Sources Of Lead Pollution Research Articles

Knowledge, attitude, and practices related to lead pollution among adolescents and caregivers of young children living near Used Lead Acid Battery (ULAB) recycling sites in Bangladesh: a cross-sectional study

BackgroundLead, a potent neurotoxin, causes irreversible damage to the nervous system, and low- and middle-income countries face huge health and economic productivity losses due to childhood lead exposure. In Bangladesh, informal Used Lead Acid Battery (ULAB) recycling sites are an important source of lead pollution. Little is known about lead awareness among communities exposed to ULAB recycling. Therefore, this study aims to assess knowledge, attitudes, and practices related to lead pollution among caregivers of young children and adolescents living adjacent to informal ULAB sites.MethodsA cross-sectional study was conducted among 732 mothers of young children and adolescents in 4 districts of Bangladesh (survey and observation). Simple and multiple linear regression was conducted to describe patterns and predictors of lead-related knowledge and practices.Results60% of respondents had heard the name ‘lead’ (“shisha”). The mean knowledge score was low (19 out of 44). Residents of high-risk districts, male respondents, and those with more than 5 years of schooling were significantly more likely to have higher knowledge scores than others. In terms of attitude, 52% of respondents perceived lead to be risky for human health but 43% thought lead pollution was controllable. Observation of households for lead exposure revealed that 63% of children and adolescents play or pass by ULAB sites, 29% ate non-food items, 41% of households had visible paint chips on the walls, 59% households used polished turmeric and 15% used lead-soldered cans to store foods. Among protective practices, 70% reported cleaning floors, 84% consumed iron-rich foods, and 48% consumed calcium-rich foods.ConclusionsThe population had a high potential for lead exposure. Their knowledge about lead was limited, and risk perception was moderate. To reduce lead exposure and increase knowledge and awareness among the at-risk population, it is crucial to take measures such as mass awareness campaigns through media and schools. It is important to strengthen the implementation of existing policies, such as policies on leaded gasoline, paints, and lead-acid batteries, that can address the sources of lead exposure for the community.

Domestic dogs as sentinels of children lead exposure: Multi-pathway identification and source apportionment based on isotope technique

Environmental lead exposure poses risks to children’ health, thus exposure sources and pathways identification remain important concern and research scope. Due to sharing the same environment, domestic animals, especially dogs, have been used as useful sentinels to identify human lead exposure. However, more evidence is needed on whether domestic dogs could be used to identify the lead exposure pathways and sources of children. Thus, this study investigated the dietary habits, behaviors, and household environment of children and dogs in a typical coal-fired area in China. The lead levels and lead isotope ratios (Acronym: LIRs, expressed as 208Pb/206Pb and 207Pb/206Pb) in dogs' and children's blood, as well as in environmental media (food, PM2.5, indoor/outdoor dust, drinking water and soil) were measured to explore the predominant lead pollution sources and exposure pathways of children. The results showed that the LIRs of children's blood (208Pb/206Pb = 2.0703 ± 0.0076, 207Pb/206Pb = 0.8501 ± 0.0052) were similar to those of dogs' blood (208Pb/206Pb = 2.0696 ± 0.0085, 207Pb/206Pb = 0.8499 ± 0.0052), as well as similar to the LIRs of environmental media, i.e. children's food (208Pb/206Pb = 2.0731 ± 0.0057, 207Pb/206Pb = 0.8491 ± 0.0036) and coal (208Pb/206Pb = 2.0683 ± 0.017, 207Pb/206Pb = 0.8515 ± 0.01). Children and dogs had similar lead exposure pathways, but the contributions of each exposure pathway were different, i.e., 83.1% vs. 76.9% for children and dogs via food ingestion, 1.4% vs. 5.6% via particulate matter exposure, and 15.5% vs. 17.5% via household dust exposure, respectively. The contribution of food via ingestion to lead exposure remains dominant, and coal combustion is a main lead exposure source for children and domestic dogs.

Hubungan Kadar Timbal Dalam Darah dengan Kadar Hemoglobin pada Operator SPBU Gombel Semarang

Lead is a heavy metal that is added in the manufacture of gasoline. Lead acts as an anti-knock to increase engine efficiency. Lead can cause air pollution. The main sources of lead pollution are motor vehicle fumes and gasoline fumes. Operator of Public Refueling Station are workers at high risk of being exposed to lead. The continuous accumulation of lead can inhibit the formation of hemoglobin. Research is needed to know the relationship between lead level in blood and hemoglobin level on the Operator of Public Refueling Station in Gombel Semarang. The research type is observational descriptive analytic with a cross sectional design. The research sample of 18 respondents is the entire population of Operator of Public Refueling Station in Gombel Semarang. Lead level in blood is an independent variable. Hemoglobin level is the dependent variable. Lead levels were measured by the ICP-MS method and using the Agilent 7700 X. Hemoglobin levels were measured by the SLS-Hemoglobin Method and using the Sysmex XN 1000. The research result was lead level in blood 1,6-5,7 μg/dL, hemoglobin level 12,4-18,1 g/dL. Test result of Spearman correlation obtained p= 0,581 ; r=-0,139. It was concluded that there was no significant correlation between the level of blood lead and level of hemoglobin on Operator of Public Refueling Station in Gombel Semarang.

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.

Concentrations and isotopic analysis for the sources and transfer of lead in an urban atmosphere-plant-soil system

Lead pollution has attracted significant attention over the years. However, research on the transfer of lead between urban atmospheric particles, soils, and plants remains rare. We measured lead concentrations and lead isotope ratios in total suspended particles (TSP), soil, and plants in an urban wetland in Beijing. The study period was September 2016–August 2017- covering all four seasons. The concentrations of lead in the atmospheric particles vary from 3.13 to 6.68 mg/m3. It is significantly higher in autumn than that in spring and summer (P < 0.05). There is also a significant difference between summer and winter (P < 0.05). The soil lead concentrations range from 57 to 114 mg/kg, with the highest concentration in spring, followed by summer, winter and autumn. The lead concentrations are 1.28–7.75 mg/kg in plants. The concentration was highest in spring and significantly higher than in summer. The bioaccumulation factor of Phragmites australis was 0.064 (<0.1), indicating that lead is not easily transferred to plants. Unlike the bioaccumulation factors, translocation factors have much higher values, indicating a higher transfer within the plants. Results also indicate an interesting seasonal pattern with almost 97% of lead in plants during spring being of atmospheric origin, whereas in autumn, soilborne sources contribute almost 94%. The isotopic compositions of lead in the urban atmosphere-soil-plant system show that lead pollution results from the mixing of geogenic and anthropogenic materials. Vehicle exhaust, crustal rocks and ore deposits are likely primary sources of lead pollution within the study domain.

Blood Lead Levels of Pregnant Women in Agricultural and Coastal Area: A SDG’s Indicator for Health and Pollution in Brebes District

Maternal mortality is still a severe problem in Indonesia. One of the causes is the blood lead levels. Blood lead levels in pregnant women can increase the risk of preeclampsia which is the cause of high maternal mortality in Indonesia. One of the factors for high blood lead levels is living close to the source of lead pollution. This study determines the differences in blood lead levels in pregnant women in agricultural and coastal areas in Brebes District. The t-test independent is used to analyze the mean differences with SPSS v 21 software with 84 samples. The results show a significant difference in the average blood lead levels in pregnant women in agricultural and coastal areas in Brebes Regency (p-value=0,047). The average blood lead levels are higher in agricultural areas (46.243 µg/dL) than in coastal areas (37.731 µg/dL). It can be implied that the risk of maternal mortality in an agricultural area is higher than in a coastal area.

A systematic review of clinical and laboratory findings of lead poisoning: lessons from case reports

Lead is one of the most toxic heavy metals in the environment. The present review aimed to highlight hazardous pollution sources, management, and review symptoms of lead poisonings in various parts of the world. The present study summarized the information available from case reports and case series studies from 2009 to March 2020 on the lead pollution sources and clinical symptoms. All are along with detoxification methods in infants, children, and adults. Our literature compilation includes results from 126 studies on lead poisoning. We found that traditional medication, occupational exposure, and substance abuse are as common as previously reported sources of lead exposure for children and adults. Ayurvedic medications and gunshot wounds have been identified as the most common source of exposure in the United States. However, opium and occupational exposure to the batteries were primarily seen in Iran and India. Furthermore, neurological, gastrointestinal, and hematological disorders were the most frequently occurring symptoms in lead-poisoned patients. As for therapeutic strategies, our findings confirm the safety and efficacy of chelating agents, even for infants. Our results suggest that treatment with chelating agents combined with the prevention of environmental exposure may be an excellent strategy to reduce the rate of lead poisoning. Besides, more clinical studies and long-term follow-ups are necessary to address all questions about lead poisoning management.

Lead Toxicity, Measurement and Control

Lead exists naturally but its huge concentration in environment is contributed by anthropogenic activity. The present review article focuses to show some current evidences of lead pollution worldwide the toxicity of lead to the flora and fauna and its measurement and control measures. Understanding the source of lead pollution, nature and chemistry of lead, industrial lead pollution, effect of plants and animals are also the objective of this paper.

A New Analytic Model to Identify Lead Pollution Sources in Soil Based on Lead Fingerprint.

Gobeil’s model is one of the most widely used models to identify lead (Pb) pollution sources in the environment. It is based on a set of equations involving Pb isotope fractions. Although a well-established numerical method, Gobeil’s model is often unable to provide an accurate estimation of each pollution sources’ contribution. This paper comprehensively examines the drawbacks of Gobeil’s model based on a numerical analysis and proposes a revised numerical method that provides a more accurate estimation of Pb pollution sources. Briefly, the mathematical inaccuracy of Gobeil’s model mainly lies in the misinterpretation of “lead fingerprint ratio balance.” To address this problem, the new analytic model relies on the mass balance of total lead in the contaminated sites, and uses a set of linear equations to obtain the contribution of each pollution source based on the lead fingerprint. A subsequent case study from an industrial park in Guanzhong area of Shaanxi Province in China shows that we can calculate the lead contribution rates accurately with the new model.

Seagrass soil archives reveal centennial-scale metal smelter contamination while acting as natural filters

The upper Spencer Gulf in South Australia hosts the world's largest single stream Pb-Zn smelter, which has caused environmental and health issues related to elevated metal concentrations in the surrounding environment. The area also has extensive seagrass meadows, occupying >4000 km2. We reconstructed the fluxes of heavy metals over the last ~3000 years through a multi-parameter study of the soil archives formed by the seagrass Posidonia australis. Pb, Zn and Cd concentrations increased up to 9-fold following the onset of smelter operations in the 1880s, and the stable Pb isotopic signatures confirmed the smelter has been the main source of lead pollution in the seagrass soils until present. Preliminary estimates suggest that over the past 15 years seagrass meadows within 70 km2 of the smelter accumulated ~7–15% of the smelter emissions in their soils. Here we demonstrate that seagrass meadows act as pollution filters and sinks while their soils provide a record of environmental conditions, allowing baseline conditions to be identified and revealing the time-course of environmental change.

Assessment of Lead Contamination in Soils of Urban Parks of Khorramabad, Iran

Background: The urban environment quality is of vital importance as most people throughout the world live in cities. For this reason, there is a need to monitor lead levels in the environment, particularly in metropolitan areas. To date, no research on soil pollution in Khorramabad urban areas has been performed. Objectives: The aim of this study was to assess soils of Khorramabad metropolis in order to establish the concentration of lead and develop a contamination factor map. MaterialsandMethods: Soil samples were collected from 25 dierent urban parks in Khorramabad, Iran. The mean Pb contents in the urban topsoil samples were compared with mean concentrations for other cities around the world. A spatial distribution map of lead was created by GIS. Results: Analysis of urban soil samples for Pb content indicated the presence of Pb in all soil samples collected from the 40 sampling sites in 25 urban parks at varying concentrations ranging from 0.05 - 35 mg/kg. Elevated levels of Pb in soil were found in the center of the city. The findings regarding contamination factor (CF) showed low to moderate contamination of urban soil by lead. Conclusions: It was revealed that the contents in lead tend to increase in the historic and central part of the city. Map of lead distribution and contamination factor were created for this city indicating vehicular emission as the main source of lead pollution and likewise role of place and age of the park in accumulation of lead.

Lead Contamination and Pollution Indexes in Roadside Soil in Tehran, Iran

Background and purpose: In the process of rapid urbanization and industrialization in developing countries, environmental pollution is a major concern. One of the fastest growing problems of environmental pollution is an excessive intake of lead in urban soils. Lead concentrations in urban soil may result from human activities such as vehicle emissions and industrial activities. This study aimed to determine of lead contents in roadside soil samples in Tehran city, Iran. Materials and Methods: One of Tehran municipality’s subsections was selected for the collection of 21 samples from seven stations along a main urban highway. In this study, samples were taken over a period of 3-month in the dry season. Sampling was performed in the order of 100 m long, perpendicular to the roadside at 0, 50, and 100 m from the road. Lab measurements were performed on the physical and chemical properties of samples. The extraction was performed using four kinds of acids (HCL, HNO3, HF, and HCLO4). Results: Lead concentrations were measured by a spectrophotometer with an average concentration of lead in soil samples of roadsides standing at 112.21 part a million (PPM), and the average lead bio-accessibility at 14.19 PPM. Conclusion: Lead concentrations showed a linear decrement in proportion to the distance from center line of the road. Human cultural activities were sources of lead pollution by examine soil contamination indexes. [Yousefi M, *Ehteshami M, Sadrnejad SA. Lead Contamination and Pollution Indexes in Roadside Soil in Tehran, Iran. Iran J Health Sci 2015; 3(4): 8-23] http://jhs.mazums.ac.ir

Comparative Study of Heavy Lead Pollution in Roadside Soil and Plants by Railway and Highway at Tangail District in Bangladesh

This study explains the effect of heavy Lead pollution in soil and plants along the highway and railway of Tangail district. The metal concentration in soil and plant is decreased with increasing distance from the road of highway and railway. Lead is one of the most toxic elements. It is non-biodegradable and its toxicity does not change with time. Use of leaded gasoline in vehicles and train are known as the major source of lead pollution. Highway and railway of Tangail are two busiest routes of Bangladesh and pollution is rising day by day. To reveal the present situation in soil and plant samples were collected at various distances (0m, 15m, 30m) from Railway and highway roads and analyzed for lead by Atomic Absorption Spectrophotometric (AAS) method. The results show that the soil and plant samples along these places are contaminated with lead. The highest lead contents 0.1931 ppm in soil and 0.1358 ppm in plant was found for highway on road at 0m distance. Conversely, the highest lead contents 0.0967 ppm in soil and 0.0652 ppm in plant was found for railway on road at 0m distance. Among two types of major transportation system railway pollution is smaller than highway and hence railway transportation system is environment friendly.

Source of lead pollution, its influence on public health and the countermeasures.

Lead is a well-known toxic heavy metal, which can have serious public health hazards at very low levels, especially for young children. This report summarized the background information on lead as well as its applications, pollution sources, poisoning pathways, biomarkers of exposure and effect, toxicities, poisoning mechanisms, preventive actions, decontamination strategies, and detoxification methods.

PENETAPAN KADAR Pb PADA SHAMPOO BERBAGAI MERK DENGAN METODE SPEKTROFOTOMETRI SERAPAN ATOM

The source of lead pollution (Pb) can come from cosmetic product including shampoo. The purpose of this research are to know wether there is Pb in the shampoo cosmetic based on different brands and colours of the shampoo. The sample of the shampoos that used in this research are A, B, C, and D. Each of the samples replicated 5 times, then analyzed with atomic absorbtion specktrophotometry. Then, one of the sample are taken from one brand with different colour and replicated 5 times. The result of this research shows that from the different brand of shampoos contain Pb. The average level of Pb that obtained from analysis are, brand A (0,4838 ppm 0,0538 ppm), brand B (0,6935 ppm 0,3131 ppm), brand C (0,8354 ppm 0,0405 ppm), and brand D ( 0,9517 ppm 0,0811 ppm). Whereas for the same shampoo brand but different in colour had average level of Pb: shampoo I (red colour)= (0,5428 0,0192) ppm, Shampoo II (yellow colour) = (0,3606 0,0255) ppm, Shampoo III (blue colour) = (0,4385 0,0062) ppm, and Shampoo IV (green colour) = (0,1427 0,0133) ppm.

Tracing lead pollution sources in abandoned mine areas using stable Pb isotope ratios

This study focused on Pb isotope ratios of sediments in areas around an abandoned mine to determine if the ratios can be used as a source tracer. For pretreatment, sediment samples were dissolved with mixed acids, and a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS, Nu plasma II) was used to investigate the Pb isotopic composition of the samples. The measured isotope ratios were then corrected for instrumental mass fractionation by measuring the (203)Tl/(205)Tl ratio. Repeated measurements with the NIST SRM 981 reference material showed that the precision of all ratios was below 104 ppm (±2σ) for 50 ng/g. The isotope ratios ((207)Pb/(206)Pb) found were 0.85073 ± 0.0004~0.85373 ± 0.0003 for the main stream, while they were 0.83736 ± 0.0010 for the tributary and 0.84393 ± 0.0002 for the confluence. A binary mixing equation for isotope ratios showed that the contributions of mine lead to neighboring areas were up to 60%. Therefore, Pb isotope ratios can be a good source tracer for areas around abandoned mines.

Health hazards of China’s lead-acid battery industry: a review of its market drivers, production processes, and health impacts

Despite China’s leaded gasoline phase out in 2000, the continued high rates of lead poisoning found in children’s blood lead levels reflect the need for identifying and controlling other sources of lead pollution. From 2001 to 2007, 24% of children in China studied (N = 94,778) were lead poisoned with levels exceeding 100 μg/L. These levels stand well above the global average of 16%. These trends reveal that China still faces significant public health challenges, with millions of children currently at risk of lead poisoning. The unprecedented growth of China’s lead-acid battery industry from the electric bike, automotive, and photovoltaic industries may explain these persistently high levels, as China remains the world’s leading producer, refiner, and consumer of both lead and lead-acid batteries.This review assesses the role of China’s rising lead-acid battery industry on lead pollution and exposure. It starts with a synthesis of biological mechanisms of lead exposure followed by an analysis of the key technologies driving the rapid growth of this industry. It then details the four main stages of lead battery production, explaining how each stage results in significant lead loss and pollution. A province-level accounting of each of these industrial operations is also included. Next, reviews of the literature describe how this industry may have contributed to mass lead poisonings throughout China. Finally, the paper closes with a discussion of new policies that address the lead-acid battery industry and identifies policy frameworks to mitigate exposure.This paper is the first to integrate the market factors, production processes, and health impacts of China’s growing lead-acid battery industry to illustrate its vast public health consequences. The implications of this review are two-fold: it validates calls for a nationwide assessment of lead exposure pathways and levels in China as well as for a more comprehensive investigation into the health impacts of the lead-acid battery industry. The continuous growth of this industry signals the urgent need for effective regulatory action to protect the health and lives of China’s future generations.

Constraining recent lead pollution sources in the North Pacific using ice core stable lead isotopes

Trends and sources of lead (Pb) aerosol pollution in the North Pacific rim of North America from 1850 to 2001 are investigated using a high‐resolution (subannual to annual) ice core record recovered from Eclipse Icefield (3017 masl; St. Elias Mountains, Canada). Beginning in the early 1940s, increasing Pb concentration at Eclipse Icefield occurs coevally with anthropogenic Pb deposition in central Greenland, suggesting that North American Pb pollution may have been in part or wholly responsible in both regions. Isotopic ratios (208Pb/207Pb and 206Pb/207Pb) from 1970 to 2001 confirm that a portion of the Pb deposited at Eclipse Icefield is anthropogenic, and that it represents a variable mixture of East Asian (Chinese and Japanese) emissions transported eastward across the Pacific Ocean and a North American component resulting from transient meridional atmospheric flow. Based on comparison with source material Pb isotope ratios, Chinese and North American coal combustion have likely been the primary sources of Eclipse Icefield Pb over the 1970–2001 time period. The Eclipse Icefield Pb isotope composition also implies that the North Pacific mid‐troposphere is not directly impacted by transpolar atmospheric flow from Europe. Annually averaged Pb concentrations in the Eclipse Icefield ice core record show no long‐term trend during 1970–2001; however, increasing208Pb/207Pb and decreasing 206Pb/207Pb ratios reflect the progressive East Asian industrialization and increase in Asian pollutant outflow. The post‐1970 decrease in North American Pb emissions is likely necessary to explain the Eclipse Icefield Pb concentration time series. When compared with low (lichen) and high (Mt. Logan ice core) elevation Pb data, the Eclipse ice core record suggests a gradual increase in pollutant deposition and stronger trans‐Pacific Asian contribution with rising elevation in the mountains of the North Pacific rim.

Differences in lead isotopic fingerprints between blood, hair and organs in lead-poisoned rats

Lead isotopic ratios of biosamples such as blood, hair and teeth are used as “fingerprints” to trace and identify sources of lead pollution in the environment. However, the reliability of this technique has not been confirmed. In previous studies, we investigated the differences in lead isotopic ratios between blood, hair, and organs from the same human body. To explore the relationship between isotopic ratios in environmental lead and biosamples, and to investigate the influence of exposure dose, rats were exposed to 0, 30, 60, and 120 mg/kg body weight of lead acetate every day for 4 weeks by intragastric administration. Lead isotopic ratios of blood, hair, liver, kidney and femur in rats, as well as that of the test substance lead acetate, were measured using inductively coupled plasma mass spectrometry. There were significant differences (P<0.05) in lead isotopic fingerprints between blood, hair, and tissues. Lead fingerprints of blood were influenced by lead exposure dose, while those of other tissues and organs were generally not. Its reliability and availability indicated that blood, but not hair, was thus a suitable biomarker for environmental lead exposure. The results of this study provide the scientific rationale for the use of lead isotopic ratios for the identification of human lead pollution sources.

Application of a simple binary mixing model to the reconstruction of lead pollution sources in two Mississippi River floodplain lakes

A simple binary mixing model is used to determine the isotopic ratios of lead (Pb) pollution sources to a lake located near a smelter closed because of excessive Pb aerosols (Horseshoe Lake Madison County, Illinois, USA). As a control, we also examine a relatively unpolluted lake in a rural area of Southern Illinois (Horseshoe Lake Alexander County). Sediment cores were taken from both lakes and analyzed for Pb and Pb isotopes by ICP-MS. The mixing model shows that Madison County Horseshoe Lake had 3 different sources of Pb in its history. The first source is sediment from the Mississippi River with an intermediate 206Pb/207Pb ratio (1.223 ± 0.009) which dominates inputs in pre-settlement times. From 1750 to 1933, the source of pollution Pb has the high 206Pb/207Pb ratio (1.256 ± 0.005) characteristic of ore from the southeast Missouri Pb mines. The most recently deposited pollution Pb comes from a source with a low 206Pb/207Pb ratio (1.202 ± 0.005). This source is similar in isotopic composition to pollution Pb found by several other investigators in the Eastern US and probably represents the mixture of ores used in modern industrial processes. It is unclear from the isotopic composition whether this source at Horseshoe Lake is the local Pb smelter or vehicle exhaust. The sediment core from Horseshoe Lake, Alexander County, shows a less variable isotopic composition. The binary mixing model showed a source composition of 1.225 ± 0.003 before 1850 and 1.231 ± 0.003 after this date. The change does not indicate a pollution source, but may be a shift in the sources of natural sediment with slightly different isotopic ratios to the lake. Our results show the value of simple binary mixing models to reconstruct the isotopic composition of Pb sources to lakes.