A global transport model of lead in the atmosphere

A global atmospheric transport model is used to calculate lead concentrations in the atmosphere. The model performance is evaluated through comparisons with observations in Europe. The model results of lead concentrations in surface air were compared with measurements in East Asia. The detailed comparisons showed generally good agreement for recent decades, although systematic underestimation was found in China. Anthropogenic lead emissions in China are estimated from economic statistics to be 56 000 t yr^?1, which is not small considering the economic scale of China. The underestimations suggest a hidden source of lead emissions. The emissions in Japan and Korea are derived from optimization by the model. The magnitude is about 2000 t yr^?1, which is much greater than that reported by the Pollutant Release and Transfer Register in Japan and Toxics Release Inventory in Korea.     

Non-destructive pollution exposure assessment by means of wood mice hair

Concentrations of cadmium, copper, lead and zinc were measured in hair, kidney, liver, lung and muscle tissue of wood mice captured along a pollution gradient. We found positive relationships between cadmium concentrations in hair and all internal tissues. Hair lead concentrations were positively correlated with lead contents in kidney and liver. Age had a significant effect on cadmium accumulation in all tissues and hair. Apart from a very weak relationship between zinc concentrations in hair and liver, no significant relation between copper or zinc content in hair and any of the internal organs was observed. In summary, our observations suggest that hair of wood mice can be used for monitoring exposure to non-essential metals like cadmium and lead, but not to homeostatically regulated metals such as copper or zinc.     

Concentrations of lead in aquatic macrophytes from Shoal Lake, Manitoba, Canada

The ability of aquatic macrophytes to accumulate lead was examined in the context of sample site, sample date, depth, organ and species. Considerable variations in lead concentrations were found between the 11 species of macrophytes studied. The mean lead concentration for all species sampled was 16 microg/g (dry weight) ranging from 0-78 microg/g. Analysis of variance indicated that there were significant differences in the mean lead content of macrophytes collected from different sample sites. Similarly, significantly higher values were observed for plants collected from the upper 2m of water. Seasonal trends in lead accumulation were not observed for Shoal Lake macrophytes.     

Controlling lead concentrations in human blood by regulating the use of lead in gasoline

After having been emitted at maximum rates in the 1960s and 1970s, lead has become less ubiquitous in industrialized countries as a result of increasingly stringent policies to limit the use of this heavy metal as an anti-knock additive in gasoline. Using a detailed reconstruction of lead emissions in Europe (PbE), of the air concentration of lead in Europe (PbC) and repeated measurements of lead concentrations in human blood (PbB) in Germany since about 1980, we have constructed an empirical model that estimates PbB given PbE. This model is used for 2 purposes: i)To estimate PbB levels for the 1960s and 1970s in Germany, when emissions were maximum and monitoring blood levels had not yet begun. It turns out that PbB peak emissions were reaching a mean level, which health officials considered potentially harmful for fetuses and small children. ii) To estimate how PbB levels may have developed if regulations of the use of lead in gasoline had been implemented differently. In case of no or delayed regulations, the model estimates that PbB levels well beyond the critical level would have emerged. Thus, the regulation instituted in Germany since the 1970s has reduced significant health hazards.     

Recombinant luminescent bacterial sensors for the measurement of bioavailability of cadmium and lead in soils polluted by metal smelters

Environmental hazard of heavy metals in soils depends to a large extent on their bioavailability. The approach used in this study enables the determination of bioavailable metals in solid-phase samples. Two recombinant bacterial sensors, one responding specifically to cadmium and the other to lead and cadmium by increase of luminescence (firefly luciferase was used as a reporter) were used to determine the bioavailability of these metals in soil-water suspensions (a contact assay) and respective particle-free extracts. Fifty agricultural soils sampled near zinc and lead smelters in the Northern France containing up to (mg/kg) 20.1 of Cd, 1050 of Pb and 1390 of Zn were analysed. As the soil matrix interferes with the assay, recombinant luminescent control bacteria lacking the metal recognizing protein and corresponding promoter (thus, being not metal-inducible) but otherwise comparable to the sensor bacteria (the same host bacterium and plasmid encoding luciferase) were used in parallel to take into account the possible quenching and/or stimulating effects of the sample on the luminescence of the sensor bacteria. Both, chemical and sensor analysis showed that only microg/l levels of metals were extracted from the soil into the water phase (0.1% of the total Cd, 0.07% of Pb and 0.5% of Zn). However, 115-fold more Cd and 40-fold more Pb proved bioavailable if the sensor bacteria were incubated in soil suspensions (i.e., in the contact assay). The bioavailability of metals in different soils varied (depending probably on soil type) ranging from 0.5% to 56% for cadmium and from 0.2% to 8.6% for lead.     

废铅酸蓄电池铅膏性质分析

为给废旧铅蓄电池铅膏的湿法回收工艺提供理论依据,对湖北金洋冶金股份有限公司破碎分选后的废铅膏进行了XRF、XRD、物理分析及化学分析等,确定了废铅膏的主要成分、理化性质等特性。结果表明,废铅膏粒径细小,碾钵磨细后能过120目的筛下物超过77.4%,这对湿法转化是有利的。废铅膏主要组成为64.5%PbSO4、29.5%PbO2、4.5%PbO、0.8%Pb及其他微量杂质元素,杂质主要包括Fe、Sb和Si等。因此,铅膏湿法处理时应该采取合适的净化工艺。     

Targeting lead in the multimedia environment in the continental United States

The U.S. Environmental Protection Agency's (EPA) lead attainment strategy for air is being expanded to address geographic areas with the potential for multimedia, multipathway exposures to lead. Geographic Information Systems (GIS) technology is used to coordinate information from various databases to identify areas of potential concern. The data retrieval and decision processes used in identifying priority sources from each medium and in evaluating identified areas of concern are described in this paper. Only EPA databases with reliable locational information were used to facilitate accurate mapping and allow correlation with other data sources. The sources of lead loadings to air, water, and soils were mapped using either latitude and longitude or zip code, or county centroids for data lacking longitudinal and latitudinal coordinates (such as the drinking water data). A multimedia cluster of lead sources was identified at the county level, since all the facility data in the five databases could be mapped to this level. An impact factor and weighting system was devised to combine the information on the number of facilities and their relative size in developing a ranking of the multimedia lead clusters of concern in each region. The counties with the highest number of points were considered clusters of highest concern for multimedia lead sources. Two separate lists of the clusters were developed according to a point system. One identified 10 multimedia lead clusters in each of the 10 EPA regions, and the other identified the 100 clusters of highest concern in the country as a whole. The project is designed to be a first step in targeting future efforts to identify potential environmental problems associated with lead. The analyses presented in this paper provide a first look at the areas in the country where there is a potential for multimedia exposure to lead. A more refined analysis at the zip code level was subsequently developed to provide a good understanding of the issues pertaining to potential exposure at the neighborhood level. The results of this analysis will ultimately help the EPA and the states to target implementation and enforcement in areas of high potential lead exposures.     

Blood lead levels and free red blood cell protoporphyrin as measure of lead exposure in mute swans

The use of blood lead levels in assessing lead exposure in mute swans, Cygnus olor (Gmelin) is investigated. 823 blood samples were taken from 456 uniquely ringed mute swans at a coarse-fish angling site over a period of 24 months. Blood lead values in individual swans monitored over several weeks were shown to conform to a recently reported kinetic model for blood lead values in birds. The highest median lead levels for flock birds were recorded in the winter and spring and the lowest during the summer moulting period. The use of Free Red Blood Cell Protoporphyrin for detecting lead exposure was examined. Whole blood lead detected 44% (n = 357) with elevated lead, while free red blood cell protoporphyrin detected 34.50%. In a large number of cases levels of protoporphyrin were above the normal level, while the corresponding lead levels were low. The value of both methods and the need to correct each value for haemoglobin is discussed.     

A comparative investigation on the biosorption of lead by filamentous fungal biomass

The removal of lead from aqueous solutions by adsorption on filamentous fungal biomass was studied. Batch biosorption experiments were performed to screen a series of selected fungal strains for effective lead removal at different metal and biomass concentrations. Biosorption of the Pb²⁺ ions was strongly affected by pH. The fungal biomass exhibited the highest lead adsorption capacity at pH 6. Isotherms for the biosorption of lead on fungal biomass were developed and the equilibrium data fitted well to the Langmuir isotherm model. At pH 6, the maximum lead biosorption capacity of Mucor rouxii estimated with the Langmuir model was 769 mg/g dry biomass, significantly higher than that of most microorganisms. Biomass of Mucor rouxii showed specific selectivity for Pb²⁺ over other metals ions such as Zn²⁺. Ni²⁺ and Cu²⁺. This fungal strain may be applied to develop potentially cost-effective biosorbent for removing lead from effluents. The technique of scanning electron microscopy coupled with X-ray dispersion analysis shows that Pb²⁺ has exchanged with K⁺ and Ca²⁺ on the cell wall of Mucor rouxii, thereby suggesting ion exchange as one of the dominant mechanisms of metal biosorption for this fungal strain.     

Equilibrium studies for the sorption of lead from effluents using chitosan

The sorption of lead ions from aqueous solution onto chitosan has been studied. Equilibrium studies have been carried out to determine the capacity of chitosan for lead ions. The effects of solution pH and chitosan particle size on the sorption capacity have been studied.The experimental data were analyzed using three equilibrium isotherm correlations, namely, Langmuir, Freundlich and Redlich-Peterson equations. The linear correlation coefficients were determined for each isotherm and the Freundlich provided the best fit. In addition, error functions have been used to determine the alternative single component equilibrium isotherm parameters by non-linear regression due to the inherent bias in using the correlation coefficient from the linearization. This technique enables the "best fit" isotherm parameters to be used in the equilibrium equations for the sorption of lead ions on chitosan within the limits and assumptions of the various error analysis methods.     

Biosorption of lead(II) in aqueous solution by spent mushroom Tricholoma lobayense

The biosorption of lead(II) ions in both simulated and real wastewater by spent mushroom Tricholoma lobayense, was studied in this work. The results show a biomass with a high potential for removing lead ions from wastewater. The optimum pH for the adsorption is 4, and the adsorption process is fast. The best sorbent mass of the biomaterial is 5 g/L with an initial lead(II) concentration of 1 mmol/L. The process follows the Langmuir isotherm model, and the biosorption capacity of lead ions reaches to 210 mg/g, which is higher than many biosorbents previously studied. The mechanism of biosorption may be mainly attributed to ion exchange. The FT-IR study identifies the functional groups responsible for this process. A scanning electron microscope showed a significant change of the sorbent surface after the biosorption process. The energy dispersive elemental analysis also confirmed the adsorption of lead(II) ions.     

Tolerance of lead by the fruiting body of Oudemansiella radicata

This study focused on the tolerance responses of the fruiting body of Oudemansiella radicata towards different concentrations of lead (250-1000 mg kg(-1)) for 2-6 d. To know about the lead tolerance and detoxification strategy, the lead content, thiol content and the activities of antioxidant enzymes were investigated. The maximum level for the lead concentration in O. radicata was recorded in the 6 d sample in each treatment, and for thiols, it was recorded in the 500 mg kg(-1) Pb/2d sample, while for superoxide dismutases (SOD) and catalases (CAT) activities, it was reached at 1000 mg kg(-1) Pb after 2 d in the stipe and cap, respectively. Peroxidases (POD) activities showed a more complex trend and glutathione reductases (GR) reached the maximum at 500 mg kg(-1) Pb after 2 d in the stipe. Overall, the results showed that low concentration lead stimulated the fruiting body of O. radicata to produce the thiols and activate the antioxidant enzymes after 2 d/4 d, while high concentration Pb resulted in the decline/decrease of the thiols and the activities of antioxidant enzymes after 4 d/6 d. Benefiting from the metal accumulation, detoxification potential and the short lifetime, mushroom have the potential for bioaccumulation of heavy metal in polluted farmland.     

Atmospheric lead concentration distribution in Northern Taiwan

Atmospheric lead concentrations were measured randomly, approximately once per week, at five traffic sites in northern Taiwan from September 1994 to May 1995. Three types of theoretical distributions, lognormal, Weibull and gamma were selected to fit the frequency distribution of the measured lead concentration. Four goodness-of-fit criteria were used to judge which theoretical distribution is the most appropriate to represent the frequency distributions of atmospheric lead.The results show that atmospheric lead concentrations in total suspended particulates fit the lognormal distribution reasonably well in northern Taiwan. The intervals of fitted theoretical cumulative frequency distributions (CFDs) can successfully contain the measured data when the population mean is estimated with a 95% confidence interval. In addition, atmospheric lead concentration exceeding a critical concentration is also predicted from the fitted theoretical CFDs.     

The analysis and levels of lead in human teeth: a review

Human teeth are a readily accessible biological tissue for which the analysis of lead has been used for the classification of people in terms of their lead exposure and absorption. However, there are three significant problem areas in the interpretation of the analytical results for lead in teeth. First, the lead is not homogeneously distributed throughout the tooth; secondly, the lead levels vary with tooth type, which relates to the age of a tooth. Lastly, there are significant variations in results from different laboratories, which, in part, reflect problems with contamination, pretreatment and analytical methods. Since teeth provide an integrated historical record of a person's lead exposure they have some attractive features as biological indicators, compared with materials such as blood. But considerable care and attention to detail is necessary to obtain reliable data.     

Kinetic studies of adsorption of lead(ll) from aqueous solution by wine-processing waste sludge.

A waste sludge produced from a wine-processing wastewater treatment process was used as an adsorbent to removal of heavy metal-lead(II) from aqueous solution. Results of kinetic experiments demonstrated that the adsorption was effective and rapid. Four different kinds of adsorption kinetic models (i.e., pseudo-first-order, pseudo-second-order, and two intra-particular mass diffusion models) were used to investigate the adsorption mechanisms. A normalized standard deviation was used to find the best adsorption kinetic model for the removal of lead(ll) by the sludge. The comparison shows that the kinetic adsorption data can be well-described by the pseudo-second-order adsorption model and that sorption might be a rate-limiting control. The adsorption-rate constant and adsorption capacity of pseudo-second-order adsorption equation were calculated. The parameters (initial lead(II) concentration, sludge-particle size, and sludge dosages), which affect the adsorption capacity of sludge, were discussed by using the pseudo-second-order adsorption equation.     

An evaluative model for lead distribution in roadside ecosystems

In roadside ecosystems lead concentrations in different environmental materials decrease with the distance from the road, following a typical pattern. A model that expresses this distribution pattern is proposed to evaluate lead contamination in these ecosystems.     

Roles of physical and chemical properties of activated carbon in the adsorption of lead ions

Elucidation of the roles of chemical and physical properties of activated carbons is an important basis for the systematic development of adsorbents with optimal properties specific for certain applications. Such an understanding has challenged most researchers and this has been attributed with the difficulty in decoupling the effect of chemical and physical properties that characterize activated carbons. This study proposed empirical modeling in resolving the effects of individual carbon properties in lead adsorption. A model based on lead adsorption and carbon properties including total surface area, mean pore size and heteroatom concentrations has been shown to adequately describe the lead adsorption onto activated carbons prepared from bagasse. To support this investigation a series of activated carbons were prepared from bagasse by physical and by chemical activation techniques. The surface chemical properties of the carbons were inferred from carbon pH and heteroatom concentrations. The physical characterizations of the carbons included total surface area by the BET technique and mean pore size measured using the Horvath-Kawazoe equation. Adsorption tests were conducted using a low concentration of lead (5 ppm) and the solution pH was maintained at 1.0 to maintain lead speciation to the un-complexed Pb(2+) ion. The adequacy of the proposed empirical models was statistically assessed. This form of analysis was shown to provide valuable information in tailor making adsorbents and selecting appropriate adsorbents for lead adsorption.     

Adsorption of lead onto smectite from aqueous solution

The purpose of this research is to study the effect of a new method of adsorption using membrane filtration to determine the maximum amount of lead adsorbed by clay and investigate the behavior of the clay after adsorption of the said metal. Treatment of wastewater contaminated with heavy metals depends on the characteristics of the effluent, the amount of final discharge, the cost of treatment, and the compatibility of the treatment process. The process of adsorption of heavy metals by clays may be a simple, selective, and economically viable alternative to the conventional physical–chemical treatment. This is justified by the importance of the surface developed by this material, the presence of negative charges on the said surface, the possibility of ion exchange taking place, and its wide availability in nature. The removal of lead from wastewater was studied by using the adsorption technique and using clay as the adsorbent. A method was optimized for adsorption through a membrane approaching natural adsorption. This new method is simple, selective, and the lead adsorption time is about 3 days. The various properties of clay were determined. It was observed that the cation exchange capacity of the clay was 56 meq/100 g of hydrated clay for the raw sample and 82 meq/100 g for the purified sample. The total surface area determined by the methylene blue method was equal to 556 and 783 m²/g for the raw and purified samples, respectively. The adsorption kinetics depends on several parameters. The Pb(II) clay, obeys the Langmuir, Freundlich, and the Elovich adsorption isotherms with high regression coefficients. The use of this adsorbent notably decreases the cost of treatment. It was concluded that clay shows a strong adsorption capacity on Pb(II), the maximum interaction occurring with purified clay treated at high concentration of lead. It is proposed that this adsorption through a membrane be extended for the treatment of effluents containing other metals.     

Time trends in the concentrations of lead in wet precipitation from rural and urban sites in Austria

Trend and time series analysis of concentrations of lead in wet precipitation at different rural and urban sampling sites in Austria, collected during intervals of 6-12 years (between 1984 and 1995) is performed. A substantial decrease of the lead concentrations for all sites in consideration is observed similar to observations in Germany, Sweden and North sea and western Atlantic regions. Reductions in rural sites between 60 and 80% in 10 years and around 90% in 10 years in urban areas are found. This trend correlates with the reduction of lead emissions from combustion of gasoline. The seasonal deconvolution model of the data set reveals a typical seasonality with lead concentration peaks in summer and spring for the rural sites and winter peaks for urban sites. The average annual lead concentration in the rural region for 1995 was 1.25 micrograms/l, in the urban region 2.25 micrograms/l.     

Transport of lead and diesel fuel through a peat soil near Juneau, AK: a pilot study

A set of peat column experiments was used to determine the transport potential of lead (Pb) and diesel range organics (DRO) in palustrine slope wetlands near Juneau, AK. This project is important to southeast Alaskan communities because limited land resources are forcing development of regional wetlands. This study was instigated by concerns that proposed modifications to a nearby rifle range using DRO-contaminated soil posed a potential risk to an anadromous fish-bearing stream 250 m from the site. Three pairs of peat columns were extracted from the rifle range for analysis, one pair along and two pairs across the natural bedding planes of the soil. One column in each pair was spiked with Pb and DRO and the other was used as a control. Approximately 1-year worth of water (171 cm) was passed through each column and leachate was collected at regular intervals. The results showed that substantial DRO transport only occurred along the bedding planes. Leads was surprisingly mobile, both along and across the bedding planes with estimated soil-water partition coefficients several orders of magnitude lower than commonly published values, probably because the peat was heavily Pb-loaded by lead from bullets and because the peat's acidic, organic-rich environment enhanced Pb mobility. The chemical outflow behavior agreed with a simple macropore transport model. These results underscore the need for caution when developing regional wetlands.