Chitin as a Sorbent Superior to Other Biopolymers: Features and Applications in Environmental Research, Energy Conversion, and Understanding Evolution of Animals

Chitin is an effective sorbent which can be used in environmental monitoring, beyond obvious applications in withholding metal-containing pollutants from wastewater- or nuclear fuel reprocessing flows, since background levels in (purified) chitin are very low except for a few metals (Fe, Cu, Al, Ti, and Zn). Since retention of Mx+ and their complexes on chitin depend on an oxidation state, and to a lesser extent the presence of possible ligands or co-ligands, partition between chitin samples exposed to sediment and those exposed to water can be changed by environmental factors such as local biota producing or absorbing/metabolizing effective ligands such as citrate or oxalate and by changes of redox potential. Thermodynamics are studied via log P, using calibration functions log P vs. 1/r or log P vs. Σσ (sum of Hammett parameters of ligand donor groups) for di- and trivalent elements not involved in biochemical activity (not even indirectly) and thus measuring “deviations” from expected values. These “deviations” can be due to input as a pollutant, biochemical use of certain elements, precipitation or (bio-induced reduction of SO42− or CO2) dissolution of solids in sediment. Biochemical processes which occur deep in sediment can be detected due to this effect. Data from grafted chitin (saturation within ≤ 10 min) and from outer surfaces of arthropods caught at the same site do agree well. Log P is more telling than total amounts retrieved. Future applications of these features of chitin are outlined.

Long term variation of 137Cs inventory in the global ocean from 1957 to 2018

<p>The spatial and temporal variations in <sup>137</sup>Cs concentrations in the surface seawater in the global ocean from 1957 to 2018 were analyzed by using the ''HAM database - global 2018'' and “IAEA-MARIS database” in order to understand the behaviors of <sup>137</sup>Cs originated atmospheric weapons tests, nuclear fuel reprocessing plants, and nuclear power plant accidents at Chernobyl and Fukushima. The global ocean was divided into 37 boxes. The 0.5yr average value of <sup>137</sup>Cs, apparent half residence times (Tap), and <sup>137</sup>Cs inventory in each box was estimated. The 0.5yr average value of <sup>137</sup>Cs in each oceanic region (box) indicate that <sup>137</sup>Cs decreased exponentially from 1970 to 2010 in the Pacific Ocean (PO), Indian Ocean (IO), and Atlantic Ocean (AO), except for the Arctic Ocean, North Atlantic Ocean and its marginal sea due to the discharge of<sup> 137</sup>Cs from the nuclear fuel reprocessing plants. The geographical difference of <sup>137</sup>Cs activity concentrations in the global ocean become to be small in the year of 2010. The temporal variation of <sup>137</sup>Cs column inventory suggests that <sup>137</sup>Cs derived from the large scale atmospheric weapon tests exist largely in the subtropical NPO, equatorial PO, and subtropical SPO (25°N-25°S). <sup>137</sup>Cs transport from the PO to the IO occurs in the region from 0°-15°S via Indonesian through flow. The signature of <sup>137</sup>Cs transport from the IO to the AO is also detected. The <sup>137</sup>Cs inventory in the surface seawater in the year 2010 is estimated to be 57±17 PBq. Considering that the radioactive decay <sup>137</sup>Cs are estimated to be 347 PBq, the<sup> 137</sup>Cs existed into the ocean interior is estimated to 173±52 PBq. These indicate that about 30% of <sup>137</sup>Cs released into the surface seawater have been transported into the ocean interior in 2010. The <sup>137</sup>Cs inventory in 2011 in the surface seawater in the global ocean were 69±15 PBq. The<sup> 137</sup>Cs released by the Fukushima Nuclear Power Plant 1 accident increased to 16.5±4.8 PBq and this value is in good agreement with previous studies.</p>

An Experimental and Computational Look at the Radiolytic Degradation of TODGA and the Effect on Metal Complexation

Diglycolamide extractants, and in particular N,N,N’N’- tetraoctyl diglycolamide (TODGA), are currently under investigation for use in nuclear fuel reprocessing by liquid-liquid separations. Several processes, such as ARTIST, i-Sanex, and EURO-GANEX...