Sulfides in petroleum

The homologous series of terpenoid sulfides previously reported to be present in Athabasca bitumen have been detected in a variety of petroleums from the Western Hemisphere. All 22 samples examined, ranging in age from Devonoan to Cretaceous, contained the terpenoid sulfides. A method is described for the isolation of sulfides from petroleums based on the selective oxidation of sulfides to more polar sulfoxides which are easily removed from the mixture and their subsequent reduction to sulfides. The sulfide content in the petroleum maltenes examined ranged from 0.3 to 16.1% w/w. In addition to the bicyclic and tetracyclic terpenoid sulfides a new series of tricyclic terpenoid sulfides has been identified, and the details of the isoprenoid side chain have been elucidated for all three homologous series. The distributions by carbon number of the bicyclic and tetracyclic homologous series of terpenoid sulfides show pronounced variations which are attributed to thermal maturity and degree of water washing of the petroleum, thus the ability to identify terpenoid sulfides should provide a useful tool for oil-oil and oil-source rock correlation studies. The bicyclic and tricyclic terpenoid sulfides have the same carbon framework as the carotenoids which suggest that these sulfides were accessory pigments in photosynthesis.     

Surface energy balance measurements at a tropical site in West Africa during the transition from dry to wet season

Summary In one of the first micrometeorological experiments at a tropical site in West Africa, direct measurements of all surface energy balance components were carried out. The experiment NIMEX-1 in Ile-Ife, Nigeria (7°33′ N, 4°33′ E), was conducted from February 19, 2004 to March 9, 2004, during the transition from the dry to the wet season. Three typical weather situations could be observed: firstly, monsoonal winds from the southwest blew over desiccated soils. Almost 100% of the available energy at the surface was transformed into sensible heat flux. Secondly, after several thundershowers, monsoonal winds swept over soils of increased water content, which led to a partitioning of the available energy corresponding to Bowen ratios between 0.3 and 0.5. Thirdly, harmattan winds advected dry dusty air from northern directions, which reduced the incoming shortwave radiation. Again, Bowen ratios range from 0.3 to 0.5 during daytime, whereas latent heat fluxes are still high during the night due to the advection of very dry air. No systematic non-closure of the surface energy balance could be found for the NIMEX-1 dataset. Unlike other experiments in Europe, most of the ogives for the sensible and latent heat flux were found to be convergent during NIMEX-1 in Ile-Ife. This can be attributed to the homogeneity of the surrounding bush, which lacks the defined borders found in agriculturally cultivated landscapes.     

The Space and Time Variations of Water Quality and Water Pollution Dynamics in the Oka Basin

Water Resources - The space–time variations in the Oka basin water chemistry have been considered. The specific features in the river water and groundwater pollution along the Oka channel and...     

Linking gold mineralization to regional-scale drivers of mineral systems using in situ U–Pb geochronology and pyrite LA-ICP-MS element mapping

Proterozoic orogens commonly host a range of hydrothermal ores that form in diverse tectonic settings at different times. However, the link between mineralization and the regional-scale tectonothermal evolution of orogens is usually not well understood, especially in areas subject to multiple hydrothermal events.Regional-scale drivers for mineral systems vary between the different classes of hydrothermal ore, but all involve an energy source and a fluid pathway to focus mineralizing fluids into the upper crust. The Mount Olympus gold deposit in the Proterozoic Capricorn Orogen of Western Australia, was regarded as an orogenic gold deposit that formed at ca. 1738 Ma during the assembly of Proterozoic Australia. However,the trace element chemistry of the pyrite crystals closely resembles those of the Carlin deposits of Nevada,with rims that display solid solution gold accompanied by elevated As, Cu, Sb, Hg, and Tl, surrounding gold-poor cores. New SHRIMP UeP b dating of xenotime intergrown with auriferous pyrite and ore-stage alteration minerals provided a weighted mean~(207) Pb*/~(206) Pb* date of 1769 ± 5 Ma, interpreted as the age of gold mineralization. This was followed by two discrete episodes of hydrothermal alteration at 1727 ± 7 Ma and 1673 ± 8 Ma. The three ages are linked to multiple reactivation of the crustal-scale Nanjilgardy Fault during repeated episodes of intracratonic reworking. The regional-scale drivers for Carlin-like gold mineralization at Mount Olympus are related to a change in tectonic regime during the final stages of the intracratonic 1820 -1770 Ma Capricorn Orogeny. Our results suggest that substantial sized Carlin-like gold deposits can form in an intracratonic setting during regional-scale crustal reworking.     

Design of controlled elastic and inelastic structures

One of the founders of structural control theory and its application in civil engineering,Professor Emeritus Tsu T.Soong,envisioned the development of the integral design of structures protected by active control devices.Most of his disciples and colleagues continuously attempted to develop procedures to achieve such integral control.In his recent papers published jointly with some of the authors of this paper,Professor Soong developed design procedures for the entire structure using a design-redesign proce...     

Hydrogen photoproduction ofA. Variabilis incorporated in a photobioreactor

H₂ photoproduction and nitrogenase activities in two strains ofAnabaena variabilis marked wild type ATCC 29413 and mutant PK84 exposed to thermal stress (temperature higher than the normal incubation temperature of 30°C) were studied. Cultures of both strains collected from any interval of logarithmic growth phase exhibited high H₂ photoproduction and nitrogenase activities when exposed to limited time heat shock during the assay process. In contrast, the algal H₂ photoproduction rate of both strains fluctuated with long term thermal stress caused by increasing the growth temperature from 30°C to 36°C.

The changes of nitrogenase (the key H₂ photobiosynthetic enzyme) activities in the mutant PK84 showed variation tendency similar to that of H₂ photoproduction during exposure to thermal stress, indicating that fluctuation of H₂ photoproduction in the mutant was mainly due to the variation of nitrogenase activities. A temporary maximal H₂ photoproduction in the mutant PK84 (wild type ATCC29413) was observed when cells grew at 36°C for 14 (6) days. However, the responses of nitrogenase activities in the wild type to thermal stress were not completely similar to those in the mutant in spite of similar variations of H₂ photoproduction in both strains. The data obtained in these studies suggested that the activities of other enzymes (in the wild strain) involved in H₂ photoproduction were affected by thermal stress since H₂ photoproduction maximized or dropped to 0 without variation tendency similar to that of nitrogenase activities.

Furthermore, an enhancement of H₂ photoproduction speed of the mutant strain cultured in a 4.4 L laboratory photobioreactor was also observed when it was subjected to short time continuous charge of argon, and temperature rise.

All these results indicated that high temperature plays an important role in the photo-autotrophic H₂ photoproduction, and that long term thermal stress is unfavourable for net H₂ photoproduction in both strains ofA. variabilis though short-time heat shock is conducive to H₂ photoproduction.

     

Critical rainfall statistics for predicting watershed flood responses: rethinking the design storm concept

Recent advances have been made to modernize estimates of probable precipitation scenarios; however, researchers and engineers often continue to assume that rainfall events can be described by a small set of event statistics, typically average intensity and event duration. Given the easy availability of precipitation data and advances in desk‐top computational tools, we suggest that it is time to rethink the ‘design storm’ concept. Design storms should include more holistic characteristics of flood‐inducing rain events, which, in addition to describing specific hydrologic responses, may also be watershed or regionally specific. We present a sensitivity analysis of nine precipitation event statistics from observed precipitation events within a 60‐year record for Tompkins County, NY, USA. We perform a two‐sample Kolmogorov–Smirnov (KS) test to objectively identify precipitation event statistics of importance for two related hydrologic responses: (1) peak outflow from the Six Mile Creek watershed and (2) peak depth within the reservoir behind the Six Mile Creek Dam. We identify the total precipitation depth, peak hourly intensity, average intensity, event duration, interevent duration, and several statistics defining the temporal distribution of precipitation events to be important rainfall statistics to consider for predicting the watershed flood responses. We found that the two hydrologic responses had different sets of statistically significant parameters. We demonstrate through a stochastic precipitation generation analysis the effects of starting from a constrained parameter set (intensity and duration) when predicting hydrologic responses as opposed to utilizing an expanded suite of rainfall statistics. In particular, we note that the reduced precipitation parameter set may underestimate the probability of high stream flows and therefore underestimate flood hazard. Copyright © 2016 John Wiley & Sons, Ltd.