Evaluation of temporal concentration profiles for ungauged rivers following pollution incidents

Abstract

In order to predict the impact of pollution incidents on rivers, it is necessary to predict the dispersion coefficient and the flow velocity corresponding to the discharge in the river of interest. This paper explores methods for doing this, particularly with a view to applications on ungauged rivers, i.e. those for which little hydraulic or morphometric data are available. An approach based on neural networks, trained on a wide-ranging database of optimized parameter values from tracer experiments and corresponding physical variables assembled for American and European rivers, is proposed. Tests using independent cases showed that the neural networks generally gave more reliable parameter estimates than a second-order polynomial regression approach. The quality of predictions of temporal concentration profiles was heavily influenced by the accuracy of the velocity prediction.

Citation Piotrowski, A. P., Napiorkowski, J. J., Rowinski, P. M. & Wallis, S. G. (2011) Evaluation of temporal concentration profiles for ungauged rivers following pollution incidents. Hydrol. Sci. J. 56(5), 883–894.     

Life-bearing primordial planets in the solar vicinity

The space density of life-bearing primordial planets in the solar vicinity may amount to ～8.1×10⁴?pc^?3 giving total of ～10¹⁴ throughout the entire galactic disk. Initially dominated by H₂ these planets are stripped of their hydrogen mantles when the ambient radiation temperature exceeds 3?K as they fall from the galactic halo to the mid-plane of the galaxy. The zodiacal cloud in our solar system encounters a primordial planet once every 26 My (on our estimate) thus intercepting an average mass of 10³ tonnes of interplanetary dust on each occasion. If the dust included microbial material that originated on Earth and was scattered via impacts or cometary sublimation into the zodiacal cloud, this process offers a way by which evolved genes from Earth life could become dispersed through the galaxy.     

Australian Climate,Energy and Water Policies: conflicts and synergies

Responding to the threat of climate change, conserving freshwater ecosystems and securing adequate energy and water supplies are among the greatest challenges facing modern societies. Yet recognition of the interdependencies between climate, energy and water policy—with resulting synergies and trade-offs—remains limited, leaving societies and governments alike vulnerable to the dangers of conflicted or unintended policy outcomes from sectoral decisions. In this paper, we analyse current Australian climate, energy and water policies to identify the risks of perverse outcomes between the three policy sectors. In doing so we categorise the conflicts and synergies between particular energy generation, carbon sequestration and water supply policies to improve understandings of the challenges facing decision makers in Australia and internationally. Four types of interventions are identified that would enable integration and optimisation of policies, namely: better cross-sectoral knowledge to inform decisions; the identification of technologies with co-benefits; markets with broader cross-sectoral participation (including linking water and carbon markets); and better-integrated governance institutions.     

Fieldwork Unbound: Spaces of Association in Postconflict Vietnam

This article traces the ways in which the field emerges and becomes emplaced among three groups of people by presenting an inclusive reading of fieldwork in postconflict Vietnam. It employs a heuristic device called spaces of association to illustrate the different yet interrelated socio-spatial fields that surface when conducting fieldwork in an environment known for violence. In shedding light on the field's ability to extend beyond the territorially defined “field site,” this article speaks to debates surrounding the socio-spatial production of multiple and overlapping fields, describes the audiences engaged with and implicated in research, and contributes to understandings of ethical research engagement with postconflict field sites.     

Fumarolic pipes in the Tshirege Member of the Bandelier Tuff on the Pajarito Plateau, Jemez Mountains, New Mexico

The objective of this study is to demonstrate the relationships among devitrification, vapor phase alteration, localization of gas emanations into fumarolic pipes, and initial deformation of the ash flow sheet during cooling and lithification. Utilizing a unique and temporary exposure of the Tshirege Member of the Bandelier Tuff near Los Alamos, New Mexico, we identify several zones of distinctly preserved fossil fumarolic activity. The fumarolic zones vary in width from a few centimeters to more than a meter. Almost ubiquitously, these zones demonstrate fines-depletion, induration of the margins, upward-flaring geometries, and intense fracturing of overlying geologic units. The fumaroles were preferentially located on post welding, early formed cooling joints that vented to the surface after the vapor phase alteration stage. The pipes were regularly spaced at distances of approximately 4.5?m (N–S) to 7?m (E–W). In turn the pipes were covered by a surge deposit and overlying tuff which rapidly lithified. The overlying tuff was then brecciated during continued fumarolic pipe emissions. Geochemical evaluations confirm the presence of high-temperature mineral (scapolite) indicative of transport of hot volcanic gases through these zones. The pipe centers and walls are depleted in SiO₂, and enriched in Al₂O₃ and FeO. The overlying tuff breccia zones are enriched in Al₂O₃, FeO and MgO, and depleted in SiO₂, NaO, and K₂O. From comparison to other ignimbrite cooling histories, the fissures, fumaroles, and structures observed all likely formed in the first few decades after the deposition of the upper Tshirege subunits. This may have significant implications as to timing of initial cooling fractures and subsequent consolidation of gas emission pathways.     

Fractional order intensity measures for probabilistic seismic demand modeling applied to highway bridges

Probabilistic seismic analysis of structures involves the construction of seismic demand models, often stated as probabilistic models of structural response conditioned on a seismic intensity measure. The uncertainty introduced by the model is often a result of the chosen intensity measure. This paper introduces the concept of using fractional order intensity measures (IMs) in probabilistic seismic demand analysis and uses a single frame integral concrete box‐girder bridge class and a seismically designed multispan continuous steel girder bridge class as case studies. The fractional order IMs considered include peak ground response and spectral accelerations at 0.2 and 1.0 s considering a single degree of freedom system with fractional damping, , as well as a linear single degree of freedom system with fractional response, . The study reveals the advantage of fractional order IMs relative to conventional IMs such as peak ground acceleration, peak ground velocity, or spectral acceleration at 0.2 and 1.0 s. Metrics such as efficiency, sufficiency, practicality, and proficiency are measured to assess the optimal nature of fractional order IMs. The results indicate that the proposed fractional order IMs produce significant improvements in efficiency and proficiency, whereas maintaining practicality and sufficiency, and thus providing superior demand models that can be used in probabilistic seismic demand analysis. Copyright © 2011 John Wiley & Sons, Ltd.     

High-frequency rock temperature data from hyper-arid desert environments in the Atacama and the Antarctic Dry Valleys and implications for rock weathering

In desert environments with low water and salt contents, rapid thermal variations may be an important source of rock weathering. We have obtained temperature measurements of the surface of rocks in hyper-arid hot and cold desert environments at a rate of 1/s over several days. The values of temperature change over 1-second intervals were similar in hot and cold deserts despite a 30 °C difference in absolute rock surface temperature. The average percentage of the time dT/dt > 2 °C/min was ~ 8 ± 3%, > 4 °C/min was 1 ± 0.9%, and > 8 °C/min was 0.02 ± 0.03%. The maximum change over a 1-second interval was ~ 10 °C/min. When sampled to simulate data taken over intervals longer than 1 s, we found a reduction in time spent above the 2 °C/min temperature gradient threshold. For 1-minute samples, the time spent above any given threshold was about two orders of magnitude lower than the corresponding value for 1-second sampling. We suggest that a rough measure of efficacy of weathering as a function of frequency is the product of the percentage of time spent above a given threshold value multiplied by the damping depth for the corresponding frequency. This product has a broad maximum for periods between 3 and 10 s.     

Ambiguous biogeographical patterns mask a more complete understanding of the Ordovician to Devonian evolution of Japan

Fossil assemblages of the Ordovician to Devonian successions of Japan suggest complex temporal, environmental and geographical controls on their biogeographical signature. Thus, limited similarity at the species‐level between the trilobite, brachiopod and ostracod faunas of the South Kitakami, Hida‐Gaien and Kurosegawa terranes in part reflects the sporadic stratigraphic distribution of shelly fauna within these terranes. As a result, and with the exception of corals and pan‐tropical radiolarians, species‐level similarities are greater with other regions of East Asia and Australia than amongst the Japanese terranes. The Silurian faunas of the South Kitakami Terrane have affinities with North America, Europe, Central Asia and Australia, but there is no overriding signature to support proximity either to South China or Gondwana. Notably, brachiopod and trilobite faunas of the Middle Devonian suggest strong connections with North China. Trilobite, coral and ostracod faunas of the Hida‐Gaien Terrane show affinity, including at species level, with Siluro‐Devonian faunas from westerly‐situated palaeocontinents, especially those of Central Asian and European affinity, suggesting a continuation of the Central Asian Orogenic Belt, or of its associated lithofacies. Greater diversity of groups such as ostracods and trilobites in this terrane may signal closer links with continental shelf faunas of East Asia. The dominant biogeographical signature of the Kurosegawa Terrane is from corals and trilobites, suggesting links with the Siluro‐Devonian of Central Asia, Australia and South China. The variable biogeographic signal of the Japanese faunas may reflect the lifestyles of organisms with different physiologies and larval dispersal mechanisms, as well as the relative incompleteness of the Japanese fossil record. The present state of knowledge of the faunas cautions against placing Japan in relative proximity to the North or South China plates, or of presenting the Japanese terranes as a unified island arc to the north of the South China Plate during the Early Palaeozoic.