Reduced sapphirine granulite xenoliths from the Lace Kimberlite,South Africa; implications for the deep structure of the Kaapvaal Craton

Sapphirine-bearing granulites, together with sapphirine-free granulites and eclogites, occur as xenoliths in the kimberlite of the Lace diatreme that penetrates the Kaapvaal craton, S. Africa. Absence of (calculated) Fe³⁺ in sapphirine, garnet and sillimanite, together with presence of graphite and sulphides, suggests highly reducing conditions of metamorphism. Chemical considerations and comparisons with experimental investigations suggest metamorphism of a sedimentary (?chlorite-montmorillonite) protolith at 900–1000° C and > 10 Kb; high Cr in the assemblage may point to a basic/ultrabasic precursor. The xenoliths indicate the presence of a very-high-grade granulite terrain, possibly similar to Enderby Land (Antarctica), beneath the Kaapval craton.     

Electrogeochemical sampling with

Trends in abundance of the 28 most common species of coastal birds on Mustang Island, Texas, were assessed for a 29-year period (1979–2007) during which the study area experienced a substantial increase in human activity. Ten of the 28 species examined declined significantly (P < 0.05) over the study period. Six of these were larids (herring gull, Forster’s tern, royal tern, gull-billed tern, Caspian tern, black skimmer), which exhibited declines in mean abundance of 53% to 88%. Other significant species declines were the great blue heron (39% decline) and the shorebirds Wilson’s plover (63%), red knot (54%), and black-bellied plover (34%). Four species showed significant increases in local abundance. Mean number of people on the beach increased fivefold during the study period. This unique dataset allows for an extremely rare assessment of bird populations in direct relation to human disturbance and may have implications for managing coastal birds worldwide.     

Trends in Abundance of Coastal Birds and Human Activity on a Texas Barrier Island Over Three Decades

Trends in abundance of the 28 most common species of coastal birds on Mustang Island, Texas, were assessed for a 29-year period (1979–2007) during which the study area experienced a substantial increase in human activity. Ten of the 28 species examined declined significantly (P < 0.05) over the study period. Six of these were larids (herring gull, Forster’s tern, royal tern, gull-billed tern, Caspian tern, black skimmer), which exhibited declines in mean abundance of 53% to 88%. Other significant species declines were the great blue heron (39% decline) and the shorebirds Wilson’s plover (63%), red knot (54%), and black-bellied plover (34%). Four species showed significant increases in local abundance. Mean number of people on the beach increased fivefold during the study period. This unique dataset allows for an extremely rare assessment of bird populations in direct relation to human disturbance and may have implications for managing coastal birds worldwide.     

Analysis of radionuclide migration through a 200-m Vadose zone following a 16-year infiltration event

Atomic weapons testing at the Nevada Test Site has introduced many tracers for quantifying subsurface hydrologic transport processes in arid climates. In 1975, groundwater adjacent to the Cambric test, conducted beneath Frenchman Flat 10 years earlier, was pumped steadily for 16 years to elicit information on the migration of residual radioactivity through the saturated zone. Radionuclides in the pumping well effluent, including tritium, ¹⁴C, ³⁶Cl, and ⁸⁵Kr, were extensively monitored prior to its discharge in an unlined ditch, where approximately a third of the flow infiltrated over a distance of 1 km. Radionuclide infiltration through a 220-m thick vadose zone created a second, and rather unique long-term field experiment. Effluent data have been utilized in conjunction with geologic data, new radionuclide measurements, isotopic age-dating estimates, and vadose zone flow and transport models to better understand the movement of radionuclides between the ditch, the water table and a nearby groundwater monitoring well. Detection of tritium in the monitoring well occurred approximately 16 years after its initial discharge into the ditch. Modeling and tritium age dating have suggested 3–5 years of this 16-year transit time occurred solely in the vadose zone. They also suggest considerable recirculation of the pumping well discharge back into the original pumping well. Notably, there have been no observations of ¹⁴C or ⁸⁵Kr in the monitoring well, suggesting their preferential retention or volatilization during transit to the water table.     

Finite strip analysis of the dynamic response of beam and slab highway bridges

This paper presents a method of analysis for the dynamic response of a simply supported beam and slab bridge under the action of a moving vehicle. The bridge is idealized as an orthotropic plate and, in the analysis, is subdivided into a number of finite strips. The vehicle is idealized as a moving sprung mass. Viscous damping is taken into account for both bridge and vehicle. The results show that there is significant variation of response across transverse sections of the bridge. Furthermore the dynamic magnification is considerably greater than that predicted by a more approximate method in which the bridge is idealized as a simple prismatic beam.     

Ecological limits to terrestrial biological carbon dioxide removal

Terrestrial biological atmospheric carbon dioxide removal (BCDR) through bioenergy with carbon capture and storage (BECS), afforestation/reforestation, and forest and soil management is a family of proposed climate change mitigation strategies. Very high sequestration potentials for these strategies have been reported, but there has been no systematic analysis of the potential ecological limits to and environmental impacts of implementation at the scale relevant to climate change mitigation. In this analysis, we identified site-specific aspects of land, water, nutrients, and habitat that will affect local project-scale carbon sequestration and ecological impacts. Using this framework, we estimated global-scale land and resource requirements for BCDR, implemented at a rate of 1 Pg C y^?1. We estimate that removing 1 Pg C y^?1 via tropical afforestation would require at least 7?×?10⁶ ha y^?1 of land, 0.09 Tg y^?1 of nitrogen, and 0.2 Tg y^?1 of phosphorous, and would increase evapotranspiration from those lands by almost 50 %. Switchgrass BECS would require at least 2?×?10⁸ ha of land (20 times U.S. area currently under bioethanol production) and 20 Tg y^?1 of nitrogen (20 % of global fertilizer nitrogen production), consuming 4?×?10¹²?m³ y^?1 of water. While BCDR promises some direct (climate) and ancillary (restoration, habitat protection) benefits, Pg C-scale implementation may be constrained by ecological factors, and may compromise the ultimate goals of climate change mitigation.     

Triangulating Social Multimedia Content for Event Localization using Flickr and Twitter

The analysis of social media content for the extraction of geospatial information and event‐related knowledge has recently received substantial attention. In this article we present an approach that leverages the complementary nature of social multimedia content by utilizing heterogeneous sources of social media feeds to assess the impact area of a natural disaster. More specifically, we introduce a novel social multimedia triangulation process that uses both Twitter and Flickr content in an integrated two‐step process: Twitter content is used to identify toponym references associated with a disaster; this information is then used to provide approximate orientation for the associated Flickr imagery, allowing us to delineate the impact area as the overlap of multiple view footprints. In this approach, we practically crowdsource approximate orientations from Twitter content and use this information to orient Flickr imagery accordingly and identify the impact area through viewshed analysis and viewpoint integration. This approach enables us to avoid computationally intensive image analysis tasks associated with traditional image orientation, while allowing us to triangulate numerous images by having them pointed towards the crowdsourced toponym location. The article presents our approach and demonstrates its performance using a real‐world wildfire event as a representative application case study.     

Groundwater Assessment for Current and Future Water Demand in the Daka Catchment,Northern Region,Ghana

The use of untreated surface water for domestic purposes has resulted in the infection of some people by guinea worm and other water borne diseases in the Northern Region of Ghana. The aim of this study is to assess the current groundwater quantity and quality conditions in the 7,820 km² Daka catchment and project the water demand in 2025. Results of groundwater analyses generally show good water quality for domestic use. Borehole analyses indicate that the catchment’s groundwater system can be characterized by a regolith aquifer underlain by a deeper fractured rock aquifer in some areas. The current per capita water demand is estimated at 40 l/day although 60 l/day is the desired amount, indicating that with the current population of 363,350, the projected water demand for the communities is 21,800 m³/day. With a projected population of 555,500 in 2025, an expected 33,300 m³/day of water is required. The estimated optimum potential groundwater available for use in the catchment is 154 × 10⁶ m³/year (4.24 × 10⁵ m³/day). However, the current total groundwater abstraction is only 8,876 m³/day or 2% of the optimum. In comparison, the projected total current and 2025 water demands are only 5 and 8%, respectively, of the optimum potential groundwater available for use in the catchment. In addition, only 1,780 m³/day (0.65 × 10⁶ m³/year) or 0.06% of the average annual flow of 1,016 × 10⁶ m³/year of the Daka River is treated for domestic use. These figures reveal that a significantly very large water resource potential exists for both surface and groundwater development in the Daka catchment. It is suggested that their development should proceed conjunctively.