Occurrence Of Pb Research Articles

Exposure to metals and arsenic from yellow and red tuna consumption

ABSTRACTTuna is one of the most frequently consumed fish and, as a predator, can biomagnify pollutants. Metal and other elements pollution is an important worldwide concern. Based on these considerations, the aim of this work was to investigate the occurrence of As, Cd, Cr, Ni, Hg and Pb in tuna coming from different FAO areas to evaluate human exposure. The analysis was performed on muscle tissues through a quadrupole inductively coupled mass spectrometry. One hundred thirty-one samples were analysed. One red tuna from the Adriatic Sea and 11 yellow tunas exceeded Pb maximum levels (MLs) with a concentration ranging 0.31–0.86 mg kg−1; three red tunas from different Mediterranean sub-areas exceeded Hg MLs, with a concentration range 1.19 to 1.80 mg kg−1. All the Hazard Indexes (HIs) were lower than one, indicating that only a negligible health hazard could derive from the ingestion of tuna, for both average and high consumers. The risk of carcinogenicity from Cr is still under debate at the concentrations detectable in food.

Occurrence, speciation, and risks of trace metals in soils of greenhouse vegetable production from the vicinity of industrial areas in the Yangtze River Delta, China.

The effect of industrial activities on trace metals in farmland of rapidly industrializing regions in developing countries has increasingly been a concern to the public. Here, soils were collected from 13 greenhouse vegetable production (GVP) farms or bases near industrial areas in the Yangtze River Delta of China to investigate the occurrence, speciation, and risks of Cr, Cu, Zn, Cd, Ni, and Pb in GVP soil. The results revealed that the main metal elements causing GVP soil pollution were Cd, Zn, Ni, and Cu, of which contamination levels were generally unpolluted to moderately polluted. Zinc pollution was mainly attributed to heavy fertilization, while Cd, Ni, and Cu pollution may be greatly ascribed to industrial effluents and coal combustion. Metal speciation studies showed that most of Cr, Ni, Cu, and Zn was present in residual fraction while more than half of Cd and Pb was present in non-residual fractions. Additionally, pollution of Cd, Cu, Ni, and Zn in GVP soil increased their corresponding mobile fractions. Risk assessment using potential ecological risk index and risk assessment code showed that Cd was the major risk contributor. Specifically, Cd generally posed moderate or considerable ecological risk as well as displayed medium or high mobility risk in GVP soil. Thus, great attention should be paid to the contribution of both industrial discharges and intensive farming to soil pollution by trace metals, especially Cd, because of its high mobility risk.

Application of Multivariate Statistic of U, Th and Pb Concentrations and Pb Isotopic Signatures in the Assessment of Geogenic and Anthropogenic Sources in a U-Mineralized Area

This work presents a Principal Component Analysis (PCA) study using Pbisotope signatures and U, Th and Pb concentrations from groundwater, sediments and rocks (granites and orthogneisses) of the Complex of Lagoa Real (Bahia, Brazil). This area is naturally enriched in U and Th, with the occurrence of Pb derived from the radioactive decay of the elements (238U, 235U and 232Th) in the form of their stable isotopes 206Pb, 207Pb and 208Pb in addition to the natural isotope 204Pb. Sampling was carried out in the rainy season (December to January) and the points were selected according to regional hydrology and geology. Thirty samples were analyzed: 12 of groundwater (AP) and 18 of sediments (S). The results show that the use of isotopic ratios allows discrimination between geogenic and anthropogenic samples. This information is not obtained using only the analysis of concentration data. Statistically, the isotopic data of Pb stand out as an efficient tool in the characterization of sources in the scenario investigated, allowing an effective environmental monitoring and a better management of the mining activities.

Modes of Occurrence of Cr, Co, Ni, Cu, Cd, and Pb in the Main Coal Seams of Southwestern China’s Nantong Coalfield

The modes of occurrence of trace elements in coal reveal essential information about environmental impact during coal exploitation and utilization. Utilizing improvements on a recently published sequential leaching protocol, this study investigated the modes of occurrence of Cr, Co, Ni, Cu, Cd, and Pb (water-soluble, ion-exchangeable, carbonate-bound, sulfide-bound, organic-bound, and silicate-bound) in coal samples collected from the Nantong coalfield in southwestern China. Results suggest the improved method favorably affected the sequential leaching experiment. The ashing temperature did not exceed 390°C and did not damage the structure of the silicate minerals, facilitating the effective extraction of trace elements within the organic matter. The case study in the Nantong coalfield demonstrated that the water-soluble and ion-exchangeable fractions account for only a small portion of the six elements. Specifically, chromium exhibited affinities with carbonates and silicates. The percentages of different target fractions for cobalt varied significantly in different samples. Nickel was almost evenly distributed in the fractions of carbonates, sulfides, organic matter, and silicates. For cadmium, silicate was the main fraction, followed by sulfides. Lead predominantly appeared in carbonates and sulfides. The correlativity of different elements in the corresponding fractions revealed carbonates and sulfides as the primary carriers for all six elements, followed by silicates and organic matter. Overall, Cr, Co, Ni, and Cu exhibited very close relationships and similar distribution patterns in different coal samples. Organic-bound Cr, Co, and Ni were noticeable in the No. 4 and 6 coal seams, though they were not the dominant fractions. The affinity between Pb and Cd indicated they have similar modes of occurrence.

Occasional Flooding Impact On Heavy Metals Content In The Soil Of Polder Beša

Abstract Three plots in Dry Polder Beša in Slovakia (E) and 3 plots in no flooded area (R) were chosen to assess the Cd, Pb and Ni contamination in the soil by using geo-accumulation index (Igeo) and anthropogenic contribution rate (ACR). Heavy metals content was measured at three depths (0‒0.2 m, 0.2‒0.4 m and 0.4‒0.6 m). It was found that the average content of Pb was 1.4 times higher and content of Ni 2.3 times higher at experimental area than at reference area. The average content of Cd were on the same level (E - 0.040 mg/kg, R - 0.041 mg/kg). The variability of heavy metals content in the soil was significantly influenced by soil depth and sampling plot and concentrations significantly correlated with soil organic carbon content (r - in the range of 0.41 to 0.65, p < 0.05). Geo-accumulation index indicates that the soils in the all of studied plots were polluted with respect to Ni, while were unpolluted with respect to Cd and Pb. Cd and Pb occurrence in these soils may be associated to the geochemical weathering. The value of the ACR indicate that anthropogenic input of Ni was 1.331 times higher in flooded area than in reference no flooded area. Different soil types can be arranged in descending Igeo values for Ni as follows: Luvisols ˃ Regosols ˃ Gleysols ˃ Chernozems. It was found that the content of Ni and Pb exceeded the critical values, in relation to transfer of contaminants from the soil to the plant , only at flooded area.

Element distribution in Lactarius rufus in comparison to the underlying substrate along a transect in southern Norway

Lactarius rufus, the rufous milkcap, is one of the most widespread fungi in northern Europe. 40 samples of Lactarius rufus were collected along a 100 km transect in an almost pristine area of southern Norway. Along the transect two mineral deposits occur (a) the Nordli porphyry molybdenum deposit and (b) the Snertingdal Pb occurrence. 53 chemical elements were analysed in Lactarius rufus and its substrate, the soil O and C horizon. Of these, 32 elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cs, Cu, Fe, Hg, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Sb, Sc, Se, Sn, Sr, Ti, Tl, V and Zn) returned values above the respective detection limits for the majority of samples.Compared to the soil C-horizon Lactarius rufus is strongly enriched (factor >2 to 72) in K, Rb, Ag, P, S, Na, Cd, Hg, Cu, Zn and Cs. Compared to the soil O horizon Rb, K, P, Cs, Cu, S and Na are the most enriched (factor >2 to 50) elements in Lactarius rufus. Compared to the median of in total 15 plant materials collected along the same transect Lactarius rufus is most strongly enriched in Ag (195 times), more than 10 times in Cs, Rb, Na, Cd and 10 to 2 times in K, Hg, P, Cu, Ti, As, S and Zn. Compared to other plants the uptake of Ba, Ca, Mn, Sr, Al and Mo by Lactarius rufus is very low. Element correlations between Lactarius rufus and the substrate are generally poor. Within Lactarius rufus only the major nutrients (K, P, S, Mg) correlate well. Part of the study was to investigate Lactarius rufus suitability for biogeochemical exploration; although this mushroom species enriches many elements, it does not provide a good indication of the presence of the mineral occurrences.

Determination of water-soluble elements in PM2.5, PM10, and PM2.5-10 collected in the surroundings of power plants

The analysis reported in this study was performed to characterize the concentrations and water-soluble content of trace elements (As, Cd, Co, Cr, Hg, Mn, Ni, Pb, Sb and Se) in PM2.5, PM10 and PM2.5-10 samples collected in the surroundings of power plants in southern Poland. The solubility of trace elements bound to PM2.5 and PM10 was higher than for PM2.5-10, and in most cases, significant differences were revealed in the relative percentage concentrations of the water-soluble fractions. The occurrence of Cd, Cr, Mn, Ni, Pb and Se in first PCA (Principal Component Analysis) factor (PC1) – indicate coal combustion processes as the potential source of these elements. Other factors indicate two further anthropogenic sources: the resuspension of road dust due to vehicular activities and waste burning in domestic sources – factor (PC2), and, soil dust sources affected by fugitive dust from the mining processes and unpaved roads, as well as transportation and deposition of coal –factor (PC3).

The Petrography, Mineralogy and Geochemistry of Some Cu- and Pb-Enriched Coals from Jungar Coalfield, Northwestern China

The petrological, geochemical, and mineralogical composition of the Carboniferous-Permian coal deposit in the Jungar coalfield of inner Mongolia, Northwestern China, were investigated using optical microscopy and field emission scanning electron microscopy in conjunction with an energy-dispersive X-ray spectrometer (SEM-EDX), as well as X-ray powder diffraction, X-ray fluorescence, and inductively coupled plasma mass spectrometry. The Jungar coal is of high volatile C/B bituminous quality with 0.58% vitrinite reflectance and has a low sulfur content of 0.70% on average. Inertinite (mineral-free basis) generally dominates in coal from the lower part of the Shanxi formation, and vitrinite is the major maceral assemblage in the coal from the Taiyuan formation, which exhibits forms suggesting variation in the sedimentary environment. The Jungar coal is characterized by higher concentrations of copper (Cu) in No. 6 coal, at 55 μg/g, and lead (Pb) in No. 4 coal at 42 μg/g. Relative to the upper continental crust, the rare earth elements (REE) in the coal are characterized by light and medium–heavy REE enrichment. The minerals in the Jungar coal are mainly kaolinite, dickite, pyrite, calcite, siderite, quartz, and, to a lesser extent, gypsum and K-feldspar. The enrichment and occurrence of the trace elements, and of the minerals in the coal, are attributed to the fragmental parent rock during diagenesis and coalification. The main elements with high enrichment factors, Cu and Pb, overall exhibit a notably inorganic sulfide affinity and a weak organic affinity. Primary and epigenetic sedimentary environment and the lithology of the terrigenous parent rock are the key factors that influence the occurrence and formation of Cu and Pb in coal. The depositional environment is more influential in the formation of Cu than Pb in coal. Lead is more easily affected by the terrigenous factors than Cu when they are under a similar depositional environment.

Relationship between Pb and Cd accumulations in house crow, their habitat, and food content from Klang area, Peninsular Malaysia.

Heavy metal pollution has become a global concern due to accumulation in tissue and transferable effects to humans via the food chain. This study focused on monitoring the accumulation of cadmium (Cd) and lead (Pb) in surface soil and body content: bone, heart, brain, liver, lung, muscle, kidney, feathers, feces, and gizzard contents of house crow Corvus splendens in the Klang region, Malaysia. The results revealed the occurrence of Pb and Cd in all biological samples from house crows, food contents, and surface soil samples. Heart and kidney accrued high amounts of Cd, while high amounts of Pb were found to accumulate in bones and feathers. Major discrepancies were also discovered in the concentrations of metals between juvenile and adults, as well as female and male bird samples. Concentrations of Pb and Cd in house crow internal tissues correlated significantly with that of bird feathers, but none could be established with that of surface soil. In addition, a significant correlation was observed between Pb concentration in the internal tissues to that of the feces, but the same was not the case when compared with the surface soil concentration. Metal accrual in the house crows feathers and feces may be through a long-term transmission via the food chain, which are eliminated from feathers via molting. This may suggest the utility of molted breast feathers of house crow in the bio-monitoring of Cd and Pb contamination, whereas feces of house crow appear only to be suitable for the bio-monitoring of Pb contamination.

Identification of new base metal mineralization in Kumaon Himalaya, India, using hyperspectral remote sensing and hydrothermal alteration

Economic mineral deposits are commonly associated with zones of intense hydrothermal alteration. Space borne hyperspectral remote sensing is one of the recent techniques that enable the identification of hydrothermally altered and weathered minerals. In this study, we identified hydrothermally altered and weathered minerals of a gossanised outcrop rich in base metal mineralization in parts of the Kumaon Himalaya, India using an EO-1 Hyperion (hyperspectral) satellite data. Spectral Angle Mapper classification method was used to map the different altered/weathered minerals within the study area. The method identified the occurrence of dolomite and dolomite with chlorite minerals from the Hyperion data. The finding was verified in the field and confirmed through laboratory analyses. Representative samples measured for spectral absorption characters, reflected and transmitted petrography, X-ray diffraction and ICP-MS analyses confirmed the occurrence of Ag, Cu, Fe, Pb, Zn, As, and Sb base metal rich elements in the Thalkedar limestone. Our study recommends the technique to the map base metals and hydrothermally altered minerals in the other parts of Thalkedar limestone of Kumaon Himalaya and similar region of the world. The study is an important case for formulating exploration strategies in terrenes with rugged topography and dense vegetation.

Scanning and transmission analytical electron microscopy (STEM-EDX) can identify structural forms of lead by mapping of clay crystals

To increase the analytical precision in identifying structural forms of heavy metals, it is necessary to refine the methodology for analysis of mineral crystals. The aim of this study was to characterize clay crystals in soils, and relate their mineralogy to the structural occurrence of Pb using scanning transmission electron microscopy (STEM) together with energy dispersive X-ray (EDX) spectrometry. We sampled soils from two areas naturally rich in heavy metals, with known occurrences of mineral deposits (PbS) in carbonate and phyllite/mica schist rocks. There was an association of P with Pb, and the main mineral phase containing Pb in the soil clay fractions was plumbogummite. No associations between Pb and Fe oxides were observed. Secondary phyllosilicate minerals, such as kaolinite and smectite, did not contain structural Pb. There was isomorphous substitution of Ti by Pb in an anatase crystal, despite the differences in ionic radii. The chemical analysis of individual crystals by STEM-EDX was hampered by the high occurrence of microaggregates of clay minerals.

Determination of ultratrace (

There is on-going concern regarding fugitive emissions of trace elements from mining and upgrading of the Athabasca Bituminous Sands (ABS) in northern Alberta, Canada, but remarkably few quantitative elemental data about the resource itself exists. By exploring advances in analytical techniques, an inductively coupled plasma sector field mass spectrometry (ICP-SFMS) method was developed for the determination of trace and ultratrace amounts (<0.1mg/kg) of several elements of environmental concern (Ag, As, Be, Bi, Cd, Pb, Sb and Tl) in bulk ABS and respective bitumen and mineral fractions as separated materials. Samples (n=7) averaged 86±4% mineral matter and 12±3% bitumen. High pressure microwave digestion employing HNO3-HBF4 yielded good recoveries (100±20%) for Ag, As, Be, Bi, Cd, Mo, Ni, Pb, Re, Sb, Tl and V in certified reference materials (NIST 1635, NIST 2711). The distribution of elements within the ABS was dichotomous, with V, Ni, Mo and Re predominantly found in the organic fraction (bitumen) and Ag, As, Be, Bi, Cd, Pb, Sb, and Tl predominantly found in the mineral residue. Trace amounts of As and Pb (0.1–2.0mg/kg), plus ultratrace amounts of Ag, Bi, Cd, Sb and Tl (<0.1mg/kg) were found in the bitumen. Despite filtration (<0.45µm), the bitumen fraction also contained trace amounts of lithophile elements (Be, Co, Ga, Sc, Y, Sm, Dy, Th), which suggested that the occurrence of Ag, As, Be, Bi, Cd, Pb, Sb, and Tl in bitumen was associated with ultrafine clays. Our demonstration of a distinct separation of the ABS trace elements into organic (V, Ni, Mo, Re) and mineral fractions (effectively all other trace elements) may have profound consequences regarding emissions of trace elements to the environment from the industrial development of this resource in northern Alberta.

Trace elements in fragments of fishing net and other filamentous plastic litter from two beaches in SW England

Filamentous plastic litter collected from two beaches in south west England has been characterized by FTIR and XRF. The majority of samples were constructed of polyethylene and consisted of twisted or braided strands of a variety of colours that appeared to be derived from commercial fishing nets. A number of different elements were detected among the samples but, from an environmental perspective, the regular occurrence of Cr and Pb and the occasional or isolated occurrence of Br, Cd and Se were of greatest concern. The highest total concentrations of Br (2420 μg g−1), Cd (1460 μg g−1), Cr (909 μg g−1), Pb (3770 μg g−1) and Se (240 μg g−1) were always encountered among orange samples and are attributed to the presence of lead chromates and cadmium sulphoselenide as colourants and to brominated compounds as flame retardants. Element bioaccessibility was evaluated by ICP-MS following an acidic extraction test that mimics the digestive tract of seabirds, with maximum values after a seven-day incubation period and relative to respective total concentrations of 0.2–0.4% for Cd, Cr and Pb and about 7% for Br. In addition to the well-documented impacts on wildlife through entrapment, filamentous plastic waste may act as a significant source of hazardous chemicals into the marine foodchain through ingestion.

Interactions between metal ions and the biopolymer in activated sludge: quantification and effects of system pH value

The quantification and effects of system pH value on the interactions between Pb(II) and the biopolymer in activated sludge were investigated. The biopolymer had two protein-like fluorescence peaks (Ex/Em = 280 nm/326–338 nm for peak A; Ex/Em = 220–230 nm/324–338 nm for peak B). The fluorescence intensities of peak B were higher than those of peak A. The fluorophores of both peaks could be largely quenched by Pb(II), and the quencher dose for peak B was about half of that for peak A. The modified Stern-Volmer equation well depicted the fluorescence quenching titration. The quenching constant (Ka) values for both peaks decreased with rising system pH value, and then sharply decreased under alkaline conditions. It could be attributed to that the alkaline conditions caused the reduction of available Pb(II) due to the occurrence of Pb(OH)2 sediments. The Ka values of peak B were bigger than those for peak A at the same system pH values. Accordingly, the aromatic proteins (peak B) played a key role in the interactions between metal ions and the biopolymer.

Occurrence and Environmental Features of Heavy Metal Elements of Coal from Coalfield in the Southeast Shanxi

The coal was sampled from No.15 coal seam in coalfield of southeast Shanxi. The Hg, As, Se, Cr and Pb occurrence in coal seam and environmental features of the heavy metal elements of coal were studied by X-ray fluorescence spectrometry (ARL Quant 'X), X-ray diffraction (XRD) and inductively couple-plasma mass spectrometry (ICP-MS). Environmental features, such as heavy metal element concentration, distribution and occurrence mode, etc., were studied by systematic determination of element concentration, inorganic element and mineral composition in coal. The results showed that the coal from No.15 coal seam had the mercury (Hg) concentration between 0.44 and 0.268 μg/g, and average Hg concentration of 0.11 μg/g; arsenic (As) concentration between 0.31 and 0.91 μg/g, 0.61 μg/g on average; selenium (Se) concentration between 0.94 and 3.56 μg/g, 2.45 μg/g on average; chromium (Cr) concentration between 9.54 and 24.58 μg/g, 17.06 μg/g on average; lead (Pb) concentration between 10.23 and 23.56 μg/g, 18.13 μg/g on average. The comparison with the Clark value showed Se was significantly enriched, As and Cr were lost, and Hg and Pb were normal. Compared with the coal from other counties and regions both at home and abroad, as was lost and other elements were normal. The elements irregularly distributed vertically. In spite of different element concentrations in adjacent coal seams, no significant enrichment occurred. The target elements mainly occurred in the form of inorganic matters except As. Hg was mainly concentrated in pyrite and clay minerals. Se, Cr and Pb were mainly concentrated in kaolinite, and Se was mainly concentrated in illite. Because of different occurrences or different forms in one mineral, the Hg, As, Se, Cr, and Pb loss rates were 99.43%, 85.91%, 77.89%, 73.81%, and 68.85% at 815°C, respectively.

Bullying and Perceived School Climate: Victims’ and Bullies’ Perspective

IntroductionPeer bullying (PB) is a problem present in schools all around the world and met by students and teachers on daily basis. Research shows that PB has a negative impact on the physical and mental health of students (Chen, Liu, & Cheng, 2012; Pecjak, 2014), thus, researchers are trying to understand the nature of PB and minimize its negative impact on students through prevention and intervention.From the systemic theories' (e.g., Bronfenbrenner's ecological theory, 1979) point of view, has an important role in these aspirations, because policy and existing prevention and intervention programs regarding PB are derived from school (Sullivan, 2011), which could also be termed culture/climate. Therefore, one of the aims of our study was to determine which sociodemographic and climate factors predict the roles of chronic victims and bullies.School climate is a complex, multidimensional construct. It refers to the quality and character of social interactions at and is defined by the norms, values, rules, organizational structures and relationship patterns unique to each (Cohen, McCabe, Michelli, & Pickeral, 2009). Positive climate may be a protective factor for different risk behaviors, and for students' aggression towards their peers (Cook, Williams, Guerra, Kim, & Sadek, 2010; Hong & Espelage, 2012).The climate in PB refers to social interactions between students participating in PB - bullies, victims and non-involved students, and to interactions between teachers and these students. There are certain values and norms in the background of these social interactions, which are advocated by schools. There are also sets of rules regarding students' behavior towards peers, and teachers' responses to PB occurrence, which are stated (or not) by the school.School climate research includes students' perceptions of their peer's behavior towards them and their perceptions of how much teachers (and other staff) care about them and treat them fairly (Hoy, Smith, & Sweetland, 2002).The schools where PB is tolerated and ignored, where a clear set of rules of behavior is not in place and where the rules are not carried out, are dysfunctional schools (Sullivan, 2011). These schools are unsafe and the only rule is survival of the fittest. On the other side, there are safe schools (Sullivan, 2011) with the philosophy that is a safe place for students and teachers, where rules of mutual respect are enforced and fair play in mutual relations is present.Two elements have to be present for an optimal climate: structure and support (Gregory & Cornell, 2009). The authors consider schools with clear structure and support as schools with authoritative (school) discipline. The structure is the degree to which schools consistently and fairly enforce rules - also in cases of PB. Research shows that students' perceptions of rules as clear and fair are consistently linked to better behavior and to less victimization (Gottfredson, Gottfredson, Payne, & Gottfredson, 2005).A supportive climate includes teachers caring for students and supporting them. Two important elements of this climate are the teachers' positive expectations towards students and their feelings of responsibility for students and for what goes on in the (Austin & Duerr, 2005; Gregory & Cornell, 2009).Adolescents' perceptions of teachers as caring and supportive have been linked to higher academic adjustment (Gregory, Cornell, Fan, Sheras, Shih, & Huang, 2010) and social adjustment by PB - they were more likely to seek help (Wilson & Deane, 2001), less likely to experience re-victimization (Smith, Talamelli, & Cowie, 2004) and had higher commitment to (Hong & Espelage, 2012).Research ProblemThe aim of our study was to investigate individual elements of climate in PB (prevalence of teasing and bullying, aggressive attitudes, willingness to seek help, supportive climate and rules, commitment to school) from the perspective of different groups of bullies and victims. …

Amendments affect lead mobility and modulated chemo-speciation under different moisture regimes in normal and salt-affected lead-contaminated soils

The total lead content in the soil itself is insufficient as a measure to indicate the actual environmental risks related to the presence of lead in the soil. Understanding the mobility of lead and its chemical speciation in soil solution is of great importance for accurately assessing environmental risks posed by lead. Therefore, a laboratory study was carried out to evaluate the effect of inorganic amendments (gypsum, rock phosphate and di-ammonium phosphate) on lead mobility and chemical speciation under different moisture regimes (flooding regime and 75 % field capacity) in normal and salt-affected lead-contaminated soils. After 2, 7, 15, 30, 100 and 110 days of incubation, pore water samples were collected by using Rhizon soil moisture samplers. In order to estimate the chemical speciation of lead in pore water, Visual MINTEQ 3.0 modeling approach was used. The results showed that presence of free Pb2+, PbCl+, Pb(SO4)22−, and PbH2PO4+ was significantly (P ≤ 0.05) affected by the soil moisture regime, incubation time and applied amendments in lead-contaminated soils. The Visual MINTEQ 3.0 predicted free Pb2+ species concentration was found higher in lead-contaminated soils, while PbCl+ was more pronounced in salt-affected soils. Gypsum increased the occurrence of Pb(SO4)22−, while di-ammonium phosphate and rock phosphate enhanced the PbH2PO4+ species formation and decreased free Pb2+ species in pore water. Thus, gypsum is the most effective in reducing lead and free Pb2+ species concentrations in the pore water under different soil moisture regimes and incubation times in normal and salt-affected lead-contaminated soils.

Exploiting biogeochemical and spectroscopic techniques to assess the geochemical distribution and release dynamics of chromium and lead in a contaminated floodplain soil

Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX) combined with a seven steps sequential extraction technique were used to assess the geochemical distribution of chromium (Cr) and lead (Pb) in a contaminated floodplain soil. Total contents of Cr and Pb were 490.3 and 402.1 mg kg−1, respectively. The residual fraction was 59.5 and 56.3% of total Cr and Pb. The crystalline iron (Fe) oxide was the dominant non-residual fraction of Cr (35.9% of total Cr). Considerable amounts of Pb were found in the organic fraction (35.4%). Using 13C nuclear magnetic resonance spectroscopy, the soil organic matter was identified as 48.9% aromatic carbon, which indicated that a certain portion of Pb and Cr might be associated with aromatic compounds. The SEM–EDX images demonstrate a concomitant occurrence of Pb, manganese (Mn), Fe, and aluminum (Al) as well as a coexistence of Cr and Fe.The release dynamics of dissolved Cr and Pb as affected by redox potential (EH), pH, Fe, Mn, dissolved organic carbon, and sulfate was quantified using an automated biogeochemical microcosm apparatus. Soil pH decreased under oxic conditions. The release of Cr, Pb, Fe, and Mn increased under acidic oxic (pH = 3.7, EH = 521 mV) conditions due to the associated decrease of pH (7.1–3.7). The mobilization of Cr and Pb was affected by the Fe and Mn. In conclusion, our multi-technique approach identified the geochemical distribution of Cr and Pb and verified major factors that explain mobilization of Cr and Pb in floodplain soils.

Fractional Characteristics of Heavy Metals Pb, Zn, Cu, and Cd in Sewer Sediment from Areas in Central Beijing, China

To identify the distribution of heavy metals in sewer sediments and assess their potential harmfulness to the environment and human health, the occurrence of Pb, Zn, Cu, and Cd in the sewer sediment of six functional areas and two streets in an inner-city suburb of Beijing, China, was investigated by using a sequential extraction procedure. Results show that the concentrations of Cu, Zn, Cd, and Pb vary between 50 and 175, between 80 and 180, between 0.75 and 2.5, and between 20 and 110 mg/kg, respectively, and Fe-Mn oxide fraction is significant for all metals in sampling areas. Pollution assessment shows that 1–2% of Cu at Chegongzhuang Street and 1–3% of Zn at Fuwai Street in the exchangeable fractions are of low risk. 10–25% of Cd at six functional areas indicates medium risk. 40–60% of Pb at Fuwai Street existing in the exchangeable fractions is of high to very high risk. The sum of these metals associated with exchangeable, carbonate bound, and Fe-Mn oxide fractions is quite high; however, these three fractions represent the proportion of heavy metals that can be remobilized by changes in environmental conditions.

Naturally Occurring Radioactive Materials in Coals and Coal Combustion Residuals in the United States.

The distribution and enrichment of naturally occurring radioactive materials (NORM) in coal combustion residuals (CCRs) from different coal source basins have not been fully characterized in the United States. Here we provide a systematic analysis of the occurrence of NORM ((232)Th, (228)Ra, (238)U, (226)Ra, and (210)Pb) in coals and associated CCRs from the Illinois, Appalachian, and Powder River Basins. Illinois CCRs had the highest total Ra ((228)Ra + (226)Ra = 297 ± 46 Bq/kg) and the lowest (228)Ra/(226)Ra activity ratio (0.31 ± 0.09), followed by Appalachian CCRs (283 ± 34 Bq/kg; 0.67 ± 0.09), and Powder River CCRs (213 ± 21 Bq/kg; 0.79 ± 0.10). Total Ra and (228)Ra/(226)Ra variations in CCRs correspond to the U and Th concentrations and ash contents of their feed coals, and we show that these relationships can be used to predict total NORM concentrations in CCRs. We observed differential NORM volatility during combustion that results in (210)Pb enrichment and (210)Pb/(226)Ra ratios greater than 1 in most fly-ash samples. Overall, total NORM activities in CCRs are 7-10- and 3-5-fold higher than NORM activities in parent coals and average U.S. soil, respectively. This study lays the groundwork for future research related to the environmental and human health implications of CCR disposal and accidental release to the environment in the context of this elevated radioactivity.