Sargassum Fluitans Research Articles

Verification of Sargassum natans (Linnaeus) Gaillon (Heterokontophyta: Phaeophyceae) from the Sargasso Sea off the coast of Brazil, western Atlantic Ocean

The Sargasso Sea, named due to the floating presence of Sargassum fluitans and S. natans, is usually reported for the tropical region of the Northern Hemisphere. On 14 July 2011, at 02°45’ N and 48°28’ W, samples of pelagic seaweed masses were collected by the Patrol Ship Bracuí of the Brazilian Navy. The seaweed was identified as S. natans, previously considered as of doubtful occurrence in Brazil.

Sargassum as a natural solution to enhance dune plant growth.

Many beach management practices focus on creating an attractive environment for tourists, but can detrimentally affect long-term dune integrity. One such practice is mechanical beach raking in which the wrack line is removed from the beach front. In Texas, Sargassum fluitans and natans, types of brown alga, are the main components of wrack and may provide a subsidy to the ecosystem. In this study, we used greenhouse studies to test the hypothesis that the addition of sargassum can increase soil nutrients and produce increased growth in dune plants. We also conducted an analysis of the nutrients in the sargassum to determine the mechanisms responsible for any growth enhancement. Panicum amarum showed significant enhancement of growth with the addition of sargassum, and while Helianthus debilis, Ipomoea stolonifera, Sporobolus virginicus, and Uniola paniculata responded slightly differently to the specific treatments, none were impaired by the addition of sargassum. In general, plants seemed to respond well to unwashed sargassum and multiple additions of sargassum, indicating that plants may have adapted to capitalize on the subsidy in its natural state directly from the ocean. For coastal managers, the use of sargassum as a fertilizer could be a positive, natural, and efficient method of dealing with the accumulation of wrack on the beach.

Habitat selection and host location by symbiotic shrimps associated with Sargassum communities: The role of chemical and visual cues

One of the most fundamental aspects of symbioses is how the symbionts establish the association. The Sargassum community is comprised of a unique and diverse assemblage of symbiotic organisms, most of which are likely seeking refuge. Host location of the Sargassum habitat by two of the most common invertebrate symbionts, Latreutes fucorum and Leander tenuicornis, was investigated. Based on our trials, neither shrimp species used chemical cues, in the absence of visual cues. Habitat selection of both shrimp species was also examined under a variety of conditions. Our results show that L. fucorum and L. tenuicornis can distinguish visually between different structures and habitats. Specifically, they selected live Sargassum over artificial Sargassum. Moreover, L. fucorum selected Sargassum natans over Sargassum fluitans when only visual cues were available, whereas large-sized L. tenuicornis selected S. fluitans under the same conditions. Conversely, habitat selection trials combining both chemical and visual cues resulted in no preference between the two Sargassum species by either shrimp species. Additional ecological factors that might influence habitat location and selection are discussed, and the importance of Sargassum in terms of pelagic fisheries management.

Optimization of a biosorption column performance.

The dynamics of copper and zinc biosorption by Sargassum fluitans was analyzed under variable column operating conditions including different column lengths (15 and 45 cm), metal-feed solution concentrations (1 and 6 meq L(-1)), metal-sorbent affinities (2.01 and 0.45), and interstitial velocities (12 and 4 cm min(-1)). The experimental breakthrough curves obtained under these varying conditions were also simulated using a mathematical model taking into account the mass transfer as well as the axial dispersion phenomena. The column performance was evaluated using two performance indicators: the service time (t(s)) and the unused portion of the column as reflected in the area under the breakthrough curve (A(c)). Sensitivity analysis results indicated that the feed stream concentration, mass transfer coefficient, column length, and interstitial velocity had the most important effect on the column performance. Applying chromatography theories, the optimization of the biosorption process for productivity and sorption performance, in terms of operating conditions (interstitial velocity) and design parameters (column length), was outlined. The corresponding optimum curve relating the interstitial velocity and the column length resulted with the pressure drop limitations recognized. As an example, a laboratory column 100 cm long will necessitate an interstitial velocity of 19 cm min(-1) to yield the best sorption results.

Multiple cues from multiple habitats: Effect on metamorphosis of the Florida stone crab, Menippe mercenaria

The Florida stone crab, Menippe mercenaria, is an economically and ecologically important species that ranges from North Carolina throughout the Caribbean and the southeastern Gulf of Mexico. However, there is little known about its early life history stages as compared to other commercially important species in the region. The goal of this research was to examine effects of putative cues on metamorphosis from the megalopa stage to the first juvenile stage. Our study investigated the effect of water-soluble exudates from four substrata, as well as natural biofilms, and exudates from adult stone crabs. In addition, the influence of natural substrata was compared to that of artificial substrata. Adult exudate had no significant effect on metamorphosis, despite a wide range of tested concentrations. In contrast, there was a significant effect on mean time to metamorphosis in experimental groups exposed to multiple cues associated with the brown alga Sargassum fluitans, rubble from stone crab habitat, the eastern oyster Crassostrea virginica, and biofilms associated with the oyster. Furthermore, we provide evidence for metamorphic responses to water-soluble chemical cues, as well as biochemical and physical cues associated with different substrata. Overall results were coherent with the relevant body of previous work on metamorphosis of brachyuran crab larvae and indicate that both physical and chemical cues are important factors in facilitating the settlement and metamorphosis of M. mercenaria larvae in juvenile nursery habitat.

Fatty acid composition of flora and fauna associated with Sargassum mats in the Gulf of Mexico

Feeding ecology of organisms associated with floating Sargassum in the northwestern Gulf of Mexico was assessed using fatty acids. Nineteen groups were collected from the Sargassum community including four autotrophs, eight invertebrates, five juvenile fishes, and two adult fishes. Spatial and temporal variability in polyunsaturated fatty acid (PUFA) signatures of se- lected taxa (Sargassum fluitans (autotroph), Leander tenuicornis (primary heterotroph), Balistes capriscus (secondary heterotroph)) was examined to quantify natural variation within these dietary tracers. Although PUFA signatures varied seasonally for all three taxa, no differences were detected between samples collected in year 2000 and 2001 or from different sample locations in the northwest Gulf. PUFA signatures made up 16.3- 62.3% of the total fatty acid composition of main autotrophs present in the pelagic environment (particu- late organic matter (POM), epiphytic algae, S. fluitans, S. natans), and PUFA profiles of selected primary pro- ducers were distinct. Specifically, levels of 20:5n3, 22:5n3, and 22:6n3 were significantly higher in POM than Sargassum spp. or epiphytic algae (Cladophora sp.). Dominant PUFA in the tissue of invertebrate and ver- tebrate consumers were 18:2n6, 20:4n6, 20:5n3, 22:5n3, 22:6n3 and multivariate analyses indicated that PUFA signatures of all consumers were highly similar to POM. As a result, heterotrophs utilizing the Sargassum complex may rely heavily on phytoplankton production rather than production by Sargassum or associated epiphytic algae.

1H-NMR study of Na alginates extracted from Sargassum spp. in relation to metal biosorption.

The use of a number of species of marine brown algae in the implementation of bioremediation strategies for toxic heavy metals is being considered and evaluated. The biosorption capacity of these algae for heavy metals resides mainly in a group of linear polysaccharides known as alginates that occur as a gel in the algal thallus. The potential for selective metal binding by the biomass of two species of Sargassum was evaluated by 1H-NMR (nuclear magnetic resonance) following a high temperature, alkaline extraction and purification of their alginate polysaccharide. The alkaline extraction protocol applied to Sargassum fluitans and Sargassum siliquosum yielded alginate samples of low viscosity, suitable for direct acquisition of well-resolved spectra. Estimates of both the ratio of beta-D-mannopyranuronosyl (M) and alpha-L-gulopyranuronosyl (G) residues along the polymer chain and the frequencies of occurrence of diad uronic acid residue pairs were obtained. Guluronic acid (G) was the major component in all extracts and the GG diads accounted for more than 49% of the polymer diads. Whereas the performance of Sargassum spp. in the metal biosorption process is a function of both its alginate content and composition, the occurrence of "G-blocks" in both purified alginates and in the raw brown seaweed is critical because it results in a well-established selectivity for divalent ions, potentially increasing the commercial effectiveness of targeted biosorption as a means of remediation.

Biosorption of lanthanum using Sargassum fluitans in batch system

Separation and purification of lanthanum from other rare-earth (RE) elements are highly complex processes comprising several steps of extraction using organic solvents or ion-exchange resins at high costs. In order to study the biosorption process as an alternative for conventional lanthanum recovery, this work investigated some basic aspects of lanthanum– Sargassum biomass interactions in batch equilibrium contact. The dynamics of biosorption, influence of pH, and the desorption of this RE were investigated. Maximum biosorption coefficient ( q max) increased from 0.05 at pH 2 to 0.53 mmol g −1 at pH 5 for lanthanum sulfate. When lanthanum chloride was used, a higher q max at pH 5 (0.73 mmol g −1) was observed as compared to the sulfate salt ( q max=0.53 mmol g −1) at the same pH. Adsorption and desorption curves pointed out a complete recovery of metal adsorbed in the Sargassum fluitans biomass, showing a reversibility of this process and indicating the potential of biosorption for lanthanum removal and recovery.

Gold-cyanide biosorption withL-cysteine

L-Cysteine increased gold-cyanide biosorption by protonated Bacillus subtilis, Penicillium chrysogenum and Sargassum fluitans biomass. At pH 2, the maximum Au uptakes were 20.5 µmol g−1, 14.2 µmol g−1 and 4.7 µmol g−1 of Au, respectively, approximately 148–250% of the biosorption performance in the absence of cysteine. Au biosorption mainly involved anionic AuCN2− species adsorbed by ionizable functional groups on cysteine-loaded biomass carrying a positive charge when protonated [(biomass–cysteine–H+)–(AuCN2−)]. Deposited gold could be eluted from Au-loaded biomass at pH 3–5. The elution efficiencies were higher than 92% at pH 5.0 with the Solid-to-Liquid ratio, S/L, = 4. Increasing solution ionic strength (NaNO)3 decreased Au uptake. FTIR analyses indicated that the main functional groups involved in gold biosorption in the presence of L-cysteine are probably N-, S- and O-containing groups. The present results confirm that certain waste microbial biomaterials are capable of effectively removing and concentrating gold from solutions containing residual cyanide if applied under appropriate conditions. © 2000 Society of Chemical Industry

Modeling Uranium-Proton Ion Exchange in Biosorption

Biosorption of uranium metal ions by a nonliving protonated Sargassum fluitans seaweed biomass was used to remove the heavy metal uranium from the aqueous solution. Uranium biosorption isotherms were established for solution pH values ranging from pH 2.5-4.0. Uranium biosorption uptake was accompanied by the release of protons from the biomass. The sorption isotherms were highly pH dependent, and the metal binding increased significantly with increasing pH values. Above pH 3.0, the maximum uranium uptakes exceeded the total biomass binding capacity as expressed in equivalents units. A mathematical model based on the ion exchange between protons in the biomass and hydrolyzed uranium ion species was developed. Given the total uranium concentration and pH value, the model can calculate the uranium and proton binding as well as the composition of uranium ionic groups in the solution and on the biosorbent. The model was capable of fitting and predicting biosorption isotherms for different pH values as well as the equilibrium uranium desorption concentrations.

Biosorption of uranium on Sargassum biomass

Protonated, non-living biomass of the brown alga Sargassum fluitans effectively sequestered uranyl ions from aqueous solution, with the maximum uranium sorption capacity exceeding 560 mg/g, 330 mg/g and 150 mg/g at pH 4.0, 3.2 and 2.6, respectively. At various pH levels, batch sorption equilibrium was reached within 3 h and the sorption isotherms were interpreted in terms of the Langmuir model. The sorption system pH profoundly affected uranium sorption capacities and sorption mechanisms through the hydrolysis of uranyl ions in aqueous solution. While only UO 2 2+ ions existing at pH 2.6 were exchanging with protons on the biomass, the high uranium sorption at pH 4.0 was attributed to the existence of hydrolysed uranyl ions, UO 2OH +, (UO 2) 3(OH) 5 + and (UO 2) 2(OH) 2 2+. Each mole of uranium binding to the biomass was accompanied by the consumption of approximately 2 mol of LiOH for maintenance of the desired constant pH. The uranium could be easily recovered from the metal-loaded biomass by elution with 0.1 N HCl. The desorption was complete and the damage to the biomass was slight. These findings indicate an enormous potential of biosorption in uranium removal from aqueous solutions.

Interference of Aluminum in Copper Biosorption by an Algal Biosorbent

Abstract Cu and Al sorption capacities of NaOH-treated Sargassum fluitans biomass were studied using equilibrium methodology. An evaluation of sorption performance and modeling in a two-metal system was carried out using a modified multicomponent Langmuir isotherm. The maximum Cu and Al uptakes calculated from the Langmuir isotherm were 1.54 mmol/g (9.8 weight percent) and 3.75 mmol/g (10.1 weight percent) at pH 4.5, respectively. However, these values were 1.35 mmol/g for Cu and 1.58 mmol/g for Al at pH 3.5. The modified Langmuir model gave the following affinity correlated coefficients: 0.20 for Cu and 6.82 for Al at pH 4.5, and 2.90 for Cu and 3.13 for Al at pH 3.5. The interference of Al in Cu biosorptive uptake was assessed by “cutting” the three-dimensional uptake isotherm surfaces at constant second-metal final concentrations. Equimolar final equilibrium concentrations of Cu and Al of 1 mM at pH 4.5 reduced Cu and Al uptakes by 83.4 and 5.5%, respectively. However, these reductions at pH 3.5 were 53.0 (Cu) and 29.1% (Al).

Characteristics of gold biosorption from cyanide solution

Gold adsorption from cyanide solution by bacterial (Bacillus subtilis), fungal (Penicillium chrysogenum) and seaweed (Sargassum fluitans) biomass was examined. At pH 2.0, these biomass types were capable of sequestering up to 8.0 µmol g−1, 7.2 µmol g−1 and 3.2 µmol g−1, respectively. An adverse effect of increasing solution ionic strength (NaNO3) on gold biosorption was observed. Gold-loaded biomass could be eluted with 0.1 mol dm−3 NaOH with efficiencies higher than 90% at pH 5.0 at the Solid-to-Liquid ratio, S/L, = 4 (g dm−3). Cyanide mass balances for the adsorption, desorption as well as for the AVR process indicated the stability of the gold-cyanide which did not dissociate either upon acidification or upon binding by biomass functional groups. Gold biosorption mainly involved anionic AuCN2− species bound by ionizable biomass functional groups carrying a positive charge when protonated. FTIR analyses indicated that the main biomass functional groups involved in gold biosorption are most probably nitrogen-containing weak base groups. The present results confirmed that waste microbial biomaterials have some potential for removing and concentrating gold from solutions where it occurs as a gold-cyanide complex. © 1999 Society of Chemical Industry

Characteristics of Aluminum Biosorption by Sargassum fluitans Biomass.

: Biomass of nonliving brown seaweed Sargassum fluitans pretreated by different methods is capable of taking up more than 10% (11 mEq/g) of its dry weight in aluminum at pH 4.5. There are indications that the biomass hydroxyl groups were involved in sequestering the aluminum in the form of polynuclear aluminum species. Aluminum-alginate complex (like cotton candy) was formed in the aluminum sorption solution as alginate was partially released from the biomass. Aluminum uptake of S. fluitans biomass was independent of residual alginate content in the biomass. Sodium ion added for pH adjustment was not adsorbed at all in the presence of aluminum ion.

Instrumental Analysis Study of Iron Species Biosorption by Sargassum Biomass

The mechanism of iron uptake by the dry biomass of the brown seaweed Sargassum fluitans was investigated at the molecular level using different instrumental techniques. Transmission electron microscopy (TEM) and the chemical microanalysis by electron dispersive spectroscopy (EDS) of the biomass exposed to iron solutions confirmed the deposition of the metal mainly in the cell wall. The analysis of the Fe(II)-exposed biomass by X-ray photoelectron spectroscopy (XPS) indicated the presence of Fe in two states of oxidation in the biomass exposed to ferrous iron solution, whereas only Fe(III) was present in ferric iron-exposed biomass, suggesting a partial oxidation of Fe(II) when in contact with the biomass. In both Fe(II)- and Fe(III)-exposed samples, XPS indicated iron complexation with sulfate groups in the biomass. The FTIR analysis of metal-loaded biomass samples revealed the chelating character of the ion complexation to carboxyl groups as well as the complexation of Fe(III) with sulfur of sulfonate groups in the biomass. This work confirmed the participation of carboxyl groups in the uptake of both Fe(II) and Fe(III), and of sulfonate groups in the uptake of Fe(III) by S. fluitans biomass.

Cadmium Biosorption Rate in Protonated Sargassum Biomass

Biosorption of the heavy metal ion Cd2+ by protonated nonliving brown alga Sargassum fluitans biomass was accompanied by the release of hydrogen protons from the biomass. The uptake of cadmium and the release of proton matched each other throughout the biosorption process. The end-point titration methodology was used to maintain the constant pH 4.0 for developing the dynamic sorption rate. The sorption isotherm could be well represented by the Langmuir sorption model. A mass transfer model assuming the intraparticle diffusion in a one-dimensional thin plate as a controlling step was developed to describe the overall biosorption rate of cadmium ions in flat seaweed biomass particles. The overall biosorption mathematical model equations were solved numerically yielding the effective diffusion coefficient De about 3.5 × 10-6 cm2/s. This value matches that obtained for the desorption process and is approximately half of that of the molecular diffusion coefficient for cadmium ions in aqueous solution.

Biomass-modified carbon paste electrodes for monitoring dissolved metal ions

Electrodes were prepared by incorporating dried, nonliving biomass of a common lichen, Ramalina stenospora, and Sphagnum (peat) moss in carbon paste. The electrodes were tested on solutions containing Pb(II) and Cu(II) ions by immersing the electrode in the solution for selected periods of time to accumulate ions. Following this the electrode was connected to a potentiostat and the applied voltage scanned from −1.0 to +0.5 V vs. SCE. Any adsorbed metal ions were stripped back into solution at the appropriate oxidizing voltage. The ratio of biomass to mineral oil to graphite has been found to be crucial to electrode performance. Different ratios of the three components using the lichen Ramalina stenospora were evaluated for maximum electrode performance. Only two electrode compositions gave a good electrode response for lead. Electrodes containing peat moss were superior in performance to lichen-containing electrodes for lead. Electrodes based on the lichens Cladina evansii and Letharia vulpina, the marine algae Ulva lactuca and Sargassum fluitans, the blue-green alga Spirulina platensis, and the aquatic plant Eichhornia crassipes did not respond to lead at all. All functioning electrodes studies showed a poor response toward copper(II) ions.

Interaction of light metals and protons with seaweed biosorbent

Based on their displacement by protons, the following ascending order of light metals affinity toward Sargassum fluitans biomass was observed: Na + ⩽ K + < Mg 2+ < Ca 2+ < Al 3+. Higher biomass-metal affinities resulted in lowering the leaching tendency of (polysaccharidic) biomass components during the sorption process. More than 12% weight loss of protonated biomass occurred during 2 min of sorption, which should be considered in all stoichiometric and sorption calculations. The rate of proton uptake for Na-loaded and Ca-loaded S. fluitans biomass at pH 4.5 was lower than the rate of desorption at pH 1.1. In the case of Na-loaded S. fluitans, the predominant proton uptake rate was of a zero order. Na uptake by protonated S. fluitans biomass did not take place at all in the presence of Ca and Al ions. However, it increased in the absence of other light metals. Since the affinity of Ca 2+ for the biomass was much greater than that of Na +, the three-component system of Na +, H + and Ca 2+ could be simplified into proton-calcium ion exchange. The initial rate of Ca uptake with protonated S. fluitans biomass at pH 4.5 was lower than that of proton release from biomass. Approximately 20% of Ca 2+ sorbed was bound to the binding site as a mono-valent ion. Titration and stoichiometric indications pointed to the fact that Al was being sorbed as a hydroxyl complex.

Optimizing Cu removal/recovery in a biosorption column

Biosorption of Cu 2+ by Sargassum fluitans seaweed biomass protonated by an acidic wash or loaded with Ca 2+ is based on ion exchange. The uptake of Cu 2+ is respectively accompanied by a release of either H + or Ca 2+ into the solution phase. The effects of Ca-, H- and H Ca -cycles on the performance of a continuous-flow biosorption fixed-bed were established. The Ca-cycle applied to Sargassum biomass in a packed bed led to a high degree of a column utilization but did not allow an effective Cu recovery. The H-cycle permitted 100% Cu recovery but also shortened the sorption column service time. The combined Ca H -cycle was shown to be inefficient due to the time consuming regeneration of biomass from the H-form to the Ca-form. Biomass pretreatment with 1% (w) solution of CaCl 2 and with 0.1 m HCl resulted in the same Cu uptake of 75 mg/g. The Ca-pretreated biomass lost approximately 30% of its Cu capacity with subsequent acidic wash. The equilibrium aspects of Cu removal and recovery in a biosorption column were analyzed through the concept of ion-exchange isotherms. The dynamics of Cu sorption and of biomass regeneration in a fixed-bed column was predicted by numerically solving the equations of a proposed ion-exchange model.

Modeling Multi-Metal Ion Exchange in Biosorption

Some types of dead microbial or seaweed biomass are capable of effectively binding heavy metals often through ion exchange. This biosorption can be used for purification of metal-bearing effluents. A recently developed two-site model for the ion exchange between divalent metal ions and protons in biosorption was extended to describe multi-site and multi-ion system behavior. A model case for two ion exchange sites and three ions was compared to the experimental data for the sorption of Cd, Cu, and Zn by protonated Sargassum fluitans biomass in systems containing two metal ions and protons at different pH values. The equilibrium constants were comparable to those obtained for systems where, in addition to protons, only one metal ion was present. This opens the possiblity of predicting the sorption performance for three-cation systems from equilibrium constants determined in two-cation systems. There was no interference between the sorbed species except for competition for the same sorption sites. The model was able to predict the equilibrium binding of all three ions as a function of pH and of the final metal concentrations. Only two equilibrium constants, which were valid for any pH and in the presence of any competing ion, were necessary for predicting the binding of each metal ion. The complete equilibrium state (final concentration and binding) can be predicted as a function of the initial state for a pH titration in the simultaneous presence of two metal ions when the equilibrium constants are used in the chemical equilibrium program MINEQL+.