Source Of Pb Research Articles

International Analysis of Sources and Human Health Risk Associated with Trace Metal Contaminants in Residential Indoor Dust.

People spend increasing amounts of time at home, yet the indoor home environment remains understudied in terms of potential exposure to toxic trace metals. We evaluated trace metal (and metalloid) concentrations (As, Cu, Cr, Mn, Ni, Pb, and Zn) and health risks in indoor dust from homes from 35 countries, along with a suite of potentially contributory residential characteristics. The objective was to determine trace metal source inputs and home environment conditions associated with increasing exposure risk across a range of international communities. For all countries, enrichments compared to global crustal values were Zn > Pb > Cu > As > Cr > Ni; with the greatest health risk from Cr, followed by As > Pb > Mn > Cu > Ni > Zn. Three main indoor dust sources were identified, with a Pb-Zn-As factor related to legacy Pb sources, a Zn-Cu factor reflecting building materials, and a Mn factor indicative of natural soil sources. Increasing home age was associated with greater Pb and As concentrations (5.0 and 0.48 mg/kg per year of home age, respectively), as were peeling paint and garden access. Therefore, these factors form important considerations for the development of evidence-based management strategies to reduce potential risks posed by indoor house dust. Recent findings indicate neurocognitive effects from low concentrations of metal exposures; hence, an understanding of the home exposome is vital.

Assessment of selected heavy metals concentrations in Mairua Reservoir, Funtua, Katsina State, Nigeria for fishing purposes

An assessment of selected heavy metal concentrations for fishing purposes was conducted at Mairua Reservoir, Funtua, Katsina State, Nigeria. This study aimed at assessing the selected heavy metal concentrations to enable the and sustainable use of the reservoir. Fishing is the major activity of the dwellers throughout the year, but there is less attention in considering the water quality in the reservoir. Eating fish harvested from polluted aquatic habitats could endanger the health Eating fish harvested from polluted aquatic habitats could endanger the health of the consumer. As such, there is the need of this research now if not continuously.Water samples were taken in five sampling points and the procedural plan was the monthly sampling of the water from February-April and June-August 2020. The heavy metals include Zinc (Zn), Iron (Fe), Nickel (Ni), Manganese (Mn), Cadmium (Cd) and Lead (Pb). Laboratory procedures include sample digestions in preparation for spectrophotometric analysis using Atomic Absorption Spectrometer (AAS). Data were analysed using Analysis of Variance (ANOVA) and independent t-test and related with FAO standard for fishing. The finding shows that most of the parameters like Cd, Zn and Pb are more in concentration at SPIII (downstream), i.e. the outlet of the water in the reservoir. It can also be seen that two parameters Fe and Ni are more concentrated at SPIV (middle towards east) and only Mn is higher at SPI (upstream). Furthermore, the analysis of variance revealed no significant difference (p >0.05) in the values of all the parameters across the five sampled collection points. The results of this study show that with the exception of cadmium (Cd) and lead (Pb), the heavy metal concentrations in water did not exceed FAO (2006) standards. However, Cd and Pb exceeded the FAO standard. The level of heavy metal concentrations was compared based on seasons (wet and dry) using independent t-test at the 0.05 level of significance. The result shows no significant difference at 0.05 between the wet and dry season values of Fe (P value 0.106), Cd (P value 0.614) Zn (P value 0.700), Mn (P value 0.950), and Ni (P value 0.937). Study on Pb concentrations revealed that the metal was affected by seasonal variation (P value 0.047). Dumping waste very close to the reservoir should be discouraged. Farmers around the reservoir should be enlightened on the negative effects of their activities into the body of the water. More studies should be carried out on physico-chemical, microbial and other heavy metal concentrations in order to provide baseline information on the ecological status of the reservoir. In line with the finding, it is recommended that for effective fishing activities in the reservoir, the use of agrochemicals and dumping municipal waste very close to the reservoir, which could be the possible sources of Cd and Pb, should be discouraged.

Distribution, source identification and environmental risk assessment of potentially toxic elements (PTEs) in the surface sediment of Sanmen Bay, Zhejiang Province, China

In this paper, the distribution, degree of pollution and sources of Cu, Pb, Zn, Cd, Cr, As, Co, Ni and Hg in the surface sediment of Sanmen Bay were studied. The average concentrations of the identified potentially toxic elements (PTEs) were in the following order: Zn > Ni > Cr > Cu > Pb > Co > As>Cd > Hg. Almost all PTEs had a significant positive correlation with TOC, clay and Al; Cr had no significant correlations. Apart from Hg, the contamination levels of 8 PTEs were at those considered to be low-to-no pollution. Comparatively, the contamination level of Hg was much higher than the background value, which indicated moderate pollution. The source of this pollution may have included industrialization, urbanization and/or transport of industrial waste materials. Both geoaccumulation index (Igeo) and potential ecological risk (RI) values suggested that Hg was the major contributor to the ecological risk posed by the selected PTEs.

Source apportionment of the atmospheric Pb using a simulation-based inversion model: A case study from India uncovers bituminous road as the prime contributor of petroleum-derived Pb

This study presents a simulation-based inversion model to estimate the quantitative contribution of Pb from different source materials to aerosols using a set of environmental proxies (206Pb/207Pb and 208Pb/206Pb). The proposed model uses location-specific dataset (206Pb/207Pbaerosol and 208Pb/206Pbaerosol) and a model parameter (a priori) that includes Pb isotopic composition of source materials and their fractional contribution to aerosol. Variability of Pb sources often causes a large spread in a priori values, resulting in erroneous interpretation. The proposed inversion model provides a means to obtain error-optimized and statistically best-fit values for the model parameter (a posteriori) thereby improving our understanding of source apportionment. As an example, the inverse model was appliedin eastern India, where it estimated that Pb-ores, coal, and unleaded petroleum produced up to 46%, 39%, and 36% of atmospheric Pb, respectively. Counter to general belief, the model revealed that a greater proportion of petroleum-derived Pb in the atmosphere was supplied by bituminous road (mechanical abrasion of road material) rather than direct usage of petrol and diesel as fuel. Increasing vehicle density and their activities on Indian roads (from 22 to 44 vehicles km−1 between the years 2005–2017) intensified Pb emissions from road materials to the atmosphere. The inversion model additionally exposed the enormity of Pb contamination in the Indian atmosphere, where the sources such as vehicular emissions, road dust, and industrial emissions (petroleum and Pb-ores) contributed up to 65% of atmospheric Pb. Together, model-derived results (ca. 90% anthropogenic Pb in aerosol), increased use of Pb-emitting raw materials and road vehicles, and the temporal distribution of Pb in aerosols confirm unrestrained Pb emissions continue in India despite the phasing-out of leaded petroleum.

Characteristics and sources of Pb exposure via household dust from the urban area of Shanghai, China

Household dust has been considered as an important pathway for children's environmental Pb exposure. Shanghai was one of the first cities in China that removed Pb from petrol and has been shown in our previous study to have the lowest childhood blood Pb levels in China. This study therefore examines household dust Pb (PbHD) in Shanghai in order to determine the extent and exposure risks of PbHD. Household vacuum cleaner dust samples (n = 40) were collected and analyzed for total Pb concentration, bio-accessible Pb concentration and Pb isotopic compositions (PbIC). The mean concentration of PbHD was 195 mg/kg, which is between 7 and 10 times the Pb concentration of background soil samples from Shanghai. Among the investigated homes, those living in neighborhoods with lower average estate prices have higher dust Pb exposure risks for children. Bio-accessibility of Pb in household dust ranged between 53 and 91%, with a mean value of 71%. Analysis of PbIC of household dust samples (208Pb/206Pb: 2.1096 ± 0.0054; 207Pb/206Pb: 0.8648 ± 0.0025) are a close match to PbIC of coal combustion and solid waste incineration and fit well with those of outdoor air PbIC and urban surface soil PbIC of Shanghai. The study shows that children living in Shanghai are subject to PbHD exposure, with children living in the homes with lower average price having increased susceptibility to PbHD exposure. The data indicate that PbHD is derived primarily from contemporary coal combustion and solid waste incineration rather than common legacy Pb sources (e.g., Pb petrol and paint). Practices including closing doors and windows on days with poor air quality or high wind and preventing shoe wearing inside homes will aid in minimizing outdoor surface soil and ambient particulate intrusion indoors.

Deciphering anomalous Ag enrichment recorded by galena in Dayingezhuang Au(-Ag) deposit, Jiaodong Peninsula, Eastern China

Texture, geochemistry, and in-situ Pb isotope of galena were investigated to probe the origin of anomalous Ag enrichment in the DayingezhuangAu(-Ag) deposit. Silver enrichment postdates the main Au mineralization and occurs in the south of the Dayingezhuang deposit. It is primarily associated with galena and the exsolution of Ag-rich sulfosalts (e.g., matildite) in distal vein-ores related to steeply dipping brittle fractures. Silver-rich galena is characterized by the least radiogenic Pb isotope signature (206Pb/204Pb 17.195–17.258 and 208Pb/204Pb 37.706–37.793), possibly indicating a metasomatized lithospheric mantle or modified lower crustal source for Pb and Ag. Both of these mafic and ultramafic source regions have been previously suggested as Au reservoirs for other Jiaodong Au deposits, implying that the metal reservoir has only a weak control on the uneven Ag-enrichment. Since the Ag-enrichment areas are located in the footwalls of both the Dayingezhuang and Zhaoping faults, the enrichment was most likely dominated by local rotational stress during coeval movements of the two faults in a NE–SW compression and NW−SE extension regime. This work highlights the shallow-crust structural deformation responsible for controlling the flow of late ore-forming fluid resulting in local anomalous metal enrichment.

Heavy metals and Pb isotopes in a marine sediment core record environmental changes and anthropogenic activities in the Pearl River Delta over a century

Heavy metal accumulation in marine sediments is associated with changes in both the natural environment and human activities. This study used heavy metals and Pb isotopes in a precisely dated (by 210Pb and 137Cs) sediment core from the Macao Sea to reconstruct the historical changes in anthropogenic activities and the environment in the western Pearl River Estuary (PRE). The distribution of heavy metals in the sediment core could be divided into four stages (pre-1950, 1950–1976, 1976–2000, and post-2000), which corresponded to the changes in anthropogenic activities and environment of the Pearl River Delta during the past 100 years. The contribution of anthropogenic metals (Pb and Zn) in the sediments increased gradually over time. However, the concentrations, enrichment factors, and fluxes of heavy metals in the sediments all displayed a downward trend since 2010, revealing a decline in metal pollutant input due to strict emission reduction policies implemented in the last decade. The Pb isotopes in the sediments showed a similar trajectory to the heavy metals, reflecting the changes in Pb sources in the sediments at different stages. Based on a binary Pb isotope mixing model, the calculated proportions of anthropogenic and natural Pb in the sediments were 0–50.9% (mean 15.9%) and 49.1–100% (mean 84.1%), respectively, suggesting that the Pb in the PRE sediments is mainly controlled by natural sources.

Evaluation of Soil and Irrigation Water Quality in Caohai Lakeside Zone

Due to the rapid population growth and over-application of fertilizers in the Caohai surrounding farmlands, controlling the non-point source pollution in the Caohai Lakeside Zone is significant for the local ecology balance and human health safety. A total of 54 soil and 24 irrigation water samples were collected in the Caohai Lakeside Zone to evaluate the current status of soil fertility and heavy metal pollution by measuring soil and water heavy metal content and soil physicochemical properties such as soil total nitrogen, total phosphorus, organic matter, and soil pH. These results showed that the total amounts of organic matter, nitrogen, phosphorus, potassium, and effective nutrient content in the Caohai Lakeside Zone were all at a rich level according to Chinese soil nutrient grade standard; the content of lead (Pb), chromium (Cr), cadmium (Cd), mercury (Hg), and arsenic (As) in the soil all exceeds the safety standard of Chinese classification of soil environmental quality assessment. In addition, the over-standard rates of Cd and Cr were 24.1% and 14.8%, respectively. On the whole, the comprehensive quality index (CQI) of the soil in the Caohai Lakeside Zone is 6.48, which is attributed to the heavy Cd pollution and the good soil fertility. The heavy metal content of the irrigation water met the requirements of irrigation water quality. It is feasible to use the irrigation water of Caohai Lake in the actual agricultural production process. Therefore, in terms of the comprehensive management and pollution control of Caohai, special attention should be paid to the control of Cd, Pb, As, and Hg pollution sources.

Relative contribution of environmental medium and internal organs to lead accumulation of wheat grain

Lead (Pb) pollution in wheat has received considerable research attention globally due to its persistence and ease of accumulation, posing severe health risks to humans. This study explored the relative contribution of the environmental medium (atmospheric deposition and soil) and wheat internal organs to Pb accumulation in wheat grains, using field experiments by contrasting treatments. The concentration and bioavailability of Pb in the soil were significantly lower than those of atmospherically deposited Pb (P < 0.05). Pb accumulation rate in wheat grains was consistent with the grain filling rate, which first increased and then decreased, reaching the highest level at the middle filling stage. Pb isotope analysis showed that atmospheric deposition was the main source of Pb in the shoots of wheat plants, contributing more than 80.0% of Pb in grains. Although the roots had the highest Pb concentration, the spikes had the greatest relative contribution (58.4%) to Pb accumulation in the wheat grains, followed by that of the leaves (24.5%), whereas the contribution of roots was the lowest (17.1%) among all plant organs. In addition, among all leaves, the contribution of flag leaves to Pb accumulation in the grain was higher than the cumulative contribution of all other leaves, where flag leaves and other leaves contributed 13.8% and 10.7%, respectively. Collectively, the absorption of atmospherically deposited Pb by wheat spikes is the leading cause of Pb pollution in wheat grains. These results may aid in formulating strategies to reduce Pb concentration in grains and ensure food quality and safety.

Pollution sources identification, health, and radiological risk assessment of naturally occurring radioisotopes and heavy metals in waste dumpsites in Ijebu-Ode, Ogun State, Southwest Nigeria

This study evaluates human health, pollution, and radiological risk assessment of potentially toxic metals (PTMs) (Pb, Cd, Cr, Ni, and Zn), radioisotopes (238U, 232Th, and 40K) and its associated radiological indices from dumpsite soils in Ogun State, Nigeria, using a calibrated atomic absorption spectrophotometer (AAS) and highly shielded γ-ray spectrometry using NaI(TI) detector. Fourier transform infrared spectrometer (FTIR) complemented by X-ray diffraction (XRD) techniques were used to evaluate the mineralogical composition of the soils. Multivariate statistical analysis was used to apportion the source of PTMs and the radioisotopes. The mean concentration of Pb, Cd, Cr, Ni, and Zn obtained were 22.35, 17.95, 20.83, 19.02, and 75.88 mg kg−1, respectively. The activity concentrations of 238U, 232Th, and 40K ranged from 49.71 ± 16.3 − 314.15 ± 55.2, BDL − 87.54 ± 7.38, and BDL − 3721.3 ± 231.6 Bqkg−1, respectively. The values obtained were above the global average value in most of the samples. According to the four-pollution and ecological risk assessment model, the dumpsite soils are strongly to low polluted and enriched with toxic metals in the order Zn > Cr > Pb > Ni > Cd. The estimated carcinogenic risk of the three carcinogenic PTMs for children and adults were higher than the acceptable limit (1 × 10−6). The results of the PCA and HCA results are consistent with the correlation coefficient analysis which showed that mixed natural, anthropogenic and lithogenic sources mainly from aggregation of lead-containing materials in the waste on the dumpsite, vehicular emission and industrial discharges are the main sources of Pb, Ni, and Cd in the three studied dumpsites. Thus, dumpsite soil poses great threat to health, increased pollution and enhances the radiological risk to the general population via human multiple exposure routes.

Security Risk and Influencing Factors of Agro-Products in Farmland Soil Around a Typical Mining Smelter

The security risks of heavy metal pollution in agro-products are becoming increasingly serious. This paper investigated the heavy metal contamination of farmland soils and agro-products around a typical mining smelter in Hunan province, and explored the influencing factors based on principal component and correlation analyses. The results showed that the soils were significantly contaminated by heavy metals, with a mean concentrations of Cd, Cu, Pb, and Zn of 9.12, 358, 303, and 185 mg·kg-1, respectively, pH range from 4.67 to 7.22. All the sites included were under strict control. With regards to the agro-products, the concentration of heavy metal elements were different, and the order of heavy metal concentrations was Zn>Cu>Pb>Cd, with an order of biological enrichment factor(BCF) of Cd>Zn>Cu>Pb. Over-the-standard elements in agro-products included Pb and Cd at 78% and 41%, respectively, which indicated a higher security risk from these products. The accumulation of the same heavy metals in leaf vegetables were generally higher than sweet potatoes and solanaceous vegetables. The heavy metal concentrations in soils corresponded to the first principal component(P<0.01), with the variance reaching 88.0%, which dominated the sources of Cd, Cu, Pb, and Zn in agro-products. The enrichment characteristics were mainly affected by the type of crops, and was also regulated by the soil pH, cation exchange capacity, and soil organic matter(the correlation coefficients of r were -0.407- -0.641, P<0.05). In conclusion, there was a combined heavy metal pollution and high risk in soils and agro-products. Therefore, the planting of crops in the study area should be avoided, and soil remediation measures should be implemented to reduce security risks.

Lead Sources in Perovskite Solar Cells: Toward Controllable, Sustainable, and Large‐Scalable Production

Organic–inorganic hybrid Pb halide perovskites have gained much attention as the most promising next generation photovoltaics, and the certificated power conversion efficiency of perovskite solar cells (PSCs) has recently reached 25.5%. For the typical solution‐processed film, the features of solutes in the precursor solution greatly influence the characteristics of the deposited film. While for Pb‐based perovskites, PbI6 octahedral is the key component of the perovskite framework, and thus the Pb source particularly plays a significant role in determining the crystallization, structural, and optoelectronic properties of the solution‐processed perovskite film. In this review, the state‐of‐the‐art studies that focus on disclosing the key role of Pb source in the performance improvement of PSCs are systematically summarized. In addition, a comprehensive discussion on the effect of various Pb sources (e.g., Pb halides, Pb salts, Pb chalcogens, metallic Pb, and recycled Pb compounds) on the crystallization kinetics and photovoltaic characteristics of perovskite film is given. Also, the significant role of Pb source in producing large‐scale PSCs in a controllable and sustainable manner is highlighted. This review is expected not only to put steps forward for the future commercialization of PSCs, but also to inspire more ideas in many other optoelectronic devices regarding raw material engineering.

Source-to-sink characteristics of the channelized submarine fan system of the Huangliu formation in the Dongfang block, Yinggehai basin, south China sea

Under the guidance of the source-to-sink system model, we conducted multi-scale research, characterizing the provenance features, transport pathway, convergence mode, sand body architecture, and controlling factors of the channelized submarine fan developed in the Huangliuformation, Dongfang block, Yinggehai basin by combining both macro and micro methods. Zircon U–Pb dating, heavy minerals, and source area lithologic geological analysis confirmed that the provenance input for the upper member of the Huangliuformation mainly originated from a northwest mixed provenance system, which includes the Red River, Lam River, and Ma River drainage area. Based on 3D seismic and well logging data, seismic interpretation and sand body tracking were performed to further reveal that the ancient delta sediments were transported along the Yingxi slope and converged on the seafloor in the central depression to form a submarine fan. Detailed seismic sedimentological analysis also confirmed that the submarine fan is characterized by a strong gravity flow channelization. The thickness of the sand body varies significantly and its spatial structure is highly heterogeneous. The channels in the area were divided into four types: main channel, medial channel, migrated channel, and distal channel, according to genetic type and morphological characteristics. The submarine fan system was divided into six stages, exhibiting various channel and lobe developments and distributions. The evolution of the multi-stage channelized submarine fan was closely related to the sediment provenance, sea level rise and fall, and paleogeomorphology. Our research is important for the natural gas field exploration and sand body reservoir evaluation in DongFang block,and have typical case value for deep-water channelized submarine fan deposition in the South China Sea.

Source apportionment of bioaccessible lead in soil reference materials using the continuous on-line leaching method and inductively coupled plasma mass spectrometry

Bioaccessibility (the amount of a contaminant extracted by the gastrointestinal fluids during digestion) is often incorporated in the assessment of contaminated soils and foods. Current methods, including those published by the United States Environmental Protection Agency (US EPA) and United States Pharmacopoeia (USP), use a batch method of analysis which requires hours of extraction prior to instrumental analysis with inductively coupled plasma mass spectrometry (ICPMS). The continuous on-line leaching method (COLM) uses a more direct method of analysis as extracts are sent directly to the ICPMS instrument, which can reduce extraction time and give real-time elution kinetics. For this study, four reference soils (NIST 2710, NIST 2710a, NIST 2711a, and BGS 102) that are typically used with bioaccessibility methods were extracted using the COLM and US EPA and USP gastrointestinal fluids. With the transient time-resolved data from the COLM, differential elution indicating multiple Pb sources was observed in NIST 2710a, NIST 2711a, and BGS 102. Two methods for calculating the Pb isotope ratios to identify these sources included a point-by-point ratio average method and a more precise regression slope method. There was no statistically significant difference between the ratios obtained by these methods of calculation. Furthermore, NIST 2710a and NIST 2711a did not have any statistically significant difference between the Pb isotope ratios of two observed sources. BGS 102 had a significantly different secondary source of Pb, which was identified to be from Pb historically added to gasoline. Investigation into the regions these soil reference materials were sourced from supported this finding as BGS 102 comes from a more densely populated, industrialized area where soil contamination with Pb from gasoline is likely to be more prevalent. This type of bioaccessibility investigation is only possible with the COLM as it gives real time elution information. Incorporation of the COLM into future bioaccessibility studies (and inclusion of other elements for isotopic analysis, like Sr) will lead to more thorough and comprehensive bioaccessibility studies in the future.

Impacts of water-sediment regulation on spatial-temporal variations of heavy metals in riparian sediments along the middle and lower reaches of the Yellow River

The water-sediment regulation scheme (WSRS) of dams influences the desorption, resuspension, and deposition processes of riparian sediments, which in turn affect the spatial-temporal variations of heavy metals (HMs) in riparian sediments and leads to severe degradation of soil and water quality. However, the difference between the trapping effect of dams and the redistribution effects of the WSRS on HMs in riparian sediments, as well as the consecutively seasonal change of HMs after the WSRS, are rarely reported. To fill this gap, the concentrations of six HMs including Cd, Cr, Cu, Ni, Pb, and Zn in riparian sediments along the Xiaolangdi Dam (XLD) Reservoir and its downstream reach were investigated, and the contamination level and potential ecological risk of HMs were assessed, to differentiate the effects of the XLD and its WSRS on the concentration, contamination level, and potential ecological risks of HMs. The results indicated that the mean HM concentrations in riparian sediments were higher than the background values in the study area and showed significant spatial and temporal variations. However, the regional differences of HM concentrations caused by the trapping effect of the XLD were less than the seasonal differences caused by the redistribution effects of the WSRS. The contamination and ecological risk assessment indicated that riparian sediments in the study area were contaminated by the six HMs, particularly by Cd and Pb, which overall exhibited a high and moderate ecological risk, respectively. The sources for Pb were likely agricultural inputs, while the sources for Cd should be attributed to both industrial and agricultural inputs. Overall, the trapping effect of the XLD led to the accumulation of HMs in riparian sediments along the reservoir area, while the regulation effects of the WSRS resulted in the redistribution of HMs in riparian sediments from the reservoir area to the downstream reach.

Superimposing porphyry Mo and vein-type Cu-Pb-Zn mineralization in the Panjiaduan deposit, Great Xing’an Range (NE China): Perspective from zircon U-Pb and sphalerite Rb-Sr dating, geochemistry and S-Pb isotopes

The southern Great Xing’an Range (SGXR) is located in the eastern Central Asian Orogenic Belt (CAOB), and represents the most important Cu-Mo-Pb-Zn polymetallic mineral province in NE China. The Panjiaduan deposit in the SGXR is characterized by superimposing mineralization: (1) porphyry Mo ore hosted by syenogranite, and (2) superimposing vein-type Cu-Pb-Zn ore, hosted by fracture zones in the Manitu Formation volcanics and granodiorite. Two zircon U-Pb ages of 233.9 ± 2.8 Ma and 236.1 ± 2.8 Ma for the syenogranite (porphyry) ore host indicate that the porphyry Mo mineralization occurred in the Late Triassic, coeval with the adjacent Laojiagou porphyry Mo deposit. Sphalerite from the Cu-Pb-Zn ore veins yielded a Rb-Sr isochron age of 138.5 ± 3.5 Ma, suggesting Early Cretaceous overprinting mineralization. The syenogranite is geochemically similar to the ore-causative monzogranite at Laojiagou. They are unfractionated I-type granites, LILE- and LREE-enriched, and HFSE- and HREE-depleted. In addition, their magma source was likely derived from partial melting of the juvenile lower crust. Major sulfides (pyrite, molybdenite, and galena) from the porphyry ores have slightly lower δ34S values (−2.8 to −0.3 ‰) than the vein-type ore sulfides (pyrite, chalcopyrite, sphalerite, and galena) (1.5 to 5.3 ‰), although they are all close to the mantle δ34S values and thus suggests a magmatic sulfur source. Meanwhile, the Pb isotope compositions of the two ore types suggest that the Pb for the porphyry mineralization was likely derived from an orogenic Pb reservoir, while the latter may have crust-mantle mixed Pb source. We suggested that both mineralization events were formed in an extensional setting, induced by the post-collision tectonics after the Paleo-Asian Ocean closure and the Paleo-Pacific subduction rollback, respectively.

XRD and UV-Vis Spectroscopic Studies of Lead Tin Sulphide (PbSnS) Thin Films

The effects of deposition cycles on the structural and optical properties of lead tin sulphide (PbSnS) thin films have been described. Successive ionic layer adsorption and reaction (SILAR) method was used to deposit the ternary material on soda-lime substrates. In the present work, the PbSnS films were grown using lead nitrate, tin chloride dehydrate and thioacetamide solutions as sources of Pb, Sn and S, respectively. XRD measurements revealed that the deposited films were polycrystalline in nature with strong adherent to the substrates. The transmittance was found to be high in the near infrared regions of the electromagnetic radiation and, also increased with deposition cycles. The band gap energy was found to vary from 1.70 to 1.75 eV for 10 and 35 deposition cycles. The study indicates that SILAR is an excellent method in depositing good quality films for device applications. HIGHLIGHTS SILAR is an excellent technique for depositing thin films of lead tin sulphide (PbSnS) Deposition cycles influences the XRD and optical properties of PbSnS thin films PbSnS thin films are useful for solar cell fabrications The band gaps of the PbSnS varies from 1.70 to 1.75 eV with deposition cycles

Source tracing of potentially toxic elements in soils around a typical coking plant in an industrial area in northern China

Coking plants are a substantial source of potentially toxic elements (PTEs) in soil. In this study, we examined the concentration of PTEs, the soil physicochemical properties, and the Pb isotopes in the soil inside and around a coking plant in an industrial city in northern China. We analyzed the spatial distribution of PTEs and the pollution risk areas by Igeo index, the enrichment factor (EF), and the Nemerow index, and we quantitatively identified the contribution of PTE pollution sources in the soil on a small- and medium-scale (plant and work section). Our results indicated that the Hg concentration inside the plant and the Cd concentration in the agricultural land around the plant were both relatively high. A comprehensive analysis of the soil in the study area was performed using the positive matrix factorization model and Pb isotope (206/207Pb, 208/206Pb) tracing method, based on the MixSIAR model, this analysis indicated that burning coal was the main source of Pb both inside (46.8%) and outside (26.3%) the coking plant. The pollution emission sources with significant influence on the soil outside the coking plant were diesel vehicles (12.5%), gas tanks (12.4%), and coke ovens (11.5%), while the sources inside the plant were quenching sections (11.1%), atmospheric deposition (11.0%), coke oven sections (9.6%), and diesel vehicles (6.1%). The results of PTE pollution risk zoning and Pb isotope tracing indicated that pollution is more serious in the western part of the plant, which is the area where coking and gas production takes place, and the most serious pollution outside the plant is mainly distributed to the southeast. This study provides theoretical and practical data indicating the contribution of industrial enterprises to soil pollution, and will help identify pollution responsibility and the management of pollution sources.

Determinants of blood and saliva lead concentrations in adult gardeners on urban agricultural sites

Soil Pb concentrations at urban agriculture sites (UAS) commonly exceed recommended safe levels. There is a lack of evidence regarding uptake of Pb by gardeners using such sites for food crops. Our study aimed to elucidate whether gardening in soil with raised Pb levels results in Pb body burdens of concern to health, and to assess confounding factors influencing Pb body burden. Our cross-sectional case study measured Pb in saliva and blood of UAS gardeners (n = 43), soil and produce samples from their UAS, and home tap water. Blood and saliva Pb concentrations were compared with those from non-UAS gardener controls (n = 29). A health risk threshold of 5 µg dL−1 blood Pb level (BLL) was selected in keeping with international guidance. Detailed surveys investigated individuals’ anthropometrics and potential Pb exposures from diet, and historic and everyday activities. Saliva was not found to be a suitable biomarker of adult Pb exposure in this context. Predictors of higher BLLs were being older, being male and eating more root vegetables and shrub fruit. Eating more green vegetables predicted a lower BLL, suggesting a protective effect against Pb uptake. UAS gardeners’ BLLs (geometric mean 1.53; range 0.6–4.1 µg dL−1) were not significantly higher (p = 0.39) than the control group (geometric mean 1.43; range 0.7–2.9 µg dL−1). All BLLs were below 5 µg dL−1 except one resulting from occupational exposure. Having paired the UAS gardeners with closely matched controls, we found Pb in UAS soils (with range 62–1300 mg kg−1from common urban sources) unlikely to pose an additional risk to adult health compared to their neighbours who did not access UAS. As such, other Pb sources may be the dominant factor controlling BLL.

Geographical drivers of geochemical and mineralogical evolution of Motianling peatland (Northeast China) exposed to different sources of rare earth elements and Pb, Nd, and Sr isotopes

Geochemical shifts triggered by surface runoff and atmospheric fallout in a Chinese peatland were investigated by using Pb, Sr, and Nd, REE and by SEM mineralogical analysis. Motianling peatland (Northeast China) is located at 1670 m a.s.l., near the China–Mongolia border. Based on division of profile into two phases of different trophy, the total ∑REE value determined for the minerotrophic part of the profile (from 62 to 46 cm) varied from 67 to 31 mg·kg−1 and mineralogical analysis revealed the occurrence of weathered volcanic rocks, supported by a high εNd value (−3.26). After the transition from minerotrophic to more ombrotrophic conditions, the peatland became independent of the local bedrock weathering, which was manifested by a much lower concentration of REE (7–20 mg·kg−1) and lower εNd values (−7.37; −8.11). Moreover, PAAS-normalized pattern of REE distribution in the bottom part revealed the highest Eu/Eu* value (1.24), as well as a slight enrichment in Eu. The anthropogenic effect was visible from 1964, during which period the spheroidal aluminosilicate particles (SAP), produced by coal-fired power-plant activity, appeared for the first time, followed by an abrupt decrease in 206Pb/207Pb isotopic signature to 1.167. The dimensions of SAP (~1.5 μm), as well as the time of first appearance, indicated long-range transport. The REE ratios obtained in this study are characteristic of the eolian deposition signature, which is like the Gobi and northern Chinese deserts. The anthropogenic activity was manifested by a slight enrichment in Gd during reduced delivery of natural dust. Both, North Chinese and Asian part of the Russian industry supply anthropogenic dust. Topography, wind direction, and patterns of precipitation, as well as the initial phases of Asian industrial development, are the most important drivers promoting the deposition of chemical elements.