Atmospheric Lead Deposition Research Articles

Central-Eastern Europe as a centre of Middle Ages extractive metallurgy

Central-eastern to southeastern Europe, from Bohemia to Greece is home to some of the richest ore deposits on earth, with archaeological evidence suggesting a long history of metal use. However, the exact timing and extent of past metal processing activities remains unclear. The Middle Ages and Early Modern period (c. 500–1800 common era (CE)) in Europe, saw the expansion of metal use at an unprecedented scale, continent-wide. Here we analysed rates of past atmospheric lead (Pb) deposition in six peat bogs from Romania, Serbia and Greece. We show that after 1000 CE, the redevelopment of central European mining industry was synchronous with Pb pollution in southeastern Europe, with the onset of metal pollution occurring in the area prior to central Europe. Therefore, southeastern Europe may have led regional mining developments, with technological advances rapidly shifting from east to west through the Middle Ages. This indicates how southeastern Europe should be included in future discussions of Middle Age metallurgy not simply as a contributor, but at times as a leader in metal production.

Temporal-spatial characteristics and sources of heavy metals in bulk deposition across China

With the rapid development of industries, agriculture, and urbanization (including transportation and population growth), there has been a significant alteration in the emission and atmospheric deposition of heavy metal pollutants. This has consequently given rise to a range of ecological and environmental health issues. In this study, we conducted a comprehensive two-year investigation on the temporal and spatial distribution characteristics of heavy metals in atmospheric deposition across China based on the Nationwide Nitrogen Deposition Monitoring Network (NNDMN). The atmospheric bulk deposition of Lead (Pb), Arsenic (As), Nickel (Ni), Selenium (Se), Chromium (Cr) and Cadmium (Cd) were 6.32 ± 1.59, 4.49 ± 0.57, 1.31 ± 0.21, 1.05 ± 0.16, 0.60 ± 0.06 and 0.21 ± 0.03 mg m−2 yr−1, respectively, with a large variation among the different regions of China. The order for atmospheric deposition flux was Southwest China > Southeast China > North China > Northeast China > Qinghai-Tibet Plateau and rural area > urban area > background area. The concentrations of heavy metals in bulk deposition exhibit seasonal variation with higher levels observed during winter compared to summer and spring, which are closely associated with anthropogenic activities. The Positive Matrix Factorization (PMF) results indicated that combustion, industrial emissions and traffic are the primary contributors to atmospheric deposition of heavy metals. The single factor pollution index (Pi) of heavy metals is consistently below 1, and the composite pollution index (Ni) is 0.16 across China, indicating that atmospheric heavy metal deposition is at a pollution-free level. The comprehensive potential ecological risk index of heavy metals is 11.8, with Cd exhibiting the highest single factor potential ecological risk index at 7.09, suggesting that more attention should be paid to Cd deposition in China. The present study reveals the spatial-temporal distribution pattern of atmospheric heavy metals deposition in China, identifying regional source characteristics and providing a theoretical foundation and strategies for reducing emissions of atmospheric pollutants.

Source Identification and Ecological Risk of Potentially Harmful Trace Elements in Lacustrine Sediments from the Middle and Lower Reaches of Huaihe River

Sediment pollution caused by potentially harmful trace elements (PHTEs) has attracted a great deal of attention, due to the persistent risks it poses to human beings and ecosystems. However, the pollution status and source identification of PHTEs from the middle and lower reaches of Huaihe River remains unclear. In this study, arsenic, cadmium, chromium, copper, nickel, zinc, lead and isotopic ratios in the lacustrine sediments of this river are investigated to determine the source of, and ecological risk posed by, these PHTEs. The results show that the concentrations of chromium, copper, nickel and zinc are generally close to the background values in the lacustrine sediments, and are assessed as representing a low degree of contamination. By contrast, significantly higher concentrations of arsenic and cadmium are commonly measured in the upper sediments, which are mainly derived from the agricultural application of fertilizers, pesticides and wastewater. Meanwhile, possible atmospheric lead deposition is identified by the isotopic analysis. Among these PHTEs, adverse biological effects of arsenic, chromium, and nickel may occur in lakes according to consensus-based sediment quality guidelines, but cadmium is selected as a PHTE for priority control according to potential ecological risk index. Our study highlights that developing regional sediment quality guidelines and soil restoration in the catchment are crucial for the freshwater ecosystem in the middle and lower reaches of Huaihe River.

The use of lichen and fungal collections in Australian herbaria to identify temporal changes in air pollution and assist environmental management: challenges to conserving herbarium specimens for the future

Context Global environmental modification is placing increased demand on taxonomic resources, especially herbarium collections, which are being utilised for information and as biological resource material in ways never previously envisaged. This increased use of herbarium collections presents current and on-going management challenges. Aims To demonstrate, with two Australian studies, the essential role of herbarium collections in investigating long-term pollution; to emphasise the importance of on-going collecting for herbaria and make recommendations for future collection management. Methods Australian case studies of a long-term pollution problem are used to show how verified lichen and fungal taxa in Australian herbaria were crucial in identifying sources of air pollution over time. Key results Chemical and isotopic analyses of lead in samples from curated herbarium collections were used to reconstruct patterns of atmospheric lead deposition over 150 years in eastern Australia. This extended time series of samples facilitated documentation of the full cycle from natural background concentrations to the introduction and increasing usage of lead both in industry and motor vehicles, to the eventual discontinuation of its use in automotive fuel. In addition to demonstrating the value of regular, long-term sampling of selected taxa and potential applications to emerging environmental problems, the importance of strict protocols for destructive sampling and analysis of herbarium specimens, especially for older collections containing small quantities of material, has been highlighted. Conclusions Both the Australian and previous studies have identified a number of problems and potential challenges to maintaining and maximising the utilisation of finite herbarium resources for the future. While acknowledging that Australasian herbaria have well documented policies and protocols for studies that sample their collections, six recommendations are made, for future implementation as appropriate. Implications Current management strategies for finite reference collections are summarised and recommendations for the future include the following: repeated, ongoing collecting over broader areas; periodic re-collection of larger samples from select reference sites with detailed field data; preparation and storage of specimens under controlled environmental conditions, with minimal chemical pest control; utilisation of common widespread taxa for research; careful supervision of destructive sampling techniques to assess compounds present; and adequate funding to facilitate the digitisation of herbarium specimens to increase access and optimise use of curated collections.

Atmospheric Deposition of Lead and Cadmium in a Central European Country over the Last Three Decades

Lead (Pb) and cadmium (Cd) levels in ambient air were explored due to their toxicity and deleterious environmental effects. The aim of this study was to assess the time tendencies and spatial changes in Pb and Cd atmospheric deposition in a Central European country with a long history of ambient air pollution. We used measured data on precipitation chemistry and ambient air pollutant concentrations in the Czech Republic (CR) obtained within a nation-wide monitoring network. Our analysis is based on spatial patterns of annual wet-only and dry deposition fluxes constructed for 1996–2021. The results indicated that both Pb and Cd deposition over the CR during the last three decades decreased substantially, about 10 times, the absolute values for Cd being one order of magnitude lower than those for Pb. The wet-only deposition pathway dominated over the dry deposition pathway. This trend reflects the heavy metal (HM) emission reductions in the CR and neighboring countries and is in line with decreasing trends in ambient air HM concentrations in Europe. The spatial patterns showed that the northern industrial portions of the CR were loaded more as compared to the southern parts, and that the extension of affected regions has recently decreased substantially.

Caribbean Lead and Mercury Pollution Archived in a Crater Lake.

Lead and mercury have long histories of anthropogenic use and release to the environment extending into preindustrial times. Yet, the timing, magnitude, and persistence of preindustrial emissions remain enigmatic, especially for mercury. Here, we quantify tropical lead and mercury deposition over the past ∼3000 years using a well-dated sediment core from a small crater lake (Lake Antoine, Grenada). Preindustrial increases in lead and mercury concentrations can be explained by varying inputs of watershed mineral and organic matter, which in turn reflect climate-driven changes in the lake level. We find no evidence that preindustrial lead and mercury use raised deposition rates in this remote ecosystem, and our results underscore the need to carefully evaluate common normalization approaches for changing lithogenic inputs and sedimentation rates. Industrial-era lead and mercury accumulation rates in Lake Antoine have been accelerated by land use and land cover change within the crater rim, yet global industrial pollution remains evident. After correcting for watershed inputs, we find that recent atmospheric lead and mercury deposition rates averaged 2925 and 24 μg/m2/y, respectively, which are in close agreement with monitoring data. Our results challenge recent assessments suggesting preindustrial mercury use raised atmospheric deposition rates globally, highlighting the unique nature of 20th Century industrial pollution.

Results of AAS-measurements of atmospheric deposition of copper and lead in the snow cover of Almaty agglomeration

Abstract The article presents the results of the study conducted on the territory of the Almaty agglomeration (AA) in the first half of 2019. During the expeditionary studies, sampling was carried out at 30 permanent points established taking into account the degree of anthropogenic load and sources of technogenic pollution. The content of trace elements (TE) in the snow was determined by a flame atomic absorption spectrometric method using an AA-7000 spectrophotometer with a hollow cathode lamp and with a nozzle burner operating on an acetylene-air mixture. The paper considers the amount of content of copper and lead in the snow, as well as the nature of their distribution over the study area. Calculations were carried out on the number of depositions of the TE in question per unit area over the territory of the agglomeration, with the allocation of zones experiencing the highest technogenic load.

The atmospheric lead emission, deposition, and environmental inequality driven by interprovincial trade in China

Lead (Pb) as a hazardous air pollutant has raised widespread concerns due to its adverse and toxic effects on the ecological environment and human health. Here we integrated the multi-regional input-output (MRIO) model and an atmospheric transport model to examine regional environmental inequality (REI) index induced by Pb emission transfers, and to evaluate the impacts of interprovincial trade on regional atmospheric Pb concentrations and dry deposition fluxes in China in 2012. In 2012, approximately 57.4% ~ 72.6% of Pb emissions in well-developed eastern regions (Beijing-Tianjin, Yangtze River Delta (YRD)) and the southern seaboard of China were embodied in other regions in China subject to the demands from these well-developed regions to industrial products and services. Our results, based on the net virtual flows of Pb emission and value-added, indicate that most provinces in the eastern seaboard of China outsource Pb emission and benefit from the interprovincial trade by reducing their Pb emissions. REI indexes show that the well-developed Guangdong province outsources its Pb emission but has low economic gains. Many less-developed provinces in central China enhance virtual Pb emission inflow but have high economic gains. Whereas, inland provinces in western China not only experience Pb emission increase, but also suffer from indirect economic loss due to trade with well-developed provinces to meet their increasing demands to Pb emission abundant industrial products from these provinces in eastern China which are mostly provided by less-developed but energy and mineral product abundant provinces in western China. For example, the province pair with highest REI index was Jiangsu-Inner Mongolia (REI = 2.47), which revealed that Jiangsu was the largest beneficiary which exported 37.2 t of net Pb emission and gained value-added of 521.4 billion RMB through trade with Inner Mongolia which suffered from both virtual Pb inflow and economic loss in 2012. As a result of interprovincial trade, Pb dry deposition in central and eastern China was decreased but increased in western China. Overall, interprovincial trade reduced 17.6% of atmospheric Pb dry deposition in China.

Cadmium and Lead Pollution Characteristics of Soils, Vegetables and Human Hair Around an Open-cast Lead-zinc Mine.

Atmospheric deposition of cadmium (Cd) and lead (Pb) was investigated together with the accumulation, distribution and health risks from potentially toxic metals in soils, vegetables and human hair at a mining area in southwest China. Annual atmospheric deposition of Cd and Pb were 41.1 and 192g ha- 1, respectively, and consisted mainly of dry deposition. Agricultural soils experienced high levels of metal pollution around the mine, with 66.4% and 57.3 % of vegetable samples grown on these polluted fields exceeding maximum permissible Cd and Pb concentrations, particularly the leafy vegetables. Residents living near the mining area had high Cd (0.75mg kg- 1) and Pb (6.87mg kg- 1) concentrations in their hair, and the maximum values occurred in occupationally exposed individuals. Long-term mining activities have resulted in high health risks to the local population due to Cd and Pb deposition and accumulation from the atmosphere, soils and vegetables.

Atmospheric deposition of arsenic, cadmium, copper, lead, and zinc near an operating and an abandoned lead smelter.

Atmospheric deposition samples were collected over 15 mo at several locations near an operating smelter and an abandoned Pb smelter to investigate the contribution of Pb smelting to depositional fluxes and potential local air quality degradation. Samples were analyzed for As, Cd, Cu, Pb, and Zn and subjected to scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS). Concentrations of Cd and Pb at both sites were greater than at the control site (p<.05), and significant correlations existed between Cd and Pb concentrations at both sites (p<.05). Monthly depositional flux variations at both sites were similar, with greater deposition during cold and dry periods. Heavy metal(loid)s deposition during these periods was correlated with wind speed. Greater Cd depositional flux differences were found between the smelter and control sites compared with other elements. The SEM images suggested that some particles at the operating smelter site were from Pb smelting material. However, most particles at both sites had no characteristics of smelting, suggesting reactions occurred between the smelter-emitted particles and soil components. The EDS results indicated that atmospheric deposition from both sites had lower Pb concentrations than smelting material or ash. The main atmospheric deposition source at the operating and abandoned sites was likely from the resuspension of heavy metal(loid)-enriched soil particles. Greater risk of air pollution from historical Pb smelting facilities exists years after closing down. Reducing soil wind erosional losses may help reduce heavy metal(loid)s dispersion across environments.

Survey of atmospheric heavy metal deposition in Suqian using moss contamination

Heavy metal pollution in the atmosphere is a major environmental problem, which has important impacts on ecosystems and human health. In this study, the atmospheric deposition of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) in Suqian, China, was investigated by using the moss Haplocladium microphyllum as a bioindicator. The survey was carried out during the summer of 2017 at 40 homogenously distributed sampling sites. Cr, Cu, Ni, Pb, V, and Zn were analyzed by inductively coupled plasma atomic emission spectrometry, and Cd was analyzed by inductively coupled plasma mass spectrometry. Wide variations in heavy metals (Cd, Pb, and Zn) indicated that the concentrations of elements are influenced by local emission sources. Spatial distribution maps of the elements were constructed using geographic information system technology. The pollution load index showed that the study area was moderately polluted to unpolluted. Significant positive correlations (p < .01) and weak positive correlations (p < .05) were identified among some of the elements, indicating that they originated from common sources. A principal component analysis classified the heavy metals into natural and anthropogenic sources, and identified four primary sources: nature soil dust, industry activities, traffic emission, and agricultural activities.

Anthropogenic and lithogenic fluxes of atmospheric lead deposition over the past 3600 years from a peat bog, Changbai Mountains, China

Ombrotrophic peatlands are widely used to reconstruct atmospheric metal deposition histories. Here, we estimated the long-term atmospheric Pb deposition flux using ombrotrophic peatland data from the Changbai Mountains, northeast China. A peat profile of 320-cm depth was sampled and cut into 164 slices for measurement of Pb and other elements by ICP-MS and ICP-AES and radiometric dating by 210Pb, 137Cs and 14C. Pb concentration in the peat ranged from 2.18 to 68.33 mg kg−1, while the atmospheric Pb deposition flux ranged from 0.12 to 12.49 mg m−2 a−1. The Little Ice Age (cold and wet climate) led to low Pb concentration, Pb/Sc ratio, and Pb deposition flux (4.40 ± 0.70 mg kg−1, 2.04 ± 0.38, and 0.28 ± 0.09 mg m−2 a−1, respectively). On the other hand, intense volcanic eruptions resulted in high Pb concentration, Pb/Sc ratio, and P flux (54.48 ± 13.08 mg kg−1, 7.85 ± 2.09, and 8.15 ± 2.85 mg m−2 a−1, respectively). In addition, rapid economic development since the 1980s resulted in a gradual increase of anthropogenic Pb concentration from 1.54 mg kg−1 to 5.85 mg kg−1; thus, the anthropogenic Pb deposition flux (0.43 ± 0.21 mg m−2 a−1) was high during this period. In general, peat Pb concentration and atmospheric Pb deposition fluxes in this region have been affected by climate change, volcanic eruptions, and human activities. It was further demonstrated that atmospheric Pb emissions and deposition in China decreased since leaded gasoline was phased out in 2001. The results are critical to understand the geochemistry of Pb and to assess the effects of human activities on atmospheric Pb emissions and deposition in China.

Distributions and pools of lead (Pb) in a terrestrial forest ecosystem with highly elevated atmospheric Pb deposition and ecological risks to insects

There is growing interest in how heavy metals in remote ecosystems are elevated and affect environmental health. However, no studies have investigated atmospheric lead (Pb) deposition influences on the Pb bioaccumulation in insects in forests. Here we measure Pb concentrations and pools in forest vegetation, litterfall, organic soil, mineral soil, as well as litterfall deposition fluxes in a region severely affected by atmospheric deposition. We also analyzed Pb in insects which feed in the polluted forest vegetation and litter. Assessment of high Pb loads causing potential ecological risk to insects was also studied. Total Pb pool in the vegetation was 0.12 g m−2 and annual litterfall deposition flux of Pb was 13.42 mg m−2, which was much higher than those in the background areas. Pools of Pb from litter to mineral topsoil averaged 4.3 g m−2, which accounted for 97.3% of total pools (biomass + soil) in the forest ecosystem. Pools of Pb in surface soils were correlated significantly with the pools of total organic matter and elevation. Atmospheric deposition was inferred the major source of Pb in the forest ecosystem, which can be supported by the highest Pb concentrations in the moss and overstory foliage. The maximum Pb concentration was showed in the dung beetle (12.1 mg kg−1) residing in the soils compared that in the longicorn and of cicada, which would potentially pose negatively influence to predators along food chains.

Comment on "Next-Generation Ice Core Technology Reveals True Minimum Natural Levels of Lead (Pb) in the Atmosphere: Insights From the Black Death" by More et al.

Key Points Results and interpretation of the subject article are surprising and conflict with expectations about atmospheric deposition of lead (Pb)Before interpretation of subject article is accepted a body of information about natural deposition of lead (Pb) must be consideredThis body of information includes knowledge of volcano emissions, chemistry of natural dusts, and isotopes of lead (Pb)

Estimating the Possibility of Surface Soil Pollution with Atmospheric Lead Deposits Using the ADMER Model

The literature assessing the risks of soil pollution from atmospheric lead (Pb) deposition is still insufficient, given that Pb deposition can cause large-scale surface soil pollution. This study estimated the possibility of Pb deposition causing soil pollution by calibrating a numerical model of deposition flux with a measured Pb content dataset in proximity to a pollution source. A total 34 surface soil samples were collected around an industrial park that emits Pb into the atmosphere. The sample’s Pb content was determined using hydrochloric acid extraction and an ICP-MS. The amount of annual Pb deposition was estimated using the atmospheric dispersion model for exposure and risk assessment (ADMER model). This approach resulted in accurate predictions of Pb distribution for most sites (&lt;800 m from the pollution source), but the results indicated that the dry deposition velocity of Pb-containing particles was a significant determinant of horizontal Pb distribution. We conducted a sensitivity analysis of the ADMER’s estimated Pb deposition flux values by changing the diameter of Pb-containing particles. This analysis showed large fluctuations in soil Pb content within 1 km of the source, within the range of the previously reported dry deposition velocity.

Study of Heavy Metal Air Pollution, Using a Moss (Grimmia dissimulate) Biomonitoring Technique

Air pollution is a problem in both developed and developing countries. As a corrective measure, constant air monitoring is usually performed by conventional techniques which are costly and time consuming hence the need for cheaper methods. Recently, biomonitoring has emerged as an effective alternative method. The aim of this study was to investigate heavy metal air pollution in the environment using Mosses. Mosses are lower plants that can provide a surrogate and time-integrated means of measuring elemental depositions from the atmosphere to terrestrial systems. Atmospheric deposition of heavy metals Chromium (Cr), Copper (Cu), lead (Pb), and Zinc (Zn) was studied at the University of Zimbabwe. Moss samples were hung on sites selected by a systematic grid sampling method, during the summer of 2016. The concentrations of heavy metals were determined by Atomic Absorption Spectroscopy (AAS). The concentrations were expressed as Relative Accumulation Factors (RAFs) and the means for Cr, Cu, Pb and Zn were 14.38; 18.17; 9.63 and 10.78 respectively. The results showed the concentration order of deposition was Cu > Cr > Zn >Pb and that Zn deposited uniformly as evidenced by its low sample variance which was more than 17 and 56 times smaller than that of Pb and Cr-Cu respectively. Although the distribution patterns of Cr and Cu were similar, Pb and Zn had their own patterns. The results suggested that the source of heavy metal could be from traffic related air pollutants.

Contemporary Mobilization of Legacy Pb Stores by DOM in a Boreal Peatland.

We examined how different landscape areas in a catchment containing a northern ombrotrophic peatland and upland mineral soils responded to dramatic decreases in atmospheric deposition of lead (Pb). Pb concentrations in the outflow stream from the peatland measured from 2009-2015 indicated continued mobilization and export of Pb derived from historic inputs to the bog. In contrast, Pb concentrations in surface peat and runoff from upland mineral soils have declined in response to reductions in atmospheric deposition. Relative to the early 1980s, Pb concentrations in the streamflow decreased only ∼50%, while Pb in surface peat and upland subsurface runoff decreased by more than 90%. Water level fluctuations in the slow-accumulating peat have allowed dissolved organic matter (DOM) to continue mobilizing Pb deposited in the peatland decades earlier. Strong correlations between dissolved organic carbon (DOC) and Pb concentrations in outflow from the peatland and in bog porewaters demonstrate Pb mobility related to DOM production. Peat stores of Pb in 2016 were less than or equal to those reported in the early 1980s despite the dry mass inventory increasing by 60-80%. Much of the loss in Pb stored in peat can be accounted for by stream runoff from the peatland.

Next-generation ice core technology reveals true minimum natural levels of lead (Pb) in the atmosphere: Insights from the Black Death.

Contrary to widespread assumptions, next‐generation high (annual to multiannual) and ultra‐high (subannual) resolution analyses of an Alpine glacier reveal that true historical minimum natural levels of lead in the atmosphere occurred only once in the last ~2000 years. During the Black Death pandemic, demographic and economic collapse interrupted metal production and atmospheric lead dropped to undetectable levels. This finding challenges current government and industry understanding of preindustrial lead pollution and its potential implications for human health of children and adults worldwide. Available technology and geographic location have limited previous ice core investigations. We provide new high‐ (discrete, inductively coupled plasma mass spectrometry, ICP‐MS) and ultra‐high resolution (laser ablation inductively coupled plasma mass spectrometry, LA‐ICP‐MS) records of atmospheric lead deposition extracted from the high Alpine glacier Colle Gnifetti, in the Swiss‐Italian Alps. We show that contrary to the conventional wisdom, low levels at or approaching natural background occurred only in a single 4 year period in ~2000 years documented in the new ice core, during the Black Death (~1349–1353 C.E.), the most devastating pandemic in Eurasian history. Ultra‐high chronological resolution allows for the first time detailed and decisive comparison of the new glaciochemical data with historical records. Historical evidence shows that mining activity ceased upwind of the core site from ~1349 to 1353, while concurrently on the glacier lead (Pb) concentrations—dated by layer counting confirmed by radiocarbon dating—dropped to levels below detection, an order of magnitude beneath figures deemed low in earlier studies. Previous assumptions about preindustrial “natural” background lead levels in the atmosphere—and potential impacts on humans—have been misleading, with significant implications for current environmental, industrial, and public health policy, as well as for the history of human lead exposure. Trans‐disciplinary application of this new technology opens the door to new approaches to the study of the anthropogenic impact on past and present human health.

Using Moss to Assess Airborne Heavy Metal Pollution in Taizhou, China.

Bryophytes act as bioindicators and bioaccumulators of metal deposition in the environment. To understand the atmospheric deposition of heavy metals (cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn)) in Taizhou, East China, samples of moss (Haplocladium microphyllum) were collected from 60 sites selected by a systematic sampling method during the summer of 2012, and the concentrations of these heavy metals were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results suggested that the concentrations of these metals varied moderately among different sites, indicating a similar contamination level for each element throughout the monitoring region. The mean values under investigation were higher than those from neighboring cities, such as Wuxi, Xuzhou, and Nanjing, and much higher than those in Europe based on a 2010 survey. Significant (p < 0.01) correlations were identified among some of the heavy metals, suggesting that these originated from identical sources. There was no statistically significant correlation between Hg and all the other elements. Spatial distribution maps of the elements over the sampled territory were created using Arc-GIS 9.0. The potential ecological risk index indicated that the air was heavily polluted by Cd and Hg, and that there was a considerable potential ecological risk from all the heavy metals studied.

Australian atmospheric lead deposition reconstructed using lead concentrations and isotopic compositions of archival lichen and fungi

Lead concentrations and their isotopic compositions were measured in lichen genera Cladonia and Usnea and fungi genus Trametes from the Greater Sydney region (New South Wales, Australia) that had been collected and archived over the past 120 years. The median lead concentrations were elevated in lichens and fungi prior to the introduction of leaded petrol (Cladonia 12.5 mg/kg; Usnea 15.6 mg/kg; Trametes 1.85 mg/kg) corresponding to early industrial development. During the period of leaded petrol use in Australian automobiles from 1932 to 2002, total median lead concentrations rose: Cladonia 18.8 mg/kg; Usnea 21.5 mg/kg; Trametes 4.3 mg/kg. Following the cessation of leaded petrol use, median total lead concentrations decreased sharply in the 2000s: Cladonia 4.8 mg/kg; Usnea 1.7 mg/kg. The lichen and fungi isotopic compositions reveal a significant decrease in 206Pb/207Pb ratios from the end of 19th century to the 1970s. The following decades were characterised by lower allowable levels of lead additive in fuel and the introduction of unleaded petrol in 1985. The environmental response to these regulatory changes was that lichen and fungi 206Pb/207Pb ratios increased, particularly from 1995 onwards. Although the lead isotope ratios of lichens continued to increase in the 2000s they do not return to pre-leaded petrol values. This demonstrates that historic leaded petrol emissions, inter alia other sources, remain a persistent source of anthropogenic contamination in the Greater Sydney region.