Alternative data reduction procedures for UVES: Wavelength calibration and spectrum addition

This paper addresses alternative procedures to the ESO supplied pipeline procedures for the reduction of UVES spectra of two quasar spectra to determine the value of the fundamental constant $\mu =M_p/M_e$ at early times in the universe. The procedures utilize intermediate product images and spectra produced by the pipeline with alternative wavelength calibration and spectrum addition methods. Spectroscopic studies that require extreme wavelength precision need customized wavelength calibration procedures beyond that usually supplied by the standard data reduction pipelines. An example of such studies is the measurement of the values of the fundamental constants at early times in the universe. This article describes a wavelength calibration procedure for the UV–visual Echelle spectrometer on the very large telescope, however, it can be extended to other spectrometers as well. The procedure described here provides relative wavelength precision of better than $3\times {10}^{-7}$ for the long-slit Thorium–Argon calibration lamp exposures. The gain in precision over the pipeline wavelength calibration is almost entirely due to a more exclusive selection of Th/Ar calibration lines.     

Speculations on the petroleum geology of the accretionary body: an example from the central Aleutians

In the 300 km wide Adak-Amlia sector of the central Aleutian Trench ≈ 36 000 km³ of offscraped trench fill makes up the wedge-shaped mass of the Aleutian accretionary body. Within this wedge, seismic reflection profiles reveal an abundance of potential hydrocarbon-trapping structures. These structures include antiforms, thrust and normal faults, and stratigraphic pinchouts. Maximum closure on these features is 2 km. In addition, the silt and possibly sand size sediment within the offscraped turbidite deposits, and the porous diatomaceous pelagic deposits interbedded with and at the base of the wedge, may define suitable reservoirs for the entrapment of hydrocarbons. Potential seals for these reservoirs include diagenetically-altered and -produced siliceous and carbonate sediment. The organic carbon input into the central Aleutian Trench, based on carbon analyses of DSDP Legs 18 and 19 core samples, suggests that the average organic carbon content within the accretionary body is approximately 0.3–0.6%. Heat flow across the Aleutian Terrace indicates that at present the oil generation window lies at a depth of 3–6.5 km. At depths of 8 km (which corresponds to the maximum depth the offscraped sediment has been seismically resolved beneath the lower trench slope), the probable high (170–180°C) temperatures prohibit all but gas generation. The dewatering of trench sediment and subducted oceanic crust should produce an abundance of fluids circulating within the accretionary body. These fluids and gases can conduct hydrocarbons to any of the abundant trapping geometries or be lost from the system through sea floor seepage. In the Aleutian accretionary body all the conditions necessary for the formation of oil and gas deposits exist. The size and ultimate preservation of these deposits, however, are dependent on the deformational history of the prism both during accretion and after the accretion process has been superceded by subsequent tectonic regimes.     

THE IMPACT OF METAL AND ORGANIC CONTAMINANTS ON THE STRUCTURE OF PERIPHYTON IN LOTIC SEDIMENTS: OBSERVATIONS AT VARIOUS SCALES

1 INTRODUCTION While wastewater discharge regulations have significantly reduced water column pollution, historical and accidental releases of organic pollutants and heavy metals continue to pose an ecological threat as these contaminants have become 搃n-place?sediment pollutants. It had been previously assumed that natural attenuation processes, such as burial or biodegradation, would decrease the contamination levels in surface sediments and, thus, diminish the environmental impact of t…     

Controls on chemistry and diagenesis of naturally occurring iron-oxide phases

The purposes of this study were to (i) document chemical and mineralogical compositions in two naturally acidic drainages over a 1 m soil profile, (ii) document organic and inorganic signatures representative of past chemical or biological processes in the soils, and (iii) determine whether mineralogical and chemical differences are a consequence of differences in original composition, depositional conditions, or diagenesis. Two sites were studied: Paymaster Creek in the Heddleston Mining District near Lincoln, Montana and the New World Mining District near Cooke City, Montana. The oldest deposits at both naturally acidic sites pre-date human mining activity by several thousand years, although there is recent human activity at both sites. Both sites have streams with high dissolved Fe and moderately low pH and actively accumulate schwertmannite on streambeds. Soil deposits away from the streambed at Paymaster Creek contained goethite with adsorbed sulfate, but no schwertmannite, suggesting either that the original conditions precluded schwertmannite precipitation or that diagenesis occurred rapidly converting the schwertmannite to goethite. The New World Mining District site showed the expected profile, which is a gradual transition from schwertmannite- and goethite-bearing soils to goethite-only soils. Concentrations of Cr, As and other trace elements shown to retard diagenesis were higher at the New World site than at the Paymaster site.     

Air–sea interactions during strong winter extratropical storms

A high-resolution, regional coupled atmosphere–ocean model is used to investigate strong air–sea interactions during a rapidly developing extratropical cyclone (ETC) off the east coast of the USA. In this two-way coupled system, surface momentum and heat fluxes derived from the Weather Research and Forecasting model and sea surface temperature (SST) from the Regional Ocean Modeling System are exchanged via the Model Coupling Toolkit. Comparisons are made between the modeled and observed wind velocity, sea level pressure, 10 m air temperature, and sea surface temperature time series, as well as a comparison between the model and one glider transect. Vertical profiles of modeled air temperature and winds in the marine atmospheric boundary layer and temperature variations in the upper ocean during a 3-day storm period are examined at various cross-shelf transects along the eastern seaboard. It is found that the air–sea interactions near the Gulf Stream are important for generating and sustaining the ETC. In particular, locally enhanced winds over a warm sea (relative to the land temperature) induce large surface heat fluxes which cool the upper ocean by up to 2 °C, mainly during the cold air outbreak period after the storm passage. Detailed heat budget analyses show the ocean-to-atmosphere heat flux dominates the upper ocean heat content variations. Results clearly show that dynamic air–sea interactions affecting momentum and buoyancy flux exchanges in ETCs need to be resolved accurately in a coupled atmosphere–ocean modeling framework.     

Undermining the Integrated Maritime Policy

The European Union’s Integrated Maritime Policy is intended in part to co-ordinate sectoral policies, to achieve joined-up thinking and action and overcome the inconsistency between policy approaches that has led to the degradation of European seas. An integrated governance would be relatively straight-forward if the different interests and actors were operating on the basis of shared values, but they are not. While the fisheries sector, whether large or small-scale, is driven by a commercial imperative which tends towards the greatest extraction of the resource possible, environmentalists would champion the removal of all human impacts, other than redress activity, as the optimum state for the ecosystem. However, the greatest impediment to an integrated approach is the failure to subject the EU’s Common Fisheries Policy to the objectives of the Integrated Maritime Policy. Instead, all decisions concerning fisheries will continue to be made in accordance with the Fisheries Regulation which demands exploitation of the fragile resource. Attention needs to be given to how EU fisheries policy is to acquire values beyond that of commercial extraction for immediate economic benefit so that it may cohere with objectives of the Integrated Maritime Policy and aid the regeneration of the seas.     

Experimentation at the interface of fluvial geomorphology,stream ecology and hydraulic engineering and the development of an effective,interdisciplinary river science

One ‘2020 vision’ for fluvial geomorphology is that it sits alongside stream ecology and hydraulic engineering as a key element of an integrated, interdisciplinary river science. A challenge to this vision is that scientists from these three communities may approach problems from different perspectives with different questions and have different methodological outlooks. Refining interdisciplinary methodology is important in this context, but raises a number of issues for geomorphologists, ecologists and engineers alike. In particular, we believe that it is important that there is greater dialogue about the nature of mutually‐valued questions and the adoption of mutually‐acceptable methods. As a contribution to this dialogue we examine the benefits and challenges of using physical experimentation in flume laboratories to ask interdisciplinary questions. Working in this arena presents the same challenges that experimental geomorphologists and engineers are familiar with (scaling up results, technical difficulties, realism) and some new ones including recognizing the importance of biological processes, identifying hydraulically meaningful biological groups, accommodating the singular behaviour of individuals and species, understanding biological as well as physical stimuli, and the husbandry and welfare of live organisms. These issues are illustrated using two examples from flume experiments designed (1) to understand how the movement behaviours of aquatic insects through the near‐bed flow field of gravelly river beds may allow them to survive flood events, and (2) how an understanding of the way in which fish behaviours and swimming capability are affected by flow conditions around artificial structures can lead to the design of effective fish passages. In each case, an interdisciplinary approach has been of substantial mutual benefit and led to greater insights than discipline‐specific work would have produced. Looking forward to 2020, several key challenges for experimentalists working on the interface of fluvial geomorphology, stream ecology and hydraulic engineering are identified. Copyright © 2009 John Wiley & Sons, Ltd.     

Seismic stratigraphy and sedimentation history of the East Mariana Basin,western Pacific

An interpretation of the seismic stratigraphy and sedimentation history of the East Mariana Basin has been made using recently collected seismic reflection and refraction data. This Mesozoic(?) age basin, between the Marshall Islands and the Mariana Trench, is subdivided into three regions. The central region with about 1000 m of sediment probably records Jurassic to Late Cretaceous sedimentation of a pelagic biogenic and clay-rich section overlain by a thick section of mainly Cenozoic carbonates shed from nearby volcanic platforms. A western region is characterized by a thinner sediment cover and a shallower acoustic basement with a similar sedimentation history except that the upper section is thinner as a consequence of fewer nearby volcanic highs. Extensive Late Cretaceous mid-plate volcanics apparently masks the lower section and forms acoustic basement. The shallower eastern region (east of 157.5°E) contains WNW-trending ridges which may be either fracture zones or high-amplitude abyssal hills. The sedimentation appears controlled by the same factors as in the other regions but the area was bypassed by most Cenozoic basin-filling turbidites because of its elevation.The isostatistically corrected basement depths between the three regions suggest that the crust in the east may be substantially younger than in the rest of the East Mariana Basin, perhaps Cretaceous in age. This requires the existence of a tectonic boundary within the basin.     

Anomalies in temperature and rainfall during warm Arctic seasons

The regional patterns of change of temperature and rainfall that might accompany a global warming due to increased carbon dioxide can be studied by experiments with theoretical models of the climate system, by reconstructing the climates of past warm epochs, and by determining the anomalies of temperature and precipitation that prevailed during years or seasons when the Arctic region was unusually warm. The current study pursues the last course, making use of the northern hemisphere meteorological data record for the period 1931–1978. Hemispheric maps of anomalies of both temperature and precipitation are presented for the 10 warmest Arctic seasons and years, and for differences between the 5 warmest and 5 coldest consecutive Arctic winters. Wintertime anomalies are generally greatest and dominate in determining the annual averages. The hemispheric temperature anomalies for these data sets are similar to those determined earlier by the first author (Williams, 1980) using 1900–1969 data, but the precipitation anomalies (for North America alone) show more variation, partly due to the method of computing the anomalies. Work reported here begun while a visitor to the National Center for Atmospheric Research. The National Center for Atmospheric Research is sponsored by the National Science Foundation.