scholarly journals Cu and Pb accumulation by the marine diatom Thalassiosira weissflogii in the presence of humic acids

2010 ◽  
Vol 7 (3) ◽  
pp. 309 ◽  
Author(s):  
Paula Sánchez-Marín ◽  
Vera I. Slaveykova ◽  
Ricardo Beiras
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Humic Acids ◽  
Metal Ion ◽  
Cell Membranes ◽  
Marine Diatom ◽  
Membrane Properties ◽  
Thalassiosira Weissflogii ◽  
Cell Surfaces ◽  
Free Metal

Environmental context.Dissolved organic matter protects aquatic microorganisms from toxic metals by complexing and decreasing the concentration of the biologically reactive species such as free metal ions. However, there are some cases of enhancement of toxic effects when humic acids are present, which is thought to be due to effects of adsorbed humic acids on cell membranes. For a marine diatom, humic acids adsorbed to cell surfaces enhanced metal adsorption, whereas intracellular metal contents decreased as a result of metal binding by humic acids. These findings suggest that the diatom wall, the frustule, presents a barrier against direct effects of adsorbed humic acids on the plasma membrane. Abstract.Metal complexation by dissolved organic matter, as humic acids, is considered to decrease metal bioavailability by lowering the free metal ion concentration. However, dissolved organic matter adsorption on cell surfaces can modify cell membrane properties, which can also influence metal uptake. Copper and lead accumulation and internalisation by the marine diatom Thalassiosira weissflogii were studied in the absence and presence of humic acids, and adsorption of humic acids to cell surfaces was evaluated. Both Pb and Cu intracellular concentrations decreased in the presence of humic acids according to labile metal concentrations measured by anodic stripping voltammetry, whereas total (intracellular plus adsorbed) metal content was enhanced in the presence of humic acids, probably owing to enhanced metal plus humics adsorption to cell surfaces. The results of the present work stress the importance of differentiating between intracellular and total cellular metal in bioavailability studies, and suggest that the silica frustule of diatoms represents a barrier against humic acids effects on cell membranes.

scholarly journals Response of Chlorophyll Fluorescence Characteristics and Dissolved Organic Matter for Marine Diatom Skeletonema dohrnii under Stress from Penicillin and Zn2+

Plants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2684
Author(s):  
Yang Liu ◽  
Xiaofang Liu ◽  
Jun Sun
Keyword(s):  
Organic Matter ◽  
Chlorophyll Fluorescence ◽  
Dissolved Organic Matter ◽  
Environmental Stress ◽  
Metal Ion ◽  
Physiological State ◽  
Marine Diatom ◽  
Chlorophyll Fluorescence Characteristics ◽  
Marine Habitats ◽  
Fluorescence Characteristics

Skeletonema dohrnii is a good model diatom for studying environmental stress and has promising applications and prospects in various fields. Antibiotics and heavy metals are commonly exceeded in the nearshore marine habitats. In this work, we investigated the effects of an antibiotic (penicillin, 2 µg/L) and a heavy metal ion (Zn2+, 10 µmol/L) stress on marine diatom S. dohrnii, mainly using excitation-emission matrices (EEMs) fluorescence methods and OJIP test. Results indicated that algal cells grown with the antibiotic showed higher biomass, specific growth rate, doubling time, chlorophyll a, and chlorophyll fluorescence variables. Moreover, excess zinc had negative effects on S. dohrnii. We found that zinc not only inhibited the relative photosynthetic electron transfer efficiency but also reduced the Chl a content, which ultimately affected algal growth and organic matter production. In addition, the combined effect of penicillin and Zn2+ further affected the physiological state of S. dohrnii. The dissolved organic matter (DOM) characteristics of the four cultures were also different, including fluorescence indices (fluorescence index, biological index, β/α, and humification index) and fluorescence peaks (peaks A, C, M and T). In brief, characterization of chlorophyll fluorescence characteristics and DOM-related variables are important for understanding the effects of environmental stress on microalgae.

Estimation of Reactive Thiol Concentrations in Dissolved Organic Matter and Bacterial Cell Membranes in Aquatic Systems

2012 ◽  
pp. 120831120231009 ◽  
Author(s):  
Claresta Joe-Wong ◽  
Elizabeth Shoenfelt ◽  
Emily J. Hauser ◽  
Nyssa Crompton ◽  
Satish C. B. Myneni
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Bacterial Cell ◽  
Cell Membranes ◽  
Aquatic Systems

Toxicity of Heavy Metals to the Marine Diatom Ditylum Brightwellii (West) Grunow: Correlation between Toxicity and Metal Speciation

1980 ◽  
Vol 60 (1) ◽  
pp. 227-242 ◽  
Author(s):  
G. S. Canterford ◽  
D. R. Canterford
Keyword(s):  
Heavy Metals ◽  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Natural Waters ◽  
Chelating Agents ◽  
Sea Water ◽  
Metal Speciation ◽  
Marine Diatom ◽  
Dissolved Organic Compounds ◽  
Inorganic Ligands

The possibility of dissolved organic compounds acting as complexing or chelating agents in natural waters has received considerable attention in the last two to three decades. Stumm & Morgan (1970) have expressed doubts about the existence of humicmetal ion complexes in natural waters. Strickland (1972) has also stated that although the addition of chelating agents to sea water often improved the growth of phytoplankton, there was little evidence that the function of dissolved organic matter in oceans and lakes was to complex metals so as to increase or decrease their availability to phytoplankton. Strickland argued that even if all dissolved organic carbon were present as a compound of strong complexing ability it would not be able to compete for most metals with inorganic ligands such as chloride, sulphate and hydroxide. However, there is an increasing amount of data indicating that metals in natural waters may exist in chelated forms with dissolved organic matter (see, for example, Davey, Morgan & Erickson, 1973; Chau & Lum-Shue-Chan, 1974).

scholarly journals Humic acid complexation to Zn and Cd determined with the new electroanalytical technique AGNES

2007 ◽  
Vol 4 (5) ◽  
pp. 347 ◽  
Author(s):  
Encarnació Companys ◽  
Jaume Puy ◽  
Josep Galceran
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Metal Ion ◽  
Deposition Time ◽  
Aquatic Environments ◽  
Free Concentration ◽  
Know How ◽  
Soil Humic Acid ◽  
Free Metal

Environmental context. Humic substances are complex mixtures that play an important role in trace metal bioavailability in soils and aquatic environments. The bioavailability of a metal depends on what chemical forms, or species, it is in. We need to know how much of the metal is present as a free metal ion in solution, and how much is bound up in complexes with humic acids, for example. This work reports the complexation of Cd and Zn to humic acids by means of a simple and robust technique, AGNES (absence of gradients and Nernstian equilibrium stripping). Abstract. AGNES (absence of gradients and Nernstian equilibrium stripping), an emerging electroanalytical technique specifically designed for the determination of the free concentration of heavy metals in aqueous solutions, is here implemented to characterise the binding of CdII and ZnII to a soil humic acid. A set of metal titration experiments were performed by adding Cd or Zn to a purified humic acid (Aldrich) at pH 4, 5, 6 and 7 and measuring the free metal concentration by AGNES. The application of a program with two potential steps along the deposition stage allows for the reduction of the deposition time in the humic titration. The polyelectrolytic effects of the macromolecular ligand were taken into account through the Donnan model. Data free of electrostatic effects were reasonably described by the NICA isotherm, which accounts for heterogeneity, considering just a monomodal distribution (because of the range of pH covered). The obtained affinity parameters indicate a similar strength for Zn and Cd binding to the purified humic acid.

Chemical and spectroscopic characteristics of humic acids and dissolved organic matter along two Alfisol profiles

Chemosphere ◽  
2014 ◽  
Vol 111 ◽  
pp. 184-194 ◽  
Author(s):  
Andreina Traversa ◽  
Valeria D’Orazio ◽  
Giuseppe Natale Mezzapesa ◽  
Eleonora Bonifacio ◽  
Karam Farrag ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Humic Acids ◽  
Spectroscopic Characteristics
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