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https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_764780 https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_764780.graph https://erddap.bco-dmo.org/erddap/files/bcodmo_dataset_764780/ public Partition coefficients of the radionuclide into colloidal organic matter from seawater of the west Pacific Ocean and the northern Gulf of Mexico To study the binding mechanisms of radionuclides to organic moieties in colloidal organic matter (COM),marine colloids (1 kDa\\u20130.2 \\u03bcm) 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 \\u03bcg-C/L in the Pacific Ocean, and were 808 \\u03bcg-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.\n\ncdm_data_type = Other\nVARIABLES:\ncompound_for_ratio (unitless)\nratio_to_OC_pcnt (unitless (percent))\nLogK_radionuclide (Log K Radionuclide, unitless)\nLogK (Log K, logKc)\ncalculation_type (unitless)\n https://erddap.bco-dmo.org/erddap/metadata/iso19115/xml/bcodmo_dataset_764780_iso19115.xml https://erddap.bco-dmo.org/erddap/info/bcodmo_dataset_764780/index.htmlTable https://www.bco-dmo.org/dataset/764780 (external link) https://erddap.bco-dmo.org/erddap/rss/bcodmo_dataset_764780.rss https://erddap.bco-dmo.org/erddap/subscriptions/add.html?datasetID=bcodmo_dataset_764780&showErrors=false&email= BCO-DMO bcodmo_dataset_764780
https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_764885 https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_764885.graph https://erddap.bco-dmo.org/erddap/files/bcodmo_dataset_764885/ public Percent activity of organic fractions from diatoms that bind with radionuclide Percent amount of organic fractions from diatoms that bind with radionuclide. In order to investigate the importance of biogenic silica associated biopolymers on the scavenging of radionuclides, the diatom Phaeodactylum tricornutum was incubated together with the radionuclides 234Th, 233Pa, 210Pb, and 7Be during their growth phase. Normalized affinity coefficients were determined for the radionuclides bound with different organic compound classes (i.e., proteins, total carbohydrates, uronic acids) in extracellular (nonattached and attached exopolymeric substances), intracellular (ethylene diamine tetraacetic acid and sodium dodecyl sulfate extractable), and frustule embedded biopolymeric fractions (BF). Results indicated that radionuclides were mostly concentrated in frustule BF. Among three measured organic components, Uronic acids showed the strongest affinities to all tested radionuclides. Confirmed by spectrophotometry and two-dimensional heteronuclear single quantum coherence-nuclear magnetic resonance analyses, the frustule BF were mainly composed of carboxyl-rich, aliphatic-phosphoproteins, which were likely responsible for the strong binding of many of the radionuclides. Results from this study provide evidence for selective absorption of radionuclides with different kinds of diatom-associated biopolymers acting in concert rather than as a single compound. This clearly indicates the importance of these diatom-related biopolymers, especially frustule biopolymers, in the scavenging and fractionation of radionuclides used as particle tracers in the ocean.\n\ncdm_data_type = Other\nVARIABLES:\nradionuclide (unitless)\nNAEPS (unitless (percent))\nAEPS (unitless (percent))\nHF_soluble (unitless (percent))\nHF_insoluble (unitless (percent))\nlt_3000_amu (unitless (percent))\nEDTA (unitless (percent))\nSDS (unitless (percent))\n https://erddap.bco-dmo.org/erddap/metadata/iso19115/xml/bcodmo_dataset_764885_iso19115.xml https://erddap.bco-dmo.org/erddap/info/bcodmo_dataset_764885/index.htmlTable https://www.bco-dmo.org/dataset/764885 (external link) https://erddap.bco-dmo.org/erddap/rss/bcodmo_dataset_764885.rss https://erddap.bco-dmo.org/erddap/subscriptions/add.html?datasetID=bcodmo_dataset_764885&showErrors=false&email= BCO-DMO bcodmo_dataset_764885

 
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