Middle and Late Devonian microbial carbonates,reefs and mounds in Guilin,South China and their sequence stratigraphic,paleoenvironmental and paleoclimatic significance

The importance of calcimicrobes and microbialite in carbonate platform and reefal environments has been stressed in recent literature. Burne and Moore[1] introduced the term microbialite to describe the clotted, laminated and undifferentiated fabrics formed by mi-crobial communities. Microbialites are organosedi-mentary deposits that have accreted as a result of ben-thic (prokaryotic or eukaryotic) communities, trapping and binding detrital sediment[1]. Microbial organisms and microbialite are…     

Application of biotic indices and relationship with structural and functional features of macrobenthic community in the lagoon of Venice: an example over a long time series of data

In the context of the application of WFD, a scientific debate is growing about the applicability of biotic indices in coastal and transitional waters. In the present work, the question about the discriminating power of different biotic indices and the relationships with the structure and functioning of the macrobenthic community in a transitional environment is discussed. A time series of samples collected during the last 70 years in the lagoon of Venice, reflecting different environmental conditions (a sort of 'pristine state' in 1935, the distrophic crisis in 1988 and subsequent modifications in 1990, the invasion by an alien species and the developing of high impacting fishery in 1999) has been used. The comparison of results obtained by applying different biotic indices, such as AMBI, Bentix and BOPA, shows differences in the discriminating power of indices and a general overestimation of environmental conditions. Discrepancies between environmental status as indicated by biotic indices and the structure and functioning of the benthic community have been highlighted.     

The shift of biogeochemical cycles indicative of the progressive marine ecosystem collapse across the Permian-Triassic boundary: An analog to modern oceans

Global warming, the most severe faunal mass extinction and the shift of biogeochemical cycles were observed in the ocean across the Permian-Triassic boundary about 252 million years ago, providing an analog to understanding the modern oceans. Along with the progressive global warming, the biogeochemical cycle was documented to show a shift from the decoupled processes of carbon, nitrogen and sulfur prior to the mass extinction to the coupled biogeochemical processes during faunal mass extinction. The coupled biogeochemical cycle was further observed to shift from the coupled C-N processes during the first episode of the faunal mass extinction to the coupled C-N-S processes during the second episode, diagnostic of the progressive development of more deteriorated marine environmental conditions and the more severe biotic crisis across the Permian-Triassic boundary. The biogeochemical cycles could thus be an indication to the progressive collapse of marine ecosystems triggered by the global warming in Earth history. In modern oceans, the coupled C-N cycle triggered by the global warming was observed in some regions. If these local C-N processes develop and expand to the global oceans, the coupled C-N-S processes might be brought into existence and the marine ecosystems are inevitable to suffer from complete collapse as observed at 252 million years ago.     

Biotic evolution and its relation with geological events in the Proterozoic Yanshan Basin,North China

The Yanshan Basin,located in northern North China,underwent three primary stages in the Mesoproterozoic,and corresponding biotas have been summarized for each stage in the present study.The three stages are stage A(the lower part of the Changcheng Group which dominated by clastic sediments),stage B(the upper part of the Changcheng Group to the Jixian Group which characterized by carbonate sediments),and stage C(the upper part of the Jixian Group which dominated by clastic sediments).This paper will focus on the evolution of biota during stage B.Microbiota of the stage B exhibits a high level of diversity and abundance.Planktonic microfossils have various forms and complex decorations.Most microfossils are small.In stage B,there was great variation in the biotic abundance and diversity,the average diameter of spherical benthic microfossils,and the maximum diameter of the spherical microfossils.We analyzed these parameters and identified two typical biotic events,and both biotic events were corresponded with geological events.The first event occurred in the third member of the Dahongyu Formation.In this era,the maximum diameter of the silicified microfossils significantly increased,and large,spherical planktonic specimens are abundant.The flourishing of large organisms in the strata is presumably related to volcanic activity.The second event occurred in the third member of the Gaoyuzhuang Formation.During this era,the microfossil assemblage changed significantly.The changes correspond with a decline in stromatolites as well as the transformations of the carbon isotope ratios and the elemental geochemistry.     

Inter-taxa differences in extinction process of Maokouan (Middle Permian) fusulinaceans

Analyses of the extinction process of fusulinacean in the Maokouan (Middle Permian) biotic crisis have revealed remarkable differences between taxa with various morphological features. Nankinellinids suffered a heavy loss of species in the early stage of the Maokouan event. Schwagerinids and neoschwagerinids both showed a stepwise decrease in species diversity, but the pulses of species extinction occurred in different stages of the extinction process. The species extinction of verbeekinids happened primarily in the Late Maokouan.     

Timing of the terrestrial Permian-Triassic boundary biotic crisis: Implications from U-Pb dating of authigenic zircons

The Late Permian to Early Triassic transition represents one of the most important Phanerozoic mass extinction episodes. The cause of this event is still in debate between catastrophic and gradual mechanisms. This study uses the U-Pb method on zircons from the uppermost Permian/lowermost Triassic clay deposits at Chahe (Guizhou Province, SW China) to examine time constraints for this event. The results of both this and previous studies show that the ages of Bed 68a and 68c (the upper clay bed of the terrestrial Permian-Triassic boundary (PTB)) respectively are 252.6±2.8 and 247.5±2.8 Ma. This age (within the margin of error) almost accords with the upper clay bed (Bed 28) age of Meishan and the eruption age of Tunguss Basalt, and is so far the most accurate age obtained from terrestrial PTB. The claystone of Bed 68 was formed in the earliest Triassic. The biotic crisis occurred at nearly the same time in terrestrial and marine environments during Permian-Triassic interval; however the extinction patterns and processes are different. The extinction pattern of the terrestrial plants shows a major decline at the PTB after long-term evolution, followed by a retarded extinction of the relicts in the earliest Triassic.     

Mass extinction and Pangea integration during the Paleozoic-Mesozoic transition

The greatest Phanerozoic mass extinction happened at the end-Permian to earliest Triassic.About 95%species,82%genera,and more than half families became extinct,constituting the sole macro-mass extinction in geological history.This event not only caused the great extinction but also destroyed the 200 Myr-long Paleozoic marine ecosystem,prompted its transition to Mesozoic ecosystem,and induced coal gap on land as well as reef gap and chert gap in ocean.The biotic crisis during the Paleozoic-Mesozoic transition was a long process of co-evolution between geospheres and biosphere.The event sequence at the Permian-Triassic boundary(PTB)reveals two-episodic pattern of rapidly deteriorating global changes and biotic mass extinction and the intimate relationship between them.The severe global changes coupling multiple geospheres may have affected the Pangea integration on the Earth’s surface spheres,which include:the Pangea integration→enhanced mountain height and basin depth,changes of wind and ocean current systems;enhanced ocean basin depth→the greatest Phanerozoic regression at PTB,disappearance of epeiric seas and subsequent rapid transgression;the Pangea integration→thermal isolation effect of continental lithosphere and decrease of mid-ocean ridges→development of continental volcanism;two-episode volcanism causing LIPs of the Emeishan Basalt and the Siberian Trap(259–251 Ma)→global warming and mass extinction;continental aridification and replacement of monsoon system by latitudinal wind system→destruction of vegetation;enhanced weathering and CH4emission→negative excursion ofδ13C;mantle plume→crust doming→regression;possible relation between the Illawarra magnetic reversal and the PTB extinction,and so on.Mantle plume produced the Late Permian LIPs and mantle convection may have caused the process of the Pangea integration.Subduction,delamination,and accumulation of the earth’s cool lithospheric material at the"D"layer of CMB started mantle plume by heat compensation and disturbed the outer core thermo-convection,and the latter in turn would generate the mid-Permian geomagnetic reversal.These core and mantle perturbations may have caused the Pangea integration and two successive LIPs in the Permian,and probably finally the mass extinction at the PTB.     

Seasonal Variation of Temperature,Alkalinity and Dissolved Oxygen in the Sagar Lake

The present study deals with the seasonal variation of temperature, alkalinity and dissolved oxygen in the Sagar lake. Different abiotic and biotic factors were investigated and a diurnal study was made, too. The investigation shows that the surface water values were always higher than the bottom water values. The water temperature ranged from 16.0 to 31.0 °C, carbonate alkalinity ranged from 0.0 to 46.0 mg/1, bicarbonate alkalinity ranged from 62.0 to 138.0 mg/1, dissolved oxygen ranged between 1.6 and 13.2 ppm. The water temperature was found to be positively correlated with carbonate alkalinity while an inverse correlation existed with bicarbonate alkalinity. Dissolved oxygen had a significant positive correlation with carbonate alkalinity, while a negative correlation was observed with bicarbonate alkalinity during all the seasons.     

Inferences on the source of long-period seismicity at Campi Flegrei from polarization analysis and reconstruction of the asymptotic dynamics

In the present paper, we analyse long-period (LP) events and seismic noise recorded at Campi Flegrei during the uplift episode of 2004–2006. The results of a detailed polarization analysis indicate that the large number of LPs detected during the seismic crisis were accompanied by a sustained activity consisting of very low-energy volcanic signals. These weak volcanic signals, which are usually absent in ambient noise recorded in the studied area, and LP events have similar properties, namely they are radially polarized towards the same LP source. The large dataset analysed allows us to study the statistics of the polarization, leading to the extraction of the average properties of the volcanic signals. An estimate of the complexity of the system can be provided by the degrees of freedom necessary to describe the asymptotic dynamics in a reconstructed phase space. This analysis shows that both LPs and low-energy signals can be described by a low-dimensional dynamical system, while ambient noise unrelated to volcanic activity is higher dimensional. Based on these observations, we interpret the phenomena observed during the seismic crisis in the framework of the theory of self-oscillating systems, in which LPs and low-energy signals represent self-oscillations generated by a persistent hydrothermal source.     

Differential kinetics and temperature dependence of abiotic and biotic processes controlling the environmental fate of TNT in simulated marine systems

This work seeks to understand how the balance of abiotic and biotic kinetic processes in sediments control the residual concentration of TNT in marine systems after release from ocean-dumped source. Kinetics of TNT disappearance were followed using marine sediments at different temperatures and under both biotic and presumably abiotic conditions (through sodium azide addition). Sediments exhibiting the highest rate of TNT disappearance under biotic conditions also exhibited the highest sorption affinity for TNT under abiotic conditions. Significant temperature dependence in the abiotic processes was observed in the diffusion coefficient of TNT and not sediment sorption affinity. At higher temperature, kinetics of biotic processes outpaced abiotic processes, but at low temperature, kinetics of abiotic processes were much more significant. We concluded that the differential influence of temperature on the kinetics of abiotic and biotic processes could provide distinguishing predictions for the potential residual concentration of TNT contamination in marine-sediment systems.     

论新闻发言人制度在地震工作中的作用

论述了地震新闻发言人制度在突发地震危机时,在政府、地震工作部门为了顺利推进某一重要工作的开展和解决公众普遍关心的热点问题以及在平息地震谣言和误传的过程中所起到的重要作用,认为,作为地震工作主管部门,建立地震新闻发言人制度是非常必要和可行的。     

Institutional conditions for IWRM: the Israeli case

Many places in the world are experiencing a water crisis. This water crisis is attributed to a governance crisis, whereas often fragmented institutional and physical water structures are used to explain a policy of overexploitation. The Israeli water system, which adopted integrated water resource management (IWRM), is often cited as a model for other countries struggling with fragmented water systems. Yet, despite the exceptional degree of integration, Israel in the past two decades has adopted an unsustainable water policy. The aim of this study is to understand this failure and thereby to postulate on the institutional conditions required for successful implementation of IWRM. The study focuses on the politics of water allocation during the drought of 1999 to 2002. It was found that the failure originates in setting administrative divisions in the decision-making process and in differential checks, with no balances implicitly instituted within the integrated water system. These two factors have resulted in a water system that is physically integrated but is not coupled by a balanced institutional structure. This case study teaches us that when reforming the water sector along IWRM lines, measures must be taken to ensure that the physical integration coincides with a balanced institutional integration-otherwise the results may be worse than if there were no integration at all.     

Distribution patterns of macrobenthic species in relation to organic enrichment within aquaculture earthen ponds

The relationship between organic enrichment and macrobenthic colonization patterns was investigated during an 8-month period in Diplodus sargus (white seabream) production ponds. A stratified sampling design was applied and each pond was divided into three zones: water entrance (WE); central (C); and automatic feeder zones (AF). Generally, the number of species and Shannon–Wiener diversity increased from the WE to the AF zone. Abundance did not present a clear trend. The recently developed marine biotic index (AMBI) was applied and showed to be sufficiently robust to discriminate, within a relatively small area, differences in macrobenthic communities due to organic enrichment. Nevertheless, caution is advised when applying this index or others based on ecological group’s assignment, as the classification of a certain area may differ when allocating a certain species to an unsuitable group. This is particularly evident when common species are involved.     

Hot fluid migration: an efficient source of ground deformation: application to the 1982–1985 crisis at Campi Flegrei-Italy

Some solutions of the forced heat advection problem in compressible media are worked out employing a perturbative approach and their implication for thermoelastic deformation are discussed. A sharp temperature front, which migrates at a speed in the order of Darcy flow rate, develops in the medium, giving rise to significant deformation via thermal expansion. A thermally induced pressure source accompanies the temperature front, which may be significant only in very high temperature cases. Results are applied to interpreting the uplift episode of 1982–1984 at Campi Flegrei (C.F.), near Naples, Italy. A mechanism is envisaged for uplift at Campi Flegrei in which a sudden connection is established between a deep, hot, high-pressure fluid reservoir and a shallow, relatively cold, low-pressure aquifer. The inclusion of fluid migration in the deformation model allows simple explanations of several geochemical and geophysical observations made during the bradyseismic crisis. It appears that the proposed mechanism may explain the large observed uplift, without requiring unreasonable pressure increase within the magma chamber. Furthermore, the deformation source may be allowed to be shallower than the magma chamber, as required by any reasonable deformation model at C.F.     

Towards an operational system for oil-spill forecast over Spanish waters: initial developments and implementation test

The ESEOO Project, launched after the Prestige crisis, has boosted operational oceanography capacities in Spain, creating new operational oceanographic services and increasing synergies between these new operational tools and already existing systems. In consequence, the present preparedness to face an oil-spill crisis is enhanced, significantly improving the operational response regarding ocean, meteorological and oil-spill monitoring and forecasting. A key aspect of this progress has been the agreement between the scientific community and the Spanish Search and Rescue Institution (SASEMAR), significantly favoured within the ESEOO framework. Important achievements of this collaboration are: (1) the design of protocols that at the crisis time provide operational state-of-the-art information, derived from both forecasting and observing systems; (2) the establishment, in case of oil-spill crisis, of a new specialized unit, named USyP, to monitor and forecast the marine oceanographic situation, providing the required met-ocean and oil-spill information for the crisis managers. The oil-spill crisis scenario simulated during the international search and rescue Exercise "Gijón-2006", organized by SASEMAR, represented an excellent opportunity to test the capabilities and the effectiveness of this USyP unit, as well as the protocols established to analyze and transfer information. The results presented in this work illustrate the effectiveness of the operational approach, and constitute an encouraging and improved base to face oil-spill crisis.     

Spatial variability in the hyporheic zone refugium of temporary streams

A key ecological role hypothesized for the hyporheic zone is as a refugium that promotes survival of benthic invertebrates during adverse conditions in the surface stream. Many studies have investigated use of the hyporheic refugium during hydrological extremes (spates and streambed drying), and recent research has linked an increase in the abundance of benthic invertebrates within hyporheic sediments to increasing biotic interactions during flow recession in a temporary stream. This study examined spatial variability in the refugial capacity of the hyporheic zone in two groundwater-dominated streams in which flow permanence varied over small areas. Two non-insect taxa, Gammarus pulex and Polycelis spp. were common to both streams and were investigated in detail. Hydrological conditions in both streams comprised a four-month period of flow recession and low flows, accompanied by reductions in water depth and wetted width. Consequent declines in submerged benthic habitat availability were associated with increases in population densities of mobile benthic taxa, in particular G. pulex. The reduction in the spatial extent of the hyporheic zone was minimal, and this habitat was therefore a potential refugium from increasing biotic interactions in the benthic sediments. Concurrent increases in the hyporheic abundance and hyporheic proportion of a taxon’s total (benthic + hyporheic) population were considered as evidence of active refugium use. Such evidence was species-specific and site-specific, with refugium use being observed only for G. pulex and at sites dominated by downwelling water. A conceptual model of spatial variability in the refugial capacity of the hyporheic zone during habitat contraction is presented, which highlights the potential importance of the direction of hydrologic exchange.     

Biomarker evidence for biotic and environmental change across the Cambrian Series 2–Series 3 boundary at the Wuliu- Zengjiayan section,Guizhou, China

The Wuliu-Zengjiayan section in Jianhe County, Guizhou Province, China has been suggested as a potential Global Stratotype Section and Point(GSSP) for the defined base of Cambrian Series 3. A molecular organic geochemical study on the Cambrian Series 2Series 3 boundary interval was carried out to reveal the biotic and environmental change during this transition. The hydrocarbons extracted from the Kaili Formation were proved to be indigenous. The various geochemical proxies such as biomarker parameter, δ13Corg, atomic H/C value of kerogen, and TOC content, co-vary along with the sedimentary column, and show a quick and significant change just across the Cambrian Series 2Series 3 boundary. The less abundance of isoprenoid hydrocarbons, the relative enrichment of midchain monomethyl branched alkanes(mmb-alkanes), the relatively negative value of δ13Corg, and the higher TOC contents may suggest that the upper Cambrian Series 2 was deposited in a relatively reducing environment with a higher organic input from cyanobacteria-predominated benthic microbial mats. On the other hand, the relative enrichment of isoprenoid hydrocarbons, the less abundance of mmb-alkanes, the relatively positive value of δ13Corg, the lower TOC contents, and the lower atomic H/C values of kerogen are combined to indicate an enhanced phytoplankton production and an increased oxygen content and nutrients in the ocean during the early Cambrian Series 3, which could have benefited the explosion of the Kaili Biota. The Wuliu-Zengjiayan section may provide a typical case to understand the co-variation of marine microbe, animal, and environment.     

Professional conduct of scientists during volcanic crises

Stress during volcanic crises is high, and any friction between scientists can distract seriously from both humanitarian and scientific effort. Friction can arise, for example, if team members do not share all of their data, if differences in scientific interpretation erupt into public controversy, or if one scientist begins work on a prime research topic while a colleague with longer-standing investment is still busy with public safety work. Some problems arise within existing scientific teams; others are brought on by visiting scientists. Friction can also arise between volcanologists and public officials. Two general measures may avert or reduce friction: (a) National volcanologic surveys and other scientific groups that advise civil authorities in times of volcanic crisis should prepare, in advance of crises, a written plan that details crisis team policies, procedures, leadership and other roles of team members, and other matters pertinent to crisis conduct. A copy of this plan should be given to all current and prospective team members. (b) Each participant in a crisis team should examine his or her own actions and contribution to the crisis effort. A personal checklist is provided to aid this examination. Questions fall generally in two categories: Are my presence and actions for the public good? Are my words and actions collegial, i.e., courteous, respectful, and fair? Numerous specific solutions to common crisis problems are also offered. Among these suggestions are: (a) choose scientific team leaders primarily for their leadership skills; (b) speak publicly with a single scientific voice, especially when forecasts, warnings, or scientific disagreements are involved; (c) if you are a would-be visitor, inquire from the primary scientific team whether your help would be welcomed, and, in general, proceed only if the reply is genuinely positive; (d) in publications, personnel evaluations, and funding, reward rather than discourage teamwork. Models are available from the fields of particle physics and human genetics, among others.