Molecular level characterization of diatom-associated biopolymers that bind 234Th, 233Pa, 210Pb, and 7Be in seawater: A case study with Phaeodactylum tricornutum Academic Article uri icon

abstract

  • AbstractIn 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 twodimensional heteronuclear single quantum coherencenuclear magnetic resonance analyses, the frustule BF were mainly composed of carboxylrich, aliphaticphosphoproteins, 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 diatomassociated biopolymers acting in concert rather than as a single compound. This clearly indicates the importance of these diatomrelated biopolymers, especially frustule biopolymers, in the scavenging and fractionation of radionuclides used as particle tracers in the ocean.

published proceedings

  • JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES

author list (cited authors)

  • Chuang, C., Santschi, P. H., Xu, C., Jiang, Y., Ho, Y., Quigg, A., ... Schumann, D.