A comparison of physiologically based extraction test (PBET) and single-extraction methods for release of Cu, Zn, and Pb from mildly acidic and alkali soils

In vitro digestion test can be applied to evaluate the bioaccessibility of soil metals by measuring the solubility of the metals in synthetic human digestive tract. Physiologically based extraction test (PBET), composed of sequential digestion of gastric and intestinal phase, is one of the frequently used in vitro digestion tests. In this study, the PBET was chosen to determine the bioaccessibility of Cu, Zn, and Pb in 14 mildly acidic and alkali (pH 5.87–8.30) soils. The phytoavailability of Cu, Zn, and Pb in the same soils was also measured using six single-extraction methods (0.1 M HNO₃, 0.4 M HOAc, 0.1 M NaNO₃, 0.01 M CaCl₂, 0.05 M EDTA, and 0.5 M DTPA). The extraction efficiencies of the methods were compared. The PBET had a strong ability to extract metals from soil, which was much greater than neutral salt extraction and close to dilute acid and complex extraction in spite of the last 2 h neutral intestinal digestion. The amounts of bioaccessible Cu, Zn, and Pb in the gastric phase and in the gastrointestinal phase were both largely determined by the total content of soil Cu, Zn, and Pb. But the results of gastrointestinal digestion reflected more differences resulting from element and soil types than those of gastric digestion did. It was noticed that most of variations in the amounts of soil Cu, Zn, and Pb extracted by EDTA were well explained by the total soil Cu, Zn, and Pb, as same as the PBET. Moreover, the solubility of Cu, Zn, and Pb in the gastric phase and gastrointestinal phase were all positively linearly correlated with the results of EDTA. It was suggested that EDTA extraction can be used to predict the bioaccessibility of Cu, Zn, and Pb in mildly acidic and alkali (pH?>?5.8) soils, and the PBET and EDTA could be applied to measure, in a certain extent, the bioaccessibility and phytoavailability of Cu, Zn, and Pb in mildly acidic and alkali (pH?>?5.8) soils at the same time.     

Bioaccessibility and health risk of arsenic, mercury and other metals in urban street dusts from a mega-city, Nanjing, China

The oral bioaccessibility and the human health risks of As, Hg and other metals (Cu, Pb, Zn, Ni, Co, Cd, Cr, Mn, V and Fe) in urban street dusts from different land use districts in Nanjing (a mega-city), China were investigated. Both the total contents and the oral bioaccessibility estimated by the Simple Bioaccessibility Extraction Test (SBET) of the studied elements varied with street dusts from different land use districts. Cd, Zn, Mn, Pb, Hg and As showed high bioaccessibility. SBET-extractable contents of elements were significantly correlated with their total contents and the dust properties (pH, organic matter contents). The carcinogenic risk probability for As and Cr to children and adults were under the acceptable level (<1 × 10⁻⁴). Hazard Quotient values for single elements and Hazard Index values for all studied elements suggested potential non-carcinogenic health risk to children, but not to adults.     

Assessment of oral bioaccessibility of arsenic in playground soil in Madrid (Spain): a three-method comparison and implications for risk assessment

Three methodologies to assess As bioaccessibility were evaluated using playground soil collected from 16 playgrounds in Madrid, Spain: two (Simplified Bioaccessibility Extraction Test: SBET, and hydrochloric acid-extraction: HCl) assess gastric-only bioaccessibility and the third (Physiologically Based Extraction Test: PBET) evaluates mouth-gastric-intestinal bioaccessibility. Aqua regia-extractable (pseudo total) As contents, which are routinely employed in risk assessments, were used as the reference to establish the following percentages of bioaccessibility: SBET - 63.1; HCl - 51.8; PBET - 41.6, the highest values associated with the gastric-only extractions. For Madrid playground soils - characterised by a very uniform, weakly alkaline pH, and low Fe oxide and organic matter contents - the statistical analysis of the results indicates that, in contrast with other studies, the highest percentage of As in the samples was bound to carbonates and/or present as calcium arsenate. As opposed to the As bound to Fe oxides, this As is readily released in the gastric environment as the carbonate matrix is decomposed and calcium arsenate is dissolved, but some of it is subsequently sequestered in unavailable forms as the pH is raised to 5.5 to mimic intestinal conditions. The HCl extraction can be used as a simple and reliable (i.e. low residual standard error) proxy for the more expensive, time consuming, and error-prone PBET methodology. The HCl method would essentially halve the estimate of carcinogenic risk for children playing in Madrid playground soils, providing a more representative value of associated risk than the pseudo-total concentrations used at present.     

Use of the physiologically-based extraction test to assess the oral bioaccessibility of metals in vegetable plants grown in contaminated soil

The oral bioaccessibility of metals in vegetable plants grown on contaminated soil was assessed. This was done using the physiologically-based extraction test (PBET) to simulate the human digestion of plant material. A range of vegetable plants, i.e. carrot, lettuce, radish and spinach, were grown on metal contaminated soil. After reaching maturity the plants were harvested and analysed for their total metal content (i.e. Cr, Cd, Cu, Fe, Mn, Mo, Ni, Pb and Zn) by inductively coupled plasma-mass spectrometry (ICP-MS). The plant samples were then subsequently extracted using an in vitro gastrointestinal approach or PBET to assess the likelihood of oral bioaccessibility if the material was consumed by humans.     

Approaches to assess the oral bioaccessibility of persistent organic pollutants: a critical review

Oral bioaccessibility, also known as in vitro gastrointestinal extraction or the physiologically based extraction test (PBET), is an important tool when assessing the risk to humans from persistent organic pollutants (POPs) (and metals). The approach seeks to mimic the processes of human food digestion and thereby assess the bioavailability of POPs (and metals) from materials consumed either accidentally or intentionally in the diet. In vitro conditions are created to simulate various actions in the stomach and intestines (although some methods also include the mouth compartment). This paper reviews the current status of oral bioaccessibility with respect to the release of POPs from soil and related samples of environmental importance. Particular emphasis is placed on the parameters that influence gastrointestinal extraction including gastric and intestinal pH, enzymes, bile salts, food constituents and residence time. In addition, important developments in the use of in vitro gastrointestinal extraction are highlighted. These developments include the use of epithelial Caco-2 cells to mimic the intestinal cell lining, the potential for biotransformation of POPs into estrogenic metabolites as a result of colon microbiota, and the use of in vivo studies to validate existing approaches.     

The effect of earthworms on the fractionation, mobility and bioavailability of Pb, Zn and Cd before and after soil leaching with EDTA

The effect of two ecologically contrasting earthworm species Eisenia fetida (epigeic) and Octolasion tyrtaeum (endogeic) on the fractionation (accessed using sequential extractions), mobility (toxicity characteristic leaching procedure, TCLP) and oral bioavailability (Ruby's physiologically based extraction test, PBET) of Pb, Zn and Cd was studied before and after soil remediation with soil leaching. Twenty-step leaching, with 2.5 mmol kg(-1) EDTA used in each step, removed 58.4%, 25.0% and 68.0% of initial soil Pb, Zn and Cd, respectively, shifted the fractionation of residual heavy metals toward less labile forms, and decreased their mobility by 83.7%, 80.3%, and 90.9%. Pb oral bioavailability was reduced by 3.1-times (in each stomach and intestinal phase). After soil leaching, both earthworm species enriched the carbonate soil fraction in their casts with residual Pb, and increased the Pb bioavailability in the simulated intestinal phase by a factor of 2.4 (E. fetida) and 2.8 (O. tyrtaeum). The concentration of Pb in TCLP leachate from E. fetida casts was 6.2-times higher than in the bulk of the remediated soil. These results indicate that the effect of biotic factors on the availability of heavy metals residual in soil after soil leaching requires consideration.     

The two-phase leaching of Pb, Zn and Cd contaminated soil using EDTA and electrochemical treatment of the washing solution

The feasibility of a novel two-phase method for remediation of Pb (1374 mg kg(-1)), Zn (1007 mg kg(-1)), and Cd (9.1 mg kg(-1)) contaminated soil was evaluated. In the first phase we used EDTA for leaching heavy metals from the soil. In the second phase we used an electrochemical advanced oxidation process (EAOP) for the treatment and reuse of washing solution for soil rinsing (removal of the soil-retained, chelant-mobilized metallic species). In EAOP, a boron-doped diamond anode was used for the generation of hydroxyl radicals and oxidative decomposition of EDTA-metal complexes at a constant current density (15 mA cm(-2)). The released metals were removed from the solution by filtration as insoluble participate and by electro-deposition on the cathode. Four consecutive additions of 5.0 mm ol kg(-1) EDTA (total 20 mmol kg(-1)) removed 44% Pb, 14% Zn and 35% Cd from the soil. The mobility of the Pb, Zn and Cd (Toxicity Characteristic Leaching Procedure) left in the soil after remediation was reduced by 1.6, 3.4 and 1.5 times, respectively. The Pb oral availability (Physiologically Based Extraction Test) in the simulated stomach phase was reduced by 2.4 and in the intestinal phase by 1.7 times. The discharge solution was clear, almost colorless, with pH 7.73 and 0.47 mg L(-1) Pb, 1.03 mg L(-1) Zn, bellow the limits of quantification of Cd and 0.023 mM EDTA. The novel method enables soil leaching with small water requirements and no wastewater generation or other emissions into the environment.     

Heavy metal availability,bioaccessibility, and leachability in contaminated soil: effects of pig manure and earthworms

A pot experiment and a leaching experiment were conducted to investigate the effects of earthworms and pig manure on heavy metals (Cd, Pb, and Zn) immobility, in vitro bioaccessibility and leachability under simulated acid rain (SAR). Results showed manure significantly increased soil organic carbon (SOC), dissolved organic carbon (DOC), available phosphorus (AP), total N, total P and pH, and decreased CaCl₂-extractable metals and total heavy metals in water and SAR leachate. The addition of earthworms significantly increased AP (from 0.38 to 1.7 mg kg^?1), and a downward trend in CaCl₂-extractable and total leaching loss of heavy metals were observed. The combined earthworm and manure treatment decreased CaCl₂-extractable Zn, Cd, and Pb. For Na₄P₂O₇-extractable metals, Cd and Pb were decreased with increasing manure application rate. Application of earthworm alone did not contribute to the remediation of heavy metal polluted soils. Considering the effects on heavy metal immobilization and cost, the application of 6% manure was an alternative approach for treating contaminated soils. These findings provide valuable information for risk management during immobilization of heavy metals in contaminated soils.

     

Influence of ozonation on extractability of Pb and Zn from contaminated soils

The effect of soil ozonation on Pb and Zn extraction with EDTA, bioavailability (Ruby's Physiologically Based Extraction Test, PBET) and mobility (Toxicity Characteristic Leaching Procedure, TCLP) of Pb was studied on contaminated soils taken from 7 different locations in the Mezica Valley, Slovenia. EDTA extraction (40 mmol kg(-1)) removed from 27.4+/-1.5% to 64.8+/-1.5% of Pb, and from 1.9+/-0.2% to 22.4+/-2.0% of Zn from tested soils, and significantly reduced soil Pb bioavailability (PBET) and mobility (TCLP). Pretreatment of tested soils with ozone before EDTA extraction enhanced EDTA extractability of Pb for 11.0 to 28.9%, but had no effect on the extractability of Zn. In most of the soils, ozonation had no statistically significant effect on bioavailability and mobility of Pb, residual after EDTA extraction. Using linear regression analysis we found a significant increase (p<0.01) in EDTA extractability of Pb after soil ozonation in soils with a higher initial Pb content. EDTA extractability of Pb after soil ozonation was also significantly higher for soils with a lower Pb extractability when treated with EDTA alone. We found no correlation between soil organic matter content and the percentage of the Pb fraction bound to soil organic matter (where from 25.6+/-1.3% to 73.2+/-0.6% of Pb reside in tested soils) and Pb extractability with EDTA after soil ozonation.     

Bioaccumulation in Porcellio scaber (Crustacea, Isopoda) as a measure of the EDTA remediation efficiency of metal-polluted soil

Leaching using EDTA applied to a Pb, Zn and Cd polluted soil significantly reduced soil metal concentrations and the pool of metals in labile soil fractions. Metal mobility (Toxicity Characteristic Leaching Procedure), phytoavailability (diethylenetriaminepentaacetic acid extraction) and human oral-bioavailability (Physiologically Based Extraction Test) were reduced by 85-92%, 68-91% and 88-95%, respectively. The metal accumulation capacity of the terrestrial isopod Porcellio scaber (Crustacea) was used as in vivo assay of metal bioavailability, before and after soil remediation. After feeding on metal contaminated soil for two weeks, P. scaber accumulated Pb, Zn and Cd in a concentration dependent manner. The amounts of accumulated metals were, however, higher than expected on the basis of extraction (in vitro) tests. The combined results of chemical extractions and the in vivo test with P. scaber provide a more relevant picture of the availability stripping of metals after soil remediation.     

Progress in assisted natural remediation of an arsenic contaminated agricultural soil

A contaminated soil was collected in a field adjacent to a derelict As((III)) smelter in Reppel (Bocholt, Belgium). A single soil treatment (% by soil weight) based on either iron grit (SS, 1%), beringite (B, 5%), or iron grit (1%) + beringite (5%) (BSS) was applied. Untreated and treated Reppel soils and a control soil were placed in lysimeters inside a greenhouse and cropped annually. The efficiency of soil treatments in decreasing As and metals in exposure sources and restoring soil functions was assessed 6 years after the treatments commenced. Decreases in extractable Cd, Mn, Zn and As occurred in the BSS soil. Only BSS treatment reduced both As and metal concentrations in leachates. BSS treatment produced best growth of lettuce and cabbage, the highest shoot and pod yields for dwarf bean, the lowest As, Cd and Zn concentrations in plant tissues, and partly restored Rhizobium nodulation on bean roots. The epigeic earthworm (Dendrobaena octaedra) could only survive in the BSS soil. Depurated living worms from the BSS soil had Cd concentration similar to those in control worms, but higher As, Ca, Fe, and Zn concentrations. Based on physiologically based extraction test (PBET), As bioaccessibility was reduced from 12% (untreated soil) to 7.4% (BSS) and 3% (SS), but only the SS treatment decreased the bioaccessibility of Cd (-30%) and Pb (-35%). The range of chemical and biological indicators suggested that BSS amendment was the most effective treatment for restoration of normal soil functions 6 years after initial treatment of the Reppel soil.     

Comparison of in vivo and in vitro methodologies for the assessment of arsenic bioavailability in contaminated soils

An in vivo swine assay was utilised for the determination of arsenic (As) bioavailability in contaminated soils. Arsenic bioavailability was assessed using pharmacokinetic analysis encompassing area under the blood plasma-As concentration time curve following zero correction and dose normalisation. In contaminated soil studies, As uptake into systemic circulation was compared to an arsenate oral dose and expressed as relative As bioavailability. Arsenic bioavailability ranged from 6.9+/-5.0% to 74.7+/-11.2% in 12 contaminated soils collected from former railway corridors, dip sites, mine sites and naturally elevated gossan soils. Arsenic bioavailability was generally low in the gossan soils and highest in the railway soils, ranging from 12.1+/-8.5% to 16.4+/-9.1% and 11.2+/-4.7% to 74.7+/-11.2%, respectively. Comparison of in vivo and in vitro (Simplified Bioaccessibility Extraction Test [SBET]) data from the 12 contaminated soils and bioavailability data collected from an As spiked soil study demonstrated that As bioavailability and As bioaccessibility were linearly correlated (in vivo As bioavailability (mgkg(-1))=14.19+0.93.SBET As bioaccessibility (mgkg(-1)); r(2)=0.92). The correlation between the two methods indicates that As bioavailability (in vivo) may be estimated using the less expensive, rapid in vitro chemical extraction method (SBET) to predict As exposure in human health risk assessment.     

Solubility of lead, zinc and copper added to mineral soils

Elevated levels of heavy metals in soils are a result of industrial activities, atmospheric deposition, and the land application of sewage sludges and industrial by-products. Their persistence in the soil environment has created interest in the possible changes in solubility. In this study, total dissolved concentrations of Pb, Zn, and Cu were monitored in seven metal-amended soils (a calcareous and six acid mineral soils). Single metal solutions were added to soils and equilibrated (aged) for 40 days. During the 40 days the soil was allowed to air-dry and was rewetted in cycles of about 5 days. At the end of this reaction period, metal solubility was measured (by atomic absorption spectrometry and direct current plasma spectrometry) at the initial soil pH and at decreased pH values which were induced by addition of small aliquots of acid. As expected, solubility of added Pb, Zn, and Cu increased with a decrease in pH. Furthermore, the results showed that the solubility relationship with pH was similar in all non-calcareous soils. This suggests that metal solubility may be controlled by similar soil components, presumably involving soil characteristics such as pH, organic matter content, and soil mineralogy. For each metal, an approximate pH value was found at which solubility deviated from the solubility of metals when they occur in soils at typical (natural) values. This pH was about (pH+/-0.2): 5.2 for Pb, 6.2 for Zn, and 5.5 for Cu. Thus, pH values below these thresholds may enhance metal mobility, biological availability and toxicity in soils. Metals dissolved at higher pH in the calcareous soil (18.8 g kg(-1) inorganic carbon, initial pH 8.2). In a calcareous soil, a significant fraction of these metals react with carbonates, and decreased pH results in much higher metal dissolution. Yet, metal solubility in soils is not determined by the formation and dissolution of single metal compounds.     

Evaluation of the effectiveness of phosphate treatment for the remediation of mine waste soils contaminated with Cd, Cu, Pb, and Zn

The effectiveness of phosphate treatment for Cd, Cu, Pb, and Zn immobilization in mine waste soils was examined using batch conditions. Application of synthetic hydroxyapatite (HA) and natural phosphate rock (FAP) effectively reduced the heavy metal water solubility generally by about 84-99%. The results showed that HA was slightly superior to FAP for immobilizing heavy metals. The possible mechanisms for heavy metal immobilization in the soil involve both surface complexation of the metal ions on the phosphate grains and partial dissolution of the phosphate amendments and precipitation of heavy metal-containing phosphates. HA and FAP could significantly reduce Cd, Cu, Pb, and Zn availability in terms of water solubility in contaminated soils while minimizing soil acidification and potential risk of eutrophication associated with the application of highly soluble phosphate sources.     

Effects of alkaline and bioorganic amendments on cadmium,lead, zinc,and nutrient accumulation in brown rice and grain yield in acidic paddy fields contaminated with a mixture of heavy metals

Paddy soils and rice (Oryza sativa L.) contaminated by mixed heavy metals have given rise to great concern. Field experiments were conducted over two cultivation seasons to study the effects of steel slag (SS), fly ash (FA), limestone (LS), bioorganic fertilizer (BF), and the combination of SS and BF (SSBF) on rice grain yield, Cd, Pb, and Zn and nutrient accumulation in brown rice, bioavailability of Cd, Pb, and Zn in soil as well as soil properties (pH and catalase), at two acidic paddy fields contaminated with mixed heavy metals (Cd, Pb, and Zn). Compared to the controls, SS, LS, and SSBF at both low and high additions significantly elevated soil pH over both cultivation seasons. The high treatments of SS and SSBF markedly increased grain yields, the accumulation of P and Ca in brown rice and soil catalase activities in the first cultivation season. The most striking result was from SS application (4.0 t ha^?1) that consistently and significantly reduced the soil bioavailability of Cd, Pb, and Zn by 38.5–91.2 % and the concentrations of Cd and Pb in brown rice by 20.9–50.9 % in the two soils over both cultivation seasons. LS addition (4.0 t ha^?1) also markedly reduced the bioavailable Cd, Pb, and Zn in soil and the Cd concentrations in brown rice. BF remobilized soil Cd and Pb leading to more accumulation of these metals in brown rice. The results showed that steel slag was most effective in the remediation of acidic paddy soils contaminated with mixed heavy metals.     

Response of kidney bean to concentration and chemical form of cadmium, zinc, and lead in polluted soils

Seven soils which had been polluted with heavy metals from a zinc smelter were sequentially extracted so that Cd, Zn, and Pb could be partitioned into five operationally defined geochemical fractions: exchangeable, carbonate, Fe-Mn oxide, organic, and residual fractions. Kidney beans were planted in the soils to examine the effect of concentration and chemical form of the metals in soil on the growth and metal uptake of the plants. The growth of kidney bean was restricted in heavy metal polluted soils compared with controls. Metal concentration and metal uptake by plants were correlated. The highest relationship was found between amount of metal uptake and the metal concentration in exchangeable + carbonate forms. The uptake of metals was according to their solubility sequence, i.e. Cd > Zn > Pb. The uptake rate of exchangeable + carbonate forms was the same for the three elements.     

Assessment of heavy metal pollution in surface soils of urban parks in Beijing, China

Assessing the concentration of potentially harmful heavy metals in the soil of urban parks is imperative in order to evaluate the potential risks to residents and tourists. To date, little research on soil pollution in China's urban parks has been conducted. To identify the concentrations and sources of heavy metals, and to assess the soil environmental quality, samples were collected from 30 urban parks located in the city of Beijing. Subsequently, the concentrations of Cu, Ni, Pb and Zn in the samples were analyzed. The investigation revealed that the accumulations of Cu and Pb were readily apparent in the soils. The integrated pollution index (IPI) of these four metals ranged from 0.97 to 9.21, with the highest IPI in the densely populated historic center district (HCD). Using multivariate statistic approaches (principal components analysis and hierarchical cluster analysis), two factors controlling the heavy metal variability were obtained, which accounted for nearly 80% of the total variance. Nickel and Zn levels were controlled by parent material in the soils, whereas Cu, Pb and, in part, Zn were accounted for mainly by anthropogenic activities. The findings presented here indicate that the location and the age of the park are important factors in determining the extent of heavy metal, particularly Cu and Pb, pollution. In addition, the accumulation of Zn did not appear to reach pollution levels, and no obvious pollution by Ni was observed in the soils of the parks in Beijing.     

Heavy metals in urban soils of East St. Louis, IL, Part I: Total concentration of heavy metals in soils

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produce organic and inorganic chemicals, and petroleum refineries. A protocol for soil analysis was developed to produce sufficient information on the extent of heavy metal contamination in East St. Louis soils. Soil cores representing every borough of East St. Louis were analyzed for heavy metals--As, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Sn, and Zn. The topsoil contained heavy metal concentrations as high as 12.5 ppm Cd, 14,400 ppm Cu, ppm quantities of Hg, 1860 ppm Pb, 40 ppm Sb, 1130 ppm Sn, and 10,360 ppm Zn. Concentrations of Sb, Cu, and Cd were well correlated with Zn concentrations, suggesting a similar primary industrial source. In a sandy loam soil from a vacated rail depot near the bank of the Mississippi River, the metals were evenly distributed down to a 38-cm depth. The clay soils within a half-mile downwind of the Zn smelter and Cu products company contained elevated Cd (81 ppm), Cu (340 ppm), Pb (700 ppm), and Zn (6000 ppm) and displayed a systematic drop in concentration of these metals with depth. This study demonstrates the often high concentration of heavy metals heterogeneously distributed in the soil and provides baseline data for continuing studies of heavy metal soil leachability.     

Heavy Metals in Urban Soils of East St. Louis,IL, Part I: Total Concentration of Heavy Metals in Soils

ABSTRACT

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produce organic and inorganic chemicals, and petroleum refineries. A protocol for soil analysis was developed to produce sufficient information on the extent of heavy metal contamination in East St. Louis soils. Soil cores representing every borough of East St. Louis were analyzed for heavy metals—As, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Sn, and Zn. The topsoil contained heavy metal concentrations as high as 12.5 ppm Cd, 14,400 ppm Cu, ppm quantities of Hg, 1860 ppm Pb, 40 ppm Sb, 1130 ppm Sn, and 10,360 ppm Zn. Concentrations of Sb, Cu, and Cd were well correlated with Zn concentrations, suggesting a similar primary industrial source. In a sandy loam soil from a vacated rail depot near the bank of the Mississippi River, the metals were evenly distributed down to a 38-cm depth. The clay soils within a half-mile downwind of the Zn smelter and Cu products company contained elevated Cd (81 ppm), Cu (340 ppm), Pb (700 ppm), and Zn (6000 ppm) and displayed a systematic drop in concentration of these metals with depth. This study demonstrates the often high concentration of heavy metals heterogeneously distributed in the soil and provides baseline data for continuing studies of heavy metal soil leachability.     

Heavy metal immobilization by chemical amendments in a polluted soil and influence on white lupin growth

The effects of chemical amendments (zeolite, compost and calcium hydroxide) on the solubility of Pb, Cd and Zn in a contaminated soil were determined. The polluted soil was from the Southwest Sardinia, Italy. It showed very high total concentrations of Pb (19663 mgkg(-1) d.m.), Cd (196 mgkg(-1) d.m.) and Zn (14667 mgkg(-1) d.m.). The growth and uptake of heavy metals by white lupin (Lupinus albus L., cv. Multitalia) in amended soils were also studied in a pot experiment under greenhouse conditions. Results showed that the amendments increased the residual fraction of heavy metals in the soils, and decreased the heavy metals uptake by white lupin compared with the unamended control. Among the three amendments, compost and Ca(OH)2 were the most efficient at reducing Pb and Zn uptake, while zeolite was the most efficient at reducing Cd uptake by the plants. White lupin growth was better in amended soils than in unamended control. The above ground biomass increased with a factor 1.8 (soil amended with zeolite), 3.6 (soil amended with compost) and 3.1 (soil amended with Ca(OH)2) with respect to unamended soil. The roots biomass increased with a factor 1.4 (soil amended with zeolite), 5.6 (soil amended with compost) and 4.8 (soil amended with Ca(OH)2). Results obtained suggest that the soil chemical treatment improved the performance of crops by reducing bioavailability of metals in the soils. However it would be therefore interesting to find a suitable mixture of these amendments to contemporarily immobilize the three main pollutants in the polluted soils.