Soil Pb Levels Research Articles

Increased Cancer Incidence in the Local Population Around Metal-Contaminated Glassworks Sites.

The aim of this study was to examine mortality causes and cancer incidence in a population cohort that have resided in close proximity to highly metal-contaminated sources, characterized by contamination of, in particular, arsenic (As), cadmium (Cd), and lead (Pb). Data from Swedish registers were used to calculate standardized mortality and cancer incidence ratios. An attempt to relate cancer incidence to metal contamination levels was made. Significantly elevated cancer incidences were observed for overall malignant cancers in both genders, cancer in the digestive system, including colon, rectum, and pancreas, and cancers in prostate among men. Dose-response relationships between Cd and Pb levels in soil and cancer risks were found. Cancer observations made, together with previous studies of metal uptake in local vegetables, may imply that exposure to local residents have occurred primarily via oral intake of locally produced foodstuffs.

Pb Uptake in Roadside Grown Wheat (Triticum aestivum L.) in the Sudan Savanna, Kano State

Cereal crops grown under irrigation in a semi-arid ecological habitat can be used to assess food quality and safety of agricultural systems at proximity to highways in the Sudan savannah of Northern Nigeria. This study focussed on the risk assessments of Pb transfer, translocation and uptake at selected growth stages (15-, 30-, 45-, 60-, 75- and 90-days representing seedling or germination, tillering, shooting/booting, earing, flowering and ripening stages respectively of two cultivars of Triticum aestivum L. The experimental (SU 1) and control (SU 2) sites were selected based on distances (345 m and 1936 m) from the Kano-Zaria Highway. Pb levels in soils and the two cultivars of Triticum aestivum L. was measured using the double-beam AAS and plant uptake factors (PUF), soil-plant transfer coefficients (TC) and translocation factors (TF) were worked out. Result reveals differences in metal levels of the cultivars of wheat according to growth stages and plant parts. Pb levels was highly significant (P=0.05 and 0.01) in the stems of Siettecerros at the control site indicating selective ability of cultivar to Pb. Pb levels were highest in both cultivars at the 30-days growth stage indicating sensitivity of tillering stage to Pb uptake. A greater than unity value indicate anthropogenic source of Pb. Siettecerros had the highest TF indicating incorporation of higher levels of Pb in the edible plant parts. A higher PUF (45), TC (6.32) and TF (7.66) for Pb in Pavon-76 and Siettecerros respectively, indicates their suitability for bioremediation particularly, phytoextraction of polluted soils from atmospheric pollutants.

Effect of spatial resolution of soil data on predictions of eggshell trace element levels in the Rook Corvus frugilegus

Although a considerable research effort has gone into studying the dietary pathways of metals to the bodies of laying female birds and their eggs in recent years, no detailed investigations have yet been carried out relating the properties of the biogeochemical environment at large spatial scales to eggshell trace element levels in typical soil-invertebrate feeding birds under natural conditions. We used data from a large-scale nationwide monitoring survey of soil quality in Poland (3724 sampling points from the 43 792 available) to predict levels of five trace elements (copper [Cu], cadmium [Cd], nickel [Ni], zinc [Zn] and lead [Pb]) in Rook Corvus frugilegus eggshells from 42 breeding colonies. Our major aim was to test whether differences exist in the explanatory power of soil data (acidity, content of elements and organic matter, and particle size) used as a correlate of concentrations of eggshell trace elements among four different distances (5, 10, 15 and 20 km) around rookeries. Over all four distances around the rookeries only the concentrations of Cu and Cd in eggshells were positively correlated with those in soil, while eggshell Pb was correlated with the soil Pb level at the two longest distances (15 and 20 km) around the rookeries. The physical properties of soil (primarily the increase in pH) adversely affected eggshell Cd and Pb concentrations. The patterns and factors governing metal bioaccumulation in soil invertebrates and eggshells appear to be coincident, which strongly suggests a general similarity in the biochemical pathways of elements at different levels of the food web. The increasing acidification of arable soil as a result of excessive fertilisation and over-nitrification can enhance the bioavailability of toxic elements to laying females and their eggs.

Differential toxicity of Pb & Hg on the development of modular traits, photosynthetic and biochemical attributes in two varieties of a forage crop species Trifolium alexandrinum L.

Heavy metal stress as result of natural and anthropogenic activities is main environmental problem. Pb and Hg are among non-biodegradable metals thus remaining persistent in soil and water. The present study was carried out to assess growth and biochemical responses of two varieties (Desi and Misri) of Trifolium alexandrinum L. after application of varying levels (25mg/kg, 50mg/kg and 100mg/kg) of Pb and Hg in soil along with control. Seed germination, biomass of above and below ground tissues, number of flowers and leaves, leaf area and nodulation was observed. For biochemical attributes, green pigments, protein and amino acids, were determined. Both varieties (Desi and Misri) showed variable responses in relation to both Pb and Hg. Similarly, the pattern of character expression was independent for metal levels and types. Misri performed consistently better as it showed best threshold for most of the attributes studied. Hg was found to be more toxic as compared to the Pb as it induced more drastic decline in parameters studied. The study showed that biometric traits can be used as good predictors and the biochemical parameters cannot be used as useful biochemical markers as they showed no marked disparity.

Newcastle Allotments Lead Biomonitoring Study: an investigation into the relationship between urban agriculture site soil lead concentrations and the blood lead concentration of gardeners

Newcastle-upon-Tyne is the regional capital of NE England with a rich industrial and mining history. Urban Agriculture Sites (UAS), known in the UK as ‘allotments’, have developed as part of urban expansion since the industrial revolution allowing retention of non-commercial agriculture. In 2004 we reported ‘tension between supporting allotment gardening as a health promoting activity and protecting public health from exposure to contaminated land and produce.’ We had found that many Newcastle UAS had soil Pb levels above the UK Soil Guideline Value of 450 mg/kg. In 2008 we reported an overview of investigations at 28 Newcastle UAS. From 400+ soil samples Pb was repeatedly found to be elevated: median: 545, P95: 684 mg/kg. Detailed quantitative risk assessments with analysis of vegetable uptake of Pb and bioaccessibility were used to avoid site closures due to overcautious risk assessment. Since then the UK soil screening level for a ‘low level toxicological concern’ for Pb in UAS has reduced to 80 mg/kg. 10x lower than soil Pb at many Newcastle UAS. The aim of this study was to determine the relationship between Pb in UAS soils and the blood Pb of gardeners to give confidence to regulators who must decide the suitability of a site. Study participants were recruited from three Newcastle UAS. Gardeners (n = 44) recruited non-UAS gardening neighbours as controls (n = 29). Participants provided blood and saliva samples and helped the team collect soil, vegetable and fruit samples from their plots. To account for confounders, participants provided tap water samples, home dust samples, atmospheric deposition samples and completed a questionnaire on potential exposure factors. This paper presents the results of the blood and soil Pb surveys in conjunction with the questionnaire data to show that UAS containing Pb from common urban sources, even at concentrations up to 10x over the current soil screening value does not result in significantly raised blood Pb.

Cross-Species Extrapolation of Models for Predicting Lead Transfer from Soil to Wheat Grain.

The transfer of Pb from the soil to crops is a serious food hygiene security problem in China because of industrial, agricultural, and historical contamination. In this study, the characteristics of exogenous Pb transfer from 17 Chinese soils to a popular wheat variety (Xiaoyan 22) were investigated. In addition, bioaccumulation prediction models of Pb in grain were obtained based on soil properties. The results of the analysis showed that pH and OC were the most important factors contributing to Pb uptake by wheat grain. Using a cross-species extrapolation approach, the Pb uptake prediction models for cultivar Xiaoyan 22 in different soil Pb levels were satisfactorily applied to six additional non-modeled wheat varieties to develop a prediction model for each variety. Normalization of the bioaccumulation factor (BAF) to specific soil physico-chemistry is essential, because doing so could significantly reduce the intra-species variation of different wheat cultivars in predicted Pb transfer and eliminate the influence of soil properties on ecotoxicity parameters for organisms of interest. Finally, the prediction models were successfully verified against published data (including other wheat varieties and crops) and used to evaluate the ecological risk of Pb for wheat in contaminated agricultural soils.

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.

Assessment of health risk of trace metal pollution in surface soil and road dust from e-waste recycling area in China

Informal recycling of e-waste and the resulting heavy metal pollution has become a serious burden on the ecosystem in Guiyu, China. In this investigation, we evaluated the trace metal concentration of community soil and road dust samples from 11 locations in Guiyu and 5 locations (consisting of residential areas, kindergarten/school, and farm field) in a reference area using graphite furnace atomic absorption spectrophotometer. The study spanned four seasons, 2012-2013, with a view to assess the risk associated with e-waste recycling in the study area. The concentrations of Pb, Cd, Cr, and Mn were 448.73, 0.71, 63.90, and 806.54mg/kg in Guiyu soil and 589.74, 1.94, 69.71, and 693.74mg/kg, in the dust, respectively. Pb and Cd values were significantly higher (P ≤ 0.05) than the reference area, and the mixed model analysis with repeated seasonal measurements revealed soil Pb and Cd levels that were 2.32 and 4.34 times, while the ratios for dust sample were 4.10 and 3.18 times higher than the reference area. Contamination factor, degree of contamination, and pollution load index indicated that all sampling points had a high level of metal contamination except farm land and kindergarten compound. The cumulative hazard index of Pb, Cd, Cr, and Mn for children in exposed area was 0.99 and 1.62 for soil and dust, respectively, suggesting non-cancer health risk potential. The significant accumulation of trace metals in the e-waste recycling area predisposes human life, especially children, to a potentially serious health risk.

Phytoextractor Potential of Cultivated Species in Industrial Area Contaminated by Lead

High growth rate is one of the criteria used for the selection of species to be used in metal phytoextraction programs. This study was carried out to characterize the growth characteristics of sunflower ( Helianthus annuus L.), castor bean ( Ricinus communis L.), corn ( Zea mays L), and vetiver [ Vetiveria zizanioides (L.) Nash] grown on a soil contaminated with lead (Pb), with and without pH correction, to improve agronomic practices regarding phytoremediation programs. The experiment was designed as a randomized block with four replications; treatments were arranged in a split-plot arrangement, with the main plot representing the species (sunflower, castor bean, corn, and vetiver), with or without pH correction and soil fertilization, and the split-plot representing harvest periods (60, 90, and 120 days after planting). After variance analysis and mean comparison analysis of the data by the Tukey test (p≤0.05), a significant effect was observed from soil pH correction for vetiver in all of the growth variables evaluated, except for the leaf area index at 120 days after planting (DAP). Castor bean and sunflower plants in soil with high acidity conditions, without pH correction (pH˂4.0), were affected by soil Pb levels. Corn plants benefited from soil pH correction and had improved results for the plant height, diameter, and leaf area variables at 60 and 90 DAP, as well as leaf area index at 60 DAP. There was no increase in these variables between the harvest periods evaluated. Regarding phytoextraction potential, corn and vetiver had the highest Pb translocation to the plant shoots at 90 DAP and were therefore considered the most suitable species for phytoremediation of the area under study. Overall, liming was essential for improving species biomass production for all the species studied in soils with high Pb availability in solution. Key words: phytoremediation; soil pollution; heavy metal; biological indicator

Levels of As, Cd and Pb in soils and sediments from gold mining areas in the municipalities of Pontes e Lacerda and Nova Lacerda, in the Vale do Alto Guaporé, (Valley of the High Guaporé ), MT

Levels of As, Cd and Pb in soils and sediments from gold mining areas in the municipalities of Pontes e Lacerda and Nova Lacerda, in the Vale do Alto Guaporé, (Valley of the High Guaporé ), MT

Distribution of Soil-Bound Lead Arising from Rainfall-Runoff Events at Impact Berm of a Military Shooting Range

Surface runoff from rainfall event is an important indicator of metal mobility in soil, which may enhance non-point source contamination of soil. This study is designed to assess the mobility of soil-bound lead through simulated rainfall runoff experiment and its spatial distribution within the vicinity of a berm at a major military shooting range. Contamination was more significant at the impact area of berm, indicating threefold increase in Pb (17,500 ± 3811 μg/g) within a space of ten years. However, the non-impact area (459 ± 147 μg/g) was less contaminated. Other metals (Cu, Cd, Cr, Ni and Zn) analyzed were about background levels except for Cu at impact area. The enrichment ratio of Pb in runoff sediments was mostly high for the 0.43 mm sediment fractions independent of rainfall condition. Principal component analysis (PCA) biplot showed strong correlation between spatial distributions of metals around the vicinity of the berm (farmlands behind the berm) with concentrations on the impact berm soil. Surface runoff simulated on impact area soil had high concentrations of Pb (40.4 - 65.6 μg/mL) which could further lead to enrichment of soil-Pb levels within the vicinity of the berm. Decontamination measure is therefore required to minimize extensive contamination of surrounding soils of the impact berm due to rainfall runoff events.

Total polyphenols content in fruits of selected cultivars of strawberries in relation to concentrations of cadmium and lead in soil

The key aim of our study was to define the correlation of total polyphenols contents in seven cultivars of strawberries (Clery, Sonata, Alba, Korona, Ázia juh, Anthea, Joly) grown in the parcels with exceeded levels of pseudo-total Cd and mobile Pb in soil. Strawberries were grown in rows long 200 m, the distance of the plants was 0.35 m and inter-row distance was 1 m. Following fertilizing was applied - at the beginning of vegetation period the doses of elements (in kg.ha-1) were: N48.2 +P78.3 +K66.3 +Mg7.2, afterwards 23 days of elements were applied in liquid irrigation in amount: N46.5 +P34.8 +K118.7. Heavy metals in contamination soil were analysed by the method of atomic absorption spectroscopy and total contents of polyphenols spectrophotometrically. The highest content of all monitored parameters (pseudo-total and mobile Cd and Pb, as well as the amount of total polyphenols) was found in Ázia juh cultivar. There was statistically significant positive relation of total polyphenols contents in Anthea cultivar to levels of all monitored forms of metals in soil and contrary, in Clery cultivar there was found non-correlation of total polyphenols contents on levels of monitored heavy metals in soil (mainly of mobile contents of Cd and Pb contents). Contents of mobile forms of individual heavy metals positively correlated with total polyphenols (except of Clery and Ázia juh cultivars). Varietal relation on levels of total polyphenols was confirmed in experiment prior to relation of these organic compounds to the presence of monitored heavy metals in soil.

Assessment of arbuscular mycorrhizal fungi status and heavy metal accumulation characteristics of tree species in a lead–zinc mine area: potential applications for phytoremediation

To select suitable tree species associated with arbuscular mycorrhizal fungi (AMF) for phytoremediation of heavy metal (HM) contaminated area, we measured the AMF status and heavy metal accumulation in plant tissues in a lead-zinc mine area, Northwest China. All 15 tree species were colonized by AM fungi in our investigation. The mycorrhizal frequency (F%), mycorrhizal colonization intensity (M%) and spore density (SP) reduced concomitantly with increasing Pb and Zn levels; however, positive correlations were found between arbuscule density (A%) and soil total/DTPA-extractable Pb concentrations. The average concentrations of Pb, Zn, Cu and Cd in plant samples were 168.21, 96.61, 41.06, and 0.79mg/kg, respectively. Populus purdomii Rehd. accumulated the highest concentrations of Zn (432.08mg/kg) and Cu (140.85mg/kg) in its leaves. Considerable amount of Pb (712.37mg/kg) and Cd (3.86mg/kg) were concentrated in the roots of Robinia pseudoacacia Linn. and Populus simonii Carr., respectively. Plants developed different strategies to survive in HM stress environment: translocating more essential metals (Zn and Cu) into the aerial parts, while retaining more toxic heavy metals (Pb and Cd) in the roots to protect the above-ground parts from damage. According to the translocation factor (TF), bioconcentration factor (BCF), growth rate and biomass production, five tree species (Ailanthus altissima (Mill.) Swingle, Cotinus coggygria Scop., P. simonii, P. purdomii, and R. pseudoacacia) were considered to be the most suitable candidates for phytoextraction and/or phytostabilization purposes. Redundancy analysis (RDA) showed that the efficiency of phytoremediation was enhanced by AM symbioses, and soil pH, Pb, Zn, and Cd levels were the main factors influencing the HM accumulation characteristics of plants.

Relationships Between Subcellular Distribution and Translocation and Grain Accumulation of Pb in Different Rice Cultivars

To test the hypothesis that lead (Pb) content of rice grain may be related to its transport and subcellular distribution in rice plant, the present study was conducted with six rice cultivars of different types under different soil Pb levels. The results showed that grain Pb concentrations were correlated positively and significantly (P 0.05) with the DR from roots to shoots. The DR from shoots to ears/grains was correlated positively and significantly (P < 0.05 or 0.01) with subcellular distribution ratios (SDRs) of Pb in soluble fraction of shoots, but negatively and significantly (P < 0.05 or 0.01) with the SDR in cell wall fraction of shoots. In conclusion, Pb transportation from the shoot to the grain is the key factor in determining Pb content of rice grain. The Pb distributed in soluble fraction of shoot tissue is the key source of Pb for transferring into the grain. The Pb precipitated in cell wall fraction is the key sink of Pb in shoot tissue that restricts the transport of Pb from the shoot to the grain.

Lead Immobilization and Phosphorus Availability in Phosphate-Amended, Mine-Contaminated Soils

Over a century of mining activities in the Coeur d'Alene mining district in Idaho have contaminated soils of the downstream basin with lead, arsenic, zinc, and cadmium. Elevated soil-Pb levels are a significant hazard to the health of humans and wildlife in the region. One in situ treatment approach for remediating Pb-contaminated soils is application of phosphorus to promote the formation of lead phosphate minerals that have low solubility. However, this remediation strategy may result in excess P runoff to surface waters, which can lead to eutrophication, particularly when used in riparian areas. Research presented in this paper describes experiments in which monopotassium phosphate (KHPO) solution was applied to two Pb-contaminated soils from the Coeur d'Alene River valley to determine how P loading rates affect both Pb immobilization and P mobility and to determine if an optimal P amendment rate can be predicted. Toxicity characteristic leaching procedure extractions were used to assess changes in Pb availability for uptake by an organism or mobilization through the soil, and Bray extractions were used to assess P availability for leaching out of the soil system. For the two soils tested, increasing phosphate amendment caused decreasing Pb extractability. Phosphorus amendment rates above approximately 70 mg kg, however, did not provide any additional Pb immobilization. Phosphorus availability increased with increasing phosphate application rate. An empirical relationship is presented that predicts extractable Pb as a function of extractable P. This relationship allows for prediction of the amount of Pb that can be immobilized at specified P leaching amounts, such as regulatory levels that have been established to minimize risks for surface water degradation. Results suggest that phosphate can be used to immobilize Pb in contaminated wetland or riparian areas without posing risks of P loading to surface waters.

Extração e fitodisponibilidade de zinco e chumbo em latossolo tratado com resíduos de siderurgia

Zinc and lead are trace elements of major environmental concern, as they can originate from point and non-point polution sources and bioacumulate in food webs, with potential risk to human health. Steel industries produce large amounts of residues that may contain Zn and Pb, and the effect of disposing these materials in the environment is little studied in Brazil. This work aimed to select different chemical extractants (water, Mehlich-1, diethylene triamine pentacetic acid - DPTA, citric acid, and concentrated nitric acid) to estimate Zn and Pb availability to elephant grass and common beans. Three different residues (steel slag, filter-press mud and phosphate mud) in five doses (0, 1, 2, 4 and 8 Mg ha-1) were added to a Latosol. Water-soluble Zn comprised a significant part of the total, suggesting its higher solubility and potential contamination of soil, water and plant, when compared to Pb. Pearson correlation coefficients between Zn in plant and soil, for all extractors, were generally higher than for Pb. The correlation coefficients of Zn and Pb levels in soils and plant tissues varied with time and extractor, and DPTA was the most adequate for both elements.

Assessment of some physicochemical properties and levels of Pb, Cu and Zn in soils of selected dumpsites in Kano Metropolis, North-West, Nigeria

Some physicochemical properties (pH, electrical conductivity (EC), cation exchange capacity (CEC), organic carbon (OC) and particle size analysis) and levels of Pb, Cu and Zn in soil samples collected from particular dumpsites within Kano Metropolis were analyzed with the view to evaluating the impact of solid wastes on the soils. Heavy metal contents were determined using Atomic Absorption Spectrophotometer while conventional analytical methods were employed for the analysis of the physicochemical properties. The results of the physicochemical properties revealed values ranging from 7.84 - 8.26 (pH), 171.3 - 286.1µScm -1 (EC), 8.22 - 14.96Cmol/kg (CEC) and 1.35 - 1.86% (OC). The textural class of the soils was mainly sandy loam. The mean concentrations of the metals analyzed from the dumpsite soil samples were in the range of 12.61 - 84.3mgkg -1 for Pb, 20.64 - 35.39mgkg -1 for Cu and 232.3 - 610.4mgkg -1 for Zn, while the mean concentrations of the metals analyzed from the control site soil samples were in the range of 0 - 11.1 mgkg -1 for Pb, 5.7 - 11.0 mgkg -1 for Cu and 69.03 - 120.8 mgkg -1 for Zn. Metal contaminations of the soil dumpsites were in the order of Zn > Pb > Cu. Correlation analysis was used to examine the dependency of heavy metals upon themselves, Pb correlates with Zn in all dumpsites. The results of the analysis of the samples evidently indicate higher contamination of heavy metals, as well as higher values for some physicochemical properties at dumpsites when compared with the control sites; this may pose a serious risk to the environment in which the dumpsites are located. Keywords : Physiochemical properties, heavy metals, dumpsite, soil, contamination.

Physiological Response of Foliar Fertilized Matricaria recutita L. Grown on Industrially Polluted Soil

Essential oil quality, quantity, and antioxidant capacity of foliar fertilized Matricaria recutita L., grown on industrially polluted with cadmium (Cd) and lead (Pb) soil were studied. The polluted field is near the waste depository of ferrous metallurgical combine “Kremikovci”. Content of Cd and Pb in the soil exceeded permissible concentrations 4.6 and 2.0 times, respectively. The presence of high levels of heavy metals in the soil resulted in retained plant growth. In M. recutita grown on industrially polluted soil, a decrease of root and shoot dry biomass and reduction of number of lateral steams was observed. Otherwise, the number and biomass of flowers per plant increased. Antioxidant defense in the foliar fertilized plants grown on industrially polluted soil could due mainly to increased levels of peroxidases with substrates ascorbate, glutathione, guaiacol, and hydrogen peroxide. Enhanced levels of Cd and Pb in soil did not influence essential oil yield and quality of chamomile.

Variations of soil lead in different land uses along the urbanization gradient in the Beijing metropolitan area.

Understanding the spatial pattern of soil lead (Pb) levels is essential to protecting human health. Most previous studies have examined soil Pb distributions by either urbanization gradient or land-use type. Few studies, however, have examined both factors together. It remains unclear whether the impacts of land use on soil Pb levels are consistent along the urbanization gradient. To fill this gap, we investigated variations in soil Pb level under different land-use types along the urbanization gradient in Beijing, China. We classified the degree of urbanization as the urban core, transitional zone, or suburban area and the land-use type as industrial area, roadside, residential area, institutional area, road greenbelt, park, or forest. Our results showed that the range of soil Pb levels in Beijing is <1 mg/kg–292 mg/kg, with a mean of 22 mg/kg. Along the urbanization gradient, the mean soil Pb level increased from the suburban area to the urban core. Land-use types have an impact on soil Pb levels, however, when the degree of urbanization is considered, the impact from land use on soil Pb level was only significant in the transitional zone. Parks and road greenbelts were found to have lower soil Pb, primarily due to soil restoration. Roadside and residential areas were found to have higher soil Pb because of traffic emissions, leaded paint, and previous industrial contamination. In the urban core and suburban area, the soil Pb level showed no significant differences among various land-use types. Given the results of soil Pb in various land-use types, we suggest that future studies consider the urbanization gradient in which different land-use samples are located.

Teores de metais pesados no solo e em girassol adubado com lodo de esgoto

Objetivou-se, com este trabalho, avaliar os teores de metais pesados no solo e em plantas de girassol adubadas com doses de lodo de esgoto. O experimento foi desenvolvido em Cambissolo Háplico, no período de abril a setembro de 2011. Os tratamentos, distribuídos no delineamento em blocos casualizados, com quatro repetições, corresponderam a um tratamento com adubação química e cinco doses de lodo de esgoto aplicadas com base nos teores de N do resíduo e na exigência de N do girassol (0; 4,84; 9,68; 19,36 e 29,04 t ha-1, em base seca). Os teores de Zn no solo e na planta foram maiores nos tratamentos com a aplicação de lodo de esgoto quando comparados com a adubação química. A aplicação de lodo de esgoto resulta em aumento nos teores de Cu, Ni e Pb no solo e não apresenta influência sobre os teores de Zn, Fe, Mn, B, Cd e Cr neste substrato. Por outro lado, na planta, com o aumento da dose de lodo de esgoto, houve aumento dos teores de Zn, Cu e Mn e redução do teor de Pb.