Geochemical and mineralogical study of a site severely polluted with heavy metals (Maatheide, Lommel, Belgium)     

L. Horckmans  R. Swennen  J. Deckers 《Environmental Geology》2006,50(5):725-742

The former zinc smelter site ‘de Maatheide’ in Lommel (Belgium) was severely polluted with heavy metals and the pollution spread into the surroundings by rain water leaching and wind transportation. This study focuses on the processes of immobilization and natural attenuation that took place on the site. Three important factors were found. Firstly, the high pH values (pH 7–8) in the topsoil influence the mobility of heavy metals. Secondly, the spodic horizons below the polluted top layer seem to accumulate heavy metals, thereby slowing down their release into the environment. Finally, the glassy phases and iron oxi/hydroxides that are present can encapsulate heavy metals during their formation/recrystallization, thereby immobilizing them. An additional shielding effect results from the reaction rims of goethite around the contaminant phases, which partially inhibit the weathering process and release of contaminants. This shielding effect is an important factor to take into account when modelling contaminant release.  相似文献   

Petrographic and geochemical study of Jurassic dolostones from Lebanon: Evidence for superimposed diagenetic events     

Fadi H. Nader  Rudy Swennen  Rob M. Ellam   《Journal of Geochemical Exploration》2006,89(1-3):288

The Jurassic rock sequence in Lebanon is characterized by pervasive dolomitization (thickness > 1000 m). Two distinct dolostones are recognized within this rock succession: fine-to-medium crystalline seepage-reflux grey dolostone and coarse-crystalline hydrothermal beige dolostone. In this contribution, field, petrographic, and geochemical investigations on a dolostone ‘tongue’, occurring in Late Jurassic carbonates in central Lebanon, are discussed. The dolostone ‘tongue’ consists predominantly of the beige Late Jurassic hydrothermal dolostones. During and/or after the deposition of the overlying continental sandstones (Early Cretaceous), meteoric water percolated through the sand layers and into the underlying beige dolostones. This resulted first in dolomite intracrystalline dissolution, and then in the precipitation of oxides/hydroxides within the pore space. Finally, the precipitation of ferroan dolomite cement — from reduced fluids during a new stage of burial — took place. This study attempts to explain how superimposed diagenetic events result in a single pervasive dolostone body.  相似文献   

Anthropogenic impact on sediment composition and geochemistry in vertical overbank profiles of river alluvium from Belgium and Luxembourg     

R. Swennen  J. Van der Sluys   《Journal of Geochemical Exploration》2002,75(1-3)

The geochemical study of alluvial sediments allows to reconstruct pollution through time. Geochemical and sedimentological variations recorded in 40 vertical overbank sediment profiles from Belgium and Luxembourg can be classified in three dominant pattern types:• type 1 profiles with dominantly non-anthropogenically influenced geochemical distribution patterns. These profiles are devoid of anthropogenic particles such as charcoal, plastic, brick and slag fragments, with the exception, in some cases, of their uppermost parts. Background concentrations thus are displayed throughout the profile (subtype 1A). However, in this group, profiles displaying anomalous values caused by the presence of heavy minerals (subtype 1B) or by base metal mineralisations in the catchment (subtype 1C) also occur;• type 2 profiles displaying clear evidence of anthropogenic influences. Most of these profiles display a gradual increase in heavy metal content in their upper part, with values doubling or tripling (subtype 2A). However, other profiles display a dramatic increase in pollution-related elements caused by past or present-day heavy industrial activities in the catchment (subtype 2B). Here also the sedimentological patterns reflect the influence of the industrial activities;• type 3 profiles contain features related to pedogenetic translocations of mobile elements. Apart from classical pedogenetic features such as illuviation/eluviation, the mobility of As and Cd is of particular importance. From a sedimentological point of view, these profiles do not necessarily differ from type 1 or 2 profiles.It should be noted that in some profiles, pattern types can be superimposed. Type 2B profiles are of particular environmental concern, because the potential release of heavy metals may have consequences for agricultural activities or groundwater contamination in the catchment. Furthermore, reworking of polluted sediments temporarily stored in the alluvial plain can also have negative effects on the ecosystem.  相似文献   

Appropriate sampling strategy and analytical methodology to address contamination by industry. Part 2: Geochemistry and speciation analysis     

Aurela Shtiza  Rudy Swennen 《Central European Journal of Geosciences》2011,3(1):53-70

The degree of contamination in soils, sediments and dusts can be assessed based on knowledge of a variety of factors, such as industrialization, type of contaminants, deposition conditions, contamination-control techniques, along with the characteristics of the recipient environmental compartments, which include pathways for contamination transport, depth of infiltration, and degree of groundwater contamination. The impact of contaminants also depends on the quantity, mobility and speciation of contaminants/wastes as well as on the sensitivity of the recipient compartments. With sufficient knowledge of these factors, a number of conclusions can be drawn concerning the status of contamination in industrialized areas. This literature review aims to scrutinize some of the methods used to analyse the occurrence, speciation, mobility, bioavailability and likely the toxic effects of contaminants in the environment.  相似文献   

Awards presented by the International Association of Sedimentologists at the 18th International Sedimentological Congress,Mendoza, Argentina
Citation of John Bridge for the Sorby Medal     

Jim Best  Rudy Slingerland 《Sedimentology》2011,58(3):824-826

  相似文献   

Discovery of a broad iron line in the black hole candidate Swift J1753.5−0127, and the disc emission in the low/hard state revisited     

Beike Hiemstra  Paolo Soleri  Mariano Méndez  Tomaso Belloni  Reham Mostafa  Rudy Wijnands 《Monthly notices of the Royal Astronomical Society》2009,394(4):2080-2088

We analysed simultaneous archival XMM–Newton and Rossi X-ray Timing Explorer observations of the X-ray binary and black hole candidate Swift J  1753.5−0127  . In a previous analysis of the same data, a soft thermal component was found in the X-ray spectrum, and the presence of an accretion disc extending close to the innermost stable circular orbit was proposed. This is in contrast with the standard picture in which the accretion disc is truncated at large radii in the low/hard state. We tested a number of spectral models and found that several of them fit the observed spectra without the need of a soft disc-like component. This result implies that the classical paradigm of a truncated accretion disc in the low/hard state cannot be ruled out by these data. We further discovered a broad iron emission line between 6 and 7 keV in these data. From fits to the line profile we found an inner disc radius that ranges between ∼6 and 16 gravitational radii, which can be in fact much larger, up to ∼250 gravitational radii, depending on the model used to fit the continuum and the line. We discuss the implications of these results in the context of a fully or partially truncated accretion disc.  相似文献   

GeV gamma-ray attenuation and the high-redshift UV background     

Rudy C. Gilmore  Piero Madau  Joel R. Primack  Rachel S. Somerville  Francesco Haardt 《Monthly notices of the Royal Astronomical Society》2009,399(4):1694-1708

We present new calculations of the evolving UV background out to the epoch of cosmological reionization and make predictions for the amount of GeV gamma-ray attenuation by electron–positron pair production. Our results are based on recent semi-analytic models of galaxy formation, which provide predictions of the dust-extinguished UV radiation field due to starlight, and empirical estimates of the contribution due to quasars. We account for the reprocessing of ionizing photons by the intergalactic medium. We test whether our models can reproduce estimates of the ionizing background at high redshift from flux decrement analysis and proximity effect measurements from quasar spectra, and identify a range of models that can satisfy these constraints. Pair production against soft diffuse photons leads to a spectral cut-off feature for gamma rays observed between 10 and 100 GeV. This cut-off varies with redshift and the assumed star formation and quasar evolution models. We find only negligible amounts of absorption for gamma rays observed below 10 GeV for any emission redshift. With observations of high-redshift sources in sufficient numbers by the Fermi Gamma-ray Space Telescope and new ground-based instruments, it should be possible to constrain the extragalactic background light in the UV and optical portion of the spectrum.  相似文献   

From outcrop and petrographic studies to basin-scale fluid flow modelling: The use of the Albanian natural laboratory for carbonate reservoir characterisation   总被引：1，自引：0，他引：1  

Nadge Vilasi  Julien Malandain  Laurie Barrier  Jean-Paul Callot  Khalid Amrouch  Nicole Guilhaumou  Olivier Lacombe  Kristaq Muska  Franois Roure  Rudy Swennen 《Tectonophysics》2009,474(1-2):367

The Albanian fold-and-thrust belt and the Peri-Adriatic Depression are well documented by means of seismic reflection profiles, GPS reference points, potential data, wells and outcrops. The continuous Oligocene to Plio-Quaternary sedimentary records help to constrain both the burial history of Mesozoic carbonate reservoirs, the timing of their deformation, and the coupled fluid flow and diagenetic scenarios.Since the mid-90s, the Albanian foothills were used as a natural laboratory to develop a new integrated methodology and work flow for the study of sub-thrust reservoir evolution, and to validate on real case studies the use of basin modelling tools as well as the application of new analytical methods for the study petroleum systems in tectonically complex areas.The integration of the interactions between petrographic and microtectonic studies, kinematic, thermal and fluid flow basin modelling, is described in detail. The fracturing of the reservoir intervals has a pre-folding origin in the Albanides and relates to the regional flexuring in the foreland. The first recorded cement has a meteoric origin, implying downward migration and the development of an earlier forebulge in the Ionian Basin. This fluid, which precipitates at a maximum depth of 1.5 km, is highly enriched in strontium, attesting for important fluid–rock interaction with the Triassic evaporites, located in diapirs. From this stage, the horizontal tectonic compression increases and the majority of the fluid migrated under high pressure, characterised by brecciated and crack-seal vein. The tectonic burial increased due to the overthrusting, that is pointed out by the increase of the precipitation temperature of the cements. Afterwards, up- or downward migration of SO₄²⁻, Ba²⁺ and Mg²⁺-rich fluids, which migrated probably along the décollement level, allows a precipitation in thermal disequilibrium. This period corresponds to the onset of the thrusting in the Ionian Zone. The last stage characterised the uplift of the Berati belt, developing a selective karstification due likely to the circulation of meteoric fluid.The main results of the fluid flow modelling show that the Upper Cretaceous–Paleocene carbonate reservoirs in the Ionian zone have been charged from the Tortonian onward, and that meteoric fluid migration should have intensely biodegraded the hydrocarbon in place. Concerning the migration paths, it has been demonstrated that the thrusts act principally as flow barriers in Albania, mainly due the occurrence of evaporites (non-permeable), except in the foreland, where they do not occur.  相似文献   

Impact of metallurgy on the geochemical signature of dusts, soils and sediments in the vicinity of Elbasan complex (Albania)     

Aurela Shtiza  Artan Tashko  Rudy Swennen  Adelheit Van den Brande 《Central European Journal of Geosciences》2009,1(1):63-83

An investigation of the metallurgical complex surroundings in Elbasani, Albania used background samples to rule out the level of contamination in the study area. Our results show that atmospheric dust particles and soils are of high concern while overbank sediments and actual river sediments are of lower concern. The heavy metals with concentrations of up to 5 times above the local background values are Zn, Cr, Ni, Cu, Fe and Co in soils; Fe, Cr, Co, Ni, Zn, Pb in dust particles; and, Cr and Zn in the actual river/stream sediments. Due to the small size of the dust particles and the atmospheric transportation mechanism primarily related to prevailing winds, the concern for the transport of dust particles is high, especially with respect to risks associated with inhalation. The people working and living in the vicinity of the metallurgical complex of Elbasani are at the highest risk of exposure. Concerns relating to soils are associated with the potential for translocation of the trace element particles into vegetation, in particular, within the upper part of the plants. Therefore, the consumption of the vegetables grown in the vicinity of the metallurgical site should be avoided. Special attention has been given to the Shkumbini river, where the long residence time of water and particulates may result in transitions of trace elements between dissolved and particulate phases downstream.  相似文献   

Sedimentology of coexisting travertine and tufa deposits in a mounded geothermal spring carbonate system,Obruktepe, Turkey   总被引：1，自引：0，他引：1       下载免费PDF全文

Benjamin Lopez  Gilbert Camoin  Mehmet Özkul  Rudy Swennen  Aurélien Virgone 《Sedimentology》2017,64(4):903-931

The recent discoveries of deeply buried Cretaceous reservoir bodies in the Atlantic Ocean revealed that relationships between the distribution of spring carbonate deposits and faults are poorly understood. The well‐exposed Quaternary deposits at Obruktepe (Denizli Basin, Turkey) provide an opportunity to reconstruct the three‐dimensional sedimentary architecture of such a system. Integration of sedimentological, lithofacies and geochemical analyses reveals complexity in the lateral relationships between sedimentary environments, faults and geothermal spring carbonates. Five environmental systems are distinguished based on the lithofacies analysis: (i) vent; (ii) smooth slope; (iii) travertine‐terrace; (iv) tufa‐barrage; and (v) flood systems. Encrusting, baffling and settling sedimentary processes are reflected in data acquired at several scales, from lithofacies observations to the morphology and arrangement of geobodies, together with microfabrics and stable carbon and oxygen isotope data. Mean values of +4·9‰ δ¹³C and −8·74‰ δ¹⁸O Vienna PeeDee Belemnite reflect geothermal circulation of springwaters. The environmental distribution and lithofacies indicate a lateral continuum between travertine and tufa deposits within this hot spring system. This finding supports two depositional models in which water flow variation is the main control on both CaCO₃ precipitation and the resulting formation of travertine and tufa. The proposed models address the factors responsible for the development of these complex mound‐shaped carbonate spring deposits, and how they are related to fluid circulation at depth and in association with faults.  相似文献