Microbial community dynamics and biodegradation of polycyclic aromatic hydrocarbons in polluted marine sediments in Hong Kong

Dynamics of microbial community and biodegradation of polycyclic aromatic hydrocarbons (PAHs) in polluted marine sediments, artificially spiked with a mixture of PAHs (fluorene, phenanthrene, fluoranthene and pyrene), were examined for a period of 60 days. Microbial communities were characterised by bacterial counts, ester-linked fatty acid methyl ester (EL-FAME) analysis and denaturing gradient gel electrophoresis (DGGE). A noted reduction in species diversity occurred only in the high PAH level treatment at onset. Both EL-FAME and DGGE demonstrated a marked shift in microbial community, in all the PAH level treatments, afterwards, with increases in the number of fatty acid degraders, the relative abundance of fatty acid biomarkers for gram-negative bacteria and a decrease in species diversity. The shift was also accompanied by the significant decrease in PAH concentrations. By the end of the experiment, diversity indices, based on both approaches, recovered when PAH concentrations declined to their background levels, except in the high PAH level treatment.     

Comparison of ecophysiological characteristics between introduced and indigenous mangrove species in China

Due to its rapid growth, the introduced mangrove species Sonneratia apetala from Bangladesh has been widely used in mangrove restoration in southeastern China since 1985. As an indigenous mangrove species in Hainan, China, Sonneratia caseolaris was also planted in Guangdong Province for afforestation purposes. Both species have developed well in their new habitats, but their ecophysiological differences with the native mangrove species have not been studied. In this study, leaf gas exchange, water and nitrogen use efficiencies of two Sonneratia species were compared with those of selected native mangrove species (Avicennia marina, Aegiceras corniculatum, Kandelia candel, and Excoecaria agallocha) in Hainan and Shenzhen. The introduced S. apetala maintained lower carbon assimilation rate (A) and photosynthetic nitrogen use efficiency (PNUE) than the indigenous S. caseolaris. In Shenzhen, the two introduced Sonneratia had comparable photosynthetic rates and water use efficiency (WUE) with the native mangrove species, except that PNUE in S. caseolaris was significantly higher than in the native mangrove species. The two Sonneratia species showed significant overlap in PNUE and long-term WUE. Photosynthetic parameters derived from leaf photosynthetic light–response curves and A–C_i curves also suggested lower carbon assimilation capacities for the introduced Sonneratia than for the native mangrove species in both study sites. The lower light compensation point (LCP) of two introduced Sonneratia in both study sites also indicated a better adaptation to a low light regime than the native mangrove species. The results of photosynthetic capacities indicated that the introduced mangrove species have little competitive advantage over local native mangrove species in their respective new habitats.     

Saturation of groundwaters with respect to minerals of the host rocks

Calculations of the saturation of groundwaters with respect to minerals of the rocks hosting these waters indicate that most of the analyzed groundwaters were saturates with respect to calcite, dolomite, and quartz. Brines of chloride-calcic composition were determined to be saturated with respect to calcite, whereas brines of chloride-sodic composition are saturated with respect to dolomite and quartz. The solution was simultaneously saturated with respect to six minerals for the association ankerite-calcite-dolomite-pyrite-quartz-strontianite. An increase in the number of minerals with respect to which solution is saturated is correlated with an increase in the diversity of types of groundwaters and an increase in the runoff rate. The paper proposes possible avenues for searches for relations between hydrogeological and geochemical parameters that make it possible to adapt the thermodynamic models to real geological-hydrogeological conditions. The research was centered on the testing of groundwaters for their saturation with respect to minerals of the rocks hosting these waters. This parameter plays a significant part in forming the geochemical type of natural waters because it reflects the crystallization of a mineral from a solution and, consequently, the removal of an element from the aqueous solution.     

X-ray transient sources

The galactic distribution and physical nature of X-ray transient sources is investigated. Two types of transients are considered. The observational data on 41 X-ray transient sources are given, and the average parameters of hard and soft X-ray transients are estimated.     

Linear mechanism of generation and intencification of internal gravity waves in the ionosphere at their interaction with a nonuniform zonal wind: 1. Model of the medium and initial dynamic equations

The specific features of the generation and intensification of internal gravity wave structures in different atmospheric-ionospheric regions, caused by zonal local nonuniform winds (shear flows), are studied. The model of the medium has been explained and an initial closed system of equations has been obtained in order to study the linear and nonlinear dynamics of internal gravity waves (IGWs) when they interact with the geomagnetic field in a dissipative ionosphere (for the D, E, and F regions).     

Sur quelques concentrations plombo-zinciferes du devonien inferieur du massif schisteux rhenan

Zusammenfassung The Lower Devonian of the Rhine Schist Massif is characterized by a fine detrital sedimentation which reflects a coastal plain environment located between the Old Red Sandstone continent in the N and the marine Bohemian Facies in the SE. Mineralisations are located within these coastal-plain sediments, especially in fractured horizons topped by pelitic and floored by sandy sediments of Sieg Emsian age. The mineralised localities occur in three zones: the districts of Bensberg, Eitorf and Mayen. The Lüderich locality (Bensberg) is the most important having approximately one million tons of Zn and Pb metal. It is localised within a zone having marked sedimentary characteristics since the Siegenian. Mineralisation occurs as penecontemporaneous lenses, fracture fillings etc, formed at abnormal contacts between lithological units having different competance during Siegenian and Lower Emsian deformation. However, locally there is lateral transition between the upper units of the sandy channel series and the lower units of the pelitic swamp facies. Vertical extension of mineralisations is strictly limited to the tectonic contact zone between the Odenspiel Sandstone and the Bensberg pelites. Study of mineralisations at various levels (mapping, morphology, structure, paragenetic and geochemical) leads to the formulation of a genetic model requiring complex fracturation at the contact between contrasting lithologies and preferential drainage through these fractured zones; metals are trapped on the sandstone floor, the pelitic roof trapping the vadose hydrothermal solutions. These basic controls seem to apply throughout the Bensberg, Eitorf and Mayen districts. On a more regional scale the age variations of the gangue sediments reflects a lateral displacement of red/grey facies limits due to coastal evolution. Thus one may demonstrate a type of mineral occurrence whose model may be that of epigenetic reconcentration within fractures affecting syngenetic geochemical anomalies.Zusammenfassung Das Unterdevon des Rheinischen Schiefergebirges wird durch eine feinkörnige detritische Sedimentation gekennzeichnet. Die Verteilung dieser detritischen Sedimente widerspiegelt eine flache Küstenlandschaft zwischen dem Kontinent des Unterrotliegenden im Norden und des Meeres mit der Böhmischen Fazies im Südosten. In diesen Schichten befinden sich gangförmige Vererzungen, die in Bruchzonen auftreten, die ein pelitisches Hangendes und ein sandsteinreiches Liegendes vom Siegen-Ems Alter haben. Die Lagerstätten kommen in drei Bezirken vor: Der Bensberger Bezirk, der Bezirk Eitorf und der Bezirk Mayen. Die Lagerstätte Lüderich (Bensberger Revier) ist die größte (ungefähr eine Million Tonnen Metall Zink+Blei). Sie befindet sich in einer Zone, in der schon in der Siegen-Stufe bemerkenswerte sedimentäre Strukturen auftreten. Die Vererzung tritt als penekonkordante Linsen, Gänge, Stockwerke in tektonischen Kontaktzonen auf. Diese Kontaktzonen befinden sich zwischen 2 verschiedenen sedimentären Einheiten, deren Gesteinseigenschaften sehr verschieden sind. Es handelt sich um Pelite mit Sandstein-Einschaltungen einerseits, die zur unteren Emsstufe gehören sollen und um fluviatile Sandsteine andererseits, die zur oberen Siegenstufe gehören sollen. Lokal ist ein lateraler Übergang durch Faziesänderung von den oberen Sandsteinen in die unteren Pelitschichten jedoch nicht unmöglich. Die Sandsteine vertreten einen fluviatilen Sedimentationsbereich, die Pelite einen sumpfigen Sedimentationsbereich. Die Vererzung (mit einer vertikalen Ausdehnung ungefähr von 300 m) tritt nur im Bereich der Kontaktzone zwischen den Odenspieler Sandsteinen und den Peliten der Unteren Bensberger Schichten auf. Die Resultate der Kartographie, der morphologischen Studie der Erzkörper, der Struktur und der Paragenese führen zu einem genetischen Modell. Dabei spielt die Anwesenheit einer Bruchstruktur an der Grenze zwischen 2 Bereichen mit verschiedenen lithologischen Eigenschaften eine Hauptrolle für die Konzentration der im Hangenden fein verteilten Metalle. Die hydrothermalen Lösungen kommen demnach nicht von der Teufe, sondern aus dem Nebengestein. Im ganzen Bensberger Erzrevier wie in der Gegend von Eitorf und in der Gegend von Mayen finden wir dieselben Leitfäden für die Vererzung in den Lagerstätten und Vorkommen. Beobachtet man die ganze Provinz, dann merkt man, daß die Altersverschiedenheiten in den Nebengesteinen der verschiedenen Lagerstätten eine geographische Wanderung der Faziesgrenze zwischen rot und grau in dieser küstennahen Ebene Widerspiegeln. Die verschiedenen Vorkommen und Lagerstätten treten immer in unmittelbarer Nähe dieser Grenze auf. Die Eigenschaften dieser Lagerstätten weisen auf eine Bildung durch eine epigenetische Umlagerung in eine gangförmige Bruchstruktur hin.     

Geoeffective Disturbances in the Solar Wind near the Solar Activity Minimum according to the Data of a Two-year Series of Observations of Interplanetary Scintillations with the BSA LPI Radio Telescope

Astronomy Reports - A joint analysis of the monitoring data of interplanetary scintillations with solar and geophysical data showed that at the descending phase of the 24 solar activity cycle, the...