Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by methanobactin from Methylosinus trichosporium OB3b

Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV–visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ.     

Comparative Evaluation of Trace Metal Distribution and Correlation in Human Malignant and Benign Breast Tissues

Selected trace metals were analyzed in human malignant and nonmalignant (benign) breast tissue samples by the flame atomic absorption spectrophotometric method. In malignant tissues, dominant mean concentrations were revealed by Na, K, Ca, Mg, Fe, Zn, and Al at 927, 552, 231, 61.7, 36.5, 18.3, and 8.94 microg/g, respectively, while the mean metal levels in benign tissues were 903, 435, 183, 63.3, 24.7, 14.5, and 10.1 microg/g, respectively. Average concentrations of Cd, Co, Cr, Cu, Fe, Mn, K, Ca, and Zn were noted to be significantly higher in the malignant tissues compared with the benign tissues. Significantly strong correlations (r > 0.50) in malignant tissues were observed between Mn and Co, Mn and Cd, Cd and Cr, Fe and Mn, Cd and Co, Fe and Co, Mg and Pb, Cd and Fe, Mg and Ni, Pb and Ni, Ni and Sr, and Fe and Pb, whereas, Cd and Co, Cd and Mn, Co and Mg, Co and Mn, Cu and Mn, Co and Ni, Mg and Ni, Cd and Cu, Cd and Ni, Ca and Mg, Mn and Pb, Cu and Ni, Fe and Ni, Cd and Mg, Co and Cu, Cr and Na, and Cd and Cr revealed strong and significant relationships in benign tissues at p < 0.001. Principal component analysis of the metals data yielded six principal components for malignant tissues and five principal components for benign tissues, with considerably different loadings, duly supported by cluster analysis. The study revealed a considerably different pattern of distribution and mutual correlations of trace metals in the breast tissues of benign and cancerous patients.     

Simultaneous production of pullulan and biosorption of metals by Aureobasidium pullulans strain CH-1 on peat hydrolysate

It was demonstrated that during the growth of Aureobasidium pullulans strain CH-1 on the acid hydrolysate of peat from the Vlasina Lake, the content of metals (Cu, Fe, Zn, Mn, Pb, Cd, Ni and Cr) decreased due to biosorption. The reduction in the metal content was found to be in the range (%): 38.2-62.2, 67.7-97.3, 0.02-62.05, 0.05-23.97, 0.16-4.24, 3.45-51.72, 1.18-35.82, 0.86-44.44, for Cu, Fe, Zn, Mn, Pb, Cd, Ni and Cr, respectively. During this process, the metals were accumulated in the biomass, while pullulan, an extracellular polysaccharide produced by Aureobasidium pullulans strain CH-1, was found not to bind the above-mentioned metals.     

Spectral and thermodynamic properties of Ag(I), Au(III), Cd(II), Co(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(IV), and Zn(II) binding by methanobactin from Methylosinus trichosporium OB3b

Methanobactin (mb) is a novel chromopeptide that appears to function as the extracellular component of a copper acquisition system in methanotrophic bacteria. To examine this potential physiological role, and to distinguish it from iron binding siderophores, the spectral (UV–visible absorption, circular dichroism, fluorescence, and X-ray photoelectron) and thermodynamic properties of metal binding by mb were examined. In the absence of Cu(II) or Cu(I), mb will bind Ag(I), Au(III), Co(II), Cd(II), Fe(III), Hg(II), Mn(II), Ni(II), Pb(II), U(VI), or Zn(II), but not Ba(II), Ca(II), La(II), Mg(II), and Sr(II). The results suggest metals such as Ag(I), Au(III), Hg(II), Pb(II) and possibly U(VI) are bound by a mechanism similar to Cu, whereas the coordination of Co(II), Cd(II), Fe(III), Mn(II), Ni(II) and Zn(II) by mb differs from Cu(II). Consistent with its role as a copper-binding compound or chalkophore, the binding constants of all the metals examined were less than those observed with Cu(II) and copper displaced other metals except Ag(I) and Au(III) bound to mb. However, the binding of different metals by mb suggests that methanotrophic activity also may play a role in either the solubilization or immobilization of many metals in situ.     

Biosorption of heavy metals by lyophilized cells of <Emphasis Type="Italic">Pseudomonas stutzeri</Emphasis>

Biosorptive capacity of Pb(II), Cd(II) and Cu(II) by lyophilized cells of Pseudomonas stutzeri was investigated based on Langmuir and Freundlich isotherms. Biosorptive capacity for Pb(II), Cd(II) and Cu(II) decreased with an increase of metal concentration, reaching 142, 43.5 and 36.2 mg/g at initial concentration of 300 mg/l, respectively. Biosorption capacity for metal ions increased with increasing pH. The optimum pH for biosorption rate of Cd(II) and Cu(II) were 5.0, and 6.0 for Pb(II) biosorption. The experimental data showed a better fit with the Langmuir model over the Freundlich model for metal ions throughout the range of initial concentrations. The maximum sorptive capacity (q _max) obtained from the Langmuir equation for Pb(II), Cd(II) and Cu(II) were 153.3 (r ²  = 0.998), 43.86 (r ²  = 0.995), and 33.16 (r ²  = 0.997) for metal ions, respectively. The selectivity order for metal ions towards the biomass of P. stutzeri was Pb(II) > Cd(II) > Cu(II) for a given initial metal ions concentration. The interactions between heavy metals and functional groups on the cell wall surface of bacterial biomass were confirmed by FTIR analysis. The results of this study indicate the possible removal of heavy metals from the environment by using lyophilized cells of P. stutzeri.     

Biosorption of Heavy Metals from Wastewater by Biosolids

In a study where the removal of heavy metals from wastewater is the primary aim, the biosorption of heavy metals onto biosolids prepared as Pseudomonas aeruginosa immobilized onto granular activated carbon was investigated in batch and column systems. In the batch system, adsorption equilibriums of heavy metals were reached between 20 and 50 min, and the optimal dosage of biosolids was 0.3 g/L. The biosorption efficiencies were 84, 80, 79, 59 and 42 % for Cr(VI), Ni(II), Cu(II), Zn(II) and Cd(II) ions, respectively. The rate constants of biosorption and pore diffusion of heavy metals were 0.013–0.089 min^–1 and 0.026–0.690 min^–0.5. In the column systems, the biosorption efficiencies for all heavy metals increased up to 81–100 %. The affinity of biosorption for various metal ions towards biosolids was decreased in the order: Cr = Ni > Cu > Zn > Cd.     

Biosorption of nickel and cadmium by metal resistant bacterial isolates from agricultural soil irrigated with industrial wastewater

Agricultural soil irrigated with industrial wastewater (more than two decades) analysed for heavy metals revealed high levels of Fe, Cr, Cu, Zn, Ni and Cd. Out of a total of 40 bacterial isolates obtained from these soils, 17 belonged to the family enterobacteriaceae and 10 were Pseudomonas spp. A maximum MIC of 200 for Cd, 400 for Zn and Cu, 800 for Ni, and 1600 microg/ml for Pb was observed. Biosorption of Ni and Cd studies over a range of metal ion concentrations with Escherichia coli WS11 both in single and bi-metal systems showed that the adsorption of Cd and Ni was dependent on the concentrations and followed the Freundlich adsorption isotherm. The biosorption of Ni increased from 6.96 to 55.31 mg/g of cells, and Cd from 4.96 to 45.37 mg/g of cells at a concentration ranging from 50 to 400 microg/ml after 2h of incubation in a single metal solution. A further increase in incubation time had no significant effect on the biosorption of metals.     

Differential pulse polarography: a method for the direct study of biosorption of metal ions by live bacteria from mixed metal solutions

The technique of differential pulse polarography is shown here to be applicable to the monitoring directly the biosorption of metal ions from solution by live bacteria from mixed metal solutions. Biosorption of Cd(II), Zn(II) and Ni(II) by P. cepacia was followed using data obtained at the potential which is characteristic of the metal ion in the absence and presence of cells. Hepes buffer (pH 7.4, 50 mM) was used as a supporting electrolyte in the polarographic chamber and metal ion peaks in the presence of cells of lower amplitude were obtained due to metal-binding by the cells. Well defined polarographic peaks were obtained in experiments involving mixtures of metal ions of Cd(II)-Zn(II), Cu(II)-Zn(II), Cu(II)-Cd(II) and Cd(II)-Ni(II). Biosorption of Cd(II), Zn(II) increased with solution pH. The method was also tested as a rapid technique for assessing removal of metal ions by live bacteria and the ability of the polarographic technique in measuring biosorption of metal ions from mixed metal solutions is demonstrated. Cu(II) was preferentially bound and removal of metals was in the order Cu(II) > Ni(II) > Zn(II), Cd(II) by intact cells of P. cepacia. This revised version was published online in August 2006 with corrections to the Cover Date.     

Biosorption of cobalt by fungi from serpentine soil of Andaman

Fungi belonging to Aspergillus, Mortierella, Paecilomyces, Penicillium, Pythium, Rhizopus and Trichoderma, isolated from serpentine soil of Andaman (India) were screened for cobalt-resistance. Eleven out of total 38 isolated fungi which tolerated > 6.0 mM Co(II) were evaluated for cobalt biosorption using dried mycelial biomass. Maximum Co(II)-loading (1036.5 microM/g, 60 min) was achieved with Mortierella SPS 403 biomass, which removed almost 50% of 4.0 mM cobalt from the aqueous solution. Co(II)-sorption kinetics of Mortierella SPS 403 biomass was fast and appreciable quantities of metal [562.5 microM/g] was adsorbed during first 10 min of incubation. The metal biosorption capacity of the isolate was accelerated with increasing cobalt concentration, while it was reverse with increase of initial biomass. The optimum pH and temperature for Co(II) removal were 7.0 and 30 degrees C, respectively. However, Co(II)-uptake was inhibited in presence of other metals (Pb, Cd, Cu, Ni, Cr and Zn). Freundlich adsorption isotherm appropriately describes Mortierella SPS 403 biomass as an efficient Co(II)-biosorbent.     

Accumulation of metals and metalloids in radish (Raphanus sativus L.) and spinach (Spinacea oleracea L.) irrigated with domestic wastewater in the peri-urban areas of Khushab City,Pakistan

Accumulation of different metals and metalloids was assessed in two vegetables radish (Raphanus sativus L.) and spinach (Spinacea oleracea L.) irrigated with domestic wastewater in the peri-urban areas of Khushab City, Pakistan. In general, the metal and metalloid concentrations in radish and spinach were higher at site-II treated with sewage water than those found at site-I treated with canal water. In case of radish at both sites the levels of metals (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Cd, and Pb) were below the permissible level except those of Mn, Ni, Mo, Cd, and Pb. At both sites, the transfer factor ranged from 0.047–228.3 mg kg^?1 with Cr having the highest transfer factor. The metal pollution index in soil was in the following order: As > Fe > Ni > Zn > Cd > Mo > Se > Co > Pb > Mn > Cr > Cu, respectively. While in case of spinach at both sites, the concentrations of metals and metalloids in vegetable samples irrigated with canal and sewage water were observed below the permissible level except Mn, Ni, Zn, Mo, and Pb. At both sites, the transfer factor ranged from 0.038–245.4 mg kg^?1 with Cr having the highest transfer factor. The metal pollution index in soil was in the following order: Cd > Ni > Co > Se > Mn > Zn > Mo > Pb > Fe > Cr > As > Cu, respectively.     

Biosorption of heavy metals by distillery-derived biomass

Biomass derived from the Old Bushmill's Distillery Co. Ltd., Northern Ireland was harvested and examined for its ability to function as a biosorbent for metals such as Cu, Zn, Fe, Pb and Ag. Binding studies were carried out using biosorption isotherm analysis. Although the material had previously been shown to be capable of efficient U biosorption, its affinity for Cu, Zn, Fe was lower. However, binding studies with Pb demonstrated that it had a maximum biosorption capacity for that metal of 189?mg/g dry weight of the biomass. In addition, the biomass exhibited a maximum biosorption capacity of 59?mg/g dry weight for Ag and this compared very favourably with previously quoted values for other industrial sources of Saccharomyces cerevisiae. On the basis of the biosorption isotherm analyses carried out in this study, preference for this series of metals by the biomass was found to be Pb?>?U?>?Ag?>?Zn?≥?Fe?>?Cu.     

浙江油茶产地土壤和果实金属元素含量特征

为探讨油茶(Camellia oleifera)产地土壤和油茶果实中金属元素分布和富集特征,在油茶果实成熟期,对浙江5个油茶产地土壤及油茶果实中金属元素进行污染分析和富集能力评价。结果表明,浙江油茶产地土壤中Pb、Cr、Cd、As、Hg、Ni、Cu和Zn含量低于农用地土壤污染风险筛选值,综合污染等级为安全。个别产区常山县土壤中As、Ni、Cu和江山县土壤中Pb、Cr、Fe含量显著高于其他产地;常山和建德土壤中Cd单因子污染指数分别为0.93和0.81,处于污染警戒线。Cr、Ni、Cu、Zn主要分布在油茶籽中,Hg主要分布在壳中,Pb、Cd、As、Fe和Mn主要分布在青皮中。油茶籽中Cu、Fe、Mn的富集系数大于0.4,吸收能力强,Ni、Zn的富集系数小于0.4,具有一定吸收能力,Pb、Cr、Cd、As和Hg的富集系数小于0.1,吸收能力低;壳中Cu、Mn的富集系数大于0.4,吸收能力强,Fe的富集系数小于0.4,具有一定吸收能力,Pb、Cr、Cd、As、Hg、Ni、Zn的富集系数小于0.1,吸收能力低;青皮中Cu、Fe、Mn的富集系数大于0.4,吸收能力强,Pb、Cr、Cd、As、Hg、Ni、Zn的富集系数小于0.1,吸收能力低。浙江油茶主产区土壤质量安全,适合油茶种植。油茶果实对Cu、Fe、Mn有一定富集能力,对Pb、Cr、Cd、As和Hg无富集能力。     

Production of a Metal-Binding Exopolysaccharide by Paenibacillus jamilae Using Two-Phase Olive-Mill Waste as Fermentation Substrate

The present study investigated the use of two-phase olive mill waste (TPOMW) as substrate for the production of exopolysaccharide (EPS) by the endospore-forming bacilli Paenibacillus jamilae. This microorganism was able to grow and produce EPS in aqueous extracts of TPOMW as a unique source of carbon. The effects of substrate concentration and the addition of inorganic nutrients were investigated. Maximal polymer yield in 100-ml batch-culture experiments (2 g l⁻¹) was obtained in cultures prepared with an aqueous extract of 20% TPOMW (w/v). An inhibitory effect was observed on growth and EPS production when TPOMW concentration was increased. Nutrient supplementation (nitrate, phosphate, and other inorganic nutrients) did not increase yield. Finally, an adsorption experiment of Pb (II), Cd (II), Cu (II), Zn (II), Co (II), and Ni (II) by EPS is reported. Lead was preferentially complexed by the polymer, with a maximal uptake of 230 mg/g EPS.     

Accumulation of heavy metals by aquatic mosses. 2: Rhynchostegium riparioides

A study was made of general ecology and metal accumulation in the widespread aquatic moss Rhynchostegium riparioides, (Hedw.) C. Jens. with a view to developing the use of this species as a monitor of heavy metal pollution. In order to establish a data bank for statistical analysis, samples of water and moss were taken within a 6-week period from 105 sites (10-m reaches) in Northern England from streams and rivers of diverse physical and chemical types. Analyses were made of 14 metals (Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba, Pb) in both 2-cm tips and whole plants. The same 14 metals were also measured in both total and filtrable water, together with 12 other variables. Samples of tips were easier to prepare for analysis, but had significantly (p < 0.001) lower concentrations of all metals except Na and K. Significant correlations (p < 0.001) between metal in moss and aqueous metal were found for ten metals (Na, K, Mg, Ca, Mn, Cu, Zn, Cd, Ba, Pb). Correlations between metals in moss and in water were in general similar for tips and whole plants, but much higher for tips with Na, Zn and Cd; the relationship was quite similar whether total or filtrable water was considered, with the exception of Ba where the correlation was much higher with the latter. A multiple regression was used to suggest which variables in water and/ or moss may influence accumulation of Co, Ni, Cu, Zn, Cd, Ba and Pb in the moss. For instance, the variables which had a very highly significant effect on Pb in tips were Pb, filtrable reactive phosphate and Zn in the water. A discussion is included of how the data may be used for monitoring purposes.     

Geochemical cycling of heavy metals in a marine coastal area: benthic flux determination from pore water profiles and in situ measurements using benthic chambers

Concentrations of the heavy metals Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn were measured in sea water, suspended matter, sediments and pore water samples collected in a coastal area of the middle Tyrrhenian Sea. Concentration factors between pore water (extracted from the first centimeter of the sediments) and the overlying sea water (taken 30 cm above the sea bed) were less than 1 for Cr, Cu and Pb, 1–10 for Cd and Ni, 10–100 for Fe and Co, 100–1000 for Mn, and 1–100 for Zn.The benthic fluxes of heavy metals at the sediment-water interface were measured directly using in situ benthic chambers and calculated using Fick's first law during two experimental periods, one in 1986 and the other in 1988. The fluxes of Cu, Ni, Pb and Zn varied significantly over time; this appeared to be related to their relatively low ( 10) concentration factors. From the benthic chamber experiments, metals with positive fluxes were in the order: Mn > Fe > Co > Cd, while those with negative fluxes were: Zn > Pb > Ni Cu. Fluxes calculated using Fick's Law were: positive – Mn > Fe > Zn (or Zn > Fe) > Ni > Co > Cd, negative fluxes Pb > Cu > Cr.Measured (benthic chamber) and calculated (Fick's first law) fluxes for Co, Cd, Mn, Pb and Fe were comparable within an order of magnitude, although less agreement was found for Cu, Ni and Zn. Removal of Ni and Zn at the sediment-water interface has been proposed to explain the fact that the measured and calculated fluxes have opposite directions for these metals.     

The metal specificity and selectivity of ZntA from Escherichia coli using the acylphosphate intermediate

ZntA from Escherichia coli is a P-type ATPase that confers resistance to Pb(II), Zn(II), and Cd(II) in vivo. We had previously shown that purified ZntA shows ATP hydrolysis activity with the metal ions Pb(II), Zn(II), and Cd(II). In this study, we utilized the acylphosphate formation activity of ZntA to further investigate the substrate specificity of ZntA. The site of phosphorylation was Asp-436, as expected from sequence alignments. We show that in addition to Pb(II), Zn(II), and Cd(II), ZntA is active with Ni(II), Co(II), and Cu(II), but not with Cu(I) and Ag(I). Thus, ZntA is specific for a broad range of divalent soft metal ions. The activities with Ni(II), Co(II), and Cu(II) are extremely low; the activities with these non-physiological substrates are 10-20-fold lower compared with the values obtained with Pb(II), Zn(II), and Cd(II). Similar results were obtained with DeltaN-ZntA, a ZntA derivative lacking the amino-terminal metal binding domain. By characterizing the acylphosphate formation reaction in ZntA in detail, we show that a step prior to enzyme phosphorylation, most likely the metal ion binding step, is the slow step in the reaction mechanism in ZntA. The low activities with Ni(II), Co(II), and Cu(II) are because of a further decrease in the rate of binding of these metal ions. Thus, metal ion selectivity in ZntA and possibly other P1-type ATPases is based on the charge and the ligand preference of particular metal ions but not on their size.     

Characterization of Heavy Metal Fractions in Agricultural Soils by Sequential Extraction Procedure: The Relationship Between Soil Properties and Heavy Metal Fractions

The present research was conducted to determine heavy metals in agricultural soils from Çanakkale, Turkey, using a sequential extraction procedure (acid soluble, reducible, oxidizable, and residual) as proposed by the Community Bureau of Reference (BCR) of the European Commission. Soil samples were taken from 12 different cultivated sites and analyzed for Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn concentrations. The results revealed an order of Mn > Cd > Pb > Co > Ni > Cu > Zn > Cr for the heavy metals based on the sum of the first three fractions (acid soluble + reducible + oxidizable). The relationships between soil properties and each metal fraction were identified through Pearsons's correlation analysis. Hierarchical cluster analysis was performed to determine the behaviors and similarities of metals in each fraction. While Mn, Pb, and Zn exhibited subjective behaviors in the acid-soluble fraction, Cd, Co, Cu, Cr, and Ni exhibited similar behaviors with each other.     

Screening of Trace Metals in the Plasma of Breast Cancer Patients in Comparison with a Healthy Population

The plasmas of breast cancer patients and healthy donors were analyzed for selected trace metals by a flame atomic absorption spectrophotometric method. In the plasma of breast cancer patients, mean concentrations of macronutrients/essential metals, Na, K, Ca, Mg, Fe, and Zn were 3584, 197.0, 30.80, 6.740, 5.266, and 6.170 ppm, respectively, while the mean metal levels in the plasma of healthy donors were 3908, 151.0, 72.40, 17.70, 6.613, and 2.461 ppm, respectively. Average concentrations of Cd, Cr, Cu, Mn, Ni, Pb, Sb, Sr, and Zn were noted to be significantly higher in the plasma of breast cancer patients compared with healthy donors. Very strong mutual correlations (r > 0.70) in the plasma of breast cancer patients were observed between Cd–Pb, Cr–Li, Li–K, Li–Cd, K–Cr, Li–Pb, Cr–Co, Cu–Ni, Co–K, Cd–K, and K–Pb, whereas, Al–Cr, Ca–Zn, Cd–Sb, Cd–Zn, Ca–Mg, Fe–Zn, and Na–Mn exhibited strong relationships (r > 0.60) in the plasma of healthy donors. The cluster analysis revealed considerably different apportionment of trace metals in the two groups of donors. The average metal concentrations of different age groups of the two donor categories were also evaluated, which showed the build-up of Al, Cd, Co, Cr, Mn, Li, Pb, Sb, and Zn in the plasma of breast cancer patients. The role of some trace metals in carcinogenesis is also discussed. The study indicated appreciably different patterns of metal distribution and correlation in the plasma of breast cancer patients in comparison with the healthy population.     

Millimeter‐scale resolution of trace metal distributions in microbial mats from a hypersaline environment in Baja California,Mexico

Microbial mats from two ponds with different salinities from the saltern of Guerrero Negro (Mexico) points toward millimeter‐scale coherent variations in trace metal (Me) concentrations (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn). Total, HCl‐leachable and pyrite‐associated Me showed a trend of increasing concentrations with increasing depth suggesting gradual addition of reactive Me probably as a result of metal sulfide precipitation at depth. The trends in Me profiles can be ascribed to the establishment and maintenance of microzones that promote geochemical processes, bacterial population distributions, and differential mass transport within the mats. Degrees of trace metal pyritization (1 ± 1% for Zn to 24 ± 7% for Cd) as well as metals associated with the pyrite fraction (<1.4–36 ± 18 nmol g^?1 for Zn and Mn, respectively) were low, as expected from a reactive Fe‐limited system like Guerrero Negro. Calculated enrichment factors showed that Ni (2.6 ± 2.1), Co (5.5 ± 4.0), Pb (9.4 ± 7.4), and Cd (57 ± 39) were, on average, enriched in the microbial mats of Guerrero Negro. Natural enrichments of Cd, Pb, and Co in sediments along the coast of Baja California and metabolical requirements of Co and Ni by the predominant cyanobacteria in the Guerrero Negro mats may explain these enrichments. Metal characteristics in microbial mats could be advantageously used as biosignatures to identify their presence in the geological record or in other planetary systems.     

Heavy metals in water,sediments, fish and plants of river Hindon,U.P., India

We analysed the concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the water, sediments, fish and plants of the River Hindon, U.P., India, at seven sampling stations, in the year 1982. Considerable variation in concentration between water, sediments, fish and plants were noted. The concentration in the water was in the order Fe > Zn > Cr > Mn > Cu > Pb > Ni > Co > Cd, in the sediments, Fe > Mn > Zn > Ni > Cr > - Co > Cu > Pb > Cd; in a fish (Heteropnuestes fossilis) Fe > Zn > Mn > Pb > Ni > Co > Cu > Cd > Cr, and in a plant (Eicchornia crassipes) Fe > Mn > Zn > Ni > Cu > Cr > Pb > Co > Cd.