Biogeochemical processes in a clay formation in situ experiment: Part C - Organic contamination and leaching data

Data interpretation of the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory has led to unexpected observations of anaerobic microbial processes which caused important geochemical perturbations of the Opalinus Clay water in the borehole. The increases of acetate to 146 mg C/L, of DIC to 109 mg C/L and of CH₄ to 0.5 mg C/L were unexpected and could not be explained without the presence of a C source in the system. The organic C fuelling the observed microbial activity was until then unknown. Leaching tests were performed on several polymers used for the fabrication of the PC equipment to identify the source of organic matter (OM). Polyethylene (PE) appears to be very inert and does not release detectable concentrations of dissolved organic C (DOC) (<1 ppb) into the water. Polyurethane (PU) leaches out a dozen different organic compounds accounting for only 13 μg DOC/g PU. Under the conditions of the leaching tests, 1 g of polyamide (PA, Nylon) also releases ∼512 μg of the plasticizer N-Butyl-Benzene-Sulfonamide (NBBS). Soaking tests with polyethylene samples immersed in acetone under conditions similar to those used to remove grease spots on the porous PE filter prior to installation showed that acetone could have been trapped in the PE filter, corresponding to an initial concentration of 1.5 g acetone/L of water. However, the accumulated amount of organic C taken into account from all these components was insufficient to satisfactorily explain the observed microbially mediated reducing perturbation. Finally, large amounts of dissolved organic C were found to be released in the system by the jelly polymer filling the reference compartment of the pH and E_h electrodes permanently installed over 5 years in flow-through cells on the water circulation loop of the PC experiment. Glycerol was further identified by chromatographic analysis as the main organic compound released by the electrodes. From the analysis results, as well as from the geochemical calculations, the most likely primary organic C source fuelling the microbial perturbation was glycerol released from the polymeric gel filling the reference electrodes (1.6 g glycerol/electrode). Other sources, such as acetone, may also have contributed to microbial processes, but only to a minor extent.     

Palynostratigraphy and paleoenvironmental significance of the Cretaceous succession in the Gebel Rissu-1 well,north Western Desert,Egypt

Palynological investigation of the Cretaceous Abu Roash, Bahariya, Kharita, Alamein, Alam El Bueib and Betty formations, encountered in the Gebel Rissu-1 well, north Western Desert, Egypt yielded 27 species of pteridophytic spores, 24 of gymnosperm pollen, 25 of angiosperm pollen and 11 of dinoflagellate cysts in addition to some acritarchs, foraminiferal test linings and freshwater algae. This enabled us to recognize five miospore biozones arranged from youngest to oldest as: Classopollis brasiliensis–Afropollis cf. kahramanensis–Dichastopollenites ghazalataensis Assemblage Zone (Late Cenomanian); Elaterosporites klaszii–Sofrepites legouxae–Afropollis jardinus Assemblage Zone (Middle/Late Albian–Early Cenomanian); Pennipollis peroreticulatus–Duplexisporites generalis-Tricolpates Assemblage Zone (Early Aptian–Early Albian); Tucanopollis crisopolensis–Afropollis sp. Assemblage Zone (Barremian) and Appendicisporites cf. tricornitatus–Ephedripites spp. Assemblage Zone (Late Neocomian).The Early Cretaceous Kharita, Alam El Bueib and the Betty formations encountered in the Gebel Rissu-1 well are interpreted to indicate oxic proximal and distal shelf deposits, characterized by type III/IV, V kerogen, which is gas prone but having little potential to produce hydrocarbons. The Upper Cretaceous Abu Roash and Bahariya formations are characterized by a distal suboxic–anoxic and marginal dysoxic–anoxic environment, and their kerogen type III/II indicates gas/oil prone nature. The Bahariya and Kharita Albian–Cenomanian sediments in the present study witnessed the onset of a semi-arid to arid climate, with local or seasonal humid conditions, based on the continuous high abundance of the elaterates pollen and Afropollis-producing plants that inhabited the paleotropical humid coastal plains.     

南京市地基稳定性区划图

为了城市土地的合理使用，保证建筑物的安全，目前在城市岩土工程问题中对土地的合理利用研究和评价方法不断涌现。本文根据南京市的基岩岩性、地貌特征、覆盖层厚度和第四纪松散沉积物分布情况，划分为五个基本类型，各个分区具有不同的工程地质特征。     

Palynological,palynofacies, paleoenvironmental and organic geochemical studies on the Upper Cretaceous succession of the GPTSW-7 well,North Western Desert,Egypt

The present study of the Abu Roash and Bahariya formations in well GPTSW-7 refines our understanding of the subsurface Cretaceous of the north Western Desert of Egypt. Our investigations are based on the palynological analyses of 71 cuttings samples, of which 24 have also been analyzed for geochemistry, in addition to 3 sidewall cores analyzed for vitrinite reflectance (R_o).