ALBERT

Description: Dataset: radionuclide uptake by humic acids

Description: The uptake and binding of six particle-reactive and/or redox-sensitive radionuclides (210Pb, 234Th, 7Be, 59Fe, 237Np and 233Pa) with different organic functionalities of three size fractions. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/738833

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: sds_page

Description: Laboratory studies were conducted to examine the sorption of selected radionuclides (234Th, 233Pa, 210Po, 210Pb, and 7Be) onto inorganic (pure silica and acid-cleaned diatom frustules) and organic (diatom cells with or without silica frustules) particles in natural seawater and the role of templating biomolecules and exopolymeric substances (EPS) extracted from the same species of diatom, Phaeodactylum tricornutum, in the sorption process. The range of partition coefficients (Kd, reported as logKd) of radionuclides between water and the different particle types was 4.78–6.69 for 234Th, 5.23–6.71 for 233Pa, 4.44–5.86 for 210Pb, 4.47–4.92 for 210Po, and 4.93–7.23 for 7Be, similar to values reported for lab and field determinations. The sorption of all radionuclides was significantly enhanced in the presence of organic matter associated with particles, resulting in Kd one to two orders of magnitude higher than for inorganic particles only, with highest values for 7Be (logKd of 7.2). Results further indicate that EPS and frustule-embedded biomolecules in diatom cells are responsible for the sorption enhancement rather than the silica shell itself. By separating radiolabeled EPS via isoelectric focusing, we found that isoelectric points are radionuclide specific, suggesting that each radionuclide binds to specific biopolymeric functional groups, with the most efficient binding sites likely occurring in acid polysaccharides, iron hydroxides, and proteins. Further progress in evaluating the effects of diatom frustule–related biopolymers on binding, scavenging, and fractionation of radionuclides would require the application of molecular-level characterization techniques. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/764688

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: Partition_coefficients_for_COC

Description: To study the binding mechanisms of radionuclides to organic moieties in colloidal organic matter (COM),marine colloids (1 kDa–0.2 μm) were isolated by cross-flow ultrafiltration from seawater of the west Pacific Ocean and the northern Gulf of Mexico. For the same purpose, exopolymeric substances (EPS) produced by laboratory cultured diatoms were collected as well. In our study areas, colloidal organic carbon (COC) concentrations ranged from 6.5 to 202 μg-C/L in the Pacific Ocean, and were 808 μg-C/L in the Gulf of Mexico. The COM compositions (organic carbon, organic nitrogen, proteins, total hydrolysable amino acids, total polysaccharides, uronic acids, hydroxamate siderophores, hydroquinone) were quantified to examine the relationships between partition coefficients (Kc) of five different radionuclides, 234Th, 233Pa, 210Pb, 210Po and 7Be, and concentration ratios to COC of individual chelating biomolecules that could potentially act as a chelating moiety. The range of partition coefficients (Kc, reported as logKc) of radionuclides between water and the different colloidal materials was 5.12 to 5.85 for 234Th, 5.19 to 6.01 for 233Pa, 4.21 to 4.85 for 210Pb, 4.87 to 5.68 for 210Po, and 4.49 to 4.92 for 7Be, similar to values previously reported for lab and field determinations under different particle concentrations. While any relationship obtained between Kc and abundance of specific moieties could not be taken as proving the existence of colloidal organic binding ligands for the different radionuclides, it could suggest possible organic moieties involved in the scavenging of these natural radionuclides. Together with results from isoelectric focusing of radiolabeled COM, we conclude that binding to different biomolecules is nuclide-specific, with colloidal hydroxamate siderophoric moieties being important for the binding of Th and Pa radionuclides. Hydroquinones/ quinone (HQ/Q) facilitated redox and chelation reactions seem to be involved in the binding of Pa and Be. However, the actual mechanisms are not clear. Individual amino acids, proteins, total polysaccharides and uronic acids did not yield significant relationships with logKc values of the different radionuclides. Nonetheless, our results provide new insights into the relative importance of different potential ligand moieties in COM in the binding and possible scavenging of specific radionuclides in the ocean. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/764780

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: IEF

Description: Isoelectric focussing electrophoresis of percent activity of radioisotopes and major constituents incubated in natural colloidal organic matter collected from stations E1, E3, C9, C11. To study the binding mechanisms of radionuclides to organic moieties in colloidal organic matter (COM),marine colloids (1 kDa–0.2 μm) were isolated by cross-flow ultrafiltration from seawater of the west Pacific Ocean and the northern Gulf of Mexico. For the same purpose, exopolymeric substances (EPS) produced by laboratory cultured diatoms were collected as well. In our study areas, colloidal organic carbon (COC) concentrations ranged from 6.5 to 202 μg-C/L in the Pacific Ocean, and were 808 μg-C/L in the Gulf of Mexico. The COM compositions (organic carbon, organic nitrogen, proteins, total hydrolysable amino acids, total polysaccharides, uronic acids, hydroxamate siderophores, hydroquinone) were quantified to examine the relationships between partition coefficients (Kc) of five different radionuclides, 234Th, 233Pa, 210Pb, 210Po and 7Be, and concentration ratios to COC of individual chelating biomolecules that could potentially act as a chelating moiety. The range of partition coefficients (Kc, reported as logKc) of radionuclides between water and the different colloidal materials was 5.12 to 5.85 for 234Th, 5.19 to 6.01 for 233Pa, 4.21 to 4.85 for 210Pb, 4.87 to 5.68 for 210Po, and 4.49 to 4.92 for 7Be, similar to values previously reported for lab and field determinations under different particle concentrations. While any relationship obtained between Kc and abundance of specific moieties could not be taken as proving the existence of colloidal organic binding ligands for the different radionuclides, it could suggest possible organic moieties involved in the scavenging of these natural radionuclides. Together with results from isoelectric focusing of radiolabeled COM, we conclude that binding to different biomolecules is nuclide-specific, with colloidal hydroxamate siderophoric moieties being important for the binding of Th and Pa radionuclides. Hydroquinones/ quinone (HQ/Q) facilitated redox and chelation reactions seem to be involved in the binding of Pa and Be. However, the actual mechanisms are not clear. Individual amino acids, proteins, total polysaccharides and uronic acids did not yield significant relationships with logKc values of the different radionuclides. Nonetheless, our results provide new insights into the relative importance of different potential ligand moieties in COM in the binding and possible scavenging of specific radionuclides in the ocean. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/764794

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: ATR_FTIR_Absorbance

Description: Laboratory studies were conducted to examine the sorption of selected radionuclides (234Th, 233Pa, 210Po, 210Pb, and 7Be) onto inorganic (pure silica and acid-cleaned diatom frustules) and organic (diatom cells with or without silica frustules) particles in natural seawater and the role of templating biomolecules and exopolymeric substances (EPS) extracted from the same species of diatom, Phaeodactylum tricornutum, in the sorption process. The range of partition coefficients (Kd, reported as logKd) of radionuclides between water and the different particle types was 4.78–6.69 for 234Th, 5.23–6.71 for 233Pa, 4.44–5.86 for 210Pb, 4.47–4.92 for 210Po, and 4.93–7.23 for 7Be, similar to values reported for lab and field determinations. The sorption of all radionuclides was significantly enhanced in the presence of organic matter associated with particles, resulting in Kd one to two orders of magnitude higher than for inorganic particles only, with highest values for 7Be (logKd of 7.2). Results further indicate that EPS and frustule-embedded biomolecules in diatom cells are responsible for the sorption enhancement rather than the silica shell itself. By separating radiolabeled EPS via isoelectric focusing, we found that isoelectric points are radionuclide specific, suggesting that each radionuclide binds to specific biopolymeric functional groups, with the most efficient binding sites likely occurring in acid polysaccharides, iron hydroxides, and proteins. Further progress in evaluating the effects of diatom frustule–related biopolymers on binding, scavenging, and fractionation of radionuclides would require the application of molecular-level characterization techniques. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/764546

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: Isoelectric_Focusing_electrophoresis

Description: Laboratory studies were conducted to examine the sorption of selected radionuclides (234Th, 233Pa, 210Po, 210Pb, and 7Be) onto inorganic (pure silica and acid-cleaned diatom frustules) and organic (diatom cells with or without silica frustules) particles in natural seawater and the role of templating biomolecules and exopolymeric substances (EPS) extracted from the same species of diatom, Phaeodactylum tricornutum, in the sorption process. The range of partition coefficients (Kd, reported as logKd) of radionuclides between water and the different particle types was 4.78–6.69 for 234Th, 5.23–6.71 for 233Pa, 4.44–5.86 for 210Pb, 4.47–4.92 for 210Po, and 4.93–7.23 for 7Be, similar to values reported for lab and field determinations. The sorption of all radionuclides was significantly enhanced in the presence of organic matter associated with particles, resulting in Kd one to two orders of magnitude higher than for inorganic particles only, with highest values for 7Be (logKd of 7.2). Results further indicate that EPS and frustule-embedded biomolecules in diatom cells are responsible for the sorption enhancement rather than the silica shell itself. By separating radiolabeled EPS via isoelectric focusing, we found that isoelectric points are radionuclide specific, suggesting that each radionuclide binds to specific biopolymeric functional groups, with the most efficient binding sites likely occurring in acid polysaccharides, iron hydroxides, and proteins. Further progress in evaluating the effects of diatom frustule–related biopolymers on binding, scavenging, and fractionation of radionuclides would require the application of molecular-level characterization techniques. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/764608

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: sample_information

Description: To study the binding mechanisms of radionuclides to organic moieties in colloidal organic matter (COM),marine colloids (1 kDa–0.2 μm) were isolated by cross-flow ultrafiltration from seawater of the west Pacific Ocean and the northern Gulf of Mexico. For the same purpose, exopolymeric substances (EPS) produced by laboratory cultured diatoms were collected as well. In our study areas, colloidal organic carbon (COC) concentrations ranged from 6.5 to 202 μg-C/L in the Pacific Ocean, and were 808 μg-C/L in the Gulf of Mexico. The COM compositions (organic carbon, organic nitrogen, proteins, total hydrolysable amino acids, total polysaccharides, uronic acids, hydroxamate siderophores, hydroquinone) were quantified to examine the relationships between partition coefficients (Kc) of five different radionuclides, 234Th, 233Pa, 210Pb, 210Po and 7Be, and concentration ratios to COC of individual chelating biomolecules that could potentially act as a chelating moiety. The range of partition coefficients (Kc, reported as logKc) of radionuclides between water and the different colloidal materials was 5.12 to 5.85 for 234Th, 5.19 to 6.01 for 233Pa, 4.21 to 4.85 for 210Pb, 4.87 to 5.68 for 210Po, and 4.49 to 4.92 for 7Be, similar to values previously reported for lab and field determinations under different particle concentrations. While any relationship obtained between Kc and abundance of specific moieties could not be taken as proving the existence of colloidal organic binding ligands for the different radionuclides, it could suggest possible organic moieties involved in the scavenging of these natural radionuclides. Together with results from isoelectric focusing of radiolabeled COM, we conclude that binding to different biomolecules is nuclide-specific, with colloidal hydroxamate siderophoric moieties being important for the binding of Th and Pa radionuclides. Hydroquinones/ quinone (HQ/Q) facilitated redox and chelation reactions seem to be involved in the binding of Pa and Be. However, the actual mechanisms are not clear. Individual amino acids, proteins, total polysaccharides and uronic acids did not yield significant relationships with logKc values of the different radionuclides. Nonetheless, our results provide new insights into the relative importance of different potential ligand moieties in COM in the binding and possible scavenging of specific radionuclides in the ocean. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/764754

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: Recoveries and partition coefficients

Description: Laboratory sorption experiments were carried out to examine the adsorption of 210Po, 210Pb and 7Be and their fractionation on inorganic nanoparticles, including SiO2,CaCO3, Al2O3, TiO2 and Fe2O3, in the presence or absence of macromolecular organic compounds (MOCs) that include humic acids (HA), acid polysaccharides (APS) and proteins (BSA), in natural seawater. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/738639

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: coccolithophore-associated biopolymers for radionuclides

Description: Laboratory incubation experiments using the coccolithophore Emiliania huxleyi were conducted in the presence of 234Th, 233Pa, 210Pb, 210Po, and 7Be to differentiate radionuclide uptake to the CaCO3 coccosphere from coccolithophore-associated biopolymers. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/738772

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453

Description: Dataset: Fe, Pu partitioning and organic biopolymers

Description: Iron (Fe), a micronutrient for algal growth, and plutonium (Pu), an anthropogenic radionuclide, share some common features. This includes similar oceanic distributions when different input modes are taken into account, as well as their chemical behavior, such as a high affinity to natural organic matter (NOM). The NOM produced by various phytoplankton communities can potentially influence Fe cycling in the ocean, and likely also influence the transport behavior of Pu. We conducted laboratory incubation experiments using the coccolithophore Emiliania huxleyi and the diatom Skeletonema costatum, in the presence of 59Fe and 238Pu as radiotracers, in order to differentiate Fe and Pu uptake by extracellular exopolymeric substances (EPS) and intracellular biopolymers. The Fe and Pu distributions in select organic compound classes including proteins, total carbohydrates (TCHO) and uronic acids (URA) produced by these two types of phytoplankton were compared. Our results indicated that most of the Fe and Pu (〉95%) were found concurrently concentrated in E. huxleyi-derived non-attached EPS, while much less (〈2%) was present in the intracellular fraction of E. huxleyi. By contrast, in the diatom S. costatum, both Fe and Pu distribution was EPS 〉 intracellular biopolymers 〉 outer cell covering (i.e., frustule). In fact, over 50% of Fe was concentrated in S. costatum-derived attached EPS and intracellular biopolymers. The diatom derived Fe-EPS complexes were more hydrophobic, with stronger tendency to aggregate in seawater. Fe binding to biopolymers in both E. huxleyi and S. costatum cultures was related to URA concentrations, but the overall distribution of URA between these two phytoplankton species was different. Our findings suggest that the presence of URA in S. costatum cellular surface (i.e., attached EPS) and its intracellular fraction could be an indicator for the Fe transport from the surrounding seawater to the diatom cells. However, for the coccolithophore E. huxleyi, Fe appeared not to be efficiently taken up during its growth. Instead, the more hydrophilic non-attached EPS (i.e., low protein/TCHO ratio) produced by E. huxleyi could have stabilized Fe in the colloidal form as Fe-EPS complexes. Similar partitioning behavior of Fe and Pu suggests that Pu isotopes can potentially serve as a tracer for the Fe biogeochemistry in the ocean. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/764480

Description: NSF Division of Ocean Sciences (NSF OCE) OCE-1356453