Hydrogeochemical modeling of organo-metallic colloids in the Nsimi experimental watershed,South Cameroon   总被引：1，自引：0，他引：1  

M. Sekhar  Jean-Jacques Braun  K. V. Hayagreeva Rao  Laurent Ruiz  Henri Robain  Jérôme Viers  Jules Rémy Ndam  Bernard Dupré 《Environmental Geology》2008,54(4):831-841

This paper presents a hydrogeochemical modeling code HYDROS, which combines the multi-component transport model with equilibrium speciation module MINTEQA2. The processes of adsorption, aqueous speciation and mineral precipitation/dissolution are represented in the model. The numerical model uses a sequential iterative approach for solving the solute transport and the equilibrium geochemistry modules. Further the transport part is solved using an operator split approach wherein a finite volume method is used for solving the advective equations while a classical finite difference method is employed for solving the dispersive equations. The model performance is evaluated by comparing it with MINTOX for a literature problem. HYDROS is then applied to the case study of the transfer of transition metals with organic colloids in the swamp groundwater system of the experimental Nsimi watershed, representative of the humid tropical ecosystem of the South Cameroon Plateau. Field observations at the site swamp system suggest that the carbon is mainly transferred as organic colloids (i.e., dissolved organic carbon) produced by the slow biodegradation of the swamp organic matter. Using HYDROS, the behaviour of Al(III) and Fe(III) elements in the base flow system is simulated during inter rain events of a short rainy season (May–June 1996). The elemental time-series for Al, Fe, Cl, pH compare well with the simulation results. The colloids are found to have a strong impact on the mobilization and transfer of Al(III) and Fe(III), which are considered to have low mobility in weathering environment.  相似文献   

The Deep Decarbonization Pathways Project (DDPP): insights and emerging issues     

Chris Bataille  Henri Waisman  Michel Colombier  Laura Segafredo  Jim Williams 《Climate Policy》2016,16(4):S1-S6

  相似文献   

The location of infinite electrodes in pole–pole electrical surveys: consequences for 2D imaging     

Henri Robain  Yves Albouy  Michel Dabas  Marc Descloitres  Christian Camerlynck  Pierre Mechler  Alain Tabbagh 《Journal of Applied Geophysics》1999,41(4):588

In 2D-multielectrode electrical surveys using the pole–pole array, the distance to ‘infinite electrodes' is actually finite. As a matter of fact, the available cable length generally imposes a poor approximation of theoretical location of these electrodes at infinity. This study shows that in most of the cases, the resulting apparent resistivity pseudosection is strongly distorted. Numerical simulation validated by field test also shows that a particular finite array provides results that are as close as possible to the ones of the ideal pole–pole array. This is achieved when two conditions that are weaker than an infinite location are fulfilled: (i) the ‘infinite electrodes' are placed symmetrically on both sides of the in-line electrodes with a spread angle of 30° and (ii) the length of ‘infinite lines' is at least 20 times the greatest distance between in-line electrodes. The electrical 2D image obtained with this enhanced array is the least distorted one with respect to the pole–pole image. The apparent resistivities are generally underestimated, but this deviation is almost homogeneous. Though the shift cannot be determined a priori, the interpretation of such an image with direct or inverse software designed for pole–pole data provides an accurate interpretation of the ground geometry.  相似文献   

Precise Quantitative Determination of Niobium at Low Level Concentrations in Geological Samples by WD-XRF     

Joël Etoubleau  Pierre Cambon  Henri Bougault  Jean-Louis Joron 《Geostandards and Geoanalytical Research》1999,23(2):187-195

  相似文献   

The origin of the strong soft excess and puzzling iron line complex in Mkn 841     

P. O. Petrucci  G. Ponti  G. Matt  L. Maraschi  J. Malzac  M. Mouchet  C. Boisson  A. Longinotti  K. Nandra  P. Ferrando  G. Henri 《Astronomische Nachrichten》2006,327(10):1043-1046

Mkn 841 has been observed during 3 different periods (January 2001, January 2005 and July 2005) by XMM‐Newton for a total cumulated exposure time of ∼108 ks. We present in this paper a broad band spectral analysis of the complete EPIC‐pn data sets. These observations confirm the presence of the strong soft excess and complex iron line profile known to be present in this source since a long time. They also reveal their extreme and puzzling spectral and temporal behaviors. Indeed, the 0.5–2 keV soft X‐ray flux decreases by a factor 3 between 2001 and 2005 and the line shape appears to be a mixed of broad and narrow components, both variable but on different timescales. The broad‐band 0.5–10 keV spectra are well described by a model including a primary power law continuum, a blurred photoionized reflection and a narrow iron line, the blurred reflection fitting self‐consistently the soft excess and the broad line component. The origin and nature of the narrow component is unclear. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Organic matter dynamics and budgets in the turbidity maximum zone of the Seine Estuary (France)     

Josette Garnier  Gilles Billen  Stéphanie Even  Henri Etcheber  Pierre Servais 《Estuarine, Coastal and Shelf Science》2008

Organic matter was studied in the turbidity maximum zone (TMZ) of the Seine Estuary during 8 tidal cycles from April to October in 2001, 2002 and 2003, covering a salinity range from 0 to 27. The hydrological conditions were quite varied (extremely wet in 2001, unusually dry in 2003). A particularly striking feature is the high organic matter content in the suspended solids (SS) of the Seine estuary (4–5%).  相似文献   

Small-scale instabilities of an island wake flow in a rotating shallow-water layer     

Samuel Teinturier  Alexandre Stegner  Henri Didelle  Samuel Viboud 《Dynamics of Atmospheres and Oceans》2010

  相似文献   

On the regional distribution of mitigation costs in a global cap-and-trade regime     

Gunnar Luderer  Enrica DeCian  Jean-Charles Hourcade  Marian Leimbach  Henri Waisman  Ottmar Edenhofer 《Climatic change》2012,114(1):59-78

This paper analyzes the regional distribution of climate change mitigation costs in a global cap-and-trade regime. Four stylized burden-sharing rules are considered, ranging from GDP-based permit allocations to schemes that foresee a long-term convergence of per-capita emission permits. The comparison of results from three structurally different hybrid, integrated energy-economy models allows us to derive robust insights as well as identify sources of uncertainty with respect to the regional distribution of the costs of climate change mitigation. We find that regional costs of climate change mitigation may deviate substantially from the global mean. For all models, the mitigation cost average of the four scenarios is higher for China than for the other macro-regions considered. Furthermore, China suffers above-world-average mitigation costs for most burden-sharing rules in the long-term. A decomposition of mitigation costs into (a) primary (domestic) abatement costs and (b) permit trade effects, reveals that the large uncertainty about the future development of carbon prices results in substantial uncertainties about the financial transfers associated with carbon trade for a given allocation scheme. This variation also implies large uncertainty about the regional distribution of climate policy costs.  相似文献   

Superimposed tectonic and hydrothermal events during the late-orogenic extension in the Western French Massif Central: a structural and ⁴⁰Ar/³⁹Ar study     

Jean-Yves Roig  Michel Faure  & Henri Maluski 《地学学报》2002,14(1):25-32

In the Western French Massif Central, the Argentat fault is a major structure through which As–Au fluids percolated in the Late Carboniferous along brittle fractures. New petrostructural investigations show that an early ductile normal-dextral faulting, coeval to leucogranite emplacement took place during the Late Visean syncollisional extension of the belt and was accompanied by a hydrothermal event marked by the growth of muscovites whose ⁴⁰Ar/³⁹Ar ages cluster around 335 Ma. This early fluid channelling is associated with brittle deformation only in the hangingwall of the Argentat fault, whereas ductile deformation is restricted to the footwall. These results provide new evidence for the upper crust implication during the syncollisional extension in the French Massif Central. This study stresses the interest of a detailed multimethod analysis to characterize hydrothermal processes, especially in basement areas where the tectonic, plutonic and metamorphic evolution is polyphased.  相似文献   

B) UNESCO—WMO IHD     

Henri Schoeller 《水文科学杂志》2013,58(2):127-139

  相似文献