Pb uptake by the freshwater alga Chlorella kesslerii in the presence of dissolved organic matter of variable composition

2008 ◽  
Vol 5 (5) ◽  
pp. 366 ◽  
Author(s):  
Cristina Lamenas ◽  
Vera I. Slaveykova
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Traditional Approach ◽  
Complex Mixture ◽  
Ion Concentration ◽  
Variable Composition ◽  
Lead Ion ◽  
Complex Nature ◽  
Quantitative Understanding ◽  
The Individual

Environmental context. Dissolved organic matter (DOM) is of utmost importance for a toxic metal’s fate and ecotoxicity in the aquatic system, but the complex nature and variable composition of DOM makes the quantitative understanding of DOM’s role in the environment very difficult. We have demonstrated that the assumption that the properties of a DOM mixture are the sum of the properties of its individual fractions can capture the main trends characterising the role of DOM in lead speciation and adsorption by freshwater microalgae. This was done by mixing the isolated, well-characterised fractions of DOM and measuring levels of free lead ion and Pb adsorbed and internalised by algae. Abstract. Dissolved organic matter (DOM) is a complex mixture of ill-defined components, which makes the quantitative understanding of DOM functions in aquatic systems a challenging task. The traditional approach for studying such complex mixtures involves their separation into groups of different components, while assuming minimal or no alteration of their properties. By mixing the pre-isolated and well-characterised individual fractions of the DOM, including humic, fulvic and alginic acids, we have demonstrated that the free Pb ion concentrations and the adsorbed Pb plus Pb internalised by the alga Chlorella kesslerii in the presence of DOM samples of different compositions can be predicted on the basis of the experiments performed in the presence of the individual DOM fractions. An additivity model assuming that the properties of the mixture can be considered as the sum of the properties of the individual components captured the Pb speciation and adsorption behaviour in the presence of DOM of variable compositions. Similarly to the results with the individual DOM fractions, internalised Pb concentrations in the presence of the reconstituted DOM were greater than that predicted by the corresponding free lead ion concentration. An improved fit between experimental observations and the model predictions of adsorbed plus internalised Pb in the presence of DOM of different compositions was observed by assuming that each individual component adsorbed by the algae gave access to additional binding sites for Pb. Furthermore, the contribution of the Pb–DOM complex to total cellular Pb was dominated by the humic and fulvic acids, whereas the contribution of alginate was minimal.

scholarly journals Structural Characterization of Dissolved Organic Matter in Permafrost Peatland Lakes

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 3059
Author(s):  
Diogo Folhas ◽  
Armando C. Duarte ◽  
Martin Pilote ◽  
Warwick F. Vincent ◽  
Pedro Freitas ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Complex Mixture ◽  
Resonance Spectroscopy ◽  
Hudson Bay ◽  
Microbial Decomposition ◽  
Thermokarst Lakes ◽  
Geochemical Properties ◽  
High Concentrations ◽  
Analytical Approaches

Thermokarst lakes result from the thawing of ice-rich permafrost and are widespread across northern landscapes. These waters are strong emitters of methane, especially in permafrost peatland regions, where they are stained black by high concentrations of dissolved organic matter (DOM). In the present study, we aimed to structurally characterize the DOM from a set of peatland thermokarst lakes that are known to be intense sites of microbial decomposition and methane emission. Samples were collected at different depths from three thermokarst lakes in the Sasapimakwananisikw (SAS) River valley near the eastern Hudson Bay community of Kuujjuarapik–Whapmagoostui (Nunavik, Canada). Samples were analyzed by spectrofluorometry, Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and elemental analysis. Fluorescence analyses indicated considerable amounts of autochthonous DOM in the surface waters of one of SAS 1A, indicating a strong bioavailability of labile DOM, and consequently a greater methanogenic potential. The three lakes differed in their chemical composition and diversity, suggesting various DOM transformations phenomena. The usefulness of complementary analytical approaches to characterize the complex mixture of DOM in permafrost peatland waters cannot be overlooked, representing a first step towards greater comprehension of the organic geochemical properties of these permafrost-derived systems.

scholarly journals SAR202 Genomes from the Dark Ocean Predict Pathways for the Oxidation of Recalcitrant Dissolved Organic Matter

mBio ◽  
2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Zachary Landry ◽  
Brandon K. Swan ◽  
Gerhard J. Herndl ◽  
Ramunas Stepanauskas ◽  
Stephen J. Giovannoni
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Complex Mixture ◽  
Deep Ocean ◽  
Oxidative Enzymes ◽  
Flavin Mononucleotide ◽  
Biological Oxidation ◽  
Refractory Compounds ◽  
Cyclic Alkanes ◽  
Oxygen Insertion

ABSTRACTDeep-ocean regions beyond the reach of sunlight contain an estimated 615 Pg of dissolved organic matter (DOM), much of which persists for thousands of years. It is thought that bacteria oxidize DOM until it is too dilute or refractory to support microbial activity. We analyzed five single-amplified genomes (SAGs) from the abundant SAR202 clade of dark-ocean bacterioplankton and found they encode multiple families of paralogous enzymes involved in carbon catabolism, including several families of oxidative enzymes that we hypothesize participate in the degradation of cyclic alkanes. The five partial genomes encoded 152 flavin mononucleotide/F420-dependent monooxygenases (FMNOs), many of which are predicted to be type II Baeyer-Villiger monooxygenases (BVMOs) that catalyze oxygen insertion into semilabile alicyclic alkanes. The large number of oxidative enzymes, as well as other families of enzymes that appear to play complementary roles in catabolic pathways, suggests that SAR202 might catalyze final steps in the biological oxidation of relatively recalcitrant organic compounds to refractory compounds that persist.IMPORTANCECarbon in the ocean is massively sequestered in a complex mixture of biologically refractory molecules that accumulate as the chemical end member of biological oxidation and diagenetic change. However, few details are known about the biochemical machinery of carbon sequestration in the deep ocean. Reconstruction of the metabolism of a deep-ocean microbial clade, SAR202, led to postulation of new biochemical pathways that may be the penultimate stages of DOM oxidation to refractory forms that persist. These pathways are tied to a proliferation of oxidative enzymes. This research illuminates dark-ocean biochemistry that is broadly consequential for reconstructing the global carbon cycle.

scholarly journals Single-cell visualization indicates direct role of sponge host in uptake of dissolved organic matter

2019 ◽  
Vol 286 (1916) ◽  
pp. 20192153 ◽  
Author(s):  
Michelle Achlatis ◽  
Mathieu Pernice ◽  
Kathryn Green ◽  
Jasper M. de Goeij ◽  
Paul Guagliardo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Secondary Ion Mass Spectrometry ◽  
Physiological Mechanism ◽  
Marine Sponges ◽  
Direct Role ◽  
Transmission Electron ◽  
High Enrichment ◽  
The Individual ◽  
Near Future

Marine sponges are set to become more abundant in many near-future oligotrophic environments, where they play crucial roles in nutrient cycling. Of high importance is their mass turnover of dissolved organic matter (DOM), a heterogeneous mixture that constitutes the largest fraction of organic matter in the ocean and is recycled primarily by bacterial mediation. Little is known, however, about the mechanism that enables sponges to incorporate large quantities of DOM in their nutrition, unlike most other invertebrates. Here, we examine the cellular capacity for direct processing of DOM, and the fate of the processed matter, inside a dinoflagellate-hosting bioeroding sponge that is prominent on Indo-Pacific coral reefs. Integrating transmission electron microscopy with nanoscale secondary ion mass spectrometry, we track 15 N- and 13 C-enriched DOM over time at the individual cell level of an intact sponge holobiont. We show initial high enrichment in the filter-feeding cells of the sponge, providing visual evidence of their capacity to process DOM through pinocytosis without mediation of resident bacteria. Subsequent enrichment of the endosymbiotic dinoflagellates also suggests sharing of host nitrogenous wastes. Our results shed light on the physiological mechanism behind the ecologically important ability of sponges to cycle DOM via the recently described sponge loop.

scholarly journals Fluorescence analysis allows to predict the oxidative capacity of humic quinones in dissolved organic matter: implication for pollutant degradation

2020 ◽  
Author(s):  
Davide Palma ◽  
Edith Parlanti ◽  
Mahaut Sourzac ◽  
Olivier Voldoire ◽  
Aude Beauger ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Water Samples ◽  
Three Dimensional ◽  
Complex Mixture ◽  
Fluorescence Analysis ◽  
Oxidative Capacity ◽  
Reactive Species ◽  
Solar Light ◽  
Pollutant Degradation

AbstractDissolved organic matter (DOM) controls the degradation and sequestration of aquatic pollutants and, in turn, water quality. In particular, pollutant degradation is performed by oxidant species that are generated by exposure of DOM to solar light, yet, since DOM is a very complex mixture of poorly known substances, the relationships between potential oxidant precursors in DOM and their oxydative capacity is poorly known. Here, we hypothesized that production of oxidant species could be predicted using fluorescence analysis. We analysed water samples from an alluvial plain by fluorescence spectroscopy; the three-dimensional spectra were then decomposed into seven individual components using a multi-way algorithm. Components include a protein-like fluorophore, e.g. tryptophan-like and tyrosine-like, three humic fluorophores, 2-naphthoxyacetic acid, and a by-product. We compared component levels with the ability of water samples to generate reactive species under solar light. The results show a strong correlation between reactive species production and the intensity of two humic-like fluorophores assigned to reduced quinones. Monitoring these fluorophores should thus allow to predict the ability of DOM degradation of pollutants in surface waters.

Ionization selectivity of electrospray and atmospheric pressure photoionization FT-ICR MS for petroleum refinery wastewater dissolved organic matter

2021 ◽  
Author(s):  
Chen He ◽  
Zhi Fang ◽  
Yongyong Li ◽  
Chunqing Jiang ◽  
Suoqi Zhao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Atmospheric Pressure ◽  
Molecular Level ◽  
Petroleum Refinery ◽  
Complex Mixture ◽  
Chemical Compositions ◽  
Refinery Wastewater ◽  
Petroleum Refinery Wastewater ◽  
Ft Icr Ms

Dissolved organic matter (DOM) in petroleum refinery wastewater is an extremely complex mixture. A better understanding of chemical compositions of DOM on molecular level is necessary for the design and...

Patterns of dissolved organic matter across the Patagonian landscape: a broad-scale survey of Chilean and Argentine lakes

2017 ◽  
Vol 68 (12) ◽  
pp. 2355 ◽  
Author(s):  
Horacio E. Zagarese ◽  
Marcela Ferraro ◽  
Claudia Queimaliños ◽  
María del Carmen Diéguez ◽  
Diego Añón Suárez ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Complex Mixture ◽  
Precipitation Gradient ◽  
Carbon Compounds ◽  
Water Retention Time ◽  
Specific Absorbance ◽  
Pattern Of Variation ◽  
The Antarctic ◽  
Broad Scale

Dissolved organic matter (DOM) is a complex mixture of carbon compounds from autochthonous and allochthonous sources. Dissolved organic carbon (DOC) concentrations and optical metrics of DOM provide clues as to the sources and processes affecting the DOM pool. Herein we provide the first broad-scale characterisation of DOM from Patagonian lakes across a strong west–east precipitation gradient. Fifty-eight lakes from Northern Patagonia (Argentina and Chile) plus six lakes from the Antarctic Peninsula were sampled during summer 2000–01. Six DOM metrics were evaluated: DOC absorbance at 254nm (a254) and 350nm (a350), DOC-specific absorbance at 254nm (a254/DOC) and 350nm (a350/DOC) and spectral slope between 275 and 295nm (S275–295). The DOM of Chilean maritime lakes and shallow (<15m) Andean lakes exhibited terrestrial signatures and a pattern of variation consistent with their occurrence across the longitudinal precipitation gradient (i.e. S275–295 increased, whereas a350/DOC decreased from west to east). The contribution of allochthonous DOM was smaller in deep (>15m) Andean lakes, which is consistent with their longer water retention time. Steppe lakes, mostly from endorheic basins, made up the most heterogeneous group with regard to DOM characteristics.

Influence of dissolved organic matter and inorganic nutrients on the biofilm bacterial community on artificial substrates in a northeastern Ohio, USA, stream

2006 ◽  
Vol 52 (6) ◽  
pp. 540-549 ◽  
Author(s):  
Ola A Olapade ◽  
Laura G Leff
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Nutrient Dynamics ◽  
Inorganic Nutrients ◽  
Artificial Substrates ◽  
Response Patterns ◽  
Ceramic Tiles ◽  
Phylogenetic Groups ◽  
Leaf Leachate ◽  
The Individual

Stream bacteria may be influenced by the composition and availability of dissolved organic matter (DOM) and inorganic nutrients, but knowledge about how individual phylogenetic groups in biofilm are affected is still limited. In this study, the influence of DOM and inorganic nutrients on stream biofilm bacteria was examined. Biofilms were developed on artificial substrates (unglazed ceramic tiles) for 21 days in a northeastern Ohio (USA) stream for five consecutive seasons. Then, the developed biofilm assemblages were exposed, in the laboratory, to DOM (glucose, leaf leachate, and algal exudates) and inorganic nutrients (nitrate, phosphate, and nitrate and phosphate in combination) amendments for 6 days. Bacterial numbers in the biofilms were generally higher in response to the DOM treatments than to the inorganic nutrient treatments. There were also apparent seasonal variations in the response patterns of the individual bacterial taxa to the nutrient treatments; an indication that limiting resources to bacteria in stream biofilms may change over time. Overall, in contrast to the other treatments, bacterial abundance was generally highest in response to the low-molecular-weight DOM (i.e., glucose) treatment. These results further suggest that there are interactions among the different bacterial groups in biofilms that are impacted by the associated nutrient dynamics among seasons in stream ecosystems.Key words: biofilms, nutrients, DOM, bacteria, in situ hybridization.

Chemical insights into the ice nucleating ability of macromolecules in immersion freezing

2020 ◽  
Author(s):  
Nadine Borduas-Dedekind ◽  
Anna Miller ◽  
Sophie Bogler ◽  
Jon Went
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Matrix Effects ◽  
Complex Mixture ◽  
Ice Nucleation ◽  
Heating Process ◽  
Biological Macromolecules ◽  
Top Down ◽  
Wide Range ◽  
Immersion Freezing

&lt;p&gt;Cloud glaciation is an atmospheric process with important implications for climate and weather. Indeed, clouds made of liquid water and of ice crystals impact the global radiative balance of the atmosphere by reflecting incoming solar radiation and by absorbing outgoing terrestrial radiation. The relevance of ice nucleating particles (INPs) to the atmosphere depends on three main factors, namely on (1) their atmospheric concentration, (2) their freezing temperature and relative humidity, and (3) their freezing mechanism (Cziczo et al., 2013). Research on characterizing ice nucleating organic matter often takes a &amp;#8220;top-down&amp;#8221; approach where a whole sample of a complex mixture of organic, often biological, macromolecules is subjected to separation techniques and heat treatments to identify IN active sub-components. Studies have used this approach for characterizing bulk soil organic matter, volcanic ash and biological macromolecules from pollen, fungi, and bacteria.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We and others have recently found that dissolved organic matter collected from rivers and swamps surprisingly contain active INP (Borduas-Dedekind et al., 2019; Knackstedt et al., 2018; Moffett et al., 2018). Yet, all three studies state that it is unclear which sub-component of the dissolved organic matter is responsible for the ice nucleating ability. There are clear challenges in attributing the ice nucleating ability when starting with a complex mixture of organic and/or biological material, including matrix effects, impurities accumulated through the separation and/or heating process and lack of molecule identity.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;We present here a &amp;#8220;bottom-up&amp;#8221; approach to compliment the top-down approach for atmospheric ice nucleation research of macromolecules. Using our home-built drop Freezing Ice Nuclei Counter (FINC) with automated imaging, a range of macromolecules were investigated. Indeed, we have analysed a wide range of dissolved organic matter subcomponents including proteins and fulvic acids. We find a range of ice nucleating ability. We find that lignin, the second most abundant biopolymer in plants, is ice active with 50% frozen fraction temperatures (T&lt;sub&gt;50&lt;/sub&gt;) at &amp;#8211;18 &amp;#176;C at a concentration of 100 mg C/L. Furthermore, we have investigated the ice nucleation ability of common diatom exudates and found that at atmospherically relevant concentration they are likely not ice active in immersion freezing within the detection of our FINC instrument. We are currently investigating the effect of atmospheric processing on these macromolecules with the goal of understanding how macromolecules&amp;#8217; ice activity evolves over their one-week lifetime in the atmosphere.&lt;/p&gt;

Toward Quantitative Understanding of the Bioavailability of Dissolved Organic Matter in Freshwater Lake during Cyanobacteria Blooming

2017 ◽  
Vol 51 (11) ◽  
pp. 6018-6026 ◽  
Author(s):  
Leilei Bai ◽  
Chicheng Cao ◽  
Changhui Wang ◽  
Huacheng Xu ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Freshwater Lake ◽  
Quantitative Understanding

scholarly journals Demographic consequences of mitigating strategies in planktonic invertebrates facing global browning of freshwater ecosystem

2021 ◽  
Vol 83 (2) ◽  
Author(s):  
Małgorzata Adamczuk
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Current Knowledge ◽  
Temporal Stability ◽  
Resting Eggs ◽  
Community Level ◽  
Freshwater Ecosystem ◽  
Freshwater Invertebrates ◽  
Chydorus Sphaericus ◽  
The Individual

AbstractRecently, it has been reported that freshwater browning has less effect on planktonic invertebrate abundances than would be expected from current knowledge regarding of the biochemical activity of dissolved organic matter. It may be that the weak responses of whole communities to browning are masked because the individual mitigating strategies of community components have disparate demographic consequences. To examine the above hypothesis, individual-, population- and community-level responses of freshwater invertebrates to varying concentrations of terrestrial dissolved organic matter (tDOM) were investigated. Common cladocerans of the Chydoridae family, Chydorus sphaericus and Acroperus harpae, were used in the experiment which revealed that species employed different strategies to cope with tDOM. C. sphaericus maintained high production of asexual offspring at the cost of individual body growth, so any decreases in the population sizes were not observed. A. harpae, conversely, invested mainly in the production of resting eggs and increased survivability, which resulted in smaller populations. Invertebrate communities showed similar resilience and temporal stability across tDOM concentrations. Therefore, the influence of tDOM was apparently negligible at community level, since the effects of the mitigating strategies of the two species complemented one another. This experiment showed that symptoms of freshwater browning might be difficult to observe at population and community level due to effective mitigating strategies performed at the level of individuals. The effects of browning on freshwater invertebrates might be better considered in the context of alterations in the demographic rates together constituting life-cycle strategies to maintain species survival.

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