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The complex processes that underlie normal nervous system development are known to be extremely vulnerable to perturbation by chemicals that are present in the human environment, either naturally or as a result of human activities. These processes include neurogenesis, differentiation and migration of neurons, myelination, and synaptogenesis. Children are generally at greater risk than adults of suffering adversities from chemical exposures because of their physiology and behavior. As a result, reductions in cognitive function, including intelligence, are among the most important effects of such exposures. This chapter surveys the harmful impacts on children’s brains and cognition of certain chemicals and chemical classes, including mercury, lead, organophosphate pesticides, air pollution, synthetic organic compounds (e.g., flame retardants, plastics), and compounds that disrupt the endocrine system. The final section illustrates how an exposure that causes relatively modest cognitive morbidity in an individual can nevertheless, if highly prevalent as many chemical exposures are, contribute substantially to the burden of disease at the population level.
The stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) and total mercury concentrations (THg) of the three marine catfish species Aspistor luniscutis, Bagre bagre and Genidens genidens were evaluated to understand their trophic relationship in northern Rio de Janeiro state, south-eastern Brazil. The δ13C was similar among the three marine catfishes, whereas δ15N was similar in A. luniscutis and B. bagre and lower in G. genidens. THg was higher in G. genidens and lower in B. bagre. The greater assimilation of Sciaenidae fishes and squids by A. luniscutis and B. bagre resulted in smaller isotopic niche areas and trophic diversity but higher isotopic niche overlap, trophic redundancy and evenness. For G. genidens, the similar assimilation of all prey items resulted in the broadest isotopic niche among the marine catfishes. The higher mercury content in G. genidens is consistent with an increased important contribution of prey with a higher Hg burden. The bioaccumulation process was indicated by significant correlations of δ15N and THg with total length and total mass. Additionally, a significant correlation between THg and δ15N reflected the biomagnification process through the food web.
This chapter provides a brief review of missions using X-ray, gamma-ray, and neutron spectroscopy to determine the chemical composition of planetary surfaces. This chapter presents the history of planetary radiation measurements, including significant discoveries. Summary tables with links to the archived data provide a resource for readers interested in working in this field. Upcoming missions and possible future directions are described.
An ever-increasing number of laboratory facilities are enabling in situ spectral reflectance measurements of materials under conditions relevant to all the bodies in the Solar System, from Mercury to Pluto and beyond. Results derived from these facilities demonstrate that exposure of different materials to various planetary surface conditions can provide insights into the endogenic and exogenic processes that operate to modify their surface spectra, and their relative importance. Temperature, surface atmospheric pressure, atmospheric composition, radiation environment, and exposure to the space environment have all been shown to measurably affect reflectance and emittance spectra of a wide range of materials. Planetary surfaces are dynamic environments, and as our ability to reproduce a wider range of planetary surface conditions improves, so will our ability to better determine the surface composition of these bodies, and by extension, their geologic history.
Space missions have shown that most terrestrial bodies have an internally generated magnetic field in their metallic core and/or a crustal field due to remanent magnetism. The latter indicates the presence of an old dynamo at the time of crust formation. Information on the two together helps to uncover the body’s magnetic field history, and it is generally accepted that convection flows driven by thermal or compositional buoyancy in the cores are the most likely source for maintaining global planetary magnetic fields. The convection flow in the core, in turn, is closely related to the interior dynamics of the mantles above and the thermal evolution of the body. This chapter describes the mechanisms for dynamo generation either by thermal or compositional convection in the core. It discusses the magnetic field evolution of Mercury, Moon, Mars, Ganymede, and planetesimals and will also address the possibility of dynamo generation in rocky exoplanets
X-ray diffraction (XRD) and high-resolution scanning electron microscopy (SEM) have been used to characterize the silver mercury amalgam particles resting on the surface that comprise the image of five daguerreotype plates that were not gilded and that were prepared by three different contemporary daguerreotype makers. The regions of interest of the surface that were examined were overexposed, solarized, and highlight (white) areas. The XRD portion of the study shows that the two main silver mercury amalgam particles identified using the International Center for Diffraction Data PF4 + database were the Schachnerite/ζ (zeta) phase amalgam, Ag1.1Hg0.9, and the mercury silver amalgam, Ag0.65Hg0.35. On one of the daguerreotypes a third silver mercury amalgam, Moschellandsbergite, Ag2Hg3, was also identified in small concentrations. High-resolution SEM images corroborate the diffraction data and show that the crystalline nature of the silver mercury amalgam particles on all five plates to be mostly hexagonal, which would correspond to the Schachnerite/ζ (zeta) phase amalgam, and fewer rectangular solid and cubic crystals corresponding to the mercury silver amalgam.
Although Newtonian physics provided a sensible explanation for why the Earth should rotate on its axis and orbit the Sun, there was still no direct evidence for Earth’s motion. The first such evidence was provided by James Bradley, who attempted to reproduce Hooke’s parallax measurements and instead discovered the aberration of starlight. This slight displacement of a star’s apparent position occurs because of the Earth’s orbital motion and the finite speed of light. It was not until the late 1830s that astronomers finally detected annual stellar parallax, again confirming Earth’s orbital motion. Astronomers also sought direct evidence for Earth’s rotation. French astronomers confirmed that the Earth bulges out slightly at the equator, an effect that Newton had predicted as a result of Earth’s rotation. Experiments on the deflection of falling bodies also seemed to confirm Earth’s rotation, but the results were clouded in uncertainty. It was Foucault’s famous pendulum that provided the best direct evidence for the rotation of the Earth. These and other successes helped to establish the validity of Newtonian physics and brought about the successful conclusion of the Copernican Revolution.
The Virgin Mary, as Mother of the Word, has long been associated with early literacy training in the medieval West, an association that, as this article argues, connects her to The Marriage of Philology and Mercury's Lady Grammar. While Gary P. Cestaro has demonstrated the ways in which representations of Lady Grammar became more maternal throughout the medieval period, this article demonstrates how and why the Virgin Mother took on the persona of Lady Grammar in both verbal and material arts from the High to the Late Middle Ages. It explores the famous sculptures of the Virgin and Lady Grammar on the Royal Portal at Chartres Cathedral, the writings of grammatical theorists that led to these depictions, and the thirteenth-century artes poetriae that portray Mary as a Christian Grammatica. From St. Augustine's declaration that grammar is a “guardian” to the claims of Gervais of Melkley, John of Garland, and Eberhard the German that Mary is the mother of beautiful expressions, grammatical thought and practice in the medieval West led to a characterization of the Virgin, guardian of the Word in her womb and parent to Wisdom, as the supreme teacher and exemplar of Latin. Adopting Lady Grammar's iconography of the nourishing breast, classroom text, and punitive whip, the Virgin Mary is not only connected to basic Latin instruction but also comes to embody its principles.
Organic mercury, especially methylmercury, poisoning causes chronic neurological disease predominantly affecting the brain. There have been documented exposures from eating fish from contaminated waters in Japan and in northwestern Ontario and in Iraq from eating bread made from seed wheat treated with methylmercuric fungicide. The neurological disease is called Minamata disease in Japan. Visual field constriction due to involvement of the calcarine cortex, sensory disturbance due to involvement of the somatosensory cortex, and cerebellar ataxia due to involvement of granule cell neurons of the cerebellum are common and characteristic features due to methylmercury poisoning. Other neurological features include dysarthria, postural and action tremor, cognitive impairment, and hearing loss and dysequilibrium. In contrast, peripheral nerve disease is more characteristic of inorganic mercury intoxication. Similarly, psychosis is more typical of exposure to inorganic mercury, which has been documented in the felt hat industry (“mad hatter”). Laboratory tests (e.g., on blood and hair and toenail samples) are of limited value in the assessment of chronic neurological disease due to mercury poisoning because they may not reflect remote neuronal injury due to mercury. Methylmercury also causes injury to fetal brains during development. There is no effective treatment.
Structural data for weishanite, an alloy of Au, Ag and Hg, were collected for the first time from a crystal from the Keystone Mine, Colorado, USA. The structure was solved in the space group P63/mmc with the unit cell a = 2.9348(8) and c = 4.8215(18) Å] and refined to R = 0.0299 for 40 observed reflections [4σ(F) level] and four parameters and to R = 0.0356 for all 47 independent reflections. The weishanite structure can be considered a derivative of the zinc structure, with Au, Ag and Hg disordered in the same structural position. On this basis, we suggest that the formula is normalized to 1 atom with Z = 2, leading, for the sample investigated, to Au0.41Ag0.31Hg0.28 (electron microprobe data). Accordingly, weishanite can be considered the Au-rich isotype of schachnerite. A comparison with other Au/Ag-Hg alloys is presented together with a critical discussion about the nomenclature rules to be applied to alloys and simple metals.
Public health messages to reduce Hg exposure for pregnant women have focused exclusively on advice on fish consumption to limit Hg exposure, with little account being taken of the positive contribution of fish to nutritional quality. The aim of the present review was to compare and contrast the content and presentation of national guidelines on fish consumption in pregnancy, and comment on their evidence base and impact on consumption.
We searched for national and international guidelines on fish consumption in pregnancy using Internet search strategies. The detailed content and style of presentation of the guidelines were compared. The evidence base for the guidelines, and evidence for the impact of the guidelines on fish consumption levels, were assessed.
We identified nineteen national guidelines and three international guidelines. There was great variation in the content, complexity and presentation style. The guidelines were based largely on the Hg content of fish with far less consideration being given to the positive beneficial effects of nutrients provided by fish. The complexity of the guidelines may lead to pregnant women reducing their fish intake, or not eating fish at all.
Guidelines on fish consumption in pregnancy should take the beneficial effects of fish into account. Guidelines need to be clear and memorable, and appropriately disseminated, to achieve impact. Guidelines could include visual rather than narrative content. Use of technology, for example apps, could enable women to record their fish consumption in real time and log compliance with guidance over a week or other time period.
Over the last decade, the Antarctic continent has been the object of intensive scientific programmes. However, the emphasis of these studies rarely focuses on the Antarctic as a source of potential elements such as mercury. The release of mercury to the environment is known to occur at Deception Island, associated with volcanic activity. In this study, a 3D hydrodynamic model was used to assess the role of water circulation on the dispersion of released mercury. Sea level variation and tidal circulation data were obtained. Residence time was calculated using two different approaches. Internal tide generation in summer and winter were recognized and the barotropic tidal components obtained. Lagrangian tracers were used to depict particle circulation (simulating particulate mercury) in a three month summer simulation for barotropic and baroclinic conditions. The results show that particles accumulate in the northern and western parts of the bay. It is acknowledged that the results of the 3D model are associated with a non-negligible uncertainty, which can only be reduced with an ongoing commitment to monitoring. The findings of this study indicate that mercury accumulation is occurring in Port Foster (Deception Island), which is a potential threat to the local ecosystem.
Humans who eat fish are exposed to mixtures of healthful nutrients and harmful contaminants that are influenced by environmental and ecological factors. Marine fisheries are composed of a multitude of species with varying life histories, and harvested in oceans, coastal waters and estuaries where environmental and ecological conditions determine fish exposure to both nutrients and contaminants. Many of these nutrients and contaminants are thought to influence similar health outcomes (i.e., neurological, cardiovascular, immunological systems). Therefore, our understanding of the risks and benefits of consuming seafood require balanced assessments of contaminants and nutrients found in fish and shellfish. In this paper, we review some of the reported benefits of fish consumption with a focus on the potential hazards of mercury exposure, and compare the environmental variability of fish oils, selenium and mercury in fish. A major scientific gap identified is that fish tissue concentrations are rarely measured for both contaminants and nutrients across a range of species and geographic regions. Interpreting the implications of seafood for human health will require a better understanding of these multiple exposures, particularly as environmental conditions in the oceans change.
Strata of Permian – Early Triassic age that include a record of three major extinction events (Capitanian Crisis, Latest Permian Extinction and the Smithian/Spathian Extinction) were examined at the Festningen section, Spitsbergen. Over the c. 12 Ma record examined, mercury in the sediments shows relatively constant background values of 0.005–0.010 μg g–1. However, there are notable spikes in Hg concentration over an order of magnitude above background associated with the three extinctions. The Hg/total organic carbon (TOC) ratio shows similar large spikes, indicating that they represent a true increase in Hg loading to the environment. We argue that these represent Hg loading events associated with enhanced Hg emissions from large igneous province (LIP) events that are synchronous with the extinctions. The Hg anomalies are consistent across the NW margin of Pangea, indicating that widespread mercury loading occurred. While this provides utility as a chemostratigraphic marker the Hg spikes may also indicate loading of toxic metals to the environment, a contributing cause to the mass extinction events.
The removal of gaseous mercury from flue gases from coal-fired power plants is currently an environmental challenge under investigation. Therefore, the main aim of this paper was to evaluate the suitability of faujasite group zeolites (Na-X) to adsorb mercury compounds. Previous, initial tests showed negligible Hg0 uptake by Na-X zeolite, but silver impregnation improved adsorption markedly. Therefore, the testing of mercury adsorption from flue gases into Ag+- impregnated Na-X synthetic zeolite (Ag-X zeolite) derived from coal fly ash was carried out. This material was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy, X-ray fluorescence and nitrogen adsorption/desorption before being evaluated for mercury removal from exhaust gas. After preliminary mercury adsorption tests (fixed bed) under a nitrogen atmosphere, the adsorbent was examined with a simulated flue gas composition under various conditions, i.e. weight of zeolite, temperature of experiment and zeolite in powder and granulated forms. The removal of mercury was shown to depend on the sorbent texture (powder or granulate), exhaust gas flow rate and contact time, as well as the temperature of the experiment. The Ag-X zeolite tested reduced the level of mercury in the flue gas and, depending on the experimental conditions, long-time mercury breakthrough ranges from 15 to 40% were obtained. The best results for mercury capture were obtained for granulated material.