1,833 research outputs found
δ Orionis: Further temporal variability and evidence for small-scale structure in the interstellar medium
We report here the detection of both spatial and temporal variations in interstellar absorption in the line of sight to δ Orionis. First, we present new high-resolution (R≈110 000) observations of the interstellar D lines of Na i towards both δ Ori A and C. Comparison of these spectra highlights variations in absorption between the two stars, indicative of small-scale spatial structure in the interstellar medium in this direction over distances of less than ≈15 000 au (the projected separation of the two stars). Components with the largest Na i column densities and lowest velocity dispersions are, in general, found to be subject to the greatest differences; in fact the narrowest component detected is only observed in one of the sightlines. This effect has also been reported by Meyer & Blades. Secondly, we present new ultra-high-resolution (R≈900 000) Na i D1 observations and high-resolution (R≈110 000) Ca ii H & K observations of δ Ori A which, through ultra-high-resolution work conducted between 1994 and 2000, has been shown to exhibit a time-variable interstellar Na i absorption component. These new observations, while revealing the further reduction in intensity of the time-variable Na i absorption, indicate constant Ca ii absorption over the same period. This results in a dramatic reduction in the Na°/Ca+ abundance ratio, perhaps indicating the line of sight to be gradually probing a less-dense outer region of an absorbing filament
Natural organic matter in sedimentary basins and its relation to arsenic in anoxic ground water: the example of West Bengal and its worldwide implications
In order to investigate the mechanism of As release to anoxic ground water in alluvial aquifers, the authors sampled ground waters from 3 piezometer nests, 79 shallow (80 m) wells, in an area 750 m by 450 m, just north of Barasat, near Kolkata (Calcutta), in southern West Bengal. High concentrations of As (200-1180 mug L-1) are accompanied by high concentrations of Fe (3-13.7 mgL(-1)) and PO4 (1-6.5 mg L-1). Ground water that is rich in Mn (1-5.3 mg L-1) contains <50 mug L-1 of As. The composition of shallow ground water varies at the 100-m scale laterally and the metre-scale vertically, with vertical gradients in As concentration reaching 200 mug L-1 m(-1). The As is supplied by reductive dissolution of FeOOH and release of the sorbed As to solution. The process is driven by natural organic matter in peaty strata both within the aquifer sands and in the overlying confining unit. In well waters, thermotolerant coliforms, a proxy for faecal contamination, are not present in high numbers (<10 cfu/100 ml in 85% of wells) showing that faecally-derived organic matter does not enter the aquifer, does not drive reduction of FeOOH, and so does not release As to ground water.Arsenic concentrations are high (much greater than50 mug L-1) where reduction of FeOOH is complete and its entire load of sorbed As is released to solution, at which point the aquifer sediments become grey in colour as FeOOH vanishes. Where reduction is incomplete, the sediments are brown in colour and resorption of As to residual FeOOH keeps As concentrations below 10 mug L-1 in the presence of dissolved Fe. Sorbed As released by reduction of Mn oxides does not increase As in ground water because the As resorbs to FeOOH. High concentrations of As are common in alluvial aquifers of the Bengal Basin arise because Himalayan erosion supplies immature sediments, with low surface-loadings of FeOOH on mineral grains, to a depositional environment that is rich in organic mater so that complete reduction of FeOOH is common. (C) 2004 Published by Elsevier Ltd
Book Reviews:THE LIFE AND WORK OF PROFESSOR J. W. GREGORY FRS (1864-1932): GEOLOGIST, WRITER AND EXPLORER
Geology behind barbed wire: James Alfred Richardson (1914-2007) and the Richardson Award of the Geologists' Association
The Richardson Award, for the best paper published annually in the Proceedings of the Geologists’ Association, was established in 1996. This paper describes the life of the Richardson family: James (‘Jim’) Richardson, the instigator of the Award, his wife Doris and their only son, Gwyn (who died in infancy). The focus is mainly on Richardson's education in the United Kingdom and early career as a field and mining geologist with the Geological Survey Department of the Federated Malay States (Malaysia) and how, having been caught up in WWII, he and his geological colleagues kept thoughts of geology alive during their time as Prisoners of War under the Japanese in Singapore, Thailand and Burma (1942–45). One of the relatively few survivors of the infamous ‘Death Railway’, his subsequent career as a petroleum geologist in the Netherlands, Venezuela, USA and Australia; and as a geologist involved in mineral exploration, artist and local historian in Australia is also described
Etymology in the Earth Sciences: from 'geologia' to 'geoscience'
The origin and usage through time of geologia, geognosy, geogony, oryctognosy, geology and geophysics, as characterised by their frequency of occurrence in the Google Books Ngram Corpus, is discussed. The English, French, German, Italian and Spanish corpuses used in this study have been normalised over the same timespan using the average frequencies of occurrence of the same set of ‘neutral’ words in each language (as advocated by Younes and Reips 2019). Use of the term geology is found to predate publication of James Hutton's Theory of the Earth in 1795 by about 100 years; geognosy, oryctognosy and geogony, much less commonly used, became established in the 1780s and began to fall out of use around 1820. The terms geologist, and geognost follow a similar pattern. The emergence of geophysics is a less familiar field: While the phrases physics of the Earth and physical geography can both be traced back to the early 1700s, geophysics only began to be used in the early 1800s and did not really become common until about 1860; geophysicist becomes common in German after 1860, but more generally after 1880. The first geophysics-related publications were bulletins from magnetic and seismic observatories and its first dedicated journal, Beiträge zur Geophysik, began publication in 1887, eighty years after the formation of The Geological Society of London. The tems earth science and geoscience, popular today, have steadily increased in their usage since being introduced in the 1880s and 1930s respectively
A petrologist in South Africa: Frederick Henry Hatch and the Witwatersrand Goldfield
The English geologist, Frederick Henry Hatch (1864–1932), today mainly recalled for a textbook on igneous petrology, emigrated to South Africa, where, in the years between 1892 and 1906, he became one of the pioneers of the geology of the Transvaal and the Witwatersrand Goldfield. This article reviews his life and, in particular, his work during this period which led to his becoming a mining geologist with connections to many of the world's goldfields, set against the political background of the Boer War which influenced the course of his work
The life and work of Robert J. Adcock. Part II: biography and establishment of authorship
Between 1870 and 1896, the American mathematician Robert Jackson Adcock (1826–1895) contributed a number of short articles to early mathematical journals such as The Analyst. His biography is given here for the first time. An obscure figure hitherto associated with the history of regression analysis and least-squares, he has, on occasion, been confused with a nephew of the same name. Before the American Civil War, Adcock was first a pupil and then taught at the Western Military Institute, which became the Kentucky Military Institute, near Frankfort, Kentucky. Afterwards, despite occasionally being hospitalized during periods of mental illness, he became a wealthy farmer who could afford mathematical recreation as a hobby. His self-published pamphlet ‘Gravitation to the sphere and the two ellipsoids of revolution’ (1872), recently discovered in the Library of the Royal Society, is discussed in Part I. Here we establish his authorship of all mathematical works by ‘R. J. Adcock’
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