Chronic effects of water-borne PFOS exposure on growth, survival and hepatotoxicity in zebrafish: A partial life-cycle test

Perfluorooctane sulfonate (PFOS) is widely distributed and persistent in the environment and wildlife. The main aim of this study was to investigate the impact of long-term exposure to low concentrations of PFOS in zebrafish. Zebrafish fry (F-0, 14d post-fertilization, dpf) were exposed via the water for 70d to 0 (control), 10, 50 and 250 mu g L-1 PFOS, followed by a further 30d to assess recovery in clean water. The effects on survival and growth parameters and liver histopathology were assessed. Although growth suppression (weight and length) was observed in fish treated with high concentrations PFOS during the exposure period, no mortality was observed throughout the 70d experiment. Embryos and larvae (F-1) derived from maternal exposure suffered malformation and mortality. Exposure to 50 and 250 mu g L-1 PFOS could inhibit the growth of the gonads (GSI) in the female zebrafish. Histopathological alterations, primary with lipid droplets accumulation, were most prominently seen in the liver of males and the changes were not reversible, even after the fish were allowed to recover for 30d in clean water. The triiodothyronine (T-3)) levels were not significantly changed in any of the exposure groups. Hepatic vitellogenin (VTG) gene expression was significantly up-regulated in both male and female zebrafish, but the sex ratio was not altered. The overall results suggested that lower concentrations of PFOS in maternal exposure could result in offspring deformation and mortality. (c) 2008 Elsevier Ltd. All rights reserved.

Polyphasic characterization of water bloom forming Raphidiopsis species (cyanobacteria) from central China

Two strains of Raphidiopsis Fritsch et Rich were isolated from a fishpond in Wuhan city, China and rendered axenic, and characterized by a combination of morphological, physiological, biochemical and genetic methods. Morphologically the strains were identified as Raphidiopsis mediterranea Skuja (straight trichomes) and R. curvata Fritsch et Rich (coiled trichomes). These two strains demonstrated slight differences in optimal temperature range and GC content, while sharing some common characteristics including inability to grow hetertrophically, similar salinity tolerance (up to 0.78%) and an identical fatty acid composition. Cyanotoxins were not found in the strain of R. mediterranea, however, the strain of R. curvata contained both deoxycylindrospermopsin and cylindrospermopsin. Phylogenetic affiliations inferred from 16S rRNA gene sequences demonstrated that both Raphidiopsis strains clustered with Cylindrospermopsis, demonstrating their phylogenetic ties to Nostocaceae. (c) 2007 Elsevier B.V. All rights reserved.

On kinematic relaxation and deposition of water droplets in the last stages of low pressure steam turbines

In the first part of the paper steady two-phase flow predictions have been performed for the last stage of a model steam turbine to examine the influence of drag between condensed fog droplets and the continuous vapour phase. In general, droplets due to homogeneous condensation are small and thus kinematic relaxation provides only a minor contribution to the wetness losses. Different droplet size distributions have been investigated to estimate at which size inter-phase friction becomes more important. The second part of the paper deals with the deposition of fog droplets on stator blades. Results from several references are repeated to introduce the two main deposition mechanisms which are inertia and turbulent diffusion. Extensive postprocessing routines have been programmed to calculate droplet deposition due to these effects for a last stage stator blade in three-dimensions. In principle the method to determine droplet deposition by turbulent diffusion equates to that of Yau and Young [1] and the advantages and disadvantages of this relatively simple method are discussed. The investigation includes the influence of different droplet sizes on droplet deposition rates and shows that for small fog droplets turbulent diffusion is the main deposition mechanism. If the droplets size is increased inertial effects become more and more important and for droplets around 1 μm inertial deposition dominates. Assuming realistic droplet sizes the overall deposition equates to about 1% to 3% of the incoming wetness for the investigated guide vane at normal operating conditions. Copyright © 2013 by Solar Turbines Incorporated.

Sedimentary records of water environment in lake Chaohu in the Yangtze delta region, China

Three lacustrine core samples were collected from Chaohu lake in December 2002 in the Yangtze delta region. The grain sizes were analyzed using a Laser Analyzer to obtain grain-size parameters. Sediment geochronology was determined in radioisotopes Cs-137 and the average sedimentary rates are 0.29cm.a(-1), 0.35 cm.a(-1) and 0.24cm-a(-1) in Cores C 1, C2 and C3, respectively. The grain-size parameters of the deposits vary regularly with the fluctuation of hydrodynamics. From 1950s to the beginning of 20th century, coarse-grained sediment was deposited, suggesting strong hydraulic conditions and high water-level periods with much precipitation; from the start of 20(th) century to latter half of 18(th) century, fine-grained sediment was deposited, indicating that weak hydraulic conditions and low water-level periods with less precipitation; before the first half of 18(th) century, coarse-grained sediment was deposited, suggesting great velocity of flow and high water-level periods of more precipitation.

Taxonomic revision of water-bloom-forming species of oscillatorioid cyanobacteria

A polyphasic approach was used to clarify the taxonomy of the water-bloom-forming oscillatorioid cyanobacteria. Seventy-five strains of oscillatorioid cyanobacteria were characterized by 16S rDNA sequence analysis, DNA base composition, DNA-DNA hybridization, fatty acid composition, phycobilin pigment composition, complementary chromatic adaptation, morphological characters, growth temperature and salinity tolerance. Phylogenetic analysis based on 165 rDNA sequences divided the strains into six groups, all of which were clearly separated from the type species of the genus Oscillatoria, Oscillatoria princeps Gomont NIVA CYA 150. Therefore, these strains should be classified into genera other than Oscillatoria. Groups I-III were closely related to one another and groups IV-VI were distinct from one another and from groups I to III. Group I was further divided into two subgroups, group I-pc, which includes strains containing only phycocyanin (PC), and group I-pe, which includes strains containing large amounts of phycoerythrin (PE) in addition to PC. This phenotypic distinction was supported by DNA-DNA hybridization studies. Based on the properties examined herein and data from traditional, botanical taxonomic studies, the groups and subgroups were classified into single species and we propose either emended or new taxonomic descriptions for Planktothrix agardhii (type strain NIES 204(T)), Planktothrix rubescens (type strain CCAP 1459/22(T)) Planktothrix pseudagardhii sp. nov. (type strain T1-8-4(T)), Planktothrix mougeotii (type strain TR1-5(T)), Planktothricoides raciborskii gen. nov., comb. nov. (type strain NIES 207(T)), Tychonema bourrellyi (type strain CCAP 1459/11B(T)) and Limnothrix redekei (type strain NIVA CYA 277/1(T)).

Effect of wind speed on loss of water from Nostoc flagelliforme colonies

The effects of wind speed on loss of water from N. flagelliforme colonies were investigated indoors in an attempt to assess its ecological significance in field. Wind enhanced the process of waterless; the half-time of desiccation at wind speeds of 2.0 and 3.4 m s(-1) was, respectively, shortened to one-third and one-fifth at 20 degrees C and, to one-sixth and one-eighth at 27 degrees C that of still air. Photosynthetic efficiency was not affected before the wet alga lost about 50% water.