Room temperature solvent extraction for simple and fast determination of total concentration of Ca,Cu, Fe,Mg, Mn,and Zn in bee pollen by FAAS along with assessment of the bioaccessible fraction of these elements using in vitro gastrointestinal digestion

Background and aimBee pollen is recognized to be a source of different nutrients, including minerals. As a food supplement, its quality and safety due to concentrations of essential macro- and microelements, and harmful trace elements has to be verified. Fast and simple element analysis of bee-collected pollen can be regarded as an important part of its quality assurance and control. The present study aimed at developping a new method for determination of selected elements (Ca, Cu, Fe, Mg, Mn, Zn) of bee pollen based on solvent extraction and completely avoiding a high temperature treatment with concentrated reagents. In addition, in vitro gastrointestinal digestion was used to assess bioavailability of elements from this food supplement.MethodsBee pollen samples were dried and pulverized. Total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn were determined by flame atomic absorption spectrometry (FAAS) in sample solutions obtained by wet digestion (WD) in concentrated HNO₃ or alternatively by solvent extraction (SE) with diluted solutions of HNO₃. Gastrointestinal digestion was mimicked using simulated solutions of gastric and intestinal juices followed by determination of Ca, Cu, Fe, Mg, Mn and Zn concentrations in the bioaccessible fraction by FAAS.ResultsA new simple and fast method for determination of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen was developed and validated. The method combined room temperature, two-hour SE with 0.5 mol L⁻¹ HNO₃ with FAAS measurements versus simple standard solutions. It provided precision within 1–5 % and trueness better than 8%, and was shown to be suitable for fast analysis of different polyfloral bee pollens. In vitro gastrointestinal digestion revealed that elements were well (70–85 % for Ca, Mg) and fairly (27–43 % for Cu, Fe, Mn, and Zn) bioaccessible from bee pollen. By pouring with water and swelling overnight, bioaccessibility of studied elements from such prepared bee pollen was increased on average by less than 15 % (Mn), 20 % (Ca, Cu, Fe, Zn) or 30 % (Mn).ConclusionsAvoiding long-lasting, high-temperature wet digestion with concentrated reagents, the proposed sample treatment along with FAAS provided precise and true results of total concentrations of Ca, Cu, Fe, Mg, Mn, and Zn in bee pollen. The method was simple and fast, and enabled to analyze a higher number of samples. Simulated gastrointestinal digestion of bee pollen have shown for the first time that Ca and Mg are the most bioaccessible from this bee product. Bioaccessibility of Cu, Fe, Mg, and Zn from bee pollen are close to or lower than 40 %.     

微波消解-FAAS法测定普通甘薯和紫甘薯中的金属元素

采用微波消解法处理普通甘薯和紫甘薯样品,运用火焰原子吸收光谱法测定其中的K、Ca、Mg、Fe、Mn、Zn、Cu 7种对人体有益的金属元素含量。结果表明,普通甘薯和紫甘薯中K、Ca、Fe、Mg元素含量较高,Mn、Zn、Cu元素含量较低,且7种金属元素含量在两者之间存在一定的差异,各元素在紫甘薯中的含量均比普通甘薯中含量高。方法的加标回收率介于98.5%～103.2%,相对标准偏差(RSD)不大于3.14%。可为普通甘薯与紫甘薯的品质评价提供理论参考。     

厚朴不同部位中微量元素的测定研究

采用微波法消解样品,用火焰原子吸收分光光度计测定秦巴山区中药厚朴根的皮、茎的皮及厚朴叶中Fe、Cu、Mn、Zn、Ni 5种微量元素的含量,优化仪器工作条件,使各元素的加标回收率在98.8%~108%之间,建立了快速简便,准确率高,精密度好的检测方法,用于标准样品和实际样品的分析和测定,结果令人满意。     

微波消解-FAAS法分析并比较旱芹(Apium graveolens L.)不同部位八种金属元素的含量

采用微波消解法处理旱芹根、茎、叶,并用火焰原子吸收法测定其中的Na、K、Ca、Mg、Fe、Mn、Zn、Cu 8种金属元素的含量。结果表明:旱芹中富含人体必需的Na、K、Mg、Fe、Ca等元素,各元素在不同部位含量有一定差异。Fe元素在旱芹根中含量为883.57μg.g-1,明显高于茎和叶;Ca、Zn和Mn元素在旱芹叶中的含量分别为11 103.74,214.04,88.07μg.g-1,明显高于茎和根;K、Na和Mg元素在旱芹茎中的含量高于根和叶中,Cu元素含量在各部位差异不大。方法的加标回收率为96.8%～105.8%,相对标准偏差(RSD)≤3.36%。     

Adsorption of Cu and Zn onto Mn/Fe Oxides and Organic Materials in the Extractable Fractions of River Surficial Sediments

The roles of the extractable components (Mn oxides, Fe oxides, and organic materials) of surficial sediments in controlling metals adsorption were investigated. Cu and Zn adsorptions were conducted before and after the surficial sediments extracted with hydroxylamine hydrochloride, an oxalate solution, and H ₂ O ₂ , respectively. The extraction removed target components with extraction efficiencies from 63 to 98%. Nonlinear regression analyses of Cu and Zn adsorptions based on the assumption of additive Langmuir adsorption isotherm were employed to estimate the relative contributions of sediment components to Cu and Zn adsorptions. The results indicate that the greatest contribution to total Cu and Zn adsorption to the surficial sediments on a molar basis was from Mn oxides in the extractable fractions. Both Cu and Zn adsorption capacities of Mn oxides exceeded those of Fe oxides by approximately one order of magnitude, fewer roles were attributed to the adsorption of organic material (OM), and the estimated contribution of the residual fraction to total Cu and Zn adsorption was insignificant. These information implied that the roles of metal oxides (Fe and Mn oxides) in the extractable form of the surficial sediments, especially Mn oxides, was the most important component in controlling heavy metal transportation in aquatic environments.     

Oxidoreductase activities of polyclonal IgGs from the sera of Wistar rats are better activated by combinations of different metal ions

It was shown that IgGs purified from the sera of healthy Wistar rats contain several different bound Me2+ ions and oxidize 3,3'-diaminobenzidine through a H2O2-dependent peroxidase and H2O2-independent oxidoreductase activity. IgGs have lost these activities after removing the internal metal ions by dialysis against EDTA. External Cu2+ or Fe2+ activated significantly both activities of non-dialysed IgGs containing different internal metals (Fe > or = Pb > or = Zn > or = Cu > or = Al > or = Ca > or = Ni > or = Mn > Co > or = Mg) showing pronounced biphasic dependencies corresponding to approximately 0.1-2 and approximately 2-5 mM of Me2+, while the curves for Mn2+ were nearly linear. Cu2+ alone significantly stimulated both the peroxidase and oxidoreductase activities of dialysed IgGs only at high concentration (> or = 2 mM), while Mn2+ weakly activated peroxidase activity at concentration >3 mM but was active in the oxidoreductase oxidation at a low concentration (<1 mM). Fe2+-dependent peroxidase activity of dialysed IgGs was observed at 0.1-5 mM, but Fe2+ was completely inactive in the oxidoreductase reaction. Mg2+, Ca2+, Zn2+, Al2+ and especially Co2+ and Ni2+ were not able to activate dialysed IgGs, but slightly activated non-dialysed IgGs. The use of the combinations of Cu2+ + Mn2+, Cu2+ + Zn2+, Fe2+ + Mn2+, Fe2+ + Zn2+ led to a conversion of the biphasic curves to hyperbolic ones and in parallel to a significant increase in the activity as compared with Cu2+, Fe2+ or Mn2+ ions taken separately; the rates of the oxidation reactions, catalysed by non-dialysed and dialysed IgGs, became comparable. Mg2+, Co2+ and Ni2+ markedly activated the Cu2+-dependent oxidation reactions catalysed by dialysed IgGs, while Ca2+ inhibited these reactions. A possible role of the second metal in the oxidation reactions is discussed.     

Chemical partitioning of Cu,Pb and Zn in the soil profile of a semi arid dry woodland

Abstract

The chemical partitioning of Cu, Pb and Zn was examined in the soil profile of the woodland system in Keoladeo National Park, India using a five-step sequential extraction procedure (SEP). Metal partitioning was assessed in the soil up to a depth of 100cm with 25-cm intervals. The amount of metals obtained from the SEP exceeded pseudototal metal levels obtained from aqua regia digestion. The SEP results showed high preferential attachment of metals with Fe—Mn hydroxides. All the three metals showed least preferences to the exchangeable pool. The attachment of metals to the OM-S phase was also less, may be because of the low organic matter in the soil. In the case of Cu, the order of the fractions in terms of metal concentrations was Fe—Mn>RES>OM-S>CA>EXC and in the case of Pb the order was Fe—Mn>OM-S>RES>CA>EXC. Zn was different from Cu and Pb in showing higher affinity towards RES phase and the order of its concentration was RES>Fe—Mn>OM-S>EXC>CA. This suggests hydrous oxides of Fe—Mn as an important binding site for Cu and Pb, whereas silicate mineral matrix (RES phase) for Zn.     

Fingernails as biological indices of metal exposure

Metal determination in human tissues is the most common application of biological monitoring for screening, diagnosis and assessment of metal exposures and their risks. Various biopsy-materials may be used. This paper deals with the quantitative determination of Cd, Pb, Cr, Mn, Fe, Ni, Cu, and Zn concentrations in nails of male subjects exposed to these metals alongwith their respective controls, while working in locomotive, carriage and roadways workshops, and lead battery factories. The levels of Cd, Pb, Cr, Mn, Fe, Ni, Cu and Zn in fingernails, assayed by atomic absorption spectrophotometry, were compared with their respective controls by student ‘t’ test. All the obtained values were correlated to the personal and medical history of the subjects under study. Significantly high levels of Cd, Pb, Cr, Fe, Ni, Cu and Zn were present in smokers, compared to nonsmokers. The concentrations of Cd, Pb, Cr, Mn and Fe were not significantly high in vegetarian subjects. It was also observed that there is no contribution of liquor towards nail-metal concentration. Significant correlations were observed between skin disease and Cr, Mn, Fe, Cu; hypertension and Cd, Mn, Cu; mental stress and Cd, Pb, Mn, Ni, Cu, Zn; diabetes and Cr, Mn, Ni; chest pain and Pb; respiratory trouble and Cr, Mn, Fe, Ni, Zn; tuberculosis and Zn; acidity and Cd; and ophthalmic problems and Mn, Fe, Ni, and Zn     

有色稻米Fe、Zn、Cu和Mn含量及与种皮颜色相关分析

用AAS方法测定了弥勒县相同生态条件下种植的27份有色稻和34份普通稻糙米4种矿质元素含量,并对有色米和普通米Fe、Zn、Cu和Mn含量进行了比较研究。结果表明,有色稻米4种矿质元素含量明显高于无色稻米,其差异均达显著水平,其含量高低依次为Zn>Fe>Cu>Mn;对黑、褐、红、黄、绿5种不同种皮颜色的稻米4种矿质元素含量进行比较研究,发现稻米Fe含量(mg/kg)依次为黑>绿>褐>红>黄,Zn含量(mg/kg)依次为绿>红>黑>褐>黄,Cu含量(mg/kg)依次为黑>褐>红>黄>绿,Mn含量(mg/kg)依次为褐>黑>红>黄>绿;并且Fe和Mn含量在不同颜色稻米间差异均达显著水平,与有色米种皮颜色密切相关,而Zn和Cu差异不显著,与有色米种皮颜色关系不大。黑米和褐米富Fe、Zn、Cu和Mn,绿米富Fe和Zn,红米富Zn和Cu,黄米4种矿质元素含量较低,Fe、Cu和Mn均低于普通稻米。     

Divalent metals inhibit and lactose stimulates zinc transport across brush border membrane vesicles from piglets

Interactions between metals of similar coordination chemistry are of relevance to infant nutrition due to the highly variable metal:metal ratios found in formulas. Using ratios similar to those found in infant formulas, our objectives were to determine the effects of metals and of lactose and other saccharides on Zn(+2) transport across intestinal brush border membranes. Brush border membrane vesicles prepared from intestines of 5 preweaned piglets were used to determine whether Ca(+2), Mg(+2), Fe(+2), Cu(+2), Cd(+2), or Mn(+2) would antagonize Zn(+2) uptake. (65)Zn(+2) uptake by brush border membrane vesicles was measured over 20 min with metal concentrations constant, and at 1 min with increasing metal concentrations. Zn(+2) bound to the external surface of vesicles was removed with ethylenediamine-tetraacetic acid. Lactose induced Zn(+2) uptake to a greater extent than glucose polymer, whereas maltose, galactose, or galactose/glucose had no effect. Over 20 min, a 10:1 concentration of Fe(+2), Cd(+2), Cu(+2), and Mn(+2) lowered Zn(+2) uptake significantly (P < 0.05). Higher concentrations of divalent cation significantly lowered Zn(+2) (0.2 or 0.1 mM) uptake for all metals tested (P < 0.05), except for Mn(+2) (0.1 mM Zn(+2)). Inhibition constant determination quantified relative competitive potential with Mg(+2) < Ca(+2) < Mn(+2) < Fe(+2) < Zn(+2) < Cu(+2). Relative amounts of Ca(+2), Mg(+2), and Fe(+2) similar to those found in infant formulas reduced Zn(+2) uptake by at least 40%. Our data demonstrate that dietary minerals compete during brush border membrane transport, and may help explain antagonistic mineral interactions observed in vivo. Divalent metal concentrations and lactose content of milk affect zinc absorption in neonates and must be carefully considered in formula design.     

Assessment of Contaminant Retention in Constructed Wetland Sediments

The A‐01 wetland treatment system (WTS) was designed to remove metals from an industrial effluent at the Savannah River Site, Aiken, SC. Sequential extraction data were used to evaluate remobilization and retention of Cu, Pb, Zn, Mn, and Fe in the wetland sediment. Remobilization of metals was determined by the Potentially Mobile Fraction (PMF) and metal retention by the Recalcitrant Factor (RF). The PMF, which includes water soluble, exchangeable, and amorphous oxides fractions, is the contaminant fraction that has the potential to enter into the mobile aqueous phase under fluctuating environmental conditions. PMF values were low for Cu, Zn, and Pb (13–27 %) and high for Fe and Mn (62–70 %). The RF, which includes crystalline oxides, sulfides or silicates and aluminosilicates, is the ratio of strongly bound fractions to the total concentration of elements in sediment. RF values ranged from 73–87 % for Cu, Zn, and Pb, indicating high retention in the sediment and from 30–38 % for Fe and Mn, indicating low retention. Contaminant retention, which is determined by solid phase metal speciation, determines the potential mobility and bioavailability of captured metals in wetland sediments; hence, their likelihood of being released if chemical, physical, or biological conditions within the wetland change.     

Iron-dependent changes of heavy metals,nicotianamine, and citrate in different plant organs and in the xylem exudate of two tomato genotypes. Nicotianamine as possible copper translocator

The influence of Fe nutrition on the distribution of the heavy metals Fe, Mn, Zn, and Cu and of the heavy metal chelators nicotianamine (NA) and citrate in 6 different shoot and 3 different root parts and in xylem exudate of a NA-containing tomato wild type and its NA-less mutant was investigated. Under the same Fe supply the mutant showed higher Fe, Mn, and Zn concentrations in all organs investigated, with exception of the shoot apex. The Cu concentration in the mutant was only in root parts higher than in the wild type but much lower in leaves. Analyses of xylem exudate showed that Fe, Mn, and Zn were readily translocated by both genotypes from the roots to the shoot at all levels of Fe supply, whereas in the absence of NA, Cu was only poorly transported. Citrate as main Fe chelator in the xylem was present in high concentrations in xylem exudate of the wild type under low Fe supply but in the mutant also at 10 M FeEDTA. NA occurred in xylem exudate of the wild type in concentrations high enough to chelate heavy metal ions.Generally, high Fe supply induced a decrease of Mn, Cu, and Zn concentrations in all organs of the wild type whereas high concentrations were observed in most cases under Fe deficiency. A positive correlation between Fe supply and NA concentration existed only in the shoot apex and in the xylem exudate of wild type plants. From the correlation between Cu and NA translocation and from the high stability constant of the NA-Cu-complex (log K=18.6) it is concluded that NA is a chelator for Cu in the xylem, whereas the translocation of Fe, Mn, and Zn is independent of NA.     

Mobilisation of iron and manganese by plant-borne and synthetic metal chelators

Phytosiderophores released by roots of iron-deficient grasses mobilise Fe, Zn, Mn and Cu in calcareous soils. Mobilisation of Fe, Zn and Cu can be explained as the chelation of these metal cations by phytosiderophores. Mobilisation of Mn could not be so explained because phytosiderophores have a much smaller affinity for Mn than for Fe, Cu and Zn. Model experiments have been made with freshly precipitated Fe(OH)₃ and different soils to study the mobilisation of iron and manganese by plant-borne chelating phytosiderophores, the synthetic metal chelators DTPA and the microbial metal chelator sulphonated ferrioxamine B (FOB). Compared with the synthetic chelator DTPA, the plant-borne chelating phytosiderophores mobilised Fe very efficiently, but no change was observed in the Mn mobilisation by phytosiderophores.Different phytosiderophores, as well as the microbial metal chelator FOB, were used to compare the mobilisation of iron and manganese in a calcareous soil.     

Total metal burdens in the freshwater amphipod Gammarus fasciatus: contribution of various body parts and influence of gut contents

1. The distribution of trace metals among body parts of the freshwater amphipod Gammarus fasciatus was investigated and the effect of depuration on the total body burden was assessed.
2. Concentrations of Cr, Fe, Mn and Ni were one order of magnitude higher in the gut contents than in the various body parts, accounting for 40–72% of the total body burdens of amphipods. Depuration caused a decrease of total metal concentrations of 35–88%.
3. Levels of Cd and Cu were higher in the hepatopancreas than in other body parts, whereas levels of Zn were relatively constant throughout the body. For Cd, Cu and Zn, depuration had no effect on mean body concentrations.
4. For Pb, an important fraction of the total body burden was associated with the exoskeleton; depuration caused a decrease in Pb body concentrations.
5. Regression between amphipod metal concentrations before and after depuration is a potential tool for correcting for the effect of gut contents. This correcting method was found to be promising for Cd, Cu, Mn and Zn, with R ² varying between 0.66 and 0.98. It was less efficient for Cr, Fe and Pb, and was useless for Ni.     

Total metal burdens in the freshwater amphipod Gammarus fasciatus: contribution of various body parts and influence of gut contents

1. The distribution of trace metals among body parts of the freshwater amphipod Gammarus fasciatus was investigated and the effect of depuration on the total body burden was assessed.
2. Concentrations of Cr, Fe, Mn and Ni were one order of magnitude higher in the gut contents than in the various body parts, accounting for 40–72% of the total body burdens of amphipods. Depuration caused a decrease of total metal concentrations of 35–88%.
3. Levels of Cd and Cu were higher in the hepatopancreas than in other body parts, whereas levels of Zn were relatively constant throughout the body. For Cd, Cu and Zn, depuration had no effect on mean body concentrations.
4. For Pb, an important fraction of the total body burden was associated with the exoskeleton; depuration caused a decrease in Pb body concentrations.
5. Regression between amphipod metal concentrations before and after depuration is a potential tool for correcting for the effect of gut contents. This correcting method was found to be promising for Cd, Cu, Mn and Zn, with R ² varying between 0.66 and 0.98. It was less efficient for Cr, Fe and Pb, and was useless for Ni.     

Periodic changes in metal content in Fucus distichus thalli under polar day conditions

Variation of Mn, Fe, Ni, Cu and Zn contents in thalli of Fucus distichus was determined under conditions of polar days. The use of spectrum analysis allowed estimates comparisons of the interrelation of periodic changes in irradiance, temperature and tidal fluctuations and quasiperiodic changes in metal contents. The effect of the diel rhythm of irradiance correlated with the accumulation of all metals except for Zn. At the same time, the changes in Mn, Fe and Cu content were delayed in respect to changes in irradiance level. The phase shift for Fe was 1 h 56 min, for Cu – 3 h 41 min and for Mn – 5 h5 min. The change in Ni content, in contrast, was 11min ahead of the change in irradiance. During the experiment an increase in water temperature up to10 °C resulted in increases in the average Mn, Ni and Cu contents in the thalli and decreases in Fe and Zn concents. The periodicity of metal thallus content did not always correspond to a diurnal rhythm, and couldbe longer (Mn, Ni: 32 h; Fe: 36 h) or shorter (Mn, Ni, Zn: 16 h; Cu: 12 h; Zn: 20, 10 h). The ANOVA of these rhythms allows an estimate of the contribution of rising and falling tidal fluctuations to the changes in Cu, Mn and Ni contents. There was a higher metal content during a falling than a rising tide. Abbreviations SDLT – semidiurnal lunartide, CDLT – closed diurnal lunar tide. This revised version was published online in August 2006 with corrections to the Cover Date.     

The role of divalent cations in structure and function of murine adenosine deaminase.

For murine adenosine deaminase, we have determined that a single zinc or cobalt cofactor bound in a high affinity site is required for catalytic function while metal ions bound at an additional site(s) inhibit the enzyme. A catalytically inactive apoenzyme of murine adenosine deaminase was produced by dialysis in the presence of specific zinc chelators in an acidic buffer. This represents the first production of the apoenzyme and demonstrates a rigorous method for removing the occult cofactor. Restoration to the holoenzyme is achieved with stoichiometric amounts of either Zn2+ or Co2+ yielding at least 95% of initial activity. Far UV CD and fluorescence spectra are the same for both the apo- and holoenzyme, providing evidence that removal of the cofactor does not alter secondary or tertiary structure. The substrate binding site remains functional as determined by similar quenching measured by tryptophan fluorescence of apo- or holoenzyme upon mixing with the transition state analog, deoxycoformycin. Excess levels of adenosine or N6- methyladenosine incubated with the apoenzyme prior to the addition of metal prevent restoration, suggesting that the cofactor adds through the substrate binding cleft. The cations Ca2+, Cd2+, Cr2+, Cu+, Cu2+, Mn2+, Fe2+, Fe3+, Pb2+, or Mg2+ did not restore adenosine deaminase activity to the apoenzyme. Mn2+, Cu2+, and Zn2+ were found to be competitive inhibitors of the holoenzyme with respect to substrate and Cd2+ and Co2+ were noncompetitive inhibitors. Weak inhibition (Ki > or = 1000 microM) was noted for Ca2+, Fe2+, and Fe3+.     

Size dependent metal concentrations in two marine gastropod species

The effect of size on the accumulation of Cd, Cr, Cu, Mn, Ni, Fe and Zn in the muscle and viscera of the gastropodsMonodonta turbinata andCerithium vulgatum was investigated. The concentration of the essential metals Cr, Mn and Ni and the non-essential metal Cd decreased with increasing size in both of the species and tissues. The concentration of the essential metals Cu, Fe and Zn, showed a less constant relation with size.     

Copper,Lead, Cadmium,and Zinc Sorption By Waterlogged and Air-Dry Soil

Competitive sorption of copper (Cu), lead (Pb), cadmium (Cd), and zinc (Zn) was studied in three soils of contrasting chemical and physical properties under air-dry and waterlogged conditions. Competitive sorption was determined using the standard batch technique using six solutions, each with Cu, Pb, Cd, and Zn concentrations of approximately 0, 2.5, 5, 10, 20, and 50?mg L^?1Waterlogged soils tended to sorb higher amounts of added Cu, Pb, Zn and Cd relative to soils in the air-dry condition; however, this increase in sorption was generally not statistically (p<0.05) significant. The magnitude of sorption under both waterlogged and air-dry conditions was affected by the type and amount of soil materials involved in metal sorption processes, and competition between other metals for the sorption sites. Metal sorption was closely correlated with soil properties such as cation exchange capacity, organic carbon, and Fe and Mn hydrous oxides. Exchangeable Al may have markedly reduced metal sorption due to its strong affinity for the sorption sites, while increases in exchangeable Mn may have enhanced Zn and Cd sorption. Heavy metal sorption was best described as a combination of both specific and nonspecific interactions. The extractability of Cu, Pb, Cd, and Zn under waterlogged and air-dry conditions was also studied. Three solutions containing these metals were mixed with each soil to achieve a final concentration of 0, 50, and 500?mg kg^?1. Each soil was extracted every 7 days using 1?M MgCl₂ (pH 7) to determine metal extractability. Metal extractability initially decreased then increased due to waterlogging. The increased extractability of added metals was closely related to increased solubility of Fe and Mn suggesting that dissolution of Fe and Mn, oxides under reducing conditions caused a release of previously sorbed Cu, Pb, Cd, and Zn.     

Biosorption of chromium, copper, manganese and zinc by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum

The study describes the sorption of Cr, Cu, Mn and Zn by Pseudomonas aeruginosa AT18 isolated from a site contaminated with petroleum and heavy metals. The concentrations studied were 50, 49, 60 and 70 (mg L(-1)) for Cr, Cu, Mn and Zn, respectively. The solution pH and ionic strength were very important factors in the metal biosorption performance and the biosorption capacity of P. aeruginosa AT18 for Cr3+,Cu2+, Mn2+ and Zn2+. In aqueous solution, the biosorption increased with increasing pH in the range 5.46-7.72. The results obtained in the experimental assays show that P. aeruginosa AT18 has the capacity for biosorption of the metallic ions Cr3+, Cu2+ and Zn2+ in solutions, although its capacity for the sorption of manganese is low (22.39 mg Mn2+/g of biomass) in comparison to the Cr3+, Cu2+ and Zn2+ ions, as shown by the individual analyses. However, 20% of the manganese was removed from an initial concentration of 49.0 mg L(-1), with a Qm value similar to that obtained in solutions containing mixtures of Cr3+, Cu2+, Mn2+and Zn2+. The chromium level sorbed by P. aeruginosa AT18 biomass was higher than that for Cu, Mn and Zn, with 100% removal in the pH range 7.00-7.72 and a Qm of 121.90-200.00 mg of Cr3+/g of biomass. The removal of Cr, Cu and Zn is also a result of precipitation processes.