Low biomass of macrobenthic fauna at a tropical mudflat: An effect of latitude?   总被引：1，自引：1，他引：0  

Agus Purwoko  Wim J. Wolff   《Estuarine, Coastal and Shelf Science》2008,76(4):869-875

The macrobenthic animal biomass of the intertidal area of the Sembilang peninsula of South Sumatra, Indonesia, has been studied in 2004. Each month (March–August) 21 core samples were taken at each of six sampling stations. Macrobenthic fauna were identified at the lowest taxonomical level possible and counted. Biomass was measured as ash-free dry mass (afdm). The average biomass over all stations and months was 3.62 g afdm m⁻², the highest biomass (47.45 g afdm m⁻²) found at a station in one month was due to abundant occurrence of the bivalve Anadara granosa. Low biomass of macrobenthic fauna at Sembilang peninsula cannot easily be explained but is in line with low biomasses found elsewhere in the tropics. For that reason we analyzed a data set of 268 soft-bottom intertidal biomasses collected world-wide to look for a relationship with latitude. It was shown that average biomass of intertidal macrobenthic fauna in the tropics was significantly (p < 0.05) lower than that at non-tropical sites. A significant second-order relationship between biomass of macrobenthic fauna and latitude was established.  相似文献   

The impact of summer temperature changes on vegetation development in Ireland during the Weichselian Lateglacial Interstadial     

Nelleke van Asch  Wim Z. Hoek 《第四纪科学杂志》2012,27(5):441-450

We analysed pollen from a sediment core from Fiddaun, a small Lateglacial lake basin in western Ireland. Results reflect the general Lateglacial vegetation development in Ireland, as reconstructed from other pollen records. The Fiddaun diagram shows a number of short‐lived regressive vegetation phases during the Interstadial. The close similarity between two pollen records from the same region (Fiddaun and Lurga) indicates that these fluctuations probably reflect regional rather than local changes. Comparison with a previously published climate reconstruction, based on a chironomid‐inferred mean July air temperature reconstruction, lithology, and oxygen and carbon isotopes of lake marl from the Fiddaun record, allowed us to establish the relationship between summer temperature and vegetation changes. Results reveal that two temporary regressive shifts in the pollen record correspond to cold oscillations, which have been correlated to Greenland Interstadial 1b and 1d. It seems that the first cold oscillation (GI‐1d) had the most distinct effect on vegetation in Ireland. In contrast, it appears that the transition from Juniperus shrubland and Empetrum heath to grassland, which is estimated at ～13.7 ka BP, was not caused by decreasing summer temperatures, as no substantial change is observed in the climate proxies. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The Influence of Path Corrections and a Three-dimensional Global <Emphasis Type="Italic">P</Emphasis>-wave Velocity Model on Seismic Event Location in Kazakhstan     

Renate?Hartog  Wim?Spakman  Clifford H.?ThurberEmail author  Chad?Trabant 《Pure and Applied Geophysics》2003,160(12):2239-2255

We relocate 81 large nuclear explosions that were detonated at the Balapan and Degelen Mountain subregions of the Semipalatinsk test site in Kazakhstan during the years 1978 to 1989. The absolute locations of these explosions are available, as well as very accurate estimates of their origin times. This ground truth information allows us to perform a detailed analysis of location capability. We use a sparse network of stations with highly accurate first arrival picks measured using a waveform cross-correlation method. These high quality data facilitate very accurate location estimates with only a few phases per event. We contrast two different approaches: 1) a calibration-based approach, where we achieve improved locations by using path corrections, and 2) a model-based approach, where we achieve improved locations by relocating in a recently published global 3-D P-velocity model. Both methods result in large improvements in accuracy of the obtained absolute locations, compared to locations obtained in a 1-D reference earth model (ak135). The calibration-based approach gives superior results for this test site, in particular when arrival times from regional stations are included. Estimated locations remain well within a 1000 km² region surrounding the ground truth locations when the path corrections for the Balapan and Degelen Mountain subregions are interchanged, but even for the short separation between these two regions, we find variations in the path corrections that cause systematic mislocations. The model-based approach also results in substantially reduced mislocation distances and has the distinct advantage that it is, in principle, transportable to other source regions around the world.  相似文献   

Effects of an oil spill in outdoor model tidal flat ecosystems     

Jan Kuiper  Peter De Wilde  Wim Wolff 《Marine pollution bulletin》1984,15(3):102-106

For several reasons the fate and effects of oil pollution are not easily studied in natural ecosystems. Furthermore, the results of laboratory tests cannot easily be extrapolated to natural systems. A logical objective of ecotoxicological research is, therefore, to simulate natural systems in model ecosystem experiments. A one-year feasibility study was carried out with MOdel TIdal Flat ecosystems (MOTIFs), designed to represent tidal flat systems typical of the Wadden Sea and other temperate estuarine areas. During the first 6 months the 4 MOTIFs studied developed very similarly. After this period an oil spill was simulated by exposing two of the four MOTIFs to a floating oil mousse for one week. During this week part of the oil was buried in the sediment by bioturbation. This sediment-bound fraction caused a prolonged exposure of the MOTIFs to oil compounds. Short- and long-term effects resulted in large differences between oil-treated and control MOTIFs. These differences persisted to the end of the experiment, 7 months after the removal of most of the oil.  相似文献   

A map-view restoration of the Alpine-Carpathian-Dinaridic system for the Early Miocene     

Kamil Ustaszewski  Stefan M. Schmid  Bernhard Fügenschuh  Matthias Tischler  Eduard Kissling  Wim Spakman 《Swiss Journal of Geoscience》2008,101(1):273-294

A map-view palinspastic restoration of tectonic units in the Alps, Carpathians and Dinarides reveals the plate tectonic configuration before the onset of Miocene to recent deformations. Estimates of shortening and extension from the entire orogenic system allow for a semi-quantitative restoration of translations and rotations of tectonic units during the last 20 Ma. Our restoration yielded the following results: (1) The Balaton Fault and its eastern extension along the northern margin of the Mid-Hungarian Fault Zone align with the Periadriatic Fault, a geometry that allows for the eastward lateral extrusion of the Alpine-Carpathian-Pannonian (ALCAPA) Mega-Unit. The Mid-Hungarian Fault Zone accommodated simultaneous strike-perpendicular shortening and strike-slip movements, concomitant with strike-parallel extension. (2) The Mid-Hungarian Fault Zone is also the locus of a former plate boundary transforming opposed subduction polarities between Alps (including Western Carpathians) and Dinarides. (3) The ALCAPA Mega-Unit was affected by 290 km extension and fits into an area W of present-day Budapest in its restored position, while the Tisza-Dacia Mega-Unit was affected by up to 180 km extension during its emplacement into the Carpathian embayment. (4) The external Dinarides experienced Neogene shortening of over 200 km in the south, contemporaneous with dextral wrench movements in the internal Dinarides and the easterly adjacent Carpatho-Balkan orogen. (5) N–S convergence between the European and Adriatic plates amounts to some 200 km at a longitude of 14° E, in line with post-20 Ma subduction of Adriatic lithosphere underneath the Eastern Alps, corroborating the discussion of results based on high-resolution teleseismic tomography.The displacement of the Adriatic Plate indenter led to a change in subduction polarity along a transect through the easternmost Alps and to substantial Neogene shortening in the eastern Southern Alps and external Dinarides. While we confirm that slab-pull and rollback of oceanic lithosphere subducted beneath the Carpathians triggered back-arc extension in the Pannonian Basin and much of the concomitant folding and thrusting in the Carpathians, we propose that the rotational displacement of this indenter provided a second important driving force for the severe Neogene modifications of the Alpine-Carpathian-Dinaridic orogenic system.  相似文献   

Exploring former subglacial Hodgson Lake,Antarctica Paper I: site description,geomorphology and limnology     

Dominic A. Hodgson  Stephen J. Roberts  Michael J. Bentley  James A. Smith  Joanne S. Johnson  Elie Verleyen  Wim Vyverman  Andy J. Hodson  Melanie J. Leng  Andreas Cziferszky  Adrian J. Fox  David C.W. Sanderson 《Quaternary Science Reviews》2009,28(23-24):2295-2309

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Quantifying garnet-melt trace element partitioning using lattice-strain theory: assessment of statistically significant controls and a new predictive model     

David S. Draper  Wim van Westrenen 《Contributions to Mineralogy and Petrology》2007,154(6):731-746

As a complement to our efforts to update and revise the thermodynamic basis for predicting garnet-melt trace element partitioning using lattice-strain theory (van Westrenen and Draper in Contrib Mineral Petrol, this issue), we have performed detailed statistical evaluations of possible correlations between intensive and extensive variables and experimentally determined garnet-melt partitioning values for trivalent cations (rare earth elements, Y, and Sc) entering the dodecahedral garnet X-site. We applied these evaluations to a database containing over 300 partition coefficient determinations, compiled both from literature values and from our own work designed in part to expand that database. Available data include partitioning measurements in ultramafic to basaltic to intermediate bulk compositions, and recent studies in Fe-rich systems relevant to extraterrestrial petrogenesis, at pressures sufficiently high such that a significant component of majorite, the high-pressure form of garnet, is present. Through the application of lattice-strain theory, we obtained best-fit values for the ideal ionic radius of the dodecahedral garnet X-site, r ₀(3+), its apparent Young’s modulus E(3+), and the strain-free partition coefficient D ₀(3+) for a fictive REE element J of ionic radius r ₀(3+). Resulting values of E, D ₀, and r ₀ were used in multiple linear regressions involving sixteen variables that reflect the possible influence of garnet composition and stoichiometry, melt composition and structure, major-element partitioning, pressure, and temperature. We find no statistically significant correlations between fitted r ₀ and E values and any combination of variables. However, a highly robust correlation between fitted D ₀ and garnet-melt Fe–Mg exchange and D _Mg is identified. The identification of more explicit melt-compositional influence is a first for this type of predictive modeling. We combine this statistically-derived expression for predicting D ₀ with the new expressions for predicting E and r ₀ outlined in the first of our pair of companion papers into an updated set of formulae that use easy-to-measure quantities (e.g. garnet composition, pressure, temperature) to predict variations in E, r ₀, and D ₀. These values are used in turn to calculate D values for those garnets. The updated model substantially improves upon a previous model (van Westrenen et al. in Contrib Mineral Petrol 142:219–234, 2001), and accounts well for trivalent cation partitioning in nominally anhydrous systems up to at least 15 GPa, including for eclogitic bulk compositions and for Fe-rich systems appropriate to magmagenesis on the Moon and Mars. The new model is slightly less successful in predicting partitioning with strongly majoritic garnets, although the mismatch is much less than with the original 2001 model. Although it also improves upon the 2001 model in predicting partitioning in hydrous systems, the mismatch between model and observation is still unacceptably large. The same statistical tools were applied in an attempt to predict tetravalent partitioning as well, because lattice-strain based techniques are not applicable to such partitioning. However, no statistically significant predictive relationships emerged from that effort. Our analyses show that future efforts should focus on filling the gap in partitioning data between ∼10 and 25 GPa to evaluate more closely the gradual transition of garnet to majorite, and on systematically expanding the hydrous partitioning database to allow extension of our model to water-bearing systems.  相似文献   

Quantifying garnet-melt trace element partitioning using lattice-strain theory: new crystal-chemical and thermodynamic constraints   总被引：1，自引：0，他引：1  

Wim van Westrenen  David S. Draper 《Contributions to Mineralogy and Petrology》2007,154(6):717-730

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The Energy Balance Experiment EBEX-2000. Part I: overview and energy balance   总被引：2，自引：1，他引：2  

Steven P. Oncley  Thomas Foken  Roland Vogt  Wim Kohsiek  H. A. R. DeBruin  Christian Bernhofer  Andreas Christen  Eva van Gorsel  David Grantz  Christian Feigenwinter  Irene Lehner  Claudia Liebethal  Heping Liu  Matthias Mauder  Andrea Pitacco  Luis Ribeiro  Tamas Weidinger 《Boundary-Layer Meteorology》2007,123(1):1-28

An overview of the Energy Balance Experiment (EBEX-2000) is given. This experiment studied the ability of state-of-the-art measurements to close the surface energy balance over a surface (a vegetative canopy with large evapotranspiration) where closure has been difficult to obtain. A flood-irrigated cotton field over uniform terrain was used, though aerial imagery and direct flux measurements showed that the surface still was inhomogeneous. All major terms of the surface energy balance were measured at nine sites to characterize the spatial variability across the field. Included in these observations was an estimate of heat storage in the plant canopy. The resultant imbalance still was 10%, which exceeds the estimated measurement error. We speculate that horizontal advection in the layer between the canopy top and our flux measurement height may cause this imbalance, though our estimates of this term using our measurements resulted in values less than what would be required to balance the budget. The National Center for Atmospheric Research is supported by the National Science Foundation  相似文献   

Baseline study of perfluorooctane sulfonate occurrence in mussels, Mytilus galloprovincialis, from north-central Portuguese estuaries     

Cunha I  Hoff P  Van de Vijver K  Guilhermino L  Esmans E  De Coen W 《Marine pollution bulletin》2005,50(10):1128-1132

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