Particle Shape and Composition of NU-LHT-2M

Particle shapes of the lunar regolith simulant NU-LHT-2M were analyzed by scanning electron microscope of polished sections. These data provide shape, size, and composition information on a particle by particle basis. 5,193 particles were measured, divided into four sized fractions: less than 200 mesh, 200-100 mesh, 100-35 mesh, and greater than 35 mesh. 99.2% of all particles were monominerallic. Minor size versus composition effects were noted in minor and trace mineralogy. The two metrics used are aspect ratio and Heywood factor, plotted as normalized frequency distributions. Shape versus composition effects were noted for glass and possibly chlorite. To aid in analysis, the measured shape distributions are compared to data for ellipses and rectangles. Several other simple geometric shapes are also investigated as to how they plot in aspect ratio versus Heywood factor space. The bulk of the data previously reported, which were acquired in a plane of projection, are between the ellipse and rectangle lines. In contrast, these data, which were acquired in a plane of section, clearly show that a significant number of particles have concave hulls in this view. Appendices cover details of measurement error, use of geometric shapes for comparative analysis, and a logic for comparing data from plane of projection and plane of section measurements

The dynamic floor of Yellowstone Lake, Wyoming, USA: The last 14 k.y. of hydrothermal explosions, venting, doming, and faulting

Hydrothermal explosions are significant potential hazards in Yellowstone National Park, Wyoming, USA. The northern Yellowstone Lake area hosts the three largest hydrothermal explosion craters known on Earth empowered by the highest heat flow values in Yellowstone and active seismicity and deformation. Geological and geochemical studies of eighteen sublacustrine cores provide the first detailed synthesis of the age, sedimentary facies, and origin of multiple hydrothermal explosion deposits.New tephrochronology and radiocarbon results provide a four-dimensional view of recent geologic activity since recession at ca. 15–14.5 ka of the \u3e1-km-thick Pinedale ice sheet. The sedimentary record in Yellowstone Lake contains multiple hydrothermal explosion deposits ranging in age from ca. 13 ka to ∼1860 CE. Hydrothermal explosions require a sudden drop in pressure resulting in rapid expansion of high-temperature fluids causing fragmentation, ejection, and crater formation; explosions may be initiated by seismicity, faulting, deformation, or rapid lake-level changes. Fallout and transport of ejecta produces distinct facies of subaqueous hydrothermal explosion deposits. Yellowstone hydrothermal systems are characterized by alkaline-Cl and/or vapor-dominated fluids that, respectively, produce alteration dominated by silica-smectite-chlorite or by kaolinite. Alkaline-Cl liquids flash to steam during hydrothermal explosions, producing much more energetic events than simple vapor expansion in vapor-dominated systems. Two enormous explosion events in Yellowstone Lake were triggered quite differently: Elliott’s Crater explosion resulted from a major seismic event (8 ka) that ruptured an impervious hydrothermal dome, whereas the Mary Bay explosion (13 ka) was triggered by a sudden drop in lake level stimulated by a seismic event, tsunami, and outlet channel erosion

Ecological Impacts of the Space Shuttle Program at John F. Kennedy Space Center, Florida

The Space Shuttle Program was one of NASAs first major undertakings to fall under the environmental impact analysis and documentation requirements of the National Environmental Policy Act of 1969 (NEPA). Space Shuttle Program activities at John F. Kennedy Space Center (KSC) and the associated Merritt Island National Wildlife Refuge (MINWR) contributed directly and indirectly to both negative and positive ecological trends in the region through the long-term, stable expenditure of resources over the 40 year program life cycle. These expenditures provided support to regional growth and development in conjunction with other sources that altered land use patterns, eliminated and modified habitats, and contributed to cultural eutrophication of the Indian River Lagoon. At KSC, most Space Shuttle Program related actions were conducted in previously developed facilities and industrial areas with the exception of the construction of the shuttle landing facility (SLF) and the space station processing facility (SSPF). Launch and operations impacts were minimal as a result of the low annual launch rate. The majority of concerns identified during the NEPA process such as potential weather modification, acid rain off site, and local climate change did not occur. Launch impacts from deposition of HCl and particulates were assimilated as a result of the high buffering capacity of the system and low launch and loading rates. Metals deposition from exhaust deposition did not display acute impacts. Sub-lethal effects are being investigated as part of the Resource Conservation and Recovery Act (RCRA) regulatory process. Major positive Space Shuttle Program effects were derived from the adequate resources available at the Center to implement the numerous environmental laws and regulations designed to enhance the quality of the environment and minimize impacts from human activities. This included reduced discharges of domestic and industrial wastewater, creation of stormwater management systems, remediation of past contamination sites, implementation of hazardous waste management systems, and creation of a culture of sustainability. Working with partners such as the USFWS and the St Johns River Water Management District (SJRWMD), wetlands and scrub restoration and management initiatives were implemented to enhance fish and wildlife populations at the Center. KSC remains the single largest preserve on the east coast of Florida in part due to NASAs commitment to stewardship. Ongoing Ecological Program projects are directed at development of information and knowledge to address future KSC management questions including the transition to a joint government and commercial launch facility, enhanced habitat management requirements for wetlands and scrub, potential impacts of emerging contaminants, and adaptation to climate change including projected sea level rise over the next 50-75 years

Comparison of dissolved and particulate arsenic distributions in shallow aquifers of Chakdaha, India, and Araihazar, Bangladesh

International audienceBackground The origin of the spatial variability of dissolved As concentrations in shallow aquifers of the Bengal Basin remains poorly understood. To address this, we compare here transects of simultaneously-collected groundwater and aquifer solids perpendicular to the banks of the Hooghly River in Chakdaha, India, and the Old Brahmaputra River in Araihazar, Bangladesh. Results Variations in surface geomorphology mapped by electromagnetic conductivity indicate that permeable sandy soils are associated with underlying aquifers that are moderately reducing to a depth of 10–30 m, as indicated by acid-leachable Fe(II)/Fe ratios 5 mg L-1. More reducing aquifers are typically capped with finer-grained soils. The patterns suggest that vertical recharge through permeable soils is associated with a flux of oxidants on the banks of the Hooghly River and, further inland, in both Chakdaha and Araihazar. Moderately reducing conditions maintained by local recharge are generally associated with low As concentrations in Araihazar, but not systematically so in Chakdaha. Unlike Araihazar, there is also little correspondence in Chakdaha between dissolved As concentrations in groundwater and the P-extractable As content of aquifer particles, averaging 191 ± 122 ug As/L, 1.1 ± 1.5 mg As kg-1 (n = 43) and 108 ± 31 ug As/L, 3.1 ± 6.5 mg As kg-1 (n = 60), respectively. We tentatively attribute these differences to a combination of younger floodplain sediments, and therefore possibly more than one mechanism of As release, as well as less reducing conditions in Chakdaha compared to Araihazar. Conclusion Systematic dating of groundwater and sediment, combined with detailed mapping of the composition of aquifer solids and groundwater, will be needed to identify the various mechanisms underlying the complex distribution of As in aquifers of the Bengal Basin

Applying Definitions of “Asbestos” to Environmental and “Low-Dose” Exposure Levels and Health Effects, Particularly Malignant Mesothelioma

Although asbestos research has been ongoing for decades, this increased knowledge has not led to consensus in many areas of the field. Two such areas of controversy include the specific definitions of asbestos, and limitations in understanding exposure-response relationships for various asbestos types and exposure levels and disease. This document reviews the current regulatory and mineralogical definitions and how variability in these definitions has led to difficulties in the discussion and comparison of both experimental laboratory and human epidemiological studies for asbestos. This review also examines the issues of exposure measurement in both animal and human studies, and discusses the impact of these issues on determination of cause for asbestos-related diseases. Limitations include the lack of detailed characterization and limited quantification of the fibers in most studies. Associated data gaps and research needs are also enumerated in this review