Evaluation of the metal uptake of several algae strains in a multicomponent matrix utilizing inductively coupled plasma emission spectrometry.

Mahan CA, Majidi V, Holcombe JA.

Three freshwater heat-killed, lyophilized blue-green algae strains have been characterized as to their ability to accumulate heavy metals with a focus on the utilization of these algae as an analytical preconcentration technique. This study examines the metal uptake in several multicomponent mixtures by using inductively coupled plasma optical emission spectrometry (ICP-OES). Six milligrams of a pure strain of algae was added to 20-mL aliquots of buffered (pH 5.5-6.5) multielement solutions containing 0.1, 0.5, 1.0, 2.0, and 4.0 mg/L of K, Mg, Ca, Fe, Sr, Co, Cu, Mn, Ni, V, Zn, As, Cd, Mo, Pb, and Se. All three algae strains exhibit relatively high adsorption affinities for Fe, Pb, and Cu, with uptake between 70 and 98% at the 4 ppm concentration level. Biosorption occurs for essentially every element with the relative affinities decreasing in the order Pb greater than Fe greater than Cu greater than Cd greater than Zn greater than Mn greater than Mo greater than Sr greater than Ni greater than V greater than Se greater than As greater than Co for Chlorella pyrenoidosa at the 4 mg/L concentration level. Although some minor differences were seen, the other algae strains (Stichococcus bacillaris and Chlamydomonas reinharti) displayed similar adsorption behavior over the concentration range studied, indicating similar cell wall binding sites. Langmuirian isotherms exhibited a minimum of two slopes over the concentration range of 0.1-4.0 mg/L, indicating the probable existence of at least two adsorption mechanisms.

PMID: 2729595 [PubMed - indexed for MEDLINE]

Spectrophotometric determination of some functional groups on Chlorella for the evaluation of their contribution to metal uptake.

Saitoh T, Nakagaki N, Uchida Y, Hiraide M, Matsubara C.

Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan.

PMID: 11707955 [PubMed - indexed for MEDLINE]

Column chromatographic pre-concentration of iron(III) in alloys and biological samples with 1-nitroso-2-naphthol-3,6-disulphonate and benzyldimethyltetradecylammonium-perchlorate adsorbent supported on naphthalene using atomic absorption spectrometry.

Miura J, Arima S, Satake M.

Faculty of Engineering, Fukui University, Japan.

The solid ion-pair material produced from the reaction between benzyldimethyltetradecylammonium chloride (BDTA) and sodium perchlorate on naphthalene provides the basis for a simple, rapid and selective technique for pre-concentrating iron from up to 500 ml of aqueous solution. Iron reacts with disodium 1-nitroso-2-naphthol-3,6-disulphonate (Nitroso-R salt) to form a water-soluble coloured chelate anion. The iron chelate anion forms a water-insoluble, stable iron-Nitroso-R-BDTA complex on naphthalene packed in a column. Trace amounts of iron are quantitatively retained on naphthalene in the pH range 3.5-7.5 and at a flow-rate of 1-2 ml min-1. The solid mass is dissolved out from the column with 5 ml of N,N-dimethylformamide and iron is determined by means of an atomic absorption spectrometer at 248 nm. The calibration graph is linear for concentrations of iron over the range of 0.5-20 micrograms in 5 ml of final solution. The standard deviation and relative standard deviation were calculated. The detection limit of the method was 0.0196 micrograms ml-1 of iron. The sensitivity for 1% absorption was 0.072 microgram ml-1 (0.165 microgram ml-1 by direct atomic absorption spectrometry of aqueous solution). The proposed method was applied to the determination of iron in standard alloys and biological samples.

PMID: 2091489 [PubMed - indexed for MEDLINE]

Biosorption of nickel in complex aqueous waste streams by cyanobacteria.

Corder SL, Reeves M.

Engineering Development Section, Oak Ridge National Laboratory, TN.

A study was undertaken to determined if a suitable biosorbent could be found for removal of nickel at low concentrations (< 20 parts per million [ppm]) from a chemically complex wastewater effluent generated by electroplating operations. Algae and cyanobacteria were chosen as candidate biosorbent materials because they are easy to grow and they have the ability to withstand processing into biosorbent materials. Several species were screened for nickel-biosorption capacity initially, and three species of cyanobacteria were selected for further study based on their performance in the scoping tests. When compared to live controls, autoclaving improved the binding capacities of all three species, but usually biosorption data from experiments with live cells were more consistent. None of the three species was able to bind nickel efficiently in actual effluent samples. Further experimentation indicated that sodium ions, which were present in high concentrations in the effluent, were interfering with the ability of the cells to bind nickel. Adsorption isotherm plots for biosorption of nickel by two species of Anabaena in NiCl2-deionized water solutions were prepared.

PMID: 8010774 [PubMed - indexed for MEDLINE]

Concurrent sorption of Ni2+ and Cu2+ by Chlorella vulgaris from a binary metal solution.

Mehta SK, Gaur JP.

Department of Botany, Banaras Hindu University, Varanasi, India.

Kinetics and capacity of Ni2+ and Cu2+ sorption by Chlorella vulgaris were studied using single and binary metal solutions at various concentrations of these metal ions. The second-order rate law best described the kinetics of metal sorption from both single and binary metal systems. C. vulgaris preferentially sorbed Cu2+ over Ni2+ in the binary system. In comparison to the single metal system, the amounts of Ni2+ and Cu2+ sorbed at equilibrium (qe) were respectively 73% and 25%, and the initial rate of sorption (h) was ca. 50% in the case of the binary metal system. The test metals inhibited sorption of each other, thereby indicating competition between Ni2+ and Cu2+ for sorption onto non-specific binding sites. The present study showed that C. vulgaris has specific as well as non-specific sites for the binding of Ni2+ and Cu2+. Participation of these sites for sorption depended on the ratio of Ni2+ and CU2+ in solution. The maximum metal sorption capacity of C. vulgaris was 6.75 mmol g(-1) from the binary metal solution at the tested biomass concentration (100 mg dry weight l(-1)). Total metal sorption was enhanced with increasing total concentration of both the metals up to 1.6 mM, beyond which a decrease occurred. Two-dimensional contour plots were successfully used for the first time for the evaluation of metal sorption potential.

PMID: 11341323 [PubMed - indexed for MEDLINE]

Screening of hexavalent chromium biosorbent for marine algae.

Lee DC, Park CJ, Yang JE, Jeong YH, Rhee HI.

Division of Food Science and Biotechnology, Kangwon National University, Chunchon, Korea.

A high-chromate-selective biosorbent with high adsorption capacity was sought by examining the chromate adsorption capacities of 48 species of red, brown, or green marine algae sampled from the east coast of Korea. Screening showed a red marine alga to have the most excellent adsorption characteristics among them, and it was identified as Pachymeniopsis sp. The period at which Pachymeniopsis sp. was sampled did not affect the adsorption capacity of the alga, but the optimum period for mass collection was April to May. The alga also showed high selectivity for chromate since its adsorption capacity for other heavy metal ions such as cadmium and manganese ions was relatively low. An investigation of the adsorption isotherm of dried powder of Pachymeniopsis sp. for chromate adsorption at 25 degrees C showed a Langmuir-type dependence. The maximum chromate adsorption capacity of the selected alga was about 225 mg/g. Desorption of the adsorbed chromate from Pachymeniopsis sp. was done by treating the sample with 1 N NaOH. It was confirmed that ion exchange type adsorption was observed with an anion exchanger but not with a cation exchanger. It is therefore believed that the chromate adsorption is based on anionic exchange of Pachymeniopsis sp.

PMID: 11030585 [PubMed - indexed for MEDLINE]

Interactions of algal ligands, metal complexation and availability, and cell responses of the diatom Ditylum brightwellii with a gradual increase in copper.

Rijstenbil JW, Gerringa LJ.

NIOO-CEMO, Netherlands Institute of Ecology, Centre for Estuarine and Coastal Ecology, P.O. Box 140, NL-4400 AC NL, Yerseke, Netherlands. [email protected]

A continuous culture experiment was conducted to study interactions between copper-binding ligands released by light-limited Ditylum brightwellii, and toxic effects of Cu on this diatom. Over 6 months, the Cu concentration in the medium has been increased in seven steps (3-173 nM). At each Cu addition, Cu speciation, characteristics of Cu sorption to cellular binding sites, and cell characteristics were determined. Physiological effects of Cu were studied, using indicators for metal detoxification (thiols) and lipid peroxidation (malondialdehyde). Minor amounts of Cu (<1.4%) were chelated by a minimum amount of EDTA (57 nM), required to maintain a stable long-term continuous culture. The responses of D. brightwellii to Cu were monitored. (1) From 3 to 47 nM added Cu, decreasing pools of glutathione, increasing malondialdehyde contents, an increased release of lipophilic ligands, and cell lysis indicated the enhancement of lipid peroxidation. (2) From 47 to 94 nM Cu, a 16-fold increase in high-affinity (strong) hydrophilic ligands was measured (conditional stability constants K' approximately 10(12)) that complexed most Cu (maximum 97%); sexual reproduction was stimulated and cell volumes increased. (3) From 126 nM Cu, glutathione pools increased again, whereas cell division rates decreased slightly. (4) At 142 nM Cu, the number of lysed cells reached a maximum, as did the production of lipophilic compounds that complexed approximately 2% Cu. As the binding sites of the strong ligands became Cu-saturated above 142 nM Cu, larger amounts of Cu were bound to low-affinity (weak) dissolved ligands (3-30%) and cellular binding sites (0.2-2.5%). Probably due to saturation of organic complexes at 142 nM Cu, the MINEQL-calculated Cu2+ concentrations increased markedly; pCu values decreased from >11 to approximately 10; division rates were further inhibited; gamma-glutamylcysteine (phytochelatin precursor) was produced. (5) At 157 nM Cu, phytochelatin synthesis started, and Cu-sorption capacities (cell walls and internal binding sites) increased. (6) At 173 nM Cu, the phytochelatin pool sizes and the number of cellular Cu-binding sites increased further. These results suggest that ligands released by a dense bloom of D. brightwellii, either by active excretion or lysis, would have lower affinities for Cu (K' approximately 10(9)-10(12)) and moderate the availability of Cu less effectively than ligands in natural environments (10(13)-10(14)). In this diatom, the concurring release of ligands, enhanced malondialdehyde production, increasing numbers of presexual cells and cell enlargement may serve as early-warning signals for Cu toxicity, rather than metal-specific phytochelatins that appeared at a stage when cell division was already clearly inhibited.

PMID: 11755700 [PubMed - indexed for MEDLINE]

The cell wall as a barrier to uptake of metal ions in the unicellular green alga Chlamydomonas reinhardtii (Chlorophyceae).

Macfie SM, Welbourn PM.

Dept. of Plant Sciences, University of Western Ontario, London, Ontario, N6A 5B7, Canada.

The cell walls of plants, including those of algae, have the capacity to bind metal ions in negatively charged sites. The authors had already shown that the wild type (walled) strain of the unicellular green alga Chlamydomonas reinhardtii Dangeard was more tolerant to Cd, Co, Cu, and Ni than a wall-less mutant of the same species. The objective of the present study was to determine if the tolerance to metals was associated with an increased adsorption of the same metals to the cell wall. Adsorbed metal was defined as that fraction that could be removed with a solution containing Na(2)EDTA and CaCl(2). The fraction that remained after the EDTA/CaCl(2) wash was considered to be strongly bound in the cell. When exposed to metals, singly, in solution for 24 h, cells of both strains accumulated the metals. The original hypothesis was supported by the results for Cd, Co, and Ni insofar as significantly higher concentrations of these metals were in the loosely bound fraction of the walled strain in comparison with the wall-less strain. However, there are three reasons why the potentially protective effect of the cell wall did not explain differential tolerance of the two strains. After 24 h of exposure (1) less Cd was accumulated internally by the wall-less strain than by the walled strain, (2) very little of the accumulated Cu was in the loosely bound fraction of the walled strain, and (3) the two strains accumulated comparable and relatively high amounts of internal Cu. Unexpectedly, significant amounts of Cd and Cu were also removable from the surface of the wall-less cells. One possible explanation for these apparently externally bound metals in the wall-less strain is that the cells exuded metal-chelating molecules that decreased the ability of metal ions to penetrate the plasma membrane. It was concluded that metal tolerance in this alga must involve a complex of mechanisms involving both internal and external detoxification of metal ions.

PMID: 11031300 [PubMed - indexed for MEDLINE]

Bioactive compounds in the aquatic environment: studies on the mode of uptake of DDE by the aquatic midge, Chironomus tentans (Diptera: Chironomidae).

Derr SK, Zabik MJ.

PMID: 4850762 [PubMed - indexed for MEDLINE]

Biological sorption and uptake of toxic metal ion from wastewaters.

Madgwick JC.

Department of Biotechnology, University of New South Wales, Sydney, NSW.

Microorganisms and algae have potential as agents for removing inorganic pollutants from wastewaters. Metal ion uptake mechanisms function either by passive chemical adsorption or by metabolically driven processes. Ion selective uptake processes are being sought in algae to facilitate purification of valuable metal ions for recycling. Sessile macroalgae growing in seawater are useful bioindicators for detecting metal ion contamination in the marine environment.

Publication Types:

Review

Review, Tutorial

PMID: 7765677 [PubMed - indexed for MEDLINE]

Study on the adsorption of vanadium (V) with Scenedesmus obliquus.

Jie N, Zhang Q, Yao G.

College of Basic Science and Technology, China Agricultural University, Beijing, 100094, People's Republic of China.

PMID: 11479674 [PubMed - indexed for MEDLINE]

Heavy metal binding and removal by phormidium.

Wang TC, Weissman JC, Ramesh G, Varadarajan R, Benemann JR.

Harbor Branch Oceanographic Institution, Inc., Fort Pierce, FL 34946, USA.

PMID: 9595189 [PubMed - indexed for MEDLINE]

Cadmium transport, resistance, and toxicity in bacteria, algae, and fungi.

Trevors JT, Stratton GW, Gadd GM.

Cadmium is an important environmental pollutant and a potent toxicant to bacteria, algae, and fungi. Mechanisms of Cd toxicity and resistance are variable, depending on the organism. It is very clear that the form of the metal and the environment it is studied in, play an important role in how Cd exerts its effect and how the organism(s) responds. A wide range of Cd concentrations have been used to designate resistance in organisms. To date, no concentration has been specified that is applicable to all species studied under standardized conditions. Cadmium exerts its toxic effect(s) over a wide range of concentrations. In most cases, algae and cyanobacteria are the most sensitive organisms, whereas bacteria and fungi appear to be more resistant. In some bacteria, plasmid-encoded resistance can lead to reduced Cd2+ uptake. However, some Gram-negative bacteria without plasmids are just as resistant to Cd as are bacteria containing plasmids encoding for Cd resistance. According to Silver and Misra (1984), there is no evidence for enzymatic or chemical transformations associated with Cd resistance. Insufficient information is available on the genetics of Cd uptake and resistance in cyanobacteria and algae. Mechanisms remain largely unknown at this point in time. Cadmium is toxic to these organisms, causing severe inhibition of such physiological processes as growth, photosynthesis, and nitrogen fixation at concentrations less than 2 ppm, and often in the ppb range (Tables 2 and 3). Cadmium also causes pronounced morphological aberrations in these organisms, which are probably related to deleterious effects on cell division. This may be direct or indirect, as a result of Cd effects on protein synthesis and cellular organelles such as mitochondria and chloroplasts. Cadmium is accumulated internally in algae (Table 4) as a result of a two-phase uptake process. The first phase involves a rapid physicochemical adsorption of Cd onto cell wall binding sites, which are probably proteins and (or) polysaccharides. This is followed by a lag period and then a slow, steady intracellular uptake. This latter phase is energy dependent and may involve transport systems used to accumulate other divalent cations, such as Mn2+ and Ca2+. Some data indicate that Cd resistance, and possibly uptake, in algae and cyanobacteria is controlled by a plasmid-encoded gene(s). Although considerable information is available on Cd toxicity to, and uptake in fungi, further work is clearly needed in several areas. There is little information about Cd uptake by filamentous fungi, and even in yeasts, information on the specificity, kinetics, and mechanisms of Cd uptake is limited.(ABSTRACT TRUNCATED AT 400 WORDS)

Publication Types:

Review

PMID: 3089567 [PubMed - indexed for MEDLINE]

Model reactor for photocatalytic degradation of persistent chemicals in ponds and waste water.

Franke R, Franke C.

[email protected]

A laboratory scale flow-through model reactor for the degradation of persistent chemicals using titanium dioxide (TiO2) as photocatalyst immobilized on glass beads is presented. In the test system with a volume of 18 L contaminated water is pumped to the upper part of the floating reactor and flows over the coated beads which are exposed to UV-radiation. The degradation of two dyes of different persistence was investigated. Primary degradation of methylene blue did not fit a first order kinetic due to coincident adsorption onto the photocatalyst and direct photolysis, resulting in a half-life of 6 h. A filtrate of a green algae suspension accelerated the colour removal. In contrast, reactive red 2 was degraded only by photocatalysis; neither adsorption nor direct photolysis led to a colour removal. The course of primary degradation followed a first order kinetic with a half-life of 18 h and a rate constant of 0.04 h-1. Analysis of the degradation products indicated mineralization by detection of NO2- and NO3-, accompanied by a decrease of pH and an increase of conductivity. A successful adaptation of the model reactor (scale 1:10) to dimensions required for surface waters and waste water treatment plants would be a cost-efficient and environmentally sustainable application of photocatalysis for the treatment of industrially polluted water and could be of relevance for third world countries, particularly those favoured by high solar radiation.

PMID: 10633546 [PubMed - indexed for MEDLINE]

Biosorption of heavy metals by marine algae.

Hamdy AA.

Microbial and Natural Products Chemistry Department, National Research Center, Dokki, Cairo, Egypt.

The ability of four different algae (three brown and one red) that have not been previously studied to adsorb Cr(3+), Co(2+), Ni(2+), Cu(2+), and Cd(2+) ions was investigated. The metal uptake was dependent on the type of biosorbent, with different accumulation affinities towards the tested elements. The HCl-treated biomass decreased the metal biosorptive capacity particularly in the case of Cr(3) adsorption with Laurencia obtusa. The extent of uptake of the different metals with the tested algae was assessed under different conditions such as pH, time of algal residence in solution with the metal, and concentration of algal biomass. The rate of uptake of the different metals was very fast in the first 2 h; thereafter the increase in metal uptake was insignificant. The amount of the metal uptake (5-15 mg range) increased steeply by increasing the weight of the biomass. An exception was L. obtusa, where a parallel increase of the uptake of different metals was observed on increasing the algal mass from 5 to 50 mg.

PMID: 10977888 [PubMed - indexed for MEDLINE]

Monitoring of labile zinc in cultures of Skeletonema costatum using a salt groundwater.

Schintu M, Koussih L, Chevolot L, Amiard JC, Robert JM.

Dipartimento di Igiene e Sanita Pubblica, Universita di Cagliari, Via Porcell 4, Cagliari, 09100, Italy.

Labile Zn concentration was monitored by differential pulse anodic stripping voltammetry (DPASV) throughout the exponential growth phase of the marine diatom Skeletonema costatum (Grev.) Cleve. Algal blooms were induced both under natural conditions and in laboratory experiments using a salt groundwater (salinity 33) from the Bay of Bourgneuf, northwest coast of France. Salt groundwater is a very complex medium containing high concentrations of dissolved organic matter and other trace metal adsorbents, such as phosphate, iron oxyhydroxides, and manganese and silicon oxides, which can bind metal ions, reducing their availability and toxicity to algae. Besides metal uptake by algae and complexation of Zn by algal exudates, the rapid decrease in the labile Zn concentration during the algal blooms was ascribed mainly to the adsorption or coprecipitation of Zn ion onto freshly formed iron hydroxides. Copyright 1999 Academic Press.

PMID: 10090809 [PubMed - indexed for MEDLINE]

Repeated use of two Chlorella species, C. vulgaris and WW1 for cyclic nickel biosorption.

Tam NF, Wong JP, Wong YS.

Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong. [email protected]

Two living Chlorella species were used to remove nickel from solution containing 30 micrograms Ni ml-1 in 10 successive cycles. The present study also examined the continued viability of these two algal species after repeated exposure to nickel. The two species of Chlorella were Chlorella vulgaris (commercially available) and WW1 (indigenous species isolated from domestic sewage and was tentatively identified as Chlorella miniata). The nickel removal percentage of WW1 cells was maintained at around 85% in the first five cycles, then declined slightly from the fifth cycle onwards, and finally achieved around 70% removal at the end of the 10th cycle. On the contrary, the removal efficiency of C. vulgaris declined from 50 to 30% during the 10 cycles of nickel bisorption. At the end of these 10 successive cycles, WW1 accumulated a substantial amount of Ni2+ (the cumulative cellular Ni concentration was 0.92% dry w.), while the value was only 0.17% in the case of C. vulgaris. These results suggest that the local isolate, WW1, had more consistent and satisfactory ability for removing Ni than the commercial C. vulgaris. Both algal species were still capable of dividing after each nickel treatment cycle, suggesting that the cells were not killed even when significant amounts of nickel were adsorbed/absorbed. However, Ni exposure adversely affected the physiological activity of algal cells as reflected by the decline in division rate and chlorophyll-a activity in both species. Such negative effects became more obvious as the number of cyclic treatments was increased. Nevertheless, WW1 cells appeared to recover from nickel treatment when re-cultivated in commercial medium for 2 weeks.

PMID: 11444009 [PubMed - indexed for MEDLINE]

Cadmium(II) removal from aqueous solutions by pre-treated biomass of marine alga Padina sp.

Kaewsarn P, Yu Q.

School of Environmental Engineering, Nathan Campus, Griffith University, Queensland, 4111 Australia.

In this study, the adsorption properties of a pre-treated biomass from marine alga Padina sp., a biomass collected from Surin Island, Thailand, for removal of cadmium(II) ions from aqueous solutions was investigated. Batch and column experiments were conducted to determine the adsorption properties of the modified biomass. At a pH of 5, the maximum removal capacity of the biomass is 0.53 mmol/g. The kinetics of cadmium(II) adsorption were fast with 90% of adsorption taking place within 35 min. This study demonstrated that the pre-treated biomass of Padina sp. could be used as an efficient biosorbent for the treatment of cadmium(II)-bearing wastewater streams.

PMID: 11234537 [PubMed - indexed for MEDLINE]

Comparative analysis of the biosorption of cadmium, lead, nickel, and zinc by algae.

Klimmek S, Stan HJ, Wilke A, Bunke G, Buchholz R.

Institute of Food Chemistry, Technical University Berlin, Germany.

Thirty strains of algae were examined for their biosorption abilities in the uptake of cadmium, lead, nickel, and zinc from aqueous solution. A wide range of adsorption capacities between the different strains of algae and between the four metals can be observed. The cyanophyceae Lyngbya taylorii exhibited high uptake capacities for the four metals. The algae showed maximum capacities according to the Langmuir Adsorption Model of 1.47 mmol lead, 0.37 mmol cadmium, 0.65 mmol nickel, and 0.49 mmol zinc per gram of dry biomass. The optimum pH for L. taylorii was between pH 3 and 7 for lead, cadmium, and zinc and between pH 4 and 7 for nickel. Studies with the algae indicated a preference for the uptake of lead over cadmium, nickel, and zinc in a four metal solution. The metal binding abilities of L. taylorii could be improved by phosphorylation of the biomass. The modified biosorbent demonstrated maximum capacities of 2.52 mmol cadmium, 3.08 mmol lead, 2.79 mmol nickel, and 2.60 mmol zinc per gram of dry biomass. Investigations with phosphated L. taylorii indicated high capacities for the four metals also at low pH. The selectivity remained quite similar to the unmodified algae.

PMID: 11718343 [PubMed - indexed for MEDLINE]

The effects of pH and surface composition on Pb adsorption to natural freshwater biofilms.

Wilson AR, Lion LW, Nelson YM, Shuler ML, Ghiorse WC.

School of Civil and Environmental Engineering, Cornell University, Ithaca, New York 14853, USA.

Two dominant variables that control the adsorption of toxic trace metals to suspended particulate materials and aquatic surface coatings are surface composition and solution pH. A model for the pH-dependent adsorption of Pbto heterogeneous particulate surface mixtures was derived from experimental evaluation of Pb adsorption to laboratory-derived surrogates. The surrogate materials were selected to represent natural reactive surface components. Pb adsorption to both the laboratory surrogates and natural biofilms was determined in chemically defined solutions under controlled laboratory conditions. Pb adsorption was measured over a pH range of 5-8, with an initial Pb concentration in solution of 2.0 microM. The surface components considered include amorphous Fe oxide, biogenic Mn oxide produced by a Mn(II) oxidizing bacterium (Leptothrix discophora SS-1), Al oxide, the common green alga Chlorella vulgaris, and Leptothrix discophora SS-1 cells. A linearization of Pb adsorption data for each adsorbent was used to quantify the relationship between Pb adsorption and pH. The parameters for individual adsorbents were incorporated into an additive model to predict the total Pb adsorption in multiple-adsorbent natural surface coatings that were collected from Cayuga Lake, NY. Pb adsorption experiments on the natural surface coatings at variable pH were utilized to verify the additive model predictions based on the pH dependent behavior of the experimental laboratory surrogates. Observed Pb adsorption is consistent with the model predictions (within 1-24%) over the range of solution pH values considered. The experimental results indicate that the combination of Fe and biogenic Mn oxides can contribute as much as 90% of Pb adsorbed on Cayuga Lake biofilms, with the dominant adsorbent switching from Mn to Fe oxide with increasing pH.

PMID: 11505999 [PubMed - indexed for MEDLINE]

Study of the mechanisms of cadmium biosorption by dealginated seaweed waste.

Romero-Gonzalez ME, Williams CJ, Gardiner PH.

Division of Chemistry, School of Science and Mathematics, Sheffield Hallam University, Howard Street, Sheffield S1 1WB, U.K.

The ability of dealginated seaweed waste, a waste material derived from the commercial processing of seaweed for alginate production, to remove cadmium from solution was determined. Cadmium sorption was found to be rapid (91% removal within 5 min), achieving a residual concentration of 0.8 mg L-1 after 1-h contact time from an initial solution concentration of 10 mg L-1. The binding of cadmium by dealginate was found to be pH dependent, optimal sorption occurring at around pH 6-8. The mechanism of cadmium ion binding by dealginate was investigated by a number of techniques. Potentiometric titration of the dealginate revealed two distinct pKa values, the first having a value similar to carboxyl groups and the second comparable with that of saturated thiols and amines. Esterification of the dealginate resulted in the subsequent reduction in cadmium sorption (95% to 17%), indicating that carboxyl groups are largely responsible for sorption. Evidence from FT-IR spectra confirmed the presence of carboxyl groups in untreated dealginate, while the number of carboxyl groups was markedly reduced in the esterified sample. Furthermore, the FT-IR spectrum for dealginate was found to be similar to that previously reported for mannuronic acid-rich calcium alginate. Determination of a molar ratio in the displacement of calcium by cadmium on dealginate further supported the presence of an ion-exchange relationship. The ion-exchange constant was calculated to be 0.329 x 10(-6). The speciation of cadmium in solution both before and after sorption was determined by an ion-selective electrode (ISE) technique. The findings of this study suggest that the sorption of cadmium by dealginate is mainly due to an ion-exchange mechanism.

PMID: 11478258 [PubMed - indexed for MEDLINE]

Homogenous and heterogenous advanced oxidation of two commercial reactive dyes.

Balcioglu IA, Arslan I, Sacan MT.

Bogazici University Institute of Environmental Sciences, Istanbul, Turkey.

Two commercial reactive dyes, the azo dye Reactive Black 5 and the copper phythalocyanine dye Reactive Blue 21, have been treated at a concentration of 75 mg l(-1) by titanium dioxide mediated photocatalytic (TiO2/UV), dark and UV-light assisted Fenton (Fe2+/H2O2) and Fenton-like (Fe3+/H2O2) processes in acidic medium. For the treatment of Reactive Black 5, all investigated advanced oxidation processes were quite effective in terms of colour, COD as well as TOC removal. Moreover, the relative growth inhibition of the azo dye towards the marine algae Dunaliella tertiolecta that was initially 70%, did not exhibit an increase during the studied advanced oxidation reactions and complete detoxification at the end of the treatment period could be achieved for all investigated treatment processes. However, for Reactive Blue 21, abatement in COD and UV-VIS absorbance values was mainly due to the adsorption of the dye on the photocatalyst surface and/or the coagulative effect of Fe3+/Fe2+ ions. Although only a limited fraction of the copper phythalocyanine dye underwent oxidative degradation, 47% of the total copper in the dye was already released after 1 h photocatalytic treatment.

PMID: 11506205 [PubMed - indexed for MEDLINE]

Biosorption and desorption of cadmium(II) by biomass of Laminaria japonica.

Yin P, Yu Q, Lin Z, Kaewsarn P.

Department of Chemistry, Jinan University, Guangzhou 51063, P.R. China.

Biosorption and desorption properties of cadmium(II) from aqueous solutions by the biomass of marine alga Laminaria japonica were investigated. Results indicated that the uptake capacities were solution pH dependent and a maximum uptake capacity of about 1.3 mmol g-1 (dry weight) was observed at pH 6. The adsorbed cadmium cannot be desorbed by distilled water, but it can be effectively recovered by using acidic or EDTA solutions. The equilibrium isotherms can be described well with the Langmuir adsorption equation. Biomass, pre-treated with calcium solution exhibited a higher (about 30%) uptake capacity and can be easily settled from aqueous solutions. Batch kinetics experiments indicated that more than 90% of the adsorption occurred within 20 minutes of agitation and equilibrium was reached within one hour. Fixed-bed experiments showed similar uptake capacities to those of batch results and sharp breakthrough curves were obtained. This study indicated that the biomass of L. japonica can be used as an efficient biosorbent for the removal and recovery of cadmium(II) from waste water streams.

PMID: 11424727 [PubMed - indexed for MEDLINE]

Influence of N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid pH buffer on the biological response of marine algae.

Vasconcelos MT, Leal MF.

LAQUIPAI, Chemistry Department, Faculty of Science, University of Porto, Portugal. [email protected]

The N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) is extensively used as pH buffer in culture media for testing chemicals. However, this study demonstrates that 0.01 M HEPES significantly reduces the rate of Cu, Pb, and Cd binding to Porphyra spp. and Enteromorpha spp. marine macroalgae. The HEPES also decreased the accumulation of Cu, Pb, and Cd but not Hg by these macroalgae. Both the extracellular adsorption and the intracellular uptake of the metals were influenced by HEPES to a similar extent. The HEPES also promoted the release of exudates by the algae, and these exudates form very stable complexes with Cu (and probably with other trace metal ions). The HEPES interference varied with the nature of the metal, the macroalga, and the season. The presence of 0.01 M HEPES in seawater cultures of the Emiliania huxleyi (a microalga) also interfered with E. huxleyi growth, liberation of Cu-complexing organic ligands, and Cu uptake. The HEPES, which displays surface activity, may facilitate the binding of metals to the algae for an initial exposure period. The metal taken up appears to stimulate the liberation of exudates that subsequently control the bioavailability of the metals and therefore metal uptake. Because HEPES can control the uptake of trace metals by algae and the production of organic ligands, the results obtained in cultures containing the HEPES pH buffer can be influenced by this component of the media.

PMID: 11837230 [PubMed - indexed for MEDLINE]

Biosorption of copper and zinc by Cymodocea nodosa.

Sanchez A, Ballester A, Blazquez ML, Gonzalez F, Munoz J, Hammaini A.

Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense, 28040, Madrid, Spain.

The adsorption of the two metal ions Cu and Zn in a single-component system by Cymodocea nodosa, a brown alga, under different pH conditions was investigated. The solution pH significantly affected the exhibited uptake, being maximum at a pH value of 4.5. Multi-component mixture biosorption in aqueous solutions is also reported. A comparison was made between the single-component saturation uptake and the multi-component uptakes. To evaluate the two-metal sorption system performance, simple isotherm curves had to be replaced by three-dimensional sorption isotherm surfaces. In order to describe the isotherm surfaces mathematically, three Langmuir-type models were evaluated. The isotherms indicate a competitive uptake with Cu being preferentially adsorbed. In addition, different tests were carried out to compare the process efficiency working continuously in small columns.

PMID: 10525164 [PubMed - indexed for MEDLINE]

Initial uptake, distribution and loss of soluble 106 Ru in marine and freshwater organisms in laboratory conditions.

Van Der Borght O, Van Puymbroeck S.

PMID: 5513695 [PubMed - indexed for MEDLINE]

Electron microscopic characterization of calcium-binding physodes in the green alga Mougeotia scalaris.

Tretyn A, Grolig F, Magdowski G, Wagner G.

Nicolaus Copernicus University, Institute of Biology, Torun, Poland.

Effect of the covalently cross-linking agents glutardialdehyde and osmium tetroxide, and of adsorption of the vital dye, neutral red, to the matrix of the calcium-binding "vesicles" from the green alga Mougeotia scalaris has been analysed in situ, both in terms of structural preservation and of the calcium-binding capacity of the vesicles. Upon cell fixation in glutardialdehyde without OsO4, the vesicles appear to dissolve, but upon simultaneous fixation in glutardialdehyde with OsO4 (1% w/v), the vesicles retain a globular form, are evenly stained by osmium and appear to be surrounded by a membrane-like structure. This structure was also observed around the vesicles in cells preincubated for 10 min in 0.1 mM neutral red and then fixed in glutardialdehyde/OsO4 for 1 h. More detailed information of the matrix structure is obtained when simultaneous fixation of the Mougeotia cells was shortened to 15 min: a membrane-like structure was no longer observed around the vesicles. After cell treatment in the presence of neutral red, no calcium at all was found inside the vesicles. A small amount of calcium remained, when cells were fixed simultaneously and extensively in the absence of neutral red. However, calcium was found, to a considerable extent, inside the vesicles after short simultaneous fixation of the cells in the absence of neutral red. Based on the ultrastructural and elemental features presented here, the calcium-binding vesicles in Mougeotia appear to represent a member of the large family of (calcium-binding) physodes in lower plants (CaBP).

PMID: 1429009 [PubMed - indexed for MEDLINE]

Biosorption: a solution to pollution?

Vieira RH, Volesky B.

Marine Science Institute-Labomar, Federal University of Ceara, Fortaleza, Brazil.

To solve the water pollution problem by toxic heavy metal contamination resulting from humans technological activities has for long presented a challenge. Biosorption can be a part of the solution. Some types of biosorbents such as seaweeds, molds, yeasts, bacteria or crab shells are examples of biomass tested for metal biosorption with very encouraging results. The uptake of heavy metals by biomass can in some cases reach up to 50% of the biomass dry weight. New biosorbents can be manipulated for better efficiency and multiple re-use to increase their economic attractiveness.

Publication Types:

Review

Review, Tutorial

PMID: 10963329 [PubMed - indexed for MEDLINE]

Extraction of mercury from groundwater using immobilized algae.

Barkley NP.

U.S. Environmental Protection Agency, Risk Reduction Engineering Laboratory, Cincinnati, Ohio.

Bio-Recovery Systems, Inc. conducted a project under the Emerging Technology portion of the United States Environmental Protection Agency's (EPAs) Superfund Innovative Technology Evaluation (SITE) Program to evaluate the ability of immobilized algae to adsorb mercury from contaminated groundwater in laboratory studies and pilot-scale field tests. Algal biomass was incorporated in a permeable polymeric matrix. The product, AlgaSORB, packed into adsorption columns, exhibited excellent flow characteristics, and functioned as a "biological" ion exchange resin. A sequence of eleven laboratory tests demonstrated the ability of this product to adsorb mercury from groundwater that contained high levels of total dissolved solids and hard water components. However, use of a single AlgaSORB preparation yielded nonrepeatable results with samples collected at different times of the year. The strategy of sequentially extracting the groundwater through two columns containing different preparations of AlgaSORB was developed and proved successful in laboratory and pilot-scale field tests. Field test results indicate that AlgaSORB could be economically competitive with ion exchange resins for removal of mercury, with the advantage that hardness and other dissolved solids do not appear to compete with heavy metals for binding capacity.

PMID: 1777231 [PubMed - indexed for MEDLINE]

Screening of marine microalgae for bioremediation of cadmium-polluted seawater.

Matsunaga T, Takeyama H, Nakao T, Yamazawa A.

Department of Biotechnology, Tokyo University of Agriculture and Technology, Japan. [email protected]

Twenty four strains out of 191 marine microalgal strains exhibited cadmium (Cd) resistance. They were tested for their Cd removal ability in growth media containing 50 microM Cd. Six strains out of 19 green algae and one out of five cyanobacteria removed more than 10% of total Cd from the medium. The marine green alga Chlorella sp. NKG16014 showed the highest removal of Cd 48.7% of total. Cd removal by NKG16014 was further quantitatively evaluated by measuring the amount of cell adsorption and intracellular accumulation. After 12 days incubation, 67% of the removed Cd was accumulated intracellularly and 25% of the Cd removed was adsorbed on the algal cell surface. The maximum Cd adsorption (qmax) was estimated to be 37.0 mg Cd (g dry cells)-1 using the Langmuir sorption model. The Cd removal by freeze-dried NKG16014 cells was also determined. Cd was more quickly adsorbed by dried cells than that by living cells, with a qmax of 91.0 mg Cd (g dry cells)-1.

PMID: 10412204 [PubMed - indexed for MEDLINE]

Characterization and localization of a flagellar-specific membrane glycoprotein in Euglena.

Rogalski AA, Bouck GB.

Purified flagella from Euglena yield a unique high molecular weight glycoprotein when treated with low concentrations of nonionic detergents. This glycoprotein termed "xyloglycorien" cannot be extracted from other regions of the cell, although a minor component that coextracts with xyloglycorien does have a counterpart in deflagellated cell bodies. Xyloglycorien is tentatively identified with a flagellar surface fuzzy layer that appears in negatively stained membrane vesicles of untreated flagella but not in similar vesicles after Nonidet P-40 extraction. The localization of xyloglycorien is further confirmed to be membrane associated by reciprocal extraction experiments using 12.5 mM lithium diiodosalicylate (LIS), which does not appreciably extract xyloglycorien, visibly solubilize membranes, or remove the fuzzy layer. Rabbit antibodies directed against the two major flagellar glycoproteins (xyloglycorien and mastigonemes) to some extent cross react, which may in part be caused by the large percentage of xylose found by thin-layer chromatography (TLC) analysis to be characteristic of both antigens. However, adsorption of anti-xyloglycorien sera with intact mastigonemes produced antibodies responding only to xyloglycorien, and vice versa, indicating the nonidentity of the two antigens. Antibodies or fragments of these antibodies used in immunofluorescence assays demonstrated that xyloglycorien is confined to the flagellum and possibly the adjacent reservoir and gullet. Binding could not be detected on the cell surface. The sum of these experiments suggests that, in addition to mastigonemes, at least one major membrane glycoprotein in Euglena is restricted to the flagellar domain and is not inserted into the contiguous cell surface region.

PMID: 6772649 [PubMed - indexed for MEDLINE]

Determination of metal ions in algal solution samples by capillary electrophoresis.

Lopez CE, Castro JM, Gonzalez V, Gonzalez E, Perez J, Seco HM, Fernandez JM.

Departamento de Quimica Analitica, Escuela Universitaria Politecnica de Ferrol, Universidade da Coruna, Spain.

Trace metals determination in aqueous samples can be readily accomplished by capillary electrophoresis (CE) via indirect absorbance detection. A method for the separation of metal ions is presented and applied to the determination of seven metals in algal solution samples. 2-Hydroxyisobutyric acid background electrolyte (BGE) containing UV CAT-1 (an ultraviolet-absorbing amine) is used to perform capillary ion analysis. Acetic acid is used to adjust the pH value of BGE to 4.4. All ions can be separated in less than 15 min. All peaks are well separated and baseline resolved (i.e., no peaks overlapped). This work presents the applicability of CE to the quantitative analysis of algal solution samples and shows the adsorption process of seven metals in solution (Mn, Cd, Cr, Ni, Zn, Pb, Cu) to Chlorella vulgaris. The innovation of the application of CE in the determination of metals bound by Chlorella vulgaris is shown to be an improvement of the pH over what has been published previously. The detection limit is in the range of 13 (Mn) to 102 (Pb) ppb with electrokinetic injection mode (15 kV, 7 s). Reproducibility was 1.4% for the migration time, better than 5% for peak area for four of the metal ions (Cr, Mn, Cd, and Cu), and lower than 5% for the other three (Ni, Zn, and Pb). Calibration curves are linear for most ions in the 10(-7)-10(-5)M range (correlation coefficient r2 = 0.9933-0.9986) using electrokinetic injection mode.

PMID: 9679302 [PubMed - indexed for MEDLINE]

Artificial life simulation of living alga cells and its sorption mechanisms.

Csonto J, Kadukova J, Polak M.

Department of Cybernetics and Artificial Intelligence, Technical University, Kosice, Slovak Republic.

Resistance mechanisms of organisms against toxic metals are based on a few different mechanisms provided by algae cells. These mechanisms can be localized on the cell wall, on the cell wall and cytoplasm membrane, and intracellular localized mechanisms. Due to these mechanisms, algae populations could be used for sorption of arsenic from contaminated waters. This process takes a long time and it's not very variable. With artificial life simulation based on multi-agent simulation system we are preparing a simulation that could at least partially substitute the real experiments with real cells. Artificial life simulation of alga Chlorella kessleri is based on real biological parameters and together with partial implementation of other mathematical models of algae population growth it will be used for simulating the process of absorbing heavy metals from contaminated water. Model implementation is done is Swarm--multi agent object based simulation system and it's libraries. Simulation is still in testing and debugging phase and it is not yet available for public.

PMID: 11433549 [PubMed - indexed for MEDLINE]

Fate of copper in ponds.

McIntosh AW.

Treatments of 3 ppm copper sulfate (CuSO4-5H2O) were applied to two small aquatic systems in Michigan in 1971. To study the pathways of the added copper, samples of water, sediment, aquatic macrophytes, filamentous algae, and fish were collected and analyzed by atomic absorption. Sampling was initiated before treatment and continued up to 4 months in one of the ponds. Dissolved copper concentrations in water decreased rapidly immediately after treatment and then gradually to background levels. Reduction of dissolved copper may have involved initial precipitation of an insoluble compound, such as malachite, followed by sediment adsorption of soluble copper complexes and copper released from aquatic plants. Levels of copper in sediment increased rapidly at first and gradually later in the study. Aquatic plants and filamentous algae accumulated very high levels of copper. Uptake rates were apparently affected by water temperature and growth stages of the plants. Data indicate that aquatic macrophytes developing in one pond 10 weeks after treatment took up copper from the sediment. Although green sunfish (Lepomis cyanellus) accumulated copper soon after treatment, levels returned to background later in the study.

PMID: 1161446 [PubMed - indexed for MEDLINE]

Similarities and dissimilarities between calmodulin and a Chlamydomonas flagellar protein.

Van Eldik LJ, Piperno G, Watterson DM.

A protein that resembles vertebrate calmodulins and troponin C has been isolated from Chlamydomonas flagella by using a calmodulin purification protocol that included calcium-dependent affinity-based adsorption chromatography on phenothiazine-Sepharose conjugates. The flagellar protein resembled calmodulin in elution from reverse-phase columns, had a peptide map similar to that of calmodulin, and competed with vertebrate calmodulin in a radioimmunoassay using antisera against vertebrate calmodulin. However, this flagellar protein did not activate phosphodiesterase, lacked N epsilon-trimethyllysine, and had an isoelectric point approximately 0.3 pH unit higher than that of vertebrate calmodulin. When analyzed by polyacrylamide gel electrophoresis under various conditions, the Chlamydomonas protein migrated between vertebrate calmodulins and rabbit skeletal muscle troponin C and did not manifest a large calcium-dependent mobility shift. This calmodulin-like protein was identified as one of the approximately 200 35S-labeled components in Chlamydomonas flagella resolved by two-dimensional gel electrophoresis. These studies indicate that calmodulin and a structurally and functionally homologous protein are present in the same cell. These studies also demonstrate that caution is necessary: (i) in identifying a protein as a calmodulin, (ii) in using phenothiazines or antisera directed against vertebrate calmodulins as specific probes for calmodulin, and (iii) in the interpretation of experiments on biological systems in which calmodulin is substituted for the homologous calmodulin-like protein.

PMID: 6254039 [PubMed - indexed for MEDLINE]

Environmental hazards of aluminum to plants, invertebrates, fish, and wildlife.

Sparling DW, Lowe TP.

National Biological Service, Patuxent Environmental Science Center, Laurel, MD 20708, USA.

Aluminum is extremely common throughout the world and is innocuous under circumneutral or alkaline conditions. However, in acidic environments, it can be a major limiting factor to many plants and aquatic organisms. The greatest concern for toxicity in North America occurs in areas that are affected by wet and dry acid deposition, such as eastern Canada and the northeastern U.S. Acid mine drainage, logging, and water treatment plant effluents containing alum can be other major sources of Al. In solution, the metal can combine with several different agents to affect toxicity. In general, Al hydroxides and monomeric Al are the most toxic forms. Dissolved organic carbons, F, PO(3)3- and SO(4)2- ameliorate toxicity by reducing bioavailability. Elevated metal levels in water and soil can cause serious problems for some plants. Algae tend to be both acid- and Al tolerant and, although some species may disappear with reduced pH, overall algae productivity and biomass are seldom affected if pH is above 3.0. Aluminum and acid toxicity tend to be additive to some algae when pH is less than 4.5. Because the metal binds with inorganic P, it may reduce P availability and reduce productivity. Forest die-backs in North America involving red spruce, Fraser fir, balsam fir, loblolly pine, slash pine, and sugar maples have been ascribed to Al toxicity, and extensive areas of European forests have died because of the combination of high soil Al and low pH. Extensive research on crops has produced Al-resistant cultivars and considerable knowledge about mechanisms of and defenses against toxicity. Very low Al levels may benefit some plants, although the metal is not recognized as an essential nutrient. Hyperaccumulator species of plants may concentrate Al to levels that are toxic to herbivores. Toxicity in aquatic invertebrates is also acid dependent. Taxa such as Ephemeroptera, Plecoptera, and Cladocera are sensitive and may perish when Al is less than 1 mg.L-1 whereas dipterans, molluscs, and isopods seem to be tolerant. In Al-sensitive species, elevated levels (approximately 500 micrograms.L-1) affect ion regulation and respiratory efficiency. Toxicity tends to be greatest near a species' threshold of pH sensitivity. At lower pHs, Al may have a slight ameliorative effect by interfering with H+ transport across membranes. Aquatic invertebrates can accumulate very high levels of Al, but most of this appears to be through adsorption rather than assimilation. Aluminum concentrations may be as high as 5000 mg.kg-1 in insects and greater than 17,000 mg.kg-1 in other invertebrates.(ABSTRACT TRUNCATED AT 400 WORDS)

Publication Types:

Review

Review, Academic

PMID: 7494908 [PubMed - indexed for MEDLINE]

Environmental cadmium in Europe.

Jensen A, Bro-Rasmussen F.

FORCE Institutes, Division for Isotope Techniques and Analysis, Brondby, Denmark.

The present article reviews information from the latest 10 years concerning fate and exposure of cadmium in the environment, on ecotoxicological effects, and on critical pathways leading to human and environmental exposure. It emphasizes the situation within the Community of European Countries by referring to limit values used in the EEC and some of its member states for emissions to water, air and soil. Estimates have been made on total emission balances for the Netherlands, Denmark, and for the EEC as a whole. The balances show that 70-90% of all cadmium circulating in the Community is disposed of as waste in solid waste deposits. Production and use patterns are presently changing, as indicated by reduced consumption in recent years of cadmium for plating, stabilizers and pigments in several countries as a result of regulations. However, significant increases in consumption for cadmium-containing batteries have occurred, resulting globally in increasing trends for the total consumption and production. Cadmium in sediments is more mobile than described earlier. Aquatic organisms can be classified in order of decreasing accumulation: algae greater than molluscs greater than crustaceans greater than fish. There is no evidence of biomagnification of cadmium within marine or fresh water food webs. Cadmium may enter into plants via roots or by foliar adsorption following atmospheric deposition. Biomagnification in terrestrial food chains is not observed. The uptake into plants is plant specific. Within plants significant variations are seen with concentrations generally decreasing in the order: roots greater than leaves greater than fruiting parts greater than seeds. A compilation of cadmium in air, in the aquatic environment and in soil is given. A downward trend during the 1970s to mid-1980s seems to be evidenced from various Northern European studies on cadmium air concentrations as well as for deposition rates of cadmium. In rivers, the dissolved cadmium concentrations are generally found to be relatively low (10-500 ng/L). In seawater, cadmium concentrations are found at 0.5-10 ng/L in oceanic or open marine areas, while elevated concentrations are reported in more closed marine areas and especially in coastal zones close to polluted estuaries. In fresh water, lake sediments concentrations 3-30 times higher than the background concentrations are reported in the surface layers of sediments. A significant decrease in such pollution has been observed within the recent 10 years. For marine sediments, enrichment factors of two are found in sediments from open areas and locally even 5-10 times.(ABSTRACT TRUNCATED AT 400 WORDS)

Publication Types:

Review

Review, Academic

PMID: 1509176 [PubMed - indexed for MEDLINE]

Public health benefits of using algae for simultaneous multiple metal extraction from waters.

Pascucci PR, Kowalak AD.

Dept. of Chemistry, University of Massachusetts-Lowell 01854, USA.

Algae have been described as inexpensive organisms for the efficient extraction and recovery of heavy-metals from polluted waters. This method is most effective when the solution conditions are adjusted for the selective adsorption of individual metals. Experiments that are designed for extracting single metals, however, do not accurately assess either environmental or water systems. In this article, we distinguish between using algae to remove individual versus multiple metals. Simultaneous multiple metal extraction has a major disadvantage, however, because all the metals in a solution may not be removed with great efficiency. Single-metal extraction is more readily optimized for almost 100% recovery.

Publication Types:

Review

Review, Tutorial

PMID: 9085436 [PubMed - indexed for MEDLINE]

[Study of the factors of Cr(III) bioaccumulation on Spirulina platensis]

[Article in Chinese]

Li ZY, Li YG, Guo SY, Li L, Zhang SL.

School of Food & Biological Engineering, South China University of Technology, Guangzhou.

Some factors of Cr(III) bioaccumulation on Spirulina platensis were studied in detail. It was found that the bioaccumulation of Cr(III) on Spirulina platensis involved two steps: rapid adsorption and slow absorption. Chromic(III) compounds with weaker chemical bond had higher bioaccumulation efficiency. Under the same algal cell concentration, Cr(III) bioaccumulation rosed up with Cr(III) concentration. On the other hand, with Cr(III) concentration not changed, the total bioaccumulation of Cr(III) on Spirulina platensis increased with algal cell concentration, but the Cr(III) bioaccumulation on unit algae reduced. The study also showed that Spirulina platensis powder could bioaccumulate more Cr(III) than fresh Spirulina platensis, pH is a quite important factor and more suitable pH for Cr(III) bioaccumulation is 7. It was also proved that Cr(III) bioaccumulation benefited from the increase of temperature and light intensity. Cations had either stimulation or inhibition effects on the Cr(III) bioaccumulation on Spirulina platensis.

PMID: 10883289 [PubMed - indexed for MEDLINE]

Biosorption of chromium(VI) from aqueous solutions by green algae Spirogyra species.

Gupta VK, Shrivastava AK, Jain N.

Department of Chemistry, University of Roorkee, India. [email protected]

Biosorption of heavy metals is an effective technology for the treatment of industrial wastewaters. Results are presented showing the sorption of Cr(VI) from solutions by biomass of filamentous algae Spirogyra species. Batch experiments were conducted to determine the adsorption properties of the biomass and it was observed that the adsorption capacity of the biomass strongly depends on equilibrium pH. Equilibrium isotherms were also obtained and maximum removal of Cr(VI) was around 14.7 x 10(3) mg metal, kg of dry weight biomass at a pH of 2.0 in 120 min with 5 mg/l of initial concentration. The results indicated that the biomass of Spirogyra species is suitable for the development of efficient biosorbent for the removal and recovery of Cr(VI) from wastewater.

PMID: 11791837 [PubMed - in process]

The adsorption kinetics of metal ions onto different microalgae and siliceous earth.

Schmitt D, Muller A, Csogor Z, Frimmel FH, Posten C.

Engler-Bunte-Institute, Department of Water Chemistry, Engler-Bunte-Ring 1, Universitat Karlsruhe, 76131 Karlsruhe, Germany.

In the present work the adsorption kinetics of the six metal ions aluminum, zinc, mercury, lead, copper, and cadmium onto living microalgae were measured. The freshwater green microalga Scenedesmus subspicatus, the brackish water diatom Cyclotella cryptica, the seawater diatom Phaeodactylum tricornutum, and the seawater red alga Porphyridium purpureum were the subject of investigation. In most cases the adsorption rate of the metals could be well described by using the equation of the Langmuir adsorption rate expression. Inverse parameter estimation allowed the determination of the rate constants of the adsorption process and the maximum metal content of the algae. The highest values for the rate constant were obtained for Porphyridium purpureum followed by Phaeodactylum tricornutum. High values for the maximum content were obtained for Cyclotella cryptica and Scenedesmus subspicatus. The maximum rate constant was 24.21 h-1 for the adsorption of Hg to Porphyridium purpureum whereas the maximum metal content (0.243 g g-1) was obtained for Zn on Cyclotella cryptica. A comparison of these values with those obtained for the mineral siliceous earth exhibiting low maximum content and high adsorption rates reveals that the mechanism of adsorption onto the algae is a mixture of adsorption and accumulation.

PMID: 11228977 [PubMed - indexed for MEDLINE]

A new method for extraction of extracellular polymeric substances from biofilms and activated sludge suitable for direct quantification of sorbed metals.

Wuertz S, Spaeth R, Hinderberger A, Griebe T, Flemming HC, Wilderer PA.

Institute of Water Quality Control and Waste Management, Technical University of Munich, Am Coulombwall, D-85748 Garching, Germany. [email protected]

A method for extraction of extracellular polymeric substances (EPSs) with a dicyclohexyl-18-crown-6 ether was developed to determine levels of organic and inorganic contaminants sorbed to EPS. The crown ether selectively binds alkaline and alkaline earth metals but not heavy metals. The effectiveness of the extraction procedure was higher than that of 2 other methods tested and comparable with that of a method based on a cation exchange resin. On average it was possible to extract 20% of the TOC, 12% of the total protein content, and 4% of the total carbohydrate content of sludge or biofilm biomass. Metal sorption studies in activated sludge showed no influence of exposure time on the fractionation of metals within the biomass. Metals sorbed mostly to cellular material. In biofilms 12.2% of the cadmium and 9.1% of the zinc added was found in the EPS. In activated sludge EPS contained only 2.9% zinc. The distribution of metals within the biomass was dose dependent. The percentage of metals found in EPS decreased with increasing metal concentration. This indicates a higher affinity of metals for cellular binding sites. Time course experiments in a rotating biofilm annular reactor, which consisted of an external cylinder with removable slides and an internal solid drum, revealed a gradual change in zinc concentration associated with EPS, although the total zinc concentration in the biomass remained constant. Concurrently, the amount of extractable EPS decreased. This was a consequence of a microbial population shift, with bacterial counts decreasing and algal and fungal biomass increasing. Using confocal laser scanning microscopy and the fluorescent metal complexing agent Newport Green for in situ detection of zinc it was shown that metals were bound to algae and fungi in the latter part of the experiment. The biofilm became more and more heterogeneous coinciding with a decrease in EPS. To summarize, the observed sorption behavior of metals cannot be explained with the conventional paradigm of EPS as hydrophilic gel. Obviously, different binding mechanisms must be invoked to explain the role of EPS in the sorption and removal of toxic substances in activated sludge and biofilm systems. It is important to consider the microbial population to understand differences in sorption in different matrices.

PMID: 11381969 [PubMed - indexed for MEDLINE]

[Influence of twovalent foreign cations on the uptake of zinc by Chlorella (author's transl)]

[Article in German]

Klunger G, Broda E.

The influence of 10(-4) divalent cations on the uptake of labelled Zn in the concentration range 10(-5) to 5 x 10(-5) M into the interior of Chlorella fusca at 30 degrees C was measured during 75 min. The Zn absorbed on the surface or contained in the free space was removed by washing with EDTA. Corrections were applied for the loss in concentration due to surface adsorption, etc. The results were consistent with competitive inhibition of Zn uptake by the foreign ions. No allosteric inhibition was found. From the Lineweaver-Burk diagram, for uninhibited Zn, KM was found as 7 x 10(-6) M and Vmax as 8.3 x 10(-9) mol.min-1.g-1 algae. The inhibitor constants were: Mg 1.3 x 10(-5), Ca 4.3 x 10(-5), Co 4.3 x 10(-5), Ni 4.3 x 10(-5), Cd 1.3 x 10(-5) and Pb 9.4 x 10(-7) M. The values given for Km and the inhibitor constant refer to the velocities of uptake after 45 min.

PMID: 160699 [PubMed - indexed for MEDLINE]

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