Smelter Area Research Articles

Structural-functional aberrations of erythrocytes in the northern red-backed vole (Clethrionomys rutilus Pallas, 1779) that inhabits the zone of influence of the copper smelter (the Middle Ural).

Red blood cell parameters were assessed in a natural population of the northern red-backed vole (Clethrionomys rutilus Pallas, 1779) in the zone of influence of the Kirovgrad Copper Smelter along a gradient of pollution by heavy metals (Cu, Zn, Cd, and Pb) at three catching sites (polluted [Imp] and controls [Bg-1, and Bg-2]). The difference of the smelter area (Imp group of voles) from both background groups (Bg-1 and Bg-2) was proven by means of a set of 13 parameters in univariate and multivariate analyses. Among the detected erythrocyte disturbances, we noted the following: a decrease in activities of Na+,K+-ATPase and antioxidant enzymes (SOD, GSH-Px, and CAT); an increase in the concentration of lipid peroxidation products, in osmotic fragility, and in intravascular hemolysis; interruption of carbohydrate metabolism; and lowered oxygen-carrying capacity. A higher load of Cd (p = 0.0009) and possibly Pb (p = 0.054) in the Imp animals was confirmed by quantitation of heavy metals in the liver. Most erythrocyte parameters (11 out of 13) covaried with individual Cd load by obeying a semilogarithmic dependence; such a relation was not found for Cu, Zn, and Pb. A decrease in the growth rate of structural and functional erythrocyte aberrations ("resistance improvement") with increasing cadmium load is probably due to compensatory enhancement of the synthesis of metallothioneins in the liver and kidneys and hence a greater proportion of Cd bound to metallothioneins. Problems of differences/similarities in Cd-associated reactivity among the animals are discussed too, taking into account the catching sites (polluted [Imp] and controls [Bg-1, and Bg-2]) and reproductive-age (i.e., immature underyearlings, mature underyearlings, and individuals that overwintered). The persistence of differences in erythrocyte status observed by us between the Imp and background groups after normalization to Cd load may be due to the action of other (unexamined) adverse factors and calls for further ecotoxicological studies.

Associations between co-exposure of metals and the renal tubular damage of the residents in the metal contaminated smelter area

Background and aim: The effects of metals to renal tubular damage have been mostly reported for individual metals. We investigated non-linear effects of multiple metals for renal tubular damage and interactions among metals of the real population living near the metal contaminated smelter area. Methods: A total of 120 individuals were included for urine sampling and survey in the Forensic Research via Omics Markers(FROM) study. Nine metals(V, Cr, Mn, Ni, Mo, Cd, Sb, Pb, and Hg) in urine were analyzed by inductively coupled plasma-mass spectroscopy and mercury analyzer. Beta-2-microglobulin(β2-MG) and N-acetyl-β-D-glucosaminidase(NAG) were applied as renal tubular damage markers. We compared the difference between the single-metal models and the multiple-metal models. And Bayesian kernel machine regression(BKMR) was conducted to examine the joint effects of multiple metals on renal tubular damage, interactions among metals and non-linear dose-response effects. Results: V for β2-MG, and Hg and Cd for NAG were consistently significant in both simple and multiple linear regression, though Ni for β2-MG was significant only in the multiple linear regression model. Mn for NAG was significant only in the single linear regression model. The BKMR analysis showed that the co-exposure of metals was significantly increased only NAG and Hg contributed the most to the NAG(PIP, posterior inclusion probability=0.608). β2-MG was increased by co-exposure of metals but not statistically significant and V contributed the most to the β2-MG(PIP=0.704). Conclusions: This study suggests that co-exposure of metals was significantly associated with NAG. The interaction among metals for renal tubular damage was not shown but further study is needed. Keywords: Metals, Co-exposure, Kidney damage, BKMR, Metal exposure The Korea Environment Industry and Technology Institute through the Core Technology Development Project for Environmental Disease Prevention and Management, funded by the Korea Ministry of Environment (grant number 2021003320003).

Source apportionment based on lead isotope ratios: Could domestic dog's blood lead be used to identify the level and sources of lead pollution in children?

Domestic dogs have been proved to be used as “sentinel organisms” to monitor human lead exposure. However, whether dogs' blood can be used to identify the levels and pollution source of children's lead exposure still needs evidence. To evaluate the potential use of domestic dogs' blood lead as an indicator of lead exposure levels and pollution source of children, accompanying with potential environmental media samples, lead concentrations and isotope ratios (expressed as 207Pb/206Pb, 208Pb/206Pb) in blood were investigated and compared between children and dogs, who came from a Pb–Zn smelter area, a coal fired area and a control area without industrial activity. The results showed that there were significant correlations in blood lead levels (BLLs) between children and dogs in the study areas (p < 0.01). The lead isotope ratios (LIRs) in blood of children and dogs were disparate among the three areas, however, the LIRs of dogs were quite correlated with those of children in each area (p < 0.01). With the comparison of LIRs between potential pollution sources (slag, ore, coal, paint) and blood samples, the identified lead sources based on dogs' blood were found to be coincident with those based on children's blood. Ore smelting and coal combustion were the main sources of lead exposure for the dogs and children in the smelting area, and coal combustion was the predominant source for the children and dogs living in the coal burning area and control area. The results showed that dogs' BLLs might be used to estimate children's BLLs, and blood LIRs measurements of dogs' could be used as an alternative for identifying the sources of children's lead exposure. This study further provided relevant evidence for dogs to be sentinels exposed to human lead exposure and an alternative method for source apportionment of children's lead exposure.

Metal contamination in soils and windowsill dusts: implication of multiple sources on dust metal accumulation within a city affected by Pb smelting.

The accumulation of total Pb, Cd, Cu, and Zn in soils (0-5cm) and windowsill dust fractions (45-125, 10-45, and < 10μm), and soil pollution indices (PI), were investigated in a long-term (~ 70years) Pb smelter area and in the nearby urban city of Jiyuan, China. Principal component analysis (PCA) was utilized to identify metal contamination sources. Results showed that mean soil Pb, Cd, Cu, and Zn concentrations in the smelter area were 803, 13.8, 118, and 323mgkg-1, while those of the urban area were 270, 7.95, 51.6, and 244mgkg-1, respectively. Lead and Cd had greater soil PI than Cu and Zn. Lead concentrations in the 45-125, 10-45, and < 10-μm urban dust fractions ranged from 197.1 to 1953 (mean 1020), 202-3962 (2407), and 51.1-1258 (310.7) mg kg-1, while Cd concentrations ranged from 11.1 to 111 (49.2), 10.4-159 (64.3) and 21.5-131 (60.0) mg kg-1, respectively. Excessive Zn concentrations (5000-22,000mgkg-1) in some urban dust samples were found at two sampling sites, while Zn concentrations were < 2600mgkg-1 in all other samples. Based on PCA results, metal accumulation near the Pb smelter was dominated by smelting activities. The PCA results further suggested that mass vehicular transportation modes may be an important source of metals such as Cu and Zn in the urban area. Certain samples in both sub-areas had unsafe potential non-carcinogenic risks of Pb for children. These findings suggest that reducing environmentally relevant metal concentrations in this, and similar areas, will likely require a multi-faceted approach.

The Effect of Smoking Habits on Blood Cadmium and Lead Levels in Residents Living Near a Mining and Smelting Area in Northwest China: a Cross-Sectional Study.

Few studies have focused on environmental cadmium (Cd) and lead (Pb) exposure while exploring the effect of smoking on blood Cd (BCd) and blood Pb (BPb) levels. Moreover, essential trace elements affect the absorption, accumulation, and toxicity of Cd and Pb. To investigate the effect of smoking on BCd and BPb levels under high Cd and Pb exposure and the influence of essential trace elements on the effect, 301 residents living near a mining and smelting area in Northwest China were included in our study. After collecting health information and measuring BCd, BPb, serum iron, magnesium, and total calcium levels, we analyzed the association between smoking and BCd and BPb levels and the influence of the essential trace elements on the association. The results showed that BCd and BPb levels in smokers were significantly higher than those in non-smokers. There was a dose-response association between pack-years and the odds ratios (ORs) of high BCd and BPb levels in all participants compared with non-smokers. Serum iron, magnesium, and calcium had a negative effect on the elevations of the ORs of high BCd and BPb levels. In addition, smoking-related elevations of BCd and BPb levels vary by sex, age, BMI, and age of smoking initiation. Our findings present evidence for the effect of smoking on BCd and BPb levels under high Cd and Pb exposure and may provide guidance for the prevention and control of BCd and BPb elevations in residents living in Cd- and Pb-polluted areas.

Analysis of the Characteristics of Heavy Metal Elements in Soil Around the Smelting Area of Pasuruan Industrial Estate, Indonesia

Abstract Smelting plant is an activity that produces emissions in the form of heavy metal particulates that can cause pollution and are harmful to human health in excessive concentrations. This research was conducted to determine the heavy metals’ characteristics in the soil around the metal smelting area of Beji industrial area, Pasuruan, Indonesia. A total of 33 soil samples were collected at 200 m, 500 m, 2km and 5km from the metal smelting area. The concentrations of heavy metals Zn (669.47 - 63.25 mg/kg), Cd (94.88 - 40.30 mg/kg) and V (198.98 - 108.19 mg/kg) in the soil were determined by using EDXRF Spectrometer Minipal 4. The concentration of zinc reduces with distance from an industrial region. The amounts of cadmium and vanadium did not change considerably with distance. Then the potential pollution risks of heavy metal in the soil were evaluated by method of assessment of heavy metal contaminations in soil. These Cf values indicated that the assessment of heavy metal contamination in soils from smelters was category: Indicates no contamination, suspected contamination, slight contamination and extreme contamination.

A comprehensive exploration on the health risk quantification assessment of soil potentially toxic elements from different sources around large-scale smelting area.

Non-ferrous metal smelting activities have always been considered as one of the foremost anthropogenic sources of potentially toxic elements (PTEs). The enrichment factor (EF) and pollution load index (PLI) were used to evaluate the pollution level of soil PTEs; positive matrix factorization (PMF), correlation analysis, and geostatistics were utilized to quantify the sources of soil PTEs; and potential ecological risk (PER) and human health risk (HHR) of different sources from farmland, construction land, and natural land were quantifiably determined via combined PTE sources with PER and HHR assessment models. Taking the smelting area of Daye City as an example, the evaluation results of EF and PLI showed that the soil PTE pollution in the study area was serious, especially Cd and Cu. And four sources were quantitatively allocated as agricultural practices (12.14%), traffic emissions (23.07%), natural sources (33.46%), and industrial activities (31.33%). For PER, industrial activities were the largest contributor to PER, accounting for 55.66%, 56.30%, and 55.36% of farmland, construction land, and natural land, respectively, and Cd was the most dangerous element. In terms of HHR, industrial activities were also the cardinal contributors under the three land use types. Children were exposed to serious non-carcinogenic risks under three land use patterns and slight carcinogenic risk in construction land (1.06E - 04). Significantly, the carcinogenic risk of children in farmland (9.06 × 10-5) was very close to the threshold (1 × 10-4), which requires attention. Both non-carcinogenic and carcinogenic risk for adults were all at acceptable levels. The health risks (carcinogenic and non-carcinogenic risks) of children from four different sources were distinctly higher than those of adults. Consequently, strict management and control of industrial activities should be given priority, and the management of agricultural practices should not be ignored.

Understanding the excretion rates of methylmercury and inorganic mercury from human body via hair and fingernails

Effective biomarkers are necessary to better understand the human mercury (Hg) exposure levels. However, mismatched biomarker sampling method causes extra uncertainty in assessing the risk of Hg exposure. To compare the differences between hair and fingernail, and further understand the excretion rates of methylmercury (MeHg) and inorganic mercury (IHg) via hair and fingernails, the total mercury (THg), MeHg, and IHg concentrations in paired hair and fingernail samples were investigated through paired samples collected from two typical mining areas, Wanshan mercury mine area (WMMA) and Hezhang zinc smelting area (HZSA). The positive correlation in THg, MeHg, and IHg concentrations (p <0.01) between hair and fingernail samples indicated that those two biomarkers can be corrected in application of assessing human Hg exposure. Compared to fingernails, the hair was suggested to be a more sensitive biomarker as the concentration of THg, MeHg and IHg were 2 ∼ 4 times higher than those in fingernails. Furthermore, the amounts of THg, MeHg, and IHg excreted via hair were 70 ∼ 226 times higher than that excreted via fingernails, and the hair plays a more important role than fingernails in the excretion of Hg from human bodies. Present study therefore provides some new insights to better understand the fate of human assimilated Hg.

Uptake, organ distribution and health risk assessment of potentially toxic elements in crops in abandoned indigenous smelting region

Inorganic pollution induced by smelting waste has threatened the safety of environment, whereas the impacts on farmlands with regards to potentially toxic elements (PTEs) receive insufficient attention. Herein, the contents, transfer pathways and potential risks of the PTEs in common crops were examined from different farmlands distributed around an indigenous Zn-smelting area in Guizhou, China. The results showed that Tl in cabbage (Brassica oleracea L.) (up to 3.74 mg/kg) and radish (Raphanus sativus L.) (up to 1.16 mg/kg) at some sites exceeded the maximum permissible level (MPL) (0.5 mg/kg) for food, and, under the same pollution condition, cabbage and radish were more likely to enrich PTEs, and the edible portion of maize was not prone to Tl risk. Hazard quotient calculations of Tl, Ba, and U were greater than 1, indicating the edible risk of crops for these PTEs. Further characterization of selected soils revealed that MnFe2O4 and Fe2O3 controlled the phase transformation of Tl(III) in rhizospheric soils. Furthermore, distinctive mullite was detected in the soil which confirmed the contribution of high temperature smelting to PTEs pollution. The findings indicate an emergent need for soil remediation around historical indigenous metal smelting areas for the sake of food security.

The Effects of Lead and Cadmium Co-exposure on Serum Ions in Residents Living Near a Mining and Smelting Area in Northwest China.

In this study, we investigated the associations between cadmium (Cd) and lead (Pb) co-exposure, and serum ion levels in two populations living near a mining/smelting area and a nature reserve (control area), respectively. A total of 445 participants were included in this study. Their blood cadmium (BCd), blood lead (BPb), and serum ion levels were determined, and the association between exposure levels and serum ion levels was analyzed. The exposure levels of subjects living in the polluted area were significantly higher (p < 0.001). Lower levels of potassium, inorganic phosphorus, and iron were observed in subjects from the polluted area, whereas their sodium and chloride levels were higher (p < 0.01). The anion gap in their serum was also significantly lower. We observed positive dose-effect relationships between Cd and/or Pb exposure and serum sodium and chloride, and negative dose-effect relationships between Cd and/or Pb exposure and serum inorganic phosphorus, iron, as well as the anion gap. High Cd-Pb, high Cd, and high Pb exposure led to modification effects in potassium, calcium, inorganic phosphorus, and iron levels, and the anion gap. No synergistic effects were observed in our results. In conclusion, our data demonstrate that Cd and Pb exposure, alone or in combination, can lead to serum ion imbalances.

Distribution characteristics and potential pollution assessment of heavy metals (Cd, Pb, Zn) in reservoir sediments from a historical artisanal zinc smelting area in Southwest China.

Reservoir sediment contamination with heavy metals produced by mining activities has aroused widespread global concern owing to its potential threat to human health. In this study, the total concentrations and speciation of heavy metals (Cd, Pb, Zn) in the Lexi (LX) and Maoshui (MS) reservoirs around the historical artisanal zinc smelting area in Southwest China were determined, and pollution indices were applied to assess the pollution levels and potential ecological risks of the two reservoirs. The results showed that all the detected samples in the two reservoirs presented significant metal accumulation, especially for Cd, as compared with the soil background values in Guizhou Province. Between the two reservoirs, the vertical distribution characteristics of each metal in sediment columns were similar. The heavy metal concentrations of the three columns in the LX reservoir reached their maxima at 35, 15, and 10cm and showed a trend of first increasing and then decreasing overall. However, the heavy metal contents of the three columns in the MS reservoir all exhibited wave-like characteristics in the vertical direction, and all of them reached a relatively obvious high point at approximately 5 and 30cm. The geoaccumulation index (Igeo) and potential ecological risk index (RI) indicated that Cd was strongly enriched and represented the main risk factor, and the pollution level of the MS reservoir was significantly higher than that of the LX reservoir. Furthermore, the effect coefficients (ERMQ) confirmed that the two reservoirs are likely to have toxic impacts on aquatic organisms and need to be controlled and mitigated. The speciation analysis of heavy metals revealed that Cd was primarily in the acid-extractable fraction (69.57%, 68.28%), Pb was chiefly in the reducible fraction (55.24%, 42.18%) and oxidizable fraction (22.60%, 38.02%), and Zn was mainly in the oxidizable fraction (32.54%, 37.65%) in the LX and MS reservoirs, respectively. The ratios of the secondary phase and primary phase (RSP) and risk assessment code (RAC) evaluation demonstrated that Cd in the sediments of the two reservoirs presents a very high potential ecological risk, and Pb and Zn were at medium to high ecological risk levels. This study highlighted that the artisanal zinc smelting activities had caused serious heavy metal pollution in reservoir sediments, posing a threat to the local ecological environment.

Soil microbial community responses to the application of a combined amendment in a historical zinc smelting area.

Farmland soils that surround a historical zinc smelting area in northwestern Guizhou, China, are characterized by high levels of heavy metal accumulation. Previous studies have mainly focused on the potential risk evaluations of heavy metals in soil and crops. However, at present, the effects of amendment applications on the bioavailability of heavy metals and on microbial community in the heavily contaminated soils of the mining region are still unclear. A pot experiment was conducted to determine the effect of applying a combined amendment (e.g. lime, sepiolite, and vermicompost) on the diversity and composition of microbial community in the contaminated soil. The results showed that the contents of DTPA- and TCLP-extractable heavy metals (e.g. Cd, Pb, and Zn) decreased and that the pH, SWC, EC, and soil available nutrient (e.g. AN, AP, and AK) contents increased after the application of the combined amendment. Furthermore, application of the combined amendment decreased the diversity of soil bacterial and fungal communities and increased the relative abundances of the dominant bacterial and fungal communities such as Proteobacteria, Bacteroidetes, and Ascomycota; however, the relative abundances of Acidobacteria and Actinobacteria decreased. Redundancy analysis (RDA) and structural equation model (SEM) analysis showed that the bioavailability of heavy metals decreased and that soil physicochemical characteristics improved and had positive or negative effects on the diversity and composition of soil microbial community.

Simulating and mitigating extreme urban heat island effects in a factory area based on machine learning

Urban heat islands (UHIs) have caused radical changes in urban climates. However, the extreme UHI (E-UHI) formed in factory areas deserves more attention. To mitigate the E-UHI, machine learning is used for simulating and quantifying the marginal utility of the scale, shape, type, stage, and structure of the factory on the land surface temperature (LST), factory LST (LSTf), surrounding LST (LSTs) and increase value (ΔLST) level. The results show that the scale of all types of factories affects LSTf and LSTs, and the shape of steel factories affects LSTs and ΔLST. The LST in factories that require high-temperature environments (e.g., smelters) is significantly higher than that in other factories (e.g., sales plants). The ΔLST of green space (GS), staff activity ground (SG), material transfer ground (MG), material storage area (MA), factory building (FB), smelting area (SA) and casting building (CB) are 3.95 °C, 4.01 °C, 5.08 °C, 5.15 °C, 5.24 °C, 5.49 °C and 7.32 °C, and their optimal ranges are 8.84%–15.09%, 16.65%–25.52%, 3.91%–35.91%, 0.00%–8.70%, 5.06%–13.60%, 23.33%–48.02%, and 0.00%–5.73%, respectively. Appropriately standardizing the scale and shape, controlling the temperature of the high-temperature generation stage, reducing the proportion of CB, MG and MA, and increasing the proportion of GS and SG are effective ways to alleviate the E-UHI. The findings provide theoretical guidance for resource-based cities to mitigate E-UHIs.

A comprehensive exploration on pollution characteristics and health risks of potentially toxic elements in indoor dust from a large Cu smelting area, Central China.

Large-scale smelting activities release large amounts of potentially toxic elements (PTEs) in fine particles. These particles floating in the air eventually settle on leaves, roads, and even indoors. In smelting areas, indoor environments are generally considered relatively safe. However, these areas are not taken seriously and need to be assessed. This paper systematically studied pollution characteristics, main sources and health risks of ten potentially toxic elements, PTEs (Mn, Ni, Cu, Zn, Hg, Cd, As, Cr, Pb, and Tl), of dust samples from different indoor environments in smelting areas using various methods. Therefore, this study analyzed dust samples from 35 indoor environments. The enrichment factors showed that the indoor dust samples were extremely enriched by Cd and Cu and significantly enriched by Hg, Pb, As, and Zn. The result of the spatial distribution showed that the high-value PTEs were mainly distributed near the Cu smeltery. Three sources were quantitatively assigned for these PTEs, and they were industrial smelting and traffic activities (44.40%), coal-fired activities (18.11%), and natural existence (37.49%). Based on the calculation of health risk, the value of THI for children was 7.57, indicating a significant non-carcinogenic risk. For carcinogenic risk, the values of TCR for children and adults were 2.91×10-2 and 2.97×10-3, respectively, which were much higher than the acceptable risk value 1×10-4. Combining health risk assessment with source discrimination, we found that the industrial discharges and traffic activities were the most main source of non-cancer and cancer risks. Therefore, smelting activities should be more strictly monitored, and traffic emission management should be strengthened.

New Insights into Selenium Enrichment in the Soil of Northwestern Guizhou, Southwest China.

Selenium (Se) is an essential trace element for animals and plants. Se in soil has an important influence on the Se intake by animals and plants. To explore the source of Se in soils of the zinc-smelting area in northwest Guizhou, China, 271 topsoils and 50 deep soil samples were collected, and the concentration, speciation and distribution of Se in soils were analysed. The results showed that the concentration of Se in topsoils ranged from 0.2mg/kg to 1.79mg/kg, with an average of 0.84mg/kg, which was more than 2 times of that in deep soil. These observations indicated that Se was enriched in the surface layer of soil. In terms of spatial distribution, high-Se topsoils (> 1.0mg/kg) were mainly distributed near the zinc smelting area, and topsoil samples with relatively low content of Se were mainly distributed in areas with less human activities influence. The Se occurrence species in topsoils were in the order of residue, organic-binding, humic-acid binding, water-soluble, Fe/Mn/Al oxide-binding, carbonate-binding and ion-exchange. The contribution of residual Se to total Se in topsoil was decisive, and the content of other species of selenium changed slightly. The Se speciation that was residual in soil is difficult for plants to utilize, which is consistent with previous studies on seleniferous soils caused by zinc smelting. These results indicated that the main reason for Se enrichment in the topsoils of northwest Guizhou Province was indigenous zinc smelting.

Reservoir sediment records of polymetallic contamination (Cd, Pb, Zn, As, Hg) in the zinc smelting area of Weining County, Guizhou Province, China

Reservoir sediment records of polymetallic contamination (Cd, Pb, Zn, As, Hg) in the zinc smelting area of Weining County, Guizhou Province, China

Fish, rice, and human hair mercury concentrations and health risks in typical Hg-contaminated areas and fish-rich areas, China

Human exposure to methylmercury (MeHg) from consuming contaminated fish has been a major concern for decades. Besides, human MeHg exposure through rice consumption has been recently found to be important in some Asian countries. China is the largest country on mercury (Hg) production, consumption, and anthropogenic emission. However, the health risks of human Hg exposure are not fully understood. A total of 624 fish, 299 rice, and 994 human hair samples were collected from typical Hg-contaminated areas and major fish-rich areas to assess the health risks from human Hg exposure in China. Fish and rice samples showed relatively low Hg levels, except the rice in the Wanshan Hg mining area (WMMA). Human hair total Hg (THg) and MeHg concentrations were significantly elevated in WMMA, Zhoushan (ZS), Xiamen (XM), Qingdao (QD), and zinc smelting area (ZSA), and 85% of hair samples in WMMA, 62% in ZS, 40% in XM, 26% in QD, and 17% in ZSA had THg concentrations exceeding the limit set by the USEPA (1 μg/g). Rice consumption was the main pathway (>85%) for human MeHg exposure in the studied Hg-contaminated areas. Meanwhile, fish was the primary human MeHg exposure source (>85%) in coastal cities. Therefore, soil remediation in typical Hg-contaminated areas and scientific guidance for fish consumption in coastal provinces are urgently needed to reduce the health risks from human Hg exposure in China.

Assessment of Airborne Lead Provenance in Northern Ontario, Canada, Using Isotopic Ratios in Snow and Cladonia rangiferina Lichens

Fresh snow and lichens (Cladonia rangiferina) were collected along two ~300-km transects in a regional survey around two smelter areas in Northern Ontario, i.e., the Sudbury and Timmins areas, in 2009–2010, as a part of a monitoring program. The samples were analyzed for Pb isotope ratios in snow from 47 sites, and in lichens from 28 sites, for background airborne lead and to determine the influence of distance versus local sources of Pb on a regional scale. Moreover, the lichen samples were split into two portions, the top portion, corresponding to recent growth (2–4 years), and the lower portion (up to 10+ years old) to determine the regime of recent versus old deposition. The study also investigated whether the isotopic signature in fresh snow (~1–2 weeks old) could correlate to the lichens’ recent growth. The Pb isotope signatures, reported as Pb isotope ratios 208Pb/206Pb and 207Pb/206Pb, in both snow and lichen recent growth were uniform over the region, except for localized influences near Sudbury and Timmins, suggesting that the background Pb represented remote sources for most of the region. Three-isotope plots 208Pb/206Pb versus 207Pb/206Pb of snow and lichens followed a linear model typical of mixing lines between two sources. As there are no statistical differences of Pb isotope ratios between fresh snow and recent lichen growth at neighboring stations, either type of sample may be used to describe the short-term record of airborne inputs. Finally, we found a strong relationship between the Pb isotope ratios of the recent growth (upper part) and old growth (lower part) of the lichens, with a slope of 0.9 between the lichen parts. This observation suggests either an isotopic segregation or the older parts of the lichens developed under different Pb source inputs in earlier times.

Heavy Metal(loid)s Contamination in Ground Dust and Associated Health Risks at a Former Indigenous Zinc Smelting Area.

Indigenous zinc smelting (IZS) is a backward technique that releases a great deal of heavy metal(loid)s into the environment. However, the contamination of heavy metal(loid)s in ground dust and the associated health risks in such areas are poorly known. In this study, a former IZS area in Guizhou, China, was surveyed during 2008–2018 with 15 elements (Ag, As, Bi, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Sb, Sn, Tl, Zn) being analyzed. The results indicate that most elements (e.g., Ag, As, Cd, Cu, Pb, Sb, Sn, Zn) in ground dust decreased significantly after the cessation of the IZS in 2006; nevertheless, some elements still remained at relatively high levels in 2018, e.g., Pb (average: 762 ± 647 mg/kg), Zn (average: 1287 ± 753 mg/kg), Cd (average: 7.76 ± 5.06 mg/kg), and As (average: 41.9 ± 34.8 mg/kg), indicating they might come from the local contaminated soils, slag residues and smelting potteries. In terms of the impacts on human health, children have both higher non-carcinogenic and carcinogenic risks than that of adults, with the latter subpopulation having a lower risk than the threshold values. Pb and As were the two elements with the highest non-carcinogenic risk for children, the hazard index of local children was still higher than the threshold of 1 (e.g., 1.43 for As, 2.09 for Pb) in 2018. The carcinogenic risk of As exposure to children dropped more than two times to 6.42 × 10−7 in 2018, which falls below the tolerable range (10−6–10−4). This study revealed that although the concentration of heavy metal(loid)s in ground dust and linked health risk in the IZS area has reduced dramatically after the cessation of IZS, continued removal of slag residues and smelting potteries is necessary for further decreasing the human health risk.

Distribution Characteristics of Heavy Metals and Pb Isotope in Profile Soils from a Mining and Smelting Area in Northwestern China

The distribution characteristics of typical heavy metals (HMs) and Pb isotopic compositions in profile soils from different areas were investigated in Baiyin district, northwest China. The soil samples from the ore district and the sewage irrigation area showed an obvious enrichment of HMs in different depths, and the difference in the longitudinal migration depth of Pb, Cu, Zn, and Cd was insignificant, which might be due to the migration behavior of HMs mainly controlled by carbonate in alkaline soil. With the sewage irrigation activities, the content of soil organic matter was no longer the main controlling factor for the migration behavior of HMs. In ore district and sewage irrigation area, the HMs contents of nonresidual fractions in topsoil were much higher than that in the corresponding deep soil, which indicated that HMs activities in topsoil were significantly high. The Pb isotopic compositions of profile soils indicated that the long-term mining and smelting activities remained the main source of vertical enrichment of HMs in Baiyin district. Moreover, the Pb isotope ratios 206Pb/207Pb of nonresidual fractions (1.1359-1.1916) were all lower than that in the corresponding residual fractions (1.1641-1.2010), showing the characteristics that HMs input from anthropogenic source were in different degrees. The Pb isotopic compositions of residual fractions in the topsoil of ore district and sewage irrigation area (1.1641 and 1.1703) were between the two end-members composed of background soil and local mineral samples, which suggested that some anthropogenic HMs might enter into the residual components in the soil that was greatly affected by the input of HMs.