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"Ridge 2000"
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Almighty : courage, resistance, and existential peril in the nuclear age
\"A riveting, chilling tale of how a group of ragtag activists infiltrated one of the most secure nuclear weapons sites in the United States, told alongside a broader history of America's nuclear stewardship, from the early stages of the Manhattan Project to our country's never-ending investment in nuclear weaponry. On Saturday, July 28, 2012, three senior citizens broke into one of the most secure nuclear weapons facilities in the world. An eighty-two-year-old Catholic nun, a Vietnam veteran, and a house painter infiltrated the Oak Ridge, Tennessee, complex in the dead of night, smearing the walls with human blood and spray-painting quotes from the Bible. Then they waited to be arrested. What was a simple plan--one far more successful than even its perpetrators expected -- spawned a complex discussion. Among the questions that the infiltration raised: How did three unarmed civilians manage to penetrate one of the most heavily guarded locations in the world, nicknamed the 'Fort Knox of Uranium'? Why does the United States continue to possess more nuclear weaponry than is needed to destroy global civilization many times over? And what does this mean for the day-to-day safety of Americans? In Almighty, Washington Post writer Dan Zak begins with the present-day axis of a seventy-year-old story, exploring how events of the twentieth century -- including the prophecies of a farmer-turned-ascetic named John Hendrix and the early stages of the Manhattan Project in Morningside Heights -- led to one of the most successful and high-profile demonstrations of anti-nuclear activism\"--Amazon.com.
Book
Volcanic Eruptions in the Deep Sea
Volcanic eruptions are important events in Earth's cycle of magma generation and crustal construction. Over durations of hours to years, eruptions produce new deposits of lava and/or fragmentary ejecta, transfer heat and magmatic volatiles from Earth's interior to the overlying air or seawater, and significantly modify the landscape and perturb local ecosystems. Today and through most of geological history, the greatest number and volume of volcanic eruptions on Earth have occurred in the deep ocean along mid-ocean ridges, near subduction zones, on oceanic plateaus, and on thousands of mid-plate seamounts. However, deepsea eruptions (> 500 m depth) are much more difficult to detect and observe than subaerial eruptions, so comparatively little is known about them. Great strides have been made in eruption detection, response speed, and observational detail since the first recognition of a deep submarine eruption at a mid-ocean ridge 25 years ago. Studies of ongoing or recent deep submarine eruptions reveal information about their sizes, durations, frequencies, styles, and environmental impacts. Ultimately, magma formation and accumulation in the upper mantle and crust, plus local tectonic stress fields, dictate when, where, and how often submarine eruptions occur, whereas eruption depth, magma composition, conditions of volatile segregation, and tectonic setting determine submarine eruption style.
Journal Article
The East Pacific Rise Between 9°N and 10°N
The East Pacific Rise from ~ 9–10°N is an archetype for a fastspreading mid-ocean ridge. In particular, the segment near 9°50'N has been the focus of multidisciplinary research for over two decades, making it one of the best-studied areas of the global ridge system. It is also one of only two sites along the global ridge where two historical volcanic eruptions have been observed. This volcanically active segment has thus offered unparalleled opportunities to investigate a range of complex interactions among magmatic, volcanic, hydrothermal, and biological processes associated with crustal accretion over a full magmatic cycle. At this 9°50'N site, comprehensive physical oceanographic measurements and modeling have also shed light on linkages between hydrodynamic transport of larvae and other materials and biological dynamics influenced by magmatic processes. Integrated results of highresolution mapping, and both in situ and laboratory-based geophysical, oceanographic, geochemical, and biological observations and sampling, reveal how magmatic events perturb the hydrothermal system and the biological communities it hosts.
Journal Article
Chemoautotrophy at Deep-Sea Vents
Chemolithoautotrophic microorganisms are at the nexus of hydrothermal systems by effectively transferring the energy from the geothermal source to the higher trophic levels. While the validity of this conceptual framework is well established at this point, there are still significant gaps in our understanding of the microbiology and biogeochemistry of deep-sea hydrothermal systems. Important questions in this regard are: (1) How much, at what rates, and where in the system is organic carbon being produced? (2) What are the dominant autotrophs, where do they reside, and what is the relative importance of free-swimming, biofilm-forming, and symbiotic microbes? (3) Which metabolic pathways are they using to conserve energy and to fix carbon? (4) How does community-wide gene expression in fluid and biofilm communities compare? and (5) How efficiently is the energy being utilized, transformed into biomass, and transferred to higher trophic levels? In particular, there is currently a notable lack of process-oriented studies that would allow an assessment of the larger role of these ecosystems in global biogeochemical cycles. By combining the presently available powerful \"omic\" and single-cell tools with thermodynamic modeling, experimental approaches, and new in situ instrumentation to measure rates and concentrations, it is now possible to bring our understanding of these truly fascinating ecosystems to a new level and to place them in a quantitative framework and thus a larger global context.
Journal Article
Diffuse Flow
Black smokers are the dramatic result of seawater being heated to high temperatures (generally 250° to 350°C) by magmatic systems, then discharging at the seafloor. However, not all seawater that circulates through the oceanic crust is heated to high temperatures. \"Diffuse flow\" is a catchall term to describe lowtemperature (< 0.2° to ~ 100°C) fluids that slowly discharge through sulfide mounds, fractured lava flows, and assemblages of bacterial mats and macrofauna. Diffuseflow fluids are generally mixtures of cold seawater and either magmatically heated fluids, conductively heated seawater, or both. Although the limited data indicate that 50–90% of the hydrothermal heat loss occurs as diffuse flow at the seafloor, modeling results coupled with geochemical data suggest that nearly 90% of the heat loss ultimately stems from magmatically heated fluids. There is a critical need to obtain more diffuse-flow measurements to improve models of heat and geochemical fluxes, better understand subsurface fluid flow dynamics, and determine the extent of the subsurface biosphere as well as the spatial and temporal variability of diffuse flow. New measurement techniques and diffuse-flow models provide insight into the characteristics of these subsurface fluids and their manifestation at the seafloor.
Journal Article
Endeavour Segment of the Juan de Fuca Ridge
Endeavour Segment of the Juan de Fuca Ridge is one of three Integrated Study Sites for the Ridge 2000 Program. It is a remarkable, dynamic environment hosting five major hydrothermal fields, numerous smaller fields, and myriad diffuse-flow sites; magma chambers underlie all fields. Over 800 individual extinct and active chimneys have been documented within the central ~ 15 km portion of the ridge, with some edifices reaching 50 m across and up to 45 m tall. Fluid flow is focused along faults within the rift zone, and seismically active faults along the western axial valley wall have been used by both magmas and upwelling hydrothermal fluids. There is significant chemical heterogeneity in basalt compositions within the axial rift valley, with the greatest diversity occurring near the base of the western axial valley wall where normal, transitional, and enriched type mid-ocean ridge basalts occur within tens of meters of each other. Endeavour is the only site where seismic intensity has been linked directly to heat flux at the individual vent field scale. Installation of the world's first high-power and high-bandwidth cabled observatory at Endeavour via NEPTUNE Canada ensures that new discoveries along the Juan de Fuca Ridge will continue into the future.
Journal Article
Larval Dispersal
Visually striking faunal communities of high abundance and biomass cluster around hydrothermal vents, but these animals don't spend all of their lives on the seafloor. Instead, they spend a portion of their lives as tiny larvae in the overlying water column. Dispersal of larvae among vent sites is critical for population maintenance, colonization of new vents, and recolonization of disturbed vents. Historically, studying larvae has been challenging, especially in the deep sea. Advances in the last decade in larval culturing technologies and more integrated, interdisciplinary time-series observations are providing new insights into how hydrothermal vent animals use the water column to maintain their populations across ephemeral and disjunct habitats. Larval physiology and development are often constrained by evolutionary history, resulting in larvae using a diverse set of dispersal strategies to interact with the surrounding currents at different depths. These complex biological and oceanographic interactions translate the reproductive output of adults in vent communities into a dynamic supply of settling larvae from sources near and far.
Journal Article
Energy Transfer Through Food Webs at Hydrothermal Vents
Tectonic and volcanic processes that drive hydrothermal fluid flow and influence its chemistry also regulate the transfer of energy to hydrothermal vent ecosystems. Chemoautotrophic bacteria use the chemical energy generated by mixing the reduced chemicals in hydrothermal fluids with deep-ocean ambient seawater to fix inorganic carbon and produce biomass. These and other microbes, or their products, are then consumed by other organisms, which are subsequently consumed by other organisms. The connections between nutritional sources and consumers form a complex food web that links the lithosphere to the biosphere at hydrothermal vents. This article traces the path of energy transfer from geochemical to biological processes in hydrothermal vent food webs and explores the implications of changes in hydrothermal fluid flux on food web structure. One of the goals of studying food webs at hydrothermal vents is to develop better predictions of community resilience to disturbance and the relationships between community structure and ecosystem function, including productivity and nutrient cycling. In addition, improved understanding of energy transfer through hydrothermal vent food webs is critical for constructing models of chemical fluxes from chemosynthetic-based ecosystems to the open ocean.
Journal Article
Measuring the Form of Iron in Hydrothermal Plume Particles
The global mid-ocean ridge (MOR) system is a 60,000 km submarine volcanic mountain range that crosses all of the major ocean basins on Earth. Along the MOR, subseafloor seawater circulation exchanges heat and elements between the oceanic crust and seawater. One of the elements released through this venting process is iron. The amount of iron released by hydrothermal venting to the ocean per year (called a flux) is similar in magnitude to that in global riverine runoff (Elderfield and Schultz, 1996). Until recently, measurements and modeling activities to understand the contribution of hydrothermal iron to the ocean budget have been largely neglected. It was thought that hydrothermal iron was removed completely from seawater by precipitation of iron-bearing minerals within plumes and then deposited at the seafloor close to vent sites. With this assumption in place, the contribution of hydrothermal fluxes to the ocean budget was considered negligible. Recent work, however, questions the validity of that assumption, and leads to what we call the \"leaky vent\" hypothesis. Our goal is to measure the forms of iron, known as speciation, present in hydrothermal plume particles to better understand the bioavailability, geochemical reactivity, and transport properties of hydrothermal iron in the ocean.
Journal Article
Biogeochemical Processes at Hydrothermal Vents
Hydrothermal vents are among the most biologically active regions of the deep ocean. However, our understanding of the limits of life in this extreme environment, the extent of biogeochemical transformation that occurs in the crust and overlying ocean, and the impact of vent life on regional and global ocean chemistry is in its infancy. Recently, scientific studies have expanded our view of how vent microbes gain metabolic energy at vents through their use of dissolved chemicals and minerals contained in ocean basalts, seafloor sulfide deposits, and hydrothermal plumes and, in turn, how they catalyze chemical and mineral transformations. The scale of vent environments and the difficulties inherent in the study of life above, on, and below the deep seafloor have led to the development of geochemical and bioenergetic models. These models predict habitability and biological activity based on the chemical composition of hydrothermal fluids, seawater, and the surrounding rock, balanced by the physiological energy demand of cells. This modeling, coupled with field sampling for ground truth and discovery, has led to a better understanding of how hydrothermal vents affect the ocean and global geochemical cycles, and how they influence our views of life on the early Earth and the search for life beyond our own planet.
Journal Article