Source Of Pb Research Articles

Winter-time pollution in Central European cities shifts the 208Pb/207Pb isotope ratio of atmospheric PM2.5 to higher values: Implications for lead source apportionment

Atmospheric lead pollution has adverse health effects on humans. Identification of anthropogenic Pb sources is thus crucial for understanding of pollution-related risks and for formulation of efficient abatement strategies. We analyzed concentrations and isotope ratios of Pb in fine air-borne particulate matter (PM2.5) in three Central European cities. Aerosol sampling in 12-h intervals was performed during summer and winter in Hradec Králové, Olomouc and Brno, regional centers of highly industrialized Czech Republic, each with a population of more than 90 thousand. Lead analysis was complemented with concentration measurements of Zn, Cu, Cd, As, Sb, and S. Trace element and PM2.5 concentrations were higher in winter than in summer in all studied cities, on average by 47%. The overall mean concentration of PM2.5 in urban air was 21 μg m−3, similar to that in Bern (Switzerland) and Vienna (Austria). Across the sites, 206Pb/207Pb ratios ranged from 1.142 to 1.178 in summer and from 1.143 to 1.173 in winter. The mean 206Pb/207Pb ratios were statistically indistinguishable in all three studied cities (1.165 in Hradec Králové, 1.163 in Olomouc, and 1.160 in Brno). In the 206Pb/207Pb vs.208Pb/207Pb graph, Pb isotope composition of summer samples formed a straight line, whereas Pb isotope composition of winter samples was shifted toward higher 208Pb/207Pb ratios. A Pb isotope inventory of regional pollution sources indicated that winter-time Pb pollution was not caused solely by household heating and increased electricity production in coal-burning power plants. Recycling of industrial Pb originating from Variscan ores and waste incineration could have shifted the 208Pb/207Pb ratio of PM2.5 to higher values, however, such sources do not emit more Pb in winter than in summer. Remobilization of legacy alkyl-Pb from gasoline additives and Pb emissions from current unleaded gasoline and diesel could have shifted both Pb isotope ratios to lower values.

Spatio-temporal accumulation and sources of anthropogenic Pb in Ulleung Basin sediments, East/Japan Sea, based on stable Pb isotope ratios.

The accumulation, pathways, and sources of anthropogenic lead (Pb) in Ulleung Basin sediments were investigated based on the temporal and spatial variations in the Pb concentration and stable Pb isotopes for 21 dated box core sediments collected from the shelf, slope, and basin in the southern East/Japan Sea. Leached (1M HCl) Pb concentrations and isotope ratios (207Pb/206Pb and 208Pb/206Pb) were nearly constant before 1930, but have increased rapidly until the present. The primary source of anthropogenic Pb is considered to be atmospheric deposition, showing the signature of a mixture of leaded gasoline and coals, which was the major anthropogenic source in the basin. However, after the 1990s, anthropogenic Pb from dumping materials added as much as 10-25% to the slope sediment and has been spreading out from the water column accompanied by the movement of the East Sea Intermediate Water. In shelf areas, inputs from nonferrous refineries in the coastal industrial complexes play an important role in pollution from anthropogenic Pb.

Spatial trend and source apportionment of metals in wet atmospheric precipitation: a study on drying Urmia Lake implications, NW Iran

ABSTRACT During this decade, the drying of Urmia Lake resulted in devastating tragedies in the region, resulting in the emission of toxic metals into the atmosphere. Urmia city’s wet atmospheric depositions were analysed to assess the quantity and spatial trends of numerous heavy metals and sodium (Na), as well as their sources. Wet precipitation was collected as rainwater, and the concentration of metals was determined using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). The mean concentrations of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), zinc (Zn), and sodium (Na) were 0.14, 0.18, 1, 3.7, 2.9, 5.6, 6.3 µg/L, and 2.6 mg/L, respectively, following the sequence Na > Zn > Ni > Cu > Pb > Cr > Cd > As. To identify the sources of these metals, enrichment factor analysis and principal component analysis (PCA) were employed. The enrichment factor analysis revealed that Na and As exhibited relatively low enrichment factors suggesting natural sources, whereas Zn, Cd, Cr, Cu, Ni, and Pb were highly enriched, indicating significant contributions from anthropogenic sources. The distribution map of Urmia City demonstrated that the northern and western parts of the city were highly polluted with As, Ni, Cr, and Zn. PCA analysis revealed that the emissions from vehicles and fuel combustion were the primary sources of Cd, Cr, Cu, Ni, and Pb, whereas the drying of the Urmia lake is the primary source of Na, As, and Zn. The process of the lake bottom drying likely releases these metals into the atmosphere, leading to their deposition in the surrounding areas.

Enhanced heavy metal discharges to marine deposits in glacial bays of two Arctic fjords (Hornsund and Kongsfjorden)

Climate change is transforming Arctic ecosystems in ways that are influencing the transport and accumulation of contaminants. The spatial and temporal variability of heavy metal distribution was studied in two Spitsbergen fjords – Kongsfjorden and Hornsund. Sediment cores from five stations in Kongsfjorden and six in Hornsund were collected in 2018–2019 and used for measurement of heavy metal concentrations (Hg, Pb, Cd, Cu, and Zn). Sediment layers were dated by the 210Pb method to reveal the history of contamination. Isotopic lead composition was used to study sources of Pb. Loads of heavy metals to fjord deposits were calculated based on mass sediment accumulation rates. The heavy metal loads varied spatially and reached ranged 0.3 mg m−2 yr−1 for Hg, 57.6 mg m−2 yr−1 for Pb, 0.5 mg m−2 yr−1 for Cd, 101 mg m−2 yr−1 for Cu, and 117 mg m−2 yr−1 for Zn. Heavy metal discharge from the glaciers to the glacial bays were much higher compared to discharge in central and outer fjord parts. This may suggest that glaciers can be important secondary sources of pollutants to fjords.

Stability of blood lead levels in children with low-level lead absorption.

Current child blood lead (Pb) screening guidelines assume that blood lead levels (BLLs) are relatively stable over time, and that only youngest children are vulnerable to the damaging effects of lower-range BLLs. This study aimed to test the stability of lower-range (≤ 10 μg/dL) child BLLs over time, and whether lower-range BLLs diminished with age among children aged 6 months to 16 years living in a lower-income neighborhood with a density of pre-1986 housing and legacy contamination. Age, sex, family income, age of residence, and/or residence proximity to point sources of Pb, were tested as potential additional factors. Capillary blood samples from 193 children were analyzed by inductively coupled plasma mass spectrometry (ICPMS). Multiple imputation was used to simulate missing data for 3 blood tests for each child. Integrated Growth Curve models with Test Wave as a random effect were used to test BLL variability over time. Among N = 193 children tested, at Time 1 testing, 8.7% had the BLLs ≥ 5 μg/dL (CDC "elevated" BLL reference value at the time of data collection) and 16.8% had BLLs ≥ 3.5 μg/dL (2021 CDC "elevated" BLL reference value). Modeling with time as a random effect showed that the variability of BLLs were attributable to changes within children. Moreover, time was not a significant predictor of child BLLs over 18 months. A sex by age interaction suggested that BLLs diminished with age only among males. Of the additional environmental factors tested, only proximity to a major source of industrial or vehicle exhaust pollution predicted child BLL variability, and was associated with a small, but significant BLL increase (0.22 μg/dL). These findings suggest that one or two BLL tests for only infants or toddlers are insufficient for identifying children with Pb poisoning.

Input Flux and the Risk of Heavy Metal(Loid) of Agricultural Soil in China: Based on Spatiotemporal Heterogeneity from 2000 to 2021

Identifying the current status of the heavy metal(loid) input of agricultural soils is vital for the soil ecological environment of agricultural-producing areas. Most previous studies have typically carried been out in small regions with limited sampling sites, which is insufficient to reveal the overall status of China. This study reviewed publications from over the past 20 years and calculated the input fluxes of heavy metal(loid)s in agricultural soil via atmospheric deposition, fertilizer, manure, and irrigation in different regions of China based on spatiotemporal heterogeneity using a meta-analysis, providing more accurate and reliable results. It was found that the heavy metal(loid) input flux of atmospheric deposition in China is large, while that of fertilizer and manure is relatively low compared to Europe. The major sources of As, Cd, Cr, Ni, and Pb entering the soil was atmospheric deposition, which accounted for 12% to 92% of the total input. Manure was responsible for 19% to 75% of the Cu and Zn input. Cd is the element presenting the most significant risk to the environment of agricultural soils in China and its safety limit will be reached within 100 years for most regions. The region we need to be concerned about is Huang-Huai-Hai due to its comprehensive pollution.

Isotopic signatures unveil the lead sources and migration in surface mangrove sediments

Mangrove sediments act as both sinks and secondary sources for lead (Pb), yet the sources, migration, and transformations of Pb in mangrove environments are poorly understood. In this study, Pb concentration in three mangrove sediments adjacent to different land-use types was evaluated. The Pb sources were quantitatively identified using Pb isotopes. Our data indicated minor Pb contamination in the mangrove sediments, possibly due to the relative lack of developed industry in this region. The Pb isotopic ratios suggested, on average, natural sources, coal combustion, agricultural activities, and traffic-related emissions respectively contributed approximately 61.4 %, 18.8 %, 14.0 %, and 5.8 % of the Pb accumulation in the mangrove sediments, suggesting that coal combustion and agriculture were important anthropogenic Pb sources. Significant relationships were observed between the 206Pb/207Pb ratios and total organic content (TOC) in mangrove sediments, which implied contrasting Pb cycling in two mangrove environments. We further suggested that organic matter and sulfur content significantly reduced Pb mobility and bioavailability in mangrove sediments. Our study provides isotopic method to investigate the Pb sources and migration in the mangrove environment.

Identification and contribution of potential sources to atmospheric lead pollution in a typical megacity: Insights from isotope analysis and the Bayesian mixing model

Atmospheric particulate matter (PM) enriched with lead (Pb) has severe irreversible effects on human health. Therefore, identifying the contribution of Pb emission sources is essential for protecting the health of residents. Using the Pb isotopic tracer method, this study explored the seasonal characteristics and primary anthropogenic Pb sources for atmospheric PM in Tianjin in 2019. We calculated the contribution of Pb sources using the end-member and MixSIAR models. The results showed that Pb loaded in PM10 was more abundant in January than in July, and was strongly influenced by meteorological conditions and anthropogenic emissions. The primary Pb sources of the aerosol samples originated from coal combustion and vehicle and steel plant emissions, mainly originating from local Pb emission sources in Tianjin. The PM10-bond Pb in January was influenced by regional transportation and local sources. The MixSIAS model calculated the contribution of coal combustion as approximately 50 %. Compared with that in January, the contribution of coal combustion decreased by 9.6 % in July. Our results indicate that some of the benefits of phased-out leaded gasoline have been short-lived, whereas other industrial activities releasing Pb have increased. Furthermore, the results emphasise the practicability of the Pb isotope tracer source approach for identifying and distinguishing between different anthropogenic Pb inputs. Based on this study, scientific and effective air pollution prevention and control programs can be formulated to provide decision support for the guidance and control of air pollutant emissions.

Lead isotope fingerprinting techniques help identify and quantify 3000 years of atmospheric lead pollution from Laguna Roya, northwestern Iberia

Legacy pollution research has established that over the past 3000 years, mining and metallurgical activities have resulted in widespread deposition of lead (Pb) pollution. However, there is still a limited understanding of how humans have impacted the long-term cycling of Pb in the environment. We present a 4,000-year lake sediment Pb isotope record from Laguna Roya, northwestern Iberia, that identifies and quantifies the predominant sources of atmospheric Pb pollution. For the first time, Pb isotopic compositions of ancient slag samples dated (∼600 BCE–200 CE) from a mining district in the southwest of the Iberian Peninsula are compared to Pb isotope ratios of Pb pollution deposited contemporaneously in lake sediments. In addition, literature Pb isotope ratios of ores from mining regions throughout Iberia are compared with those of leaded gasoline and coal to identify additional sources of anthropogenic Pb. Deposition of atmospheric Pb pollution begins after 950 BCE, and until 1750 CE, the Pb isotopic composition most resembles the southwestern slag deposits, containing a mixture of Pb ores from southeast Iberia (up to 36%) and southwest Iberia (∼74%). Between 1750 and 1960 CE, Pb pollution is attributed to Pb mining in southcentral Iberia. After 1960 CE, the dominant Pb pollution source (∼85%) is again metal refining in southwestern Iberia, and only ∼15% is from leaded gasoline. Provenance and reconstruction of the temporal and spatial distribution of legacy Pb pollution further our understanding of how humans have affected the biogeochemical cycle of this toxic element in the environment over time.

Assessment of heavy metal pollution and preschool children health risk in urban street dusts from different functional areas in a typical industrial and mining city, NW China.

To assess the pollution characteristics and health risks associated with street dust exposure among preschool children in typical industrial and mining areas, we analyzed heavy metal concentrations of 20 urban street dusts in commercial area (CA), residential area (RA), scientific and educational area (SEA) and industrial and mining area (IMA) from Baiyin, NW China. The average concentrations of Cr, Mn, Ni, Cu, Zn, Cd, Pb, As and Hg were 614.96, 484.25, 1757.74, 6868.86, 893.19, 77.62, 1473.99, 15.01 and 0.59mg·kg-1, respectively. The ecological risk indexes for Cd, Cu and Hg were found as 20,075.20, 1425.07 and 1174.86, respectively, and the ecological risk was extremely high. The pollution load indexes (PLI) were > 1 for all four functional areas. The total hazard index (THI) for different functional areas were more than 1, and the main exposure pathway for children was ingestion route. Heavy metals in street dust of the IMA had the highest THI for children (43.88), and HI of Pb was being most significant (17.38). In addition, the carcinogenic risk to children via the respiratory route was acceptable. Furthermore, factor analysis and cluster analysis classified heavy metals into two groups, indicating common anthropogenic sources for Cr, Ni, Cu, Zn, Cd, Pb, As and Hg. In conclusion, urban street dusts from industrial and mining area of Baiyin, NW China were found polluted by heavy metals and the pollution would pose an obvious non-carcinogenic risk to preschool children.

A Permian intermediate-sulfidation epithermal Pb–Zn–Ag deposit in the northern margin of North China Craton

Recent Pb–Zn–Ag exploration in the northern margin of North China Craton has made significant new discoveries. Here we report one Pb–Zn–Ag deposit in the Shaolanghe orefield with typical signatures of intermediate-sulfidation epithermal deposits. Zhangjiagou Pb–Zn–Ag mineralization occurs within the Early Permian quartz diorite and Late Permian andesite. Three mineralization stages were identified: white quartz–rhodochrosite–sulfide Pb–Zn–mineralization stage (I), smoky quartz–sulfide Pb–Zn–Ag–mineralization stage (II), and calcite–quartz non–mineralization stage (III). Four sphalerite samples yield the Rb–Sr age of 265.3 Ma, indicating that Pb–Zn–Ag mineralization was associated with the Late Permian andesite. The liquid-rich fluid inclusions of Stage I show low–medium temperatures of 190–270 °C and low salinities (1–3 wt%), and those of Stage III are slightly lower (190–250 °C, 0.5–2 wt%), suggesting a low-salinity, low-temperature H2O–NaCl fluid system for the Zhangjiagou deposit. The H–O–C isotopic signatures indicate a mixed fluid of magmatic water with meteoric water. S and Pb isotopes suggest magmatic source for Zhangjiagou Pb–Zn–Ag mineralization, most likely shallow hydrous intermediate magma. Collectively, these geological, geochronological, and geochemical features indicate that Zhangjiagou is an intermediate-sulfidation epithermal Pb–Zn–Ag deposit.

A comprehensive approach to quantify the source identification and human health risk assessment of toxic elements in park dust.

In this research, enrichment factor (EF) and pollution load index were utilized to explore the contamination characteristics of toxic elements (TEs) in park dust. The results exhibited that park dust in the study area was mainly moderately polluted, and the EF values of dust Cd, Zn, Pb, Cu and Sb were all > 1. The concentrations of Cr, Cu, Zn and Pb increased with the decrease of dust particle size. The investigation results of chemical speciation and bioavailability of TEs showed that Zn had the highest bioavailability. Three sources of TEs were determined by positive matrix factorization model, Pearson correlation analysis and geostatistical analysis, comprising factor 1 mixed sources of industrial and transportation activities (46.62%), factor 2 natural source (25.56%) and factor 3 mixed source of agricultural activities and the aging of park infrastructures (27.82%). Potential ecological risk (PER) and human health risk (HHR) models based on source apportionment were exploited to estimate PER and HHR of TEs from different sources. The mean PER value of TEs in the park dust was 114, indicating that ecological risk in the study area was relatively high. Factor 1 contributed the most to PER, and the pollution of Cd was the most serious. There were no significant carcinogenic and non-carcinogenic risks for children and adults in the study area. And factor 3 was the biggest source of non-carcinogenic risk, and As, Cr and Pb were the chief contributor to non-carcinogenic risk. The primary source of carcinogenic risk was factor 2, and Cr was the cardinal cancer risk element.

The influence of thickness layers on the efficiency of MAPI solar cells

In this work, a modest method for creating Perovskite solar cells (PSCs) by recycling car batteries is used. Trying to get rid of some structures or materials which are harm to the environment. However, by reusing car batteries we will avoid the disposal of toxic battery materials and provide an alternative technique, readily-available Pb source for fabricating PSCs. Perovskite solar cells (PSCs) were prepared by two-step spin coating solution method on the FTO glass substrate. Lead iodide (PbI2) and methyl-ammonum iodide (CH3NH3I) used to form the structure of the precursor (CH3NH3PbI3). The photovoltaic performance of PSCs and the effect of chemical composition of perovskite layer on performance of PSCs was investigated. Characterization of PSCs by using X-ray diffraction, SEM and the effect of chemical composition on of MAPI films was achieved. It was found that the thickness ratio of (PbI2/MAI) with 3.0:1 have highest fill factor and maximum efficiency.

Complexities in attributing lead contamination to specific sources in an industrial area of Philadelphia, PA

Globally, lead (Pb) contamination is one of the top ten chemical exposure issues affecting public health. The identification of specific Pb sources provides valuable information to determine assignment of liability for site cleanup, improve sampling plans and develop remedial strategies. This paper examines Pb concentrations and Pb isotopic data from samples collected at and near the site of a Pb paint production facility with a long operating history. Although high soil Pb concentrations were found at the site, Pb concentrations in surrounding neighborhoods did not simply decline with distance from the site. We evaluated soil concentrations and isotopic mixing lines to explore potential sources of Pb pollution. Three-isotope plots showed overlap of site samples and the surrounding neighborhood, consistent with pollution from the facility affecting offsite soils. A major challenge in separation of potential sources, however, is that the isotopic signatures of other potential Pb sources fall within the range of the soil data. The long operational site history, soil disturbances, the presence of nearby smelters, and other local and remote sources affect identification of lead sources. This analysis demonstrates that source attribution can be confounded by incomplete site and material sourcing information. An integrated approach that includes in-depth site characterization and an evaluation of historical activities (e.g., Pb ores used over time, amounts of Pb emitted by all area smelters, land use changes, and soil disturbances) is important for determining source attribution. This analysis provides insight into future site investigations where soil lead contamination has resulted from a long industrial history in an urban setting.

Risk assessment of combined exposure to lead, cadmium, and total mercury among the elderly in Shanghai, China

Lead (Pb), cadmium (Cd) and total mercury (THg) are toxic heavy metals (THMs) that are widely present in the environment and can cause substantial health problems. However, previous risk assessment studies have rarely focused on the elderly population and have usually targeted a single heavy metal, which might underestimate the long-term accumulative and synergistic effects of THMs in humans. Based on the food frequency questionnaire and inductively coupled plasma mass spectrometry, this study assessed external and internal exposures to Pb, Cd and THg in 1747 elderly people in Shanghai. Probabilistic risk assessment with the relative potential factor (RPF) model was used to assess the neurotoxicity and nephrotoxicity risks of combined THMs exposures. The mean external exposures of Pb, Cd and THg in Shanghai elderly were 46.8, 27.2 and 4.9 μg/day, respectively. Plant-based foods are the main source of Pb and THg exposure, while Cd is mainly from animal-based foods. The mean concentrations of Pb, Cd and THg were 23.3, 1.1 and 2.3 μg/L in the whole blood, and 6.2, 1.0 and 2.0 μg/L in the morning urine, respectively. Combined exposure to THMs leading to 10.0 % and 7.1 % of Shanghai elderly at risk of neurotoxicity and nephrotoxicity. The results of this study have important implications for understanding the profiles of Pb, Cd and THg exposure in the elderly living in Shanghai and provide data support for risk assessment and control of nephrotoxicity and neurotoxicity from combined THMs exposure in the elderly.

Exchange of Pb from Indian to Atlantic Ocean is driven by Agulhas current and atmospheric Pb input from South Africa

Using a spatiotemporal dataset of dissolved lead (dPb) from the subtropical oceans surrounding South Africa, this study quantifies the exchange of dPb between the Indian and Atlantic Oceans. Despite the absence of a major Pb source within the South Atlantic sector and the complete phase-out of leaded petroleum in Southern Africa, the ecologically important southeast Cape Basin shows an elevated surface dPb concentration (21–30 pmol kg−1). We estimated up to 90% of the measured dPb in surface waters of the Cape Basin was delivered from the Indian Ocean via the Agulhas Current (AC). Eddy dynamics and leakage at Agulhas retroflection result in an increased Pb flux from winter to summer, while a long-term (2008–2019) temporal change in dPb in the AC-derived water of Cape Basin was contemporaneous to a change in atmospheric Pb emissions from South Africa. The South African-origin atmospheric Pb, however, contributes first to the Agulhas waters in the West Indian Ocean, which is then transported to the South Atlantic, thereby regulating the dPb inventory of the Cape Basin. This indirect mechanism of Pb transfer emphasizes the importance of regulating Pb emissions from Southern Africa to protect rich fishing grounds associated with the Benguela marine ecosystem.

Integration of fractal modeling and correspondence analysis reconnaissance for geochemically high-potential promising areas, NE Iran

Most geochemical and geostatistical analysis in mining exploration requires removing regional trends in order to obtain local anomalies. In this paper, stream sediment samples, which collected from Khusf area (NE Iran), was studied based on Concentration-Area (C-A) fractal model as well as correspondence analysis methods to find high-potential areas elements. Correspondence analysis with 170 samples through 20 elements concentration values in each sample was performed. According to correspondence analysis, among one or several elements in the study area, local anomalies were separated which the highest concentration relates to the variables Pb, As, and Cd elements. After the correspondence analysis, the best variogram for the Khusf area was studied. Elemental concentration maps was then produced through estimating the values using kriging method. Therefore, using the fractal method, between three statistical sets of elements, it was concluded that the third set showed the anomaly for Pb, As, and Cd elements with local anomaly values respectively determined as 55, 7.2, and 0.88 ppm. Although Cd element is not genetically related to same source of Pb and As, utilizing integrated approach, Cd anomalies has also been detected in the area as a promising element zone. Finally, it is suggested that this region has the possibility of Basic Metals occurrence and suggests further geophysical operations on a local identification scale.

55.3: One‐step extruding method for fabricating perovskite quantum dot light diffusers

All‐inorganic perovskite quantum dots (PQDs) exhibit excellent physics properties and application prospects in the field of LED lighting applications and display devices. However, poor long‐term stability to light irradiation, water, heat, and oxygen hinders the further development of commercialization. Using polymer plastics, such as PS (polystyrene), PC (polycarbonate), PMMA (polymethyl methacrylate), PP (polypropylene), as the matrix along with proper Cs, Pb and halogen (X) sources as perovskite precursors, CsPbX3 PQDs/polymer composites can be synthesized via a solvent‐free and in‐situ polymeric melt encapsulation method. Special attention was paid to the effects of growth conditions on the photoluminescent quantum yield (PLQY) of the composites. The optimized CsPbX3 PQDs/polymer composite demonstrated excellent performance with more than 90% PLQY and 22 nm full width at a halfmaximum (FWHM) for green and 35 nm FWHM for red. Particularly, we combined this in‐situ melting synthesis technology with industrial production, and used a melting extruder to directly fabricate perovskite quantum dot optical diffuser products for backlight display. Under the protection of multi‐layer structure, the PQD diffusers exhibited remarkable long‐term stability. This study provides a novel solvent‐free and in‐situ synthesis route for fabricating diffuser products, which is quite friendly to industrialization and commercialization for perovskite materials.

Assessment of seasonal changes in groundwater quality of waste rock dump in temperate continental climate, northern Japan

Understanding seasonal groundwater quality changes in temperate continental climate waste rock dumps (WRDs) is necessary for sustainable environmental risk prevention and legacy mine contamination management. Therefore, we conducted a field investigation of a WRD to determine the mechanisms controlling its groundwater quality dynamics. The research aimed to understand the impact of seasonal changes on heavy metals released from the WRD. Three monitoring wells were installed in the WRD to investigate the pH, electrical conductivity (EC), and groundwater level (GL). The mineral composition of the waste rock was determined. Groundwater and river water samples from the monitoring wells and rivers surrounding the WRD were collected for chemical analysis. The sphalerite and galena concentrated in the WRD were assumed to be the main sources of Zn, Pb, and Cd contamination. Summer rainfall was the dominant recharge source of river water, which rapidly infiltrated to the WRD, altering the pH, EC, and GL of the groundwater. The pH, EC, and GL were stable in winter because snowpack covering the surface soil prevented groundwater recharge to the WRD. However, snow melting affected the pH, EC, and GL in the WRD. The sources of groundwater recharge (rainfall, river water, and snowmelt) altered the behaviour of the heavy metals in the WRD through two main mechanisms: the dissolution of sulphide minerals and efflorescent salts upon contact with the recharge water, and the dilution effect of the recharge water, which mixes with the groundwater in the WRD, reducing the heavy metal concentration. Sulphide mineral and efflorescent salt dissolution were significant in the deepest monitoring well and rainfall was the dominant recharge source which increased sulphide mineral and efflorescent salt dissolution in the WRD.

Multi-year monitoring of atmospheric dust fall as a sink for lead in an agro-industrial and petrochemical city of Argentina. Geo-accumulation and ecological risk assessment.

A multi-year monitoring data set of potentially harmful elements (PHEs), which are present in the chemical composition of atmospheric settleable particulate matter (SPM) in the urban, industrial and port areas in Bahía Blanca, was studied in order to assess potential ecological risk. The selected PHEs were metal elements of local and regional environmental importance (Cd, Cr, Cu, Ni, Pb, and Zn). Seventeen sampling campaigns were carried out between April 2013 and September 2019. After the microwave-assisted acid digestion of samples, the total contents of the PHEs were determined by ICP-OES. The annual dry deposition rate, the indexes associated with the potential ecological risk (RI) and the degree of geo-accumulation (Igeo) of each PHE were calculated. The results indicated that: (a) there are 3 groups (I, II, III) of PHEs with differentiated concentration levels, ranked I (Pb > Zn > Cu) > II (Cr ≈ Ni) > III (Cd) (p < 0.01) in all the studied areas; (b) the median of the total deposition rate was 1mgcm-2. month-1 with a significant relative contribution of Pb; (c) a considerable increase in geo-accumulation of Pb indicated that SPM was functioning as a sink for Pb, and also reflected a significant progressive increase in the potential ecological risk in all sites (p < 0.01); and (d) there were chemometrically identified potential sources of Pb, Cu and Zn emissions that would be associated mainly to the resuspension of dust from geogenic, industrial and urban origin, and to a lesser extent, to other gaseous emissions of the industrial sector. This work highlights three major aspects of environmental assessment: (a) the value of continuous monitoring as an important tool to detect long-term trends; (b) the importance of the role of dust fall as a useful environmental indicator of lead geo-accumulation; and (c) the great utility of geo-accumulation and potential ecological risk indices as rapid quantitative assessment tools of environmental pollution.