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Molecular level characterization of diatom‐associated biopolymers that bind 234 Th, 233 Pa, 210 Pb, and 7 Be in seawater: A case study with Phaeodactylum tricornutum
Author(s) -
Chuang ChiaYing,
Santschi Peter H.,
Xu Chen,
Jiang Yuelu,
Ho YiFang,
Quigg Antonietta,
Guo Laodong,
Hatcher Patrick G.,
Ayranov Marin,
Schumann Dorothea
Publication year - 2015
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2015jg002970
Subject(s) - chemistry , frustule , phaeodactylum tricornutum , diatom , nuclear chemistry , radiochemistry , botany , biology
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 234 Th, 233 Pa, 210 Pb, and 7 Be 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.