxic pollutants to the ecological environment and humans. Centipedegrass, a fast-growing warm-season turfgrass, is excellent for Pb pollution remediation. Exogenous low-molecular-weight organic acid (LMWOA) treatment is a promising approach for assisted phytoremediation. However, the effects of this treatment on the tolerance and Pb accumulation of centipedegrass are unclear. This study investigated these effects on the physiological growth response and Pb accumulation distribution characteristics of centipedegrass. Applications of 400 μM citric acid (CA), malic acid (MA) and tartaric acid (TA) significantly reduced membrane lipid peroxidation levels of leaves and improved biomass production of Pb-stressed plants. These treatments mainly increased peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) activities and enhanced free protein (Pro), ascorbic acid (AsA) and phytochelatins (PCs) contents, ultimately improving the Pb tolerance of centipedegrass. Their promoting effects decreased as follows: TA>CA>MA. All the treatments decreased root Pb concentrations and increased stem and leaf Pb concentrations, thus increasing total Pb accumulation and TF values. MA had the best and worst effects on Pb accumulation and Pb transportation, respectively. CA had the best and worst effects on Pb transportation and Pb accumulation, respectively. TA exhibited strong effects on both Pb accumulation and transport. Furthermore, all treatments changed the subcellular Pb distribution patterns and distribution models of the chemical forms of Pb in each tissue. The root Pb concentration was more highly correlated with the Pb subcellular fraction distribution pattern, while the stem and leaf Pb concentrations were more highly correlated with the distribution models of the chemical forms of Pb. Overall, TA improved plant Pb tolerance best and promoted both Pb absorption and transportation well and is considered the best candidate for Pb-contaminated soil remediation with centipedegrass. This study provides a new idea for Pb-contaminated soil remediation with centipedegrass combined with LMWOAs.

Distribution pattern of Pb and Zn contamination in rivers near industrial zone in Aceh, Indonesia, revealed by principal component analysis (PCA)

The research aims to evaluate the pollution of Pb and Zn in water, sediment, and Faunus ater samples collected from Krueng Balee (KB) and Kreung Reuleung (KR) Rivers, Aceh, Indonesia. The samples were collected at the upstream, midstream, and downstream of each river and analyzed using Atomic Absorption Spectrophotometry (AAS). The distribution of Pb and Zn pollution was analyzed using Principal Component Analysis (PCA). Our investigation revealed that the presence of Pb and Zn is still safe for water and sediment samples. Nevertheless, Pb and Zn contamination found in F. ater samples had exceeded the national safety limit for food. PCA analysis revealed correlations between samples suggesting the roles of physical and chemical properties of the river in the pollutant retainment. The analysis also indicated the possible antagonism between Pb and Zn accumulation in F. ater which has never been reported previously. We suggest routine monitoring of Pb and Zn concentrations. The role of the surrounding industry in the Pb and Zn pollution should be further studied.

Concentration of dissolved lead in the upper Northwestern Pacific Ocean

During a cruise in 2016, samples of clean seawater were collected, and the first high-quality dataset of total dissolvable Pb concentration ([TDPb]) was developed for the upper 750 m of the low-latitude Northwestern Pacific Ocean (NWPO). The distribution of [TDPb] was influenced by the low-latitude NWPO current system. The surface [TDPb] ranged from 22 to 60 pmol/kg, with two significant maxima occurring in the North Equatorial Current (NEC) and the Kuroshio Current (KC). The vertical [TDPb] ranged from 16 to 70 pmol/kg. The [TDPb] profile to the north of 13°N, where the NEC occupys, was characterized by a significant sub-surface maximum, and this feature extended eastward to the North Equatorial Countercurrent (NECC) and possibly, to the Mindanao Current (MC). In the area south of 5°N, which is affected by currents originating from the eastern equator and the southern hemisphere, [TDPb] was greatly reduced and its distribution was uniform vertically. The vertical Pb maximum characteristic was continuous throughout the North Pacific subtropical gyre at σθ = 25.2–26.2, which was associated with high surface Pb at 30°N–40°N in Northwestern Pacific. The lateral transport of Pb in the NEC along 130°E amounted to approximately 16.8–22.5 Gg/yr, which could be considered to be the convergence budget of the advection transport of the North Pacific. With the bifurcation of the NEC, approximately 4.5–9.0 Gg/yr of Pb was distributed into the northward-flowing KC which rejoins the subtropical circulation of the North Pacific, while another 7.8–18.0 Gg/yr of Pb was distributed into the southward-flowing MC, which joins the tropical circulation of the Pacific or enters the Indian Ocean via the Indonesian through-flow (ITF). The distribution pattern of Pb in the low-latitude western Pacific is influenced by the western boundary current system and possible changes associated with the climate change.

Immobilization of Pb and Cu by organic and inorganic amendments in contaminated soil

Soil contamination with heavy metals has become a global environmental-health concern. A series of greenhouse experiments were conducted to investigate the effects of rice straw, rice straw derived biochar (BC), multi-walled carbon nanotubes, and single superphosphate (SSP) on immobilization of Pb and Cu via sequential extraction of BCR, total characteristics leaching procedure (TCLP), and metals phytoavailability to rapeseed in Pb and Cu spiked soil. Moreover, the residual effect of applied soil amendments on growth and uptake of Pb and Cu in tomato was also investigated in the metals spiked soil. In results, the addition of BC to Pb and Cu spiked soil proved the most effective amendment in modifying the distribution pattern of Pb and Cu from acid-soluble (less bioavailable) to residual fraction (non-toxic), thereby improving the geochemical stability of contaminated soil. The application of BC (6% w/w) reduced the uptake of Pb and Cu in shoot and root by 46 and 36%, and 77 and 58%, respectively. While investigating the residual impact in tomato, the uptake was decreased by 36 and 66% for Pb and 29 and 61% for Cu in shoot and root samples, respectively. With the application of BC (6% w/w), the concentrations of Pb and Cu in the shoot portion of tomato were below the permissible limits as set by the world health organization. The application of SSP was more effective in reducing TCLP-Pb to 0.2 mg L−1 in metals spiked soil compared to the other amendments. However, the bioavailability of Cu was increased with increasing SSP addition. In conclusion, the application of BC was more effective in reducing Pb and Cu phytoavailability through immobilization in contaminated soil compared to the other organic and inorganic amendments.

Altitudinal-modulated sediment inputs rather than the land-uses determine the distribution of lead in the riparian soils of the Three Gorges Reservoir.

Lead (Pb) as a toxic metal has potential ecological hazards for aquatic quality. However, the variation in the distribution patterns of Pb and its fractions in flooding soils with frequent and anti-seasonal water-level fluctuation and various human disturbances remains unclear. In this study, the distribution of Pb and its fractions in the riparian soils of the Three Gorges Reservoir (TGR) were delineated based on the differences in altitude and land-uses including farmland, orchard, forest and residential area. Then, we assessed the contamination and eco-risk of Pb in the soils and deciphered the key factors determining the distribution of Pb and its fractions. The results showed that the concentrations of Pb and its fractions in the soils decreased significantly with altitude, while the significant difference was not observed among the land-uses. The contamination of Pb in the soils reached a moderate level, and its eco-risk was very low by the potential eco-risk index and mobile Pb fraction. The source of soil Pb at the upper zone (> 160m) was mainly from natural inputs, while the source at the lower zone (≤ 160m) was attributed to anthropogenic contributions including ores mining, fossil fuel combustion, vehicle emissions and atmospheric deposition indicated by Pb isotopic ratios. With the limited effect of land-uses, the sediment inputs regulated by frequent water-level fluctuation determined the altitudinal distribution of Pb and its fractions in the flooding soils. The soil particle size dominated the migration and transformation of Pb over other soil properties such as pH and organic matters. The results of this study indicate that the anthropogenic Pb mainly exists in the soils of lower riparian zone in the TGR, and the frequent and anti-seasonal dry and rewetting alternation aggravates the potential for the Pb migration downstream due to the determinant of soil particles.

Immune response, MT and HSP70 gene expression, and bioaccumulation induced by lead exposure of the marine crab, Charybdis japonica

In order to understand the mechanisms of the toxicity of lead (Pb) on invertebrates, the immunotoxic effects of Pb in the marine crab, Charybdis japonica, were evaluated in the present study. The crabs were exposed to 0.066, 0.132, 1.318, 2.636, 6.590, and 13.181 μM of lead acetate and a control over 30 days, and the hemolymph was sampled terminally for testing the immunity-related indices, including total hemocyte count (THC), hemocyanin content, the activities of the phenoloxidase (PO) and lysozyme (LSZ). In addition, tissue samples were collected from the hepatopancreas, gill, muscle and ovary after 30 days of exposure for detecting the Pb accumulation in the major organs. The gene expression profiles of metallothionein (MT) and heat shock protein 70 (HSP70) in the hepatopancreas of C. japonica upon exposure to lead acetate over 96 h were also analyzed. The results showed a decline in the majority of the immunity-related parameters after an initial rise, and their levels were significantly lower in the treatment groups compared with those in the control, except in the group exposed to 0.066 μM of lead acetate for 30 days. Furthermore, a significant negative correlation was observed between the lead acetate concentration and the hemocyanin content, the activities of PO and LSZ (P<0.01). The expression levels of MT and HSP70 genes were rapidly induced, reaching a peak level after 12 and 24 h of exposure, respectively, and remained at a significantly higher level than the control after 96 h of exposure. It was also observed that the distribution pattern of Pb in the tissues of exposed crabs was in the order of gill > hepatopancreas > ovary and muscle, and exhibited a concentration-dependent response. Taken together, the results revealed that Pb exposure induced the immunosuppression of C. japonica and resulted in bioaccumulation, which could subsequently increase the disease susceptibility and threaten the food safety.

Spatial Distribution of Heavy Metals and 137Cs in Spruce Forest Soil under Conditions of Regional Pollution

The influence of horizontal structure of spruce forest on the spatial distribution of acid-soluble Zn, Cd, Pb compounds and 137Cs in the litter and the humus horizon of soddy podzolic soil has been studied in the territory with the regional background level of industrial fallout. It has been found that the distribution pattern of Zn in the forest litter is a result of biogeochemical processes. The litter in fern–wood sorrel microplots contains increased amounts of Zn and Cd, while the contents of Pb and 137Cs are decreased. The distribution patterns of Pb and 137Cs in the litter are positively correlated with each other, since both elements are deposited from the atmosphere, and similar mechanisms account for their redistribution in the spruce forest ecosystem.

Distribution Assessment and Source Identification Using Multivariate Statistical Analyses and Artificial Neutral Networks for Trace Elements in Agricultural Soils in Xinzhou of Shanxi Province, China

Multivariate statistical analyses were used to assess the contents and distributions of trace elements in agricultural soils in Xinzhou of Shanxi Province, China, and to identify their sources. Samples with high levels of trace elements were concentrated in eastern Xinzhou, with contents declining from the east to west. Principal component and redundancy analyses revealed strong correlations among Co, Cu, Mn, Ni, Se, V, and Zn contents, suggesting that these elements were derived from similar parent materials. There were also strong correlations between the contents of these elements and soil properties. Contents of Cd and Pb were significantly higher in the agricultural soil samples than in the background soil samples (P < 0.05), and were higher in areas with higher levels of gross domestic product but decreased with distance to the nearest road. Therefore, human activities appear to have a strong influence on the Cd and Pb distribution patterns. A novel artificial neural network (ANN) model, using environmental input data, was used to predict the soil Cd and Pb contents of specified test dates. The performances of the ANN model and a traditional multilinear model were compared. The ANN model could successfully predict Cd and Pb content distributions, projecting that soil Cd and Pb contents will increase by 128% and 25%, respectively, by 2020. The results thus indicated that the economic condition of an area has a greater effect on trace element contents and distributions in the soil than the scale of the economy itself.

Potential toxic trace element (PTE) contamination in Baoji urban soil (NW China): spatial distribution, mobility behavior, and health risk.

Rapid urbanization and industrialization may cause increased exposure levels to potential toxic trace elements (PTEs) and associated health risks for population living in cities. The main objectives of this study are to investigate systematically the occurrence, source, fate, and risk of PTE contamination from industrial influence in Baoji urban soil. Seven PTE levels (Pb, Zn, Cu, Cr, V, Sb, and As) were surveyed in 50 composite samples from Baoji urban soil by wavelength dispersive X-ray fluorescence spectrometry. Results reveal that the long-term industrial activities have increased PTEs Pb (409.20mg/kg mean value), Cu (107.19mg/kg mean value), Zn (374.47mg/kg mean value), and Sb (26.00mg/kg mean value) to enrich in urban soil at the different extents. The same results concur with the significant similarity of spatial distribution patterns of Pb, Zn, Cu, and Sb (slightly similar distribution) interpolated by GIS, implying a considerable Pb, Zn, Cu, and Sb contamination pool in urban soil disturbance from local metallic industrial activities. Whereas As in study area mainly controls parent material leaching and therefore has natural sources. Cr and V with the heterogeneous spatial distributions are possibly inclined to coal combustion sources. Those conclusions are also confirmed by the results of multivariate analysis. The chemical forms of PTEs fractionated by BCR three-stage sequential extraction procedure show that Pb and Cu are highly associated to the reducible phase (62.55 and 36.41%, respectively). However, Zn is highly associated to the oxidizable phase (33.68%), and a significant concentration is associated to acid and water extractable fractionation of 15.93% for Zn and 34.40% for Pb. In contrast, As, Cr, V, and Sb are mainly bound to the residual phase (>65% for all elements) with low concentrations retained to water extractable fractionation. The health risk assessed by a new classification Modified Integrate Risk Assessment Code (MI-RAC) reveals that the Pb poses the extremely high risk for human health than others. The results of PTE leaching in organic acids (artificial chelating agent and LMMOAs) indicate that low pH and more carboxyl groups of organic acid can quickly increase the PTEs release from soil and induce more mobility. By comparison, DTPA and EDTA are the effective extractant for Pb and Sb. The leaching kinetics of most PTEs are best described with the Elovich equation model and which involve the ligand exchange (LE) and ligand-enhanced dissolution (LED) two major process. It is a conclusion that long-term metallic industrial activities would accelerate the PTE accumulations in Baoji urban soil and enhance their mobility in a local scale. The considerable mobility and extremely high risk of Pb in Baoji ecoenvironment should be paid more attentions, and the phytoremediation with organic acid leaching assistant could be used to reduce total metal content of multiPTE contaminants in Baoji soils. The research will give the scientific knowledge for controlling the pollution of PTEs in urban soil and can be used as guidance to control the soil pollution in similar cities worldwide.

Spatial distribution and pollution evaluation of heavy metals in soils surrounding a typical municipal solid waste incineration plant in Hang-Jia-Hu plain

In this study, soil samples around the typical municipal solid waste incineration (MSWI) plant in Hangzhou-Jiaxing-Huzhou Plain were collected. The concentrations of heavy metals were determined using X-ray fluorescence spectrometry (XRF), atomic absorption spectrometry (AAS) and mercury analyser. Mean concentrations of Cr, Mn, Cu, Pb and Fe were 174, 708, 47.68, 41.95 and 39,058 mg/kg in this region, respectively. Principal component analysis and cultural enrichment factor (CEF) analysis showed that Cr, Mn and Fe were present as background origin in soils surrounding the incineration plant. Combined with historic land use information, the results showed that the application of pesticide with high content of Cu probably contributed to Cu distributions in the study region. The MSWI plant with high Pb emission from stack resulted in the Pb distribution patterns in surrounding soils. The study highlighted that MSWI could contribute to heavy metal accumulation in surrounding soil.

Effect of industrial sludge on concentration and distribution pattern of Lead, Cadmium and Nickel in root, stem and leaf of Red Amaranth (Amaranthus gangeticus L.) in silty clay loam soil

A pot experiment was carried out to evaluate the concentration and distribution of Lead, Cadmium and Nickel in industrial sludge. The test crop was Red Amaranth (Amaranthus gangeticus L.). Nitrogen was applied comprising the five combinations of different proportion of urea and industrial sludge and a control. Red Amaranth was harvested at 30 and 42 Days after sowing (DAS). Different physical and chemical analysis of soil, sludge, root, stem and leaf of the plant were carried out as required. Heavy metals concentration indicated the trends of Pb&gt;Ni&gt;Cd and distribution pattern of Pb, Cd and Ni were identified Leaf&gt; root&gt; stem, Root&gt; leaf&gt; stem and Root&gt; leaf&gt; stem respectively, both at 30 and 42 DAS with little exception. Industrial sludge had a significant influence on heavy metal concentration and distribution and contaminant food chain, although the data were below the maximum acceptable level. DOI: http://dx.doi.org/10.3329/jasbs.v38i1.15321 J. Asiat. Soc. Bangladesh, Sci. 38(1): 67-74, June 2012

Assessment of heavy metal pollution in Xuzhou urban topsoils by magnetic susceptibility measurements

Abstract The concentrations of four selected heavy metals (Pb, Zn, Ni and Cr) were measured on 167 topsoil samples collected from the city of Xuzhou, China via inductively coupled plasma mass spectroscopy (ICP-MS). It was found that Pb and Zn were principally derived from anthropogenic inputs whereas Cr and Ni distributions were mainly controlled by parent materials. The spatial distribution patterns of Pb, and Zn were similar to that from low field magnetic susceptibility (χlf), suggesting interaction among them. Two threshold values for magnetic susceptibility and frequency-dependent susceptibility percentage (χfd) were applied to discriminate between polluted and unpolluted samples according to their magnetic susceptibility, resulting in 109 samples populating the “polluted” subset. The Pb and Zn concentrations of the “polluted” subset were statistically significantly higher than those measured in the “unpolluted” one. The heavy metal concentrations were also investigated varying the magnetic susceptibility thresholds to change the “polluted” subset.

Analisis Beban Pencemar dan Kapasitas Asimilasi di Estuari Sungai Belau Teluk Lampung

Utilization around of Belau Rivers was diverse, such as agriculture, industry, households, hotels, markets, residential population and fishing boats. According to the explanation, the purpose of this study was to determine distribution and concentration distribution patterns of Pb, Cd, and Cr which evaluated from the distribution of salinity, calculate the assimilation capacity in marine and analyzing the direction of environmental management Estuary Belau at Lampung Bay. The data was analyzed by using the view pattern of relationship between dissolved heavy metals and salinity through mixing graph approach. Furthermore, to know the pollutant load and capacity of assimilation were use a graph of the relationship between the concentration of each parameter with pollutant load on these parameters. The results analysis of pollutant loads and assimilation capacity showed that the parameters of TSS, BOD and COD were still able to perform self purification, whereas for the parameters of nitrate, phosphate, Pb, Cd and Cr were unable to perform self-purification. The management must be built not only within the autority of Lampung Government and the staffs, but also must be holistic upstream to downstream along the river that involves several government autority.

长沙城市森林土壤7种重金属含量特征及其潜在生态风险

采用调查分析方法,研究长沙城市森林土壤Zn、Cu、Ni、Pb、As、Cd、Hg7种重金属含量,并以长沙市土壤背景值和湖南省土壤背景值为参比值,采用Hakanson潜在生态危害指数法评价不同城市化梯度森林土壤重金属潜在生态风险。结果表明:7种重金属的平均含量均随着城市化程度提高而增加,Pb增幅最大,As增幅最小。同一城市化梯度森林土壤均以Zn平均含量最高,Cd最低,但均未超过土壤环境质量标准(GB15618-1995)Ⅱ级标准值。在城市中心区,桂花树林、樟树+桂花树混交林土壤Zn、Cu、Pb、As、Hg平均含量普遍较高,而樟树+马尾松混交林、桂花树+杜英混交林土壤Cu、Ni、As、Cd、Hg平均含量普遍较低,Pb、Zn空间分布差异明显,Cd、Ni、As空间分布比较均匀,Cu、Ni、Pb、As、Cd、Hg之间(除Cd与As、Ni之间外)均存在显著(<em>P</em>＜0.05)或极显著(<em>P</em>＜0.01)的相关性,与土壤有机质之间也呈显著(<em>P</em>＜0.05)或极显著(<em>P</em>＜0.01)的相关性,Zn、Cu、Ni、Pb、As、Cd、Hg主要是人为输入;中心区森林土壤重金属的潜在生态危害已达到中等生态危害程度,边缘区接近中等生态危害程度,郊区为轻微生态危害程度,Zn、Cu、Ni、Pb、As均为轻微生态危害程度,Cd、Hg已达到中等生态危害程度以上。;In order to understand the influence of urbanization on distribution of heavy metals in soils, concentrations characteristics of 7 heavy metals (Zn, Cu, Ni, Pb, As, Cd, and Hg) in various forest types were investigated along an urban gradient in Changsha, a capital city of Hunan Province, China. The concentrations and potential ecological risk of heavy metals in the urban soils was assessed when compared to the background values of heavy metals in soils in both Changsha city and Hunan Province. A total nineteen major forest types were selected at three locations (namely urban district location, urban fringe location, and suburban location) along the urban gradient degree in urban forests soil in the Changsha city. Two forest plots (each with the size of 20m × 20m) were built in each forest types. Three subplots were (each with an area of 1 m²) were set up in each of the plots. Five soil samples (from 0-20 cm depth) were randomly taken within each subplot and pooled to a soil sample for heavy metals chemical analysis, 0-20cm soil samples were collected from different urban gradient (urban district, urban fringe, suburban) forest to analyze the concentrations of Zn, Cu, Ni, Pb, As, Cd, and Hg, and the potential ecological hazard assessment indices by Hakanson was used to assess the soil heavy metals potential ecological risk degree in urban forest, based on the background values of soil in Changsha City and in Hunan Province. Results showed that the average concentration of the same heavy metal elements in urban forest soils tended to increase with degree of urbanization. Pb had the maximum increasing value and As the minimum. In the same urbanization location degree, Zn had the highest average concentration and Cd had the lowest one among the studied of all test heavy metals., On average, while the average the concentrations of all examined heavy metals them in study sites were lower than those in the Environmental Quality Standard for Soil (Ⅱgrade) in China.,. The heavy metals whose concentrations were higher than the background values in Changsha cite and the accumulation tendency of test heavy metals in urban forest were as in the order as of Cd＞Hg＞As＞Pb＞Cu (Ni)＞Zn in the study sites. The concentration of re existed some differences in the same heavy metal element varied concentration with among different types forest types in the city, The average concentrations of Zn, Cu, Pb, As, and Hg were as higher in <em>Osmanthus fragrans</em> forests and, <em>Cinnamomum camphora Presl.</em> and<em> Osmanthus fragrans </em>mixed forests, but that of Cu, Ni, As, Cd, and Hg were found to be was low concentrations in<em> Cinnamomum camphora Presl.+ Pinus massoniana </em>mixed forests and, <em>Osmanthus fragrans +Elaeocarpus sylvestris Poir </em>mixed forests, the spatial distribution patterns of Pb and Zn was significant different in the study area, while Cd, Ni and As were more evenly distributed. Significant correlations were found among Zn, Cu, Ni, Pb, As, Cd, and Hg concentrations in soils (<em>P</em>< 0.05), except the relationships between Cd and As, and Ni. The 7 heavy metals had positively significant correlations with soil organ matter. It was found that Zn, Cu, Ni, Pb, As, Cd and Hg mainly came form the anthropogenic inputs in the urban district forests. Based on potential ecological risk assessment, the situation of heavy metals was in the medium ecological risk level in urban district locations, was in closing to the medium level in urban fringe locations, and was in a slight level in suburban locations in Changsha cite. Among the studied heavy metals, Zn, Cu, Ni, Pb, and As were in a slight risk level, while Cd and Hg were in medium or strong ecological risk level. Our study provided scientific reference to estimate and evaluate the impact of urbanization on heavy metals in Southern China.

Evaluating the Relationships between Pb Species and Leaching Properties in Simulated MSWI Fly Ash with Thermal Treatment by ESCA

AbstractThe aim of this study was to develop a fundamental understanding of the association between lead (Pb) species and leachability behavior in the simulated municipal solid waste incinerator (MSWI) fly ash during the thermal treatment process. Two main factors that influence this process, temperature and the carbon content in the simulated ash, were also studied. In the sequential extraction results, the main distribution pattern of Pb in treated simulated ash was carbonate fraction with different temperatures when the carbon content was 3.5%. The chief fraction of the raw simulated ash (carbon content=0%) was carbonate and that of raw simulated ash when carbon content was increased was Fe-Mn oxide Electron spectroscopy for chemical analysis (ESCA) results showed that Pb (element) in treated simulated ash could increase the toxicity characteristic leaching procedure (TCLP) concentration of Pb when temperatures reached 700°C. With a temperature of 900°C, PbSiO3 was present in the treated simulated ash ...

Investigation of the origin and distribution of heavy metals around Ebenezer Dam, Limpopo Province, South Africa

This study was based on the outcome of the soil geochemical survey which was conducted by the Council for Geoscience around Ebenezer Dam during 1995-1996, the results of which indicated high concentrations of lead (Pb), zinc (Zn) and arsenic (As). The current study therefore focused on the origin and distribution patterns of Pb, Zn, Cu, As and Cr within the environs of Ebenezer Dam and their potential impacts on the environment and human health. The work involved soil, sediment, rock and water sampling and analysis. Atomic absorption and x-ray fluorescence spectrometry were used to determine the metal concentrations. The occurrence of anomalous concentrations of these metals in the study area was established. The anomalies registered maximum concentrations of (mg/g): 57 for Pb, 157 for Zn, 313 for Cu, 73 for As and 888 for Cr. The concentrations of these metals in sediments along the streams were high near the anomalies, but decreased downstream. Concentrations of heavy metals in water around the Ebenezer Dam were found to be less than 0.01 mg/g , except for As which was less than 1.0 mg/g. Thus Pb, Zn, Cu and Cr values were below the target water quality ranges for domestic, irrigation, livestock watering and aquatic ecosystem use. The study confirmed that the distribution of heavy metals in this area is localised within and around the source rocks that are felsic in nature, namely; granites and pegmatites that formed domes in the area.

Determination of total lead and lead species according to their lability in coastal seawater by Chelex-100 titration and electrothermal-atomic absorption spectrometry

A speciation method based on Chelex-100 titration in combination with electrothermal-atomic absorption spectrometry has been developed to study the distribution of Pb among different fractions in coastal seawater. The method allows an accurate determination of total Pb, thereby avoiding the effect of the saline matrix. Additionally, the distribution patterns of Pb among species with different lability can be established in seawater as a function of pH. Four Pb fractions have been obtained in a model seawater and two seawater samples from Ria de Vigo (NE Atlantic ocean), i.e. free Pb ion, inorganic Pb fraction, organic Pb fraction and inert Pb fraction. The inert and labile organic Pb fractions dominate at natural pH (≈8).Complexation mechanisms of Pb were investigated from the sorption curves of lead on Chelex-100 according to the Gibbs–Donnan model. Three complexes were formed, PbL, PbL2 and Pb(HL)2 with the following intrinsic complexation constants logβ(1np) = −3.25, −10.10 and −1.98, respectively. The formation of the complex PbL is negligible in all range of pH studied, while the complex Pb(HL)2 predominates up to pH 4 and PbL2 from pH 4.

Pb/Ca in Thailand Coral Determined by LA-ICP-MS: Anthropogenic Pb Input of River Run-off into a Coral Reef from Urbanised Areas

In order to monitor lead pollution from urban areas to coral reefs in the Gulf of Thailand, linear and two-dimensional distributions of Pb in corals from Khang Khao Island, Thailand and Rukan-sho, Okinawa, were analysed with high resolution. Laser ablation inductively coupled plasma mass spectrometry was applied to measure Pb content in coral skeletons using synthetic Pb standards in a CaCO3 matrix as calibration materials. Linear and two-dimensional ablation schemes were applied to determine the Pb content in corals collected from Khang Khao Island, Thailand and Rukan-sho, Okinawa. The coral skeleton was ablated by Nd:YAG laser (wavelength of 266 nm, beam diameter of 155 µm, scanning speed of 10 µm s−1 and frequency of 10 Hz) along the growth axis, and ion counts for 208Pb were normalised to 42Ca. Lead content in the corals was determined using a calibration curve obtained from the synthetic Pb standards (0–141 µg g−1). The linear ablation track of the sample from Khang Khao showed over 30 peaks of Pb with an average value of 3.55 µg g−1, while Pb content in the coral from Rukan-sho showed relatively small variation with an average value of 0.132 µg g−1. Two-dimensional imaging of Pb in the coral skeletons was also carried out for an area of 7 × 20 mm on the sample from Khang Khao. The distribution patterns of Pb and Ba in the Thailand coral co-varied. These observations from the linear and imaging analyses suggest discontinuous inputs of anthropogenic Pb from rivers to the Gulf of Thailand.