The distributions of particulate atmospheric trace metals and mineral aerosols over the Indian Ocean     

R. Chester  A. S. Berry  K. J. T. Murphy 《Marine Chemistry》1991,34(3-4)

Data are presented for the concentrations of Al, Fe, Mn, Ni, Co, Cr, V, Cu, Zn, Pb and Cd in aerosols collected over two contrasting regions of the Indian Ocean. These are: (1) the northern Arabian Sea (AS), from which samples were collected in the northeast monsoon, during which the region receives an input of crustal material from the surrounding arid land masses; and (2) the Tropical Southern Indian Ocean (TSIO), a remote region from which samples were collected from air masses for which there were no large-scale up-wind continental aerosol sources. The TSIO samples can be divided into two populations: Population I aerosols, collected from air masses which have probably impinged on Madagascar, and Population II aerosols, which have been confined to open-ocean regions to the south of the area.The data indicate that there are strong latitudinal variations in the chemical signatures of aerosols over the Indian Ocean. The input of crustal material to the Arabian Sea gives rise to an average Al concentration of about 1000 ng m⁻³ of air in the northeast monsoon regime. As a result, the concentrations of all trace metals are relatively high, and the values of crustal enrichment factors are less than 10 for most metals, in the AS aerosols. In contrast, TSIO Population II ‘open-ocean southern air’ sampled during the southwest monsoon season, has an average Al concentration of only about 10 ng m⁻³ of air. Trace metal concentrations in the TSIO ‘open-ocean southern air’ during the southwest monsoon season are representative of ‘clean’ remote marine air and are generally similar to those reported over the central North Pacific.Mineral dust concentrations over the Indian Ocean decrease in a north to south direction, from about 15–20 μg m⁻³ of air in the extreme north to about 0.01–0.25 μg m⁻³ of air in the far south. The deposition of mineral dust over the northern Arabian Sea can account for approximately 75% of the non-carbonate material incorporated into the underlying sediments.In the Arabian Sea the dissolved atmospheric inputs of all the trace metals, with the exception of Cu and Co, exceed those from fluvial run-off by factors which range from 9.6 for Pb to 1.6 for Cr.  相似文献   

Measuring Urban Streetscapes for Livability: A Review of Approaches   总被引：1，自引：0，他引：1  

Chester Harvey  Lisa Aultman-Hall 《The Professional geographer》2016,68(1):149-158

Increasing interest in urban livability demands that geographers and planners more precisely define what constitutes a livable streetscape, a fundamental building block of urban places. Widespread examination of streetscape livability will require precise and efficient measurements of (1) physical characteristics at the spatial scale of individual streetscapes and (2) indicators of experiential quality based on revealed behavior or stated preference. This article reviews approaches to collecting both types of measurements, showing that innovative methods using geographic information systems (GIS), Internet-enabled surveys, and even social media could be useful complements to traditional qualitative methods for collecting streetscape measurements.  相似文献   

MARLI: a mobile application for regional landslide inventories in Ecuador     

Sellers  Chester Andrew  Buján  Sandra  Miranda  David 《Landslides》2021,18(12):3963-3977

The regions of Central and South America most susceptible to the occurrence of landslides will become even more vulnerable in the context of climate change. The Josefina disaster, in 1993, demonstrated both the vulnerability of local infrastructures and communities in the Paute River basin (Ecuador). Since this natural phenomena, several landslide inventories and susceptibility studies were developed, revealing the vulnerability of the Paute River basin to unstable terrain and the need for further studies throughout the basin. Despite this, no studies have been done since then to update the information generated. This paper describes a Mobile Application for Regional Landslide Inventories (MARLI), a simple but efficient open-access platform to report landslide events using the Open Data Kit system. Its design makes reporting fast, simple and cost-effective with an added benefit, and a specialized knowledge is not required for its use. MARLI was tested for the collection of landslides in Cuenca (Ecuador). From the data taken in the field, it was possible to analyze the performance and suitability of collected data and compare the results with regional inventories in the same area. Additionally, these results can be used for the elaboration and update of large-scale inventories or the training of automatic identification systems of landslides and later evaluation of their precision in a small-medium scale. Likewise, this product constitutes a fundamental input for the formulation of mitigation strategies, to formulate the appropriate response and in time, also the elaboration of reconstruction plans before the increase in the occurrence of such phenomena.

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Fabric evolution and crack propagation in salt during consolidation and cyclic compression tests     

Shen  Xianda  Ding  Jihui  Lordkipanidze  Ilia  Arson  Chloé  Chester  Judith S.  Chester  Frederick M. 《Acta Geotechnica》2021,16(6):1679-1697

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The Valle del Bove, Mount Etna: Its origin and relation to the stratigraphy and structure of the volcano — Reply     

J.E. Guest  D.K. Chester  A.M. Duncan 《Journal of Volcanology and Geothermal Research》1985,26(3-4)

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The quaternary stratigraphy of mount Etna,sicily: the effects of differing palaeoenvironments on styles of volcanism     

A. M. Duncan  D. K. Chester  J. E. Guest 《Bulletin of Volcanology》1984,47(3):497-516

Using recently published radiometric dates of important horizons within the Etna succession, correlations are proposed with the Late Quaternary biostratigraphies of the Italian mainland and the Mediterranean sea floor. This enables palaeoclimatic, palaeohydrological and palaeogeographical conditions on Etna to be established at stages in the volcano's evolution. It is argued that several major volcaniclastic suites were formed through the operation of processes that were under complex environmental, rather than simple volcanological control alone. In particular it is suggested that certain episodes of phreatomagmatic and laharic activity cannot be related to episodes of more evolved magma production, but rather to times during which the environment, height and configuration of Etna favoured the eruption and emplacement of these deposits. The authors reiterate their explanation of the formation of the Valle del Bove through processes of massive slope failure and indicate that conditions favouring this occurred at an appropriate stage in the history of the volcano. It is concluded that on active basaltic volcanoes, especially those like Etna which are also high mountains, the explanation of more violent phases requires the consideration of both internal volcanological and external environmental and morphological variables and that this is particularly important when its development has been set within the context of Late Quaternary environmental change. Finally the implications of these findings for the assessment of hazard are considered.

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Resumé Utilisant récemment des publications sur les datations radiométriques de couches importantes à l'intérieur de la succession de l'Etna, nous proposons d'établir des corrélations entre les biostratigraphies du Quaternaire Récent de la Péninsule Italienne et due fond marin Méditerranéen. Par ce procédé, nous pouvons établir les conditions paléoclimatiques, paléohydrologiques et paléogéographiques par stades selon l'évolution du volcan, capendant il faut tenir compte du fait que plusieurs suites volcaniclastiques majeures se sont formées à partir d'opérations de processus qui etaient eux-mêmes sous une complexe influence écologique plutôt que volcanologique seulement. Il est suggéré, en particulier, que certains épisodes d'activités phreatomagmatiquer et laharique ne puissent être reliés à des épisodes de production de magma plus elaborée, mais plutôt à des périodes pendant lesquelles le milieu, la hauteur et la configuration de l'Etna ont favorisé l'éruption et la localisation de ces dépôts. Les auteurs réitèrant leur explication sur la formation de la Vallée del Bove selon un processus de rupture radicale de pente et indiquent que les conditions favorables à ce dernier sont survenues à un stade opportun dans l'histoire du volcan. Ceci amènè à conclure que, sur des volcans basaltiques actifs comme l'Etna en particulier qui sont egalement des montagnes élevées, l'explication de phases plus violentes demande la consideration de facteurs volcanologiques internes d'une part, et morphologiques et écologiques externes d'autre part et que ceci est essential lorsque son développement a été fixé dans le contexte du changement de milieu au Quaternaire Recent. Enfin, il faut tenir compte de l'implication de ces résultats face aux incidences de risques.

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Post-collapse volcanic history of calderas on a composite volcano: an example from Roccamonfina,southern Italy     

P D Cole  J E Guest  A M Duncan  D K Chester  R Bianchi 《Bulletin of Volcanology》1992,54(4):253-266

Roccamonfina, part of the Roman Potassic Volcanic Province, is an example of a composite volcano with a complex history of caldera development. The main caldera truncates a cone constructed predominantly of this caldera may have been associated with one of the ignimbritic eruptions of the Brown Leucitic Tuff (BLT) around 385 000 yr BP. The Campagnola Tuff, the youngest ignimbrite of the BLT, however, drapes the caldera margin and must postdate at least the initial stages of collapse. During the subsequent history of the caldera there were several major explosive eruptions. The largest of these was that of the Galluccio Tuff at about 300 000 yr BP. It is likely that there was further collapse within the main caldera associated with these eruptions. It is of note that despite these subsequent major explosive eruptions later collapse occurred within the confines of the main caldera. Between eruptions caldera lakes developed producing numerous lacustrine beds within the caldera fill. Extensive phases of phreatomagmatic activity generated thick sequences of pyroclastic surge and fall deposits. Activity within the main caldera ended with the growth of a large complex of basaltic trachyandestite lava domes around 150 000 yr BP. Early in the history of Roccamonfina sector collapse on the northern flank of the volcano formed the northern caldera. One of the youngest major events on Roccamonfina occurred at the head of this northern caldera with explosive activity producing the Conca Ignimbrite and associated caldera. There is no evidence that there was any linkage in the plumbing systems that fed eruptions in the main and northern calderas.  相似文献   

Mascali,Mount Etna Region Sicily: An Example of Fascist Planning During the 1928 Eruption and Its Continuing Legacy     

Chester  David K.  Duncan  Angus M.  Dibben  Christopher  Guest  John E.  Lister  Philip H. 《Natural Hazards》1999,19(1):29-46

The 1928 eruption of Etna, Sicily, although the largest such event this century, has not been studied in detail. In this paper the nature of the eruption, the destruction it caused – including the complete devastation of the town of Mascali (pre-eruption population 2,000) – and emergency responses of the authorities to it are reviewed in the context of fascist politics and planning priorities. It is contended that, although at one level the response to the 1928 eruption was successful, at another fascism merely continued and enhanced a reactive, propitiatory approach to hazard mitigation. We argue that this legacy was not successfully overcome until the middle of the nineteen eighties. Finally contemporary Italian moves towards a more proactive approach to disaster planning, both generally and in the context of Etna, are discussed.  相似文献   

Trace elements in sediments from the lower Severn Estuary and Bristol Channel     

R Chester  J.H Stoner 《Marine pollution bulletin》1975,6(6):92-96

Sediments are very important as trace element traps, particularly in estuaries and high levels of heavy metals have previously been reported in sediments in the Severn estuary and parts of the Bristol Channel. In this paper the concentration and distribution of thirteen elements are reported. The concentrations of tin, zinc and lead, in particular, may have ecological consequences and should be viewed with some concern.  相似文献   

Depositional history of artificial radionuclides in the Ross Ice Shelf,Antarctica     

Minoru Koide  Robert Michel  Edward D. Goldberg  Michael M. Herron  Chester C. Langway 《Earth and Planetary Science Letters》1979,44(2):205-223

The annual fluxes of artificial radionuclides (²³⁸Pu,^239+240Pu,²⁴¹Am,¹³⁷Cs,⁹⁰Sr and³H) from the atmosphere to the Ross Ice Shelf in Antarctica were determined from measurements in strata dated by²¹⁰Pb. Recognizable sources include the U.S. tests (Mike-Ivy and Castle Hill) in the early 1950s, the U.S.S.R. tests of the early 1960s, the SNAP-9A burnup of 1964 and the French and Chinese tests in the late 1960s and 1970s. There are several problems still awaiting resolution: the differences in atmospheric chemistries of fission products and of transuranics produced in weapons tests and the anomalous fluxes of²³⁸Pu to the ice shelf which do not appear to reflect a one-year stratospheric residence. There is no evidence for a smearing of the fallout record as a consequence of diffusion of these radionuclides in the glacial column.  相似文献