Sequence analytical approach to the Upper Kimmeridgian-Lower Tithonian storm-dominated ramp deposits of the Boulonnais (Northern France). A landward time-equivalent to offshore marine source rocks

An interdisciplinary approach based on high-resolution physical stratigraphy, biostratigraphy, organic matter analysis and clay mineralogy has been applied to the mixed siliciclastic/carbonate Kimmeridgian/Tithonian deposits of the Boulonnais (north-western France). These rocks are the age-equivalents of some of the offshore marine source rocks of the North Sea and were deposited in an overall storm-dominated homoclinal ramp setting which may represent one of the most shore-proximal sediments of this age cropping out in north-western Europe. Comparison with data from the Yorkshire, Dorset, Lorraine and Aquitaine areas allows the discrimination of three major transgressive-regressive sediment packages with disconformities of interregional extent: (1) from the Baylei Zone to top Eudoxus Zone; (2) from the Autissiodorensis Zone to base Scitulus Zone; (3) from the upper Scitulus Zone to the Pectinatus Zone. The lower two regionally correlative disconformities correspond to the sequence boundaries at the top of the Eudoxus Zone and the top of the Autissiodorensis Zone, formed by high-frequency relative sea-level variations during the periods of maximum transgression of the platform. The latter disconformity (the P1 nodule bed) reflects a major tectonically induced reorganization of the north-west European intrashelf sedimentary basin, characterized by a shift in both the location of the main depocentre and the sources of sediment production.     

An appraisal of air quality,thermal comfort,acoustic, and health risk of household kitchens in a developing country

Environmental Science and Pollution Research - Few studies have documented the air quality, noise, thermal comfort, and health risk assessment of household kitchens related to Sub-Sahara Africa. In...     

Potential antitermite compounds from Juniperus procera extracts

Thin layer chromatography (TLC) analysis revealed that destructive distillation of Juniperus procera tree gave ten major components, whereas Croton megalocarpus tree yielded five components. This was confirmed by gas chromatography (GC). The components were isolated by column chromatography and analysed using infrared, ultra-violet, visible and mass spectroscopy (MS) techniques. The whole extract was about 30.3% of the starting material (sawdust) and consisted of 77.5% water and 22.5% oily reddish-brown layer. The extracts had alcoholic and phenolic compounds together with acids. Cedrol, a tertiary tricyclic alcohol, was found to be in the greatest proportion in the oily layer. IR spectra with a peak beyond 3000 cm(-1), UV-VIS absorption maxima at 230 nm and mass spectra with m/e 204 suggested the presence of cedrene in the extract.     

Comparison of particulate mass, chemical species for urban, suburban and rural areas in central Taiwan, Taichung

Aerosol samples for PM2.5, PM(2.5-10) and TSP were collected from June to September 1998 and from February to March 1999 in central Taiwan. Ion chromatography was used to analyze the acidic anions: sulfate, nitrate and chloride in the Universal samples. The ratios of fine particle concentrations to coarse particle concentrations displayed that the fine particle concentrations are almost greater than that of coarse particle concentrations in Taichung area. The average concentrations of PM2.5, PM(2.5-10) and TSP in urban sites are higher than in suburban and rural sites at both daytime and night-time. Chloride dominated in the coarse mode in daytime and in fine mode in night-time. Nitrate can be found in both the coarse and fine modes. Sulfate dominated in fine mode in both daytime and night-time.     

Photooxidation mechanism of nitrogen-containing compounds at TiO2/H2O interfaces: an experimental and theoretical examination of hydrazine derivatives

The photocatalytic oxidation of oxalyldihydrazide, N,N'-bis(hydrazocarbonyl)hydrazide, N,N'-bis(ethoxycarbonyl)hydrazide, malonyldihydrazide, N-malonyl-bis[(N'-ethoxycarbonyl)hydrazide] was examined in aqueous TiO2 dispersions under UV illumination. The photomineralization of nitrogen and carbon atoms in the substrates into N2 gas, NH4+ (and/or NO3-) ions, and CO2 gas was determined by HPLC and GC analysis. The formation of carboxylic acid intermediates also occurred in the photooxidation process. The photocatalytic mechanism is discussed on the basis of the experimental results, and with molecular orbital (MO) simulation of frontier electron density and point charge. Substrate carbonyl groups readily adsorb on the TiO2 surface, and the bonds between carbonyl group carbon atoms and adjacent hydrazo group nitrogen atoms are cleaved predominantly in the initial photooxidation process. The hydrazo groups were photoconverted mainly into N2 gas (in mineralization yields above 70%) and partially to NH4 ions (below 10%). The formation of NO3- ions was scarcely recognized.     

Vertical distribution of Cd, Pb and Zn in soils near smelters in the North of France

The analysis of the horizons of 12 soil profiles confirm occasionally significant levels of Cd, Pb and Zn contamination in the areas surrounding two lead and zinc smelters in the North of France. A pedological approach enabled the original Cd, Pb and Zn content of the horizons to be estimated, based on physico-chemical characteristics of soil unaffected by contamination. The main contamination was found in the upper 20-30 cm. Traces of Cd and Zn contamination were found at a depth of around 2 m. The mobility of the metals may be classified in the following order: Cd>Pb> or =Zn. The concentration profile of a metal seems insufficient to evaluate its movement as the metal could have been leached beyond the contaminated horizons. The depth reached by the metals increases with their concentration in the surface horizon; a decrease in pH and an increase in sand content seem to facilitate their movement. The depth reached by Zn increases with the organic carbon content in the surface horizon. Earthworm galleries act as paths via which metals migrate downwards     

Mercury levels in muscle of two fish species and sediments from the Cartagena Bay and the Ciénaga Grande de Santa Marta, Colombia

Mercury (Hg) content in sediments and muscle from two fish species were determined in Cartagena Bay and Ciénaga Grande de Santa Marta, an industrialized bay and an unpolluted estuary in the Caribbean coast of Colombia. Sampling was conducted four times during March-November 1996, including both the dry and rainy seasons. Significant differences in Hg concentration were detected both for fish and sediments between the two waterbodies. Hg values ranged from 94 to 10,293 microg/kg dry weight (dw) in sediments from Cartagena Bay and between 20 and 109 microg/kg dw in Ciénaga Grande de Santa Marta. Highest Hg concentrations were observed for the omnivorous species Eugerres plumieri, and lowest concentrations were found in the detritivorous Mugil incilis. High Hg concentrations in sediments of Cartagena Bay were detected in front of the sewage discharge of an extinct chlor-alkali plant, with decreasing concentrations in stations far from the source. Our results suggest that Hg can be persistent in the sediments of previously exposed ecosystems and that the use of their biological resources should be avoided until decontamination programs guarantee safe levels of the metal in the environment.     

Flotation of metal-loaded clay anion exchangers. Part I: the case of chromates

Synthetic hydrotalcite-like layered materials are known for their ability to remove anions, like the chromates. These sorbents usually exist in powder form, thereby exhibiting high surface area and rapid kinetics for adsorption, but presenting appreciable problems in the subsequent solid/liquid separation process. Almost complete removals were obtained in this paper, from batchwork dispersed-air flotation in presence of a flocculant. Due to the experienced difficulty of flotation of thermally activated (at 500 degrees C) hydrotalcite metal-loaded particles, the application of various surfactants was studied. Continuous-flow laboratory runs certified also the effectiveness of this combined process of sorptive flotation, a promising innovative treatment technology.     

Dynamics of radionuclide concentrations in calcified tissues of reindeer in the western Russian Arctic

The specific activities of artificial and natural nuclides were determined in bone and teeth of reindeer that had lived before, during, and after nuclear tests on the Archipelago Novaya Zemlya and of reindeer from the nearby mainland region. In bone of reindeer from Novaya Zemlya, 90Sr and 210Pb are the main source of beta-activity, the 210Po is the main source of the alpha activity. In bone of reindeer that lived on Novaya Zemlya during underground tests, the 90Sr activity was relatively high (0.75 +/- 0.20 Bq/g dry weight). In animals that lived after the tests were banned, the level was significantly lower (0.44 +/- 0.17 Bq/g) and did not differ from the level of the 90Sr activity found in the mainland reindeer bone. On Novaya Zemlya, the concentrations of the natural 210Pb in bone of the recent reindeer (0.57 +/- 0.19 Bq/g) is similar to that which was in the teeth of reindeer a hundred years ago (0.65-0.75 Bq/g) and significantly higher than in the recent mainland reindeer from different regions (0.18-0.17 Bq/g).