Photocatalytic ozonation of 2, 4-dichlorophenoxyacetic acid in water with a new TiO2 fiber

More effective techniques are required to mineralize the increasing number of recalcitrant organic contaminants at low concentrations in the water environment using advanced oxidation process. Though relatively new, photocatalytic ozonation (O₃/UV/TiO₂) is considered superior to ozonation (O₃) and photocatalysis (UV/TiO₂), due to synergistic effects and use of immobilized TiO₂ photocatalysts is a milestone in advance oxidation process. This article aimed to elucidate 2, 4-dichlorophenoxyacetic acid (2, 4-D) mineralization characteristics in low aqueous solutions by O₃/UV/TiO₂ using the world’s first high-strength TiO₂ fiber catalyst in laboratory experiments. 2, 4-D degradation and TOC removal in O₃, UV/TiO₂ and O₃/UV/TiO₂ followed pseudo-first order reaction kinetic. The removal rates for 2, 4-D and TOC in O₃/UV/TiO₂ were respectively about 1.5 and 2.4-fold larger than the summation of the corresponding values in O₃ and UV/TiO₂. The O₃/UV/TiO₂ process was characterized by short-lived few aromatic intermediates, faster degradations of aliphatic intermediates and dechlorination as a major step in 2, 4-D mineralization. The significantly enhanced 2, 4-D mineralization in the process was attributed to increased ozone decomposition and reduced electron-hole recombination on TiO₂ surface resulting to a large number of OH generation. The O₃/UV/TiO₂ process with the TiO₂ fiber catalyst was very promising with respect to the major challenges being faced in AOP involving TiO₂, namely separation of powder catalyst in suspension and reduced efficiency of immobilized catalysts (e.g. TiO₂ film/fiber).     

Variation with depth in the number of chambers in planktonic foraminiferal shells

A study of planktonic foraminiferal shells collected in the northern Pacific and the Bering and Chukchi Seas revealed that the number of chambers was large in layers above and in the thermocline but small in the underlying layer. The mean number in both strata was 6.2±0.65 and 4.1±0.36, respectively. This observation indicates that the recruitment of foraminifera occurs at depth and juveniles grow in the productive surface layers.     

Infrared spectroscopic study of the silicate anionic structures of some magmatic silicate melts

Summary The relation between the species of silicate anions in a silicate melt and their infrared characteristic frequency is discussed. A simple relation approximated with a quadratic equation is established between the ratio of non-bridging oxygens to silicon atoms of a silicate anion and the characteristic frequency. Based on this relation, the silicate anions in some magmatic silicate melts were estimated. The results obtained in the present study agreed well qualitatively with those estimated by some researchers on the basis of other spectroscopic methods.The constituent silicate segments and the distribution of AlO₄ tetrahedra in fully polymerized melts, albite, jadeite and anorthite, have been investigated. The polymerization degree of the silicate segments in the network seemed to decrease with the increase of AlO₄ tetrahedron. It is also suggested, that AlO₄ in the albite melt distributed more randomly, while those in anorthite melt had a tendency to form an aluminous segment.

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Infrarot-spektroskopische Untersuchungen der Silikatanionen-Strukturen einiger magmatischer Silikatschmelzen

Zusammenfassung Die Beziehungen zwischen den Spezies der Silikatanionen in den Silikatschmelzen und ihrer charakteristischen Infrarot-Frequenz wurde untersucht. Es gibt eine einfache Beziehung zwischen dem Verhältnis nicht brückenbildender Sauerstoffatome zu Si-Atomen der Silikatanionen und der charakteristischen Frequenz, die mit einer quadratischen Gleichung beschrieben werden kann. Auf Grund dieser Beziehung werden die Silikatanionen in einigen magmatischen Schmelzen abgeschätzt. Das Ergebnis dieser Untersuchung stimmt qualitativ mit den Werten überein, die von einigen Forschern durch andere spektroskopische Methoden erhalten wurden.Die Silikatsegmente und die Verteilung der AlO₄-Tetraeder in vollkommen polymerisierten Schmelzen, in Albit, Jadeit und Anorthit wurden untersucht. Der Polymerisationsgrad der Silikatsegmente in den Netzwerken scheint mit der Zunahme der AlO₄-Tetraeder geringer zu werden. Die Untersuchungläßt erkennen, daß AlO₄-Tetraeder in Albit unregelmäßig verteilt sind, und in Anorthit die Neigung haben, ein Al-Segment zu bilden.

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With 6 Figures     

Resting cells of microorganisms in the 20–100 μm fraction of marine sediments in an Antarctic coastal area

We investigated the morphological features, vertical sinking fluxes, and number densities of the resting cells of ice-associated microorganisms in the 20–100 μm fraction of natural marine sediments collected from ice-covered and ice-free areas around Syowa Station, Lützow-Holm Bay, East Antarctica. We identified the resting cells of various taxonomic groups, including the spores of a diatom, cysts of three dinoflagellates, cysts of five oligotrich ciliates, and the eggs of a mesozooplankton. This is the first report of oligotrich ciliate cysts from Antarctic waters. The resting spores of Thalassiosira australis (diatom), cysts of Polarella glacialis (dinoflagellate), and egg type 1 sink to the bottom sediment during summer. Our results suggest that some planktonic and ice-associated microorganisms in Antarctic coastal areas send their resting cells to the bottom sediments as seed populations for the following generation.     

Contaminant concentrations, biochemical and hematological biomarkers in blood of West Indian manatees Trichechus manatus from Brazil

The West Indian manatee Trichechus manatus is threatened with extinction in Brazil, and this study focused on nondestructive blood samples analyzed for metals, polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), as well as biochemical and hematological biomarkers. Studied manatees were kept at Projeto Peixe-Boi headquarters in Pernambuco State, and at two natural areas in estuaries where they are released to the wild. Manatees kept at the natural estuary in Paraiba State have blood concentrations of Al, Pb, Cd, Sn that are 11, 7, 8 and 23 times greater, respectively, than the concentrations found in blood of animals from the same species in Florida, USA. An inhibition of butyrylcholinesterase in manatees kept at the two reintroduction sites in Alagoas and Paraiba States indicated possible exposure of the animals to cholinesterase inhibitor insecticides. PCBs and OCPs were not detected. Results from this study will help delineate conservation efforts in the region.     

Genetic diversity and population structure of the golden cuttlefish,Sepia esculenta (Cephalopoda: Sepiidae) indicated by microsatellite DNA variations

The golden cuttlefish, Sepia esculenta Hoyle, 1885 (Cephalopoda: Sepiidae) is a valuable and important fishery resource for China, Japan and Korea. This fishery has experienced severe population decline largely due to overexploitation in past decades. To provide guidelines for fisheries management, we estimated genetic diversity and population structure across four locations along the coast of Japan and one location in China (a total 281 individuals) using nine microsatellite DNA loci. Sepia esculenta showed high genetic variability with mean allele richness ranging from 15.8 to 21.4, and mean heterozygosity from 0.80 to 0.90. Weak but significant genetic differentiation was present and the F_ST value was 0.020 across all five populations. The useful information obtained in this study will offer insights into how to fine‐tune conservation and fishery management measures for this species and resource in the future.     

Spatial variability of submarine groundwater discharge,Ubatuba, Brazil

Submarine groundwater discharge (SGD) is delivered into the oceans at various hydrogeological settings. Where coastal aquifers have spatial heterogeneous properties such as preferential flowpaths, SGD is also commonly heterogeneously distributed along the coast. SGD from a heterogeneous, fractured rock aquifer on the Ubatuba coast, Brazil has been investigated by depth profiling of ground conductivity. On spatial scales of <10 m, a significant variation in sub-surface conductivity and associated discharge rate is documented. These geophysical observations were used to identify preferential flowpaths, and to explain significant differences in average discharge rates observed in seepage meter records placed only a few metres apart from each other. This paper illustrates the utility of sub-surface conductivity measurements for accurate investigations of SGD fluxes.