Geochemical characteristics of mineral air particles emitted inside a clay atomisation plant which introduces waste recycling processes

The objective of this work is to assess the concentrations of three factions of air particles (settable particles, TSP and PM10) and the levels of several toxic elements in a clay atomisation industry through aerosol sampling at several points inside an industrial plant. Mechanical activities, which produce diffuse emissions, are the main process of discharge of particles in both indoor and outdoor workplace environments in the atomisation plant. The levels of As, Cd, Pb, Zn, Ba and Ni increase in the zones with higher concentrations of particles and lower ventilation. The concentrations of As and F are not influenced by the recycling processes. The levels of Cd and Pb do not show great enrichment in air particles collected inside the atomisation plant although the content of both elements is associated with ceramic muck recycling. Finally, the content of B in waste water is mainly transferred in gaseous phase to the atmosphere during the process of drying by atomisation.     

Retrofit-reinforcement of cohesive soil slopes using high strength geotextiles with drainage capability

A series of geotechnical centrifuge physical modeling tests were performed to assess the potential use of a new cost-effective mechanically stabilized earth system for retrofitting marginally stable cohesive slopes. The proposed system utilizes the dual functions of reinforcement and drainage by directly inserting high strength non-woven geotextile strips into slopes, with little or no excavation required behind the slope face. The system significantly increases the factor of safety of potentially unstable cohesive slopes, and can be constructed at less expense and more rapidly than conventional mechanically stabilized earth systems.     

Magmatic zircon oxygen isotopes of 1.88–1.87 Ga orogenic and 1.65–1.54 Ga anorogenic magmatism in Finland

Summary Oxygen isotope ratios of igneous zircon from magmatic rocks in Finland provide insights into the evolution and growth of the Precambrian crust during the Svecofennian orogeny. These data preserve magmatic δ¹⁸O values and correlate with major discontinuities in the lower crust. Oxygen isotope ratios of zircon across the 1.88–1.87 Ga Central Finland granitoid complex (CFGC) range from 5.50‰ to 6.84‰, except for three plutons in contact with the adjacent greenstone and metasedimentary belts (δ¹⁸O(Zrc) = 7.60‰–7.78‰). There is a systematic variation in δ¹⁸O(Zrc) with respect to geographic location in the CFGC, ranging from 6.60±0.23‰ (σ) in the northeast to 5.90±0.40‰ in the west-southwest. These values correlate with a change in crustal thickness and shift in geochemical composition. The oxygen isotope composition of the 1.65–1.54 Ga rapakivi granites and related rocks in southern Finland show a decreasing trend from north to south, independent of their emplacement age. The southern anorogenic granite group has an average δ¹⁸O in zircon of 6.14±0.07‰ and the northern anorogenic group has an average δ¹⁸O in zircon of 8.14±0.59‰. This difference reflects the boundary between island arc terrains accreted during the Paleoproterozoic. Deceased     

Age, distribution, tectonics, and eustatic controls of the Paranense and Caribbean marine transgressions in southern Bolivia and Argentina

Marine transgression onto the South American continent took place at least twice in the Miocene along distinct paleogeographic corridors. The first event occurred between 15 and 13 Ma and the second between 10 and 5? Ma. Each event has particular dominant variables (tectonism, eustacy, sediment accumulation rate) that permitted the preservation of the record and development of the sea on the continent. The 15–13 Ma transgression was tectonically and eustatically controlled, flooding older sedimentary accommodation zones on the South American plate during a global high sea level, whereas the 105? Ma event was predominantly tectonically controlled, generated by tectonic loading created in the Cordillera Oriental fold-and-thrust belt. A new 7.72±0.31 Ma ⁴⁰Ar/³⁹Ar date from the Río Parapetí in Bolivia suggests that the 15–13 Ma transgression registered in Argentina produced no continental connection to the Caribbean transgression, registered in Bolivia, because of temporal constraints.     

Modeling of packed absorption tower for volatile organic compounds emission control

Development of chemical industry and high vapor pressure of volatile organic compounds (VOCs) have been caused that these materials recently be considered as a source of air pollution. These are different methods for separation of VOC from air that absorption by suitable and selective solvent is an efficient method. In this research, mathematical modeling of a packed absorption tower for separation of VOCs from air has been presented. Then, acetone vapors separation in this tower and with Intalox saddle packing has been investigated. Concentration of acetone in inlet air stream was 1.5 mol % which has reduced to 150 ppm (0.015 mol %) in effluent air stream. The results show that the packed absorption tower with this type of packing can separate 99% of acetone vapors. Comparison of the results obtained by Intalox saddle packing with the results obtained by another type of packing (with trade mark of Kerapak patented by Sulzer Company) shows that the tower gives the same efficiency for acetone separation. Thus, the efficiency of absorption process, mainly, depends on solvent type, composition of VOC in feed air, desired composition of VOC in outlet air (or percentage of VOC separation) and pressure drop.     

Détermination expérimentale des paramètres équivalents d'un milieu poreux hétérogène en écoulements uniforme ou radial

Tracer tests are carried out in a heterogeneous porous medium that has a 3D correlated random distribution of the permeabilities. The fitting of numerical models provides the values of equivalent permeability and macrodispersivity characterizing a 2D homogeneous horizontal medium. Different flow configurations are studied: uniform, radial and pump and treat (doublet). The fitted parameter sets are independent of the flow type, except for the doublet. They are greater than the values predicted by stochastic theories, due to the small number of correlation lengths explored by the tracer and the limited extension of the experimental set-up. To cite this article: C. Danquigny, P. Ackerer, C. R. Geoscience 337 (2005).