528 research outputs found
Three-dimensional geological modelling of anthropogenic deposits at small urban sites: a case study from Sheepcote Valley, Brighton, U.K.
No full textImprovements in computing speed and capacity and the increasing collection and digitisation of geological data now allow geoscientists to produce meaningful 3D spatial models of the shallow subsurface in many large urban areas, to predict ground conditions and reduce risk and uncertainty in urban planning. It is not yet clear how useful this 3D modelling approach is at smaller urban scales, where poorly characterised anthropogenic deposits artificial/made ground and fill) form the dominant subsurface material and where the availability of borehole and other geological data is less comprehensive. This is important as it is these smaller urban sites, with complex site history, which frequently form the focus of urban regeneration and redevelopment schemes. This paper examines the extent to which the 3D modelling approach previously utilised at large urban scales can be extended to smaller less wellcharacterised urban sites, using a historic landfill site in Sheepcote Valley, Brighton, UK as a case study. Two 3D models were generated and compared using GSI3D� software, one using borehole data only, one combining borehole data with local geological maps and results from a desk study (involving collation of available site data, including ground contour plans). These models clearly delimit the overall subsurface geology at the site, and allow visualisation and modelling of the anthropogenic deposits present. Shallow geophysical data collected from the site partially validate the 3D modelled data, and can improve GSI3D� outputs where boundaries of anthropogenic deposits may not be clearly defined by surface, contour or borehole data. Attribution of geotechnical and geochemical properties to the 3D model is problematic without intrusive investigations and sampling. However, combining available
borehole data, shallow geophysical methods and site histories may allow attribution of generic fill properties, and consequent reduction of urban development risk and uncertainty
Performance of a micro-engineered ultrasonic particle manipulator
No full textAn ultrasonic microfluidic particle manipulator has been modeled and its experimentally measured separation performance has been compared with the modeled results for 1 µm latex particles, and yeast particles in water
Dynamics of inertial disk particles in turbulent channel flow
No full textA suspension of oblate spheroidal (disk-like) particles in turbulent channel flow has been investigated with focus on the translational and rotational particle statistics. The effects of particle aspect ratio and inertia have been explored. The disk-like particles exhibited a significant preferential orientation in the plane of the mean shear. The influence of the particle shape on the orientation and rotation diminished as translational inertia increased from Stokes number 1 to 30. Isotropization of both orientation and rotation could be observed in the core region of the channel. Keywords: oblate spheroids, preferential orientation, shape effects, inertia effects
Influence of geology, glacial processes and land use on soil composition and Quaternary landscape evolution in The Burren National Park, Ireland
No full textInertial effects on non-spherical particle rotation on turbulent channel flow
No full textWe investigated the rotation of non-spherical particles (rod-like and disk-like) in turbulent channel flow with focus on inertial effects. A direct numerical simulation (DNS) with an Eulerian-Lagrangian approach was performed. A wide range of particle aspect ratios, λ, ranging from 0.01 to 50 were considered for Stokes numbers St equal to 1 and 30. In the particle reference frame, statistical results reveal the importance of shape effect on the particle rotation. The rods (λ > 1) are spinning (rotation about their symmetry axis) more than tumbling (rotation about other axes) whereas disks (λ < 1) behave oppositely. With increasing particle inertia, i.e. higher St, the preferential tumbling of the disks and the spinning of the rods are reduced. We ascribe these observations to the varying degree of alignment of the particle symmetry axis with the fluid vorticity vector
Geology, geochemistry and petrology of the Foss stratiform barite-base metal deposit and adjacent Dalradian metasediments, near Aberfeldy, Scotland
Full text link2 volsAvailable from British Library Document Supply Centre- DSC:D66694/86 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Influence of geology, glacial processes and land use on soil composition and Quaternary landscape evolution in The Burren National Park, Ireland
No full textThe Burren in County Clare, western Ireland is a glaciated karstic landscape with a fragmented soil and vegetation cover on a predominantly limestone substrate. A representative area approximately 4 km2 in extent located within The Burren National Park was studied in order to determine the distributions of soil types and relate these to geology, glacial erosion and deposition, post-glacial mass movements and land use. Mineralogical and particle size analyses indicate the presence of two distinct soil types, one shale-bearing, the other granite-bearing. Geochemical analyses confirm this division and also reveal soils of mixed composition and a distinctive subtype of granite-bearing soil that occurs exclusively on drumlin-like landforms. The soils on the drumlins formed by the decalcification of limestone-rich glacial diamicton (till) containing granite and metamorphic rocks derived from County Galway to the north. The occurrence of mineralogically similar though geochemically heterogeneous soils throughout the area suggests that there was once an extensive thin cover of diamicton, which has almost entirely vanished because of pedogenesis and erosion. Soils containing shale fragments occur in a glacial dispersion train extending south from outcrops of a small body of shale-rich limestone breccia. Isolated patches of shale-bearing soil occurring up to 1.2 km from these outcrops may have formed by the weathering of ice-transported boulders. The presence of relatively deep soil cover on outcrops of the shale/limestone unit is attributed to Holocene weathering to form an erosion-resistant clay-rich soil. Tree charcoal, 14C-dated to 3300 BP and buried to a depth of 2 m by mixed granite- and shale-bearing soil, indicates that Bronze Age deforestation triggered mass movement and soil erosion. Denudation processes are still active in the Burren landscape
Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf
Full text linkBering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC) concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 ?moles kg?1 over the inner shelf to ~2400 ?moles kg?1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt, terrestrial inputs, and primary production. Concentrations were found to be as low ~1800 ?moles kg?1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 ?moles kg?1 in the upper 30 m of the water column due to primary production and calcium carbonate formation between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of NCP on the inner, middle, and outer shelf averaged 28 ± 9 mmoles C m?2 d?1. However, higher rates of NCP (40–47 mmoles C m?2 d?1) were observed in the "Green Belt" where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total NCP across the shelf was on the order of ~96 Tg C yr?1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming more or less productive. However, as changing climate continues to modify the character of the Bering Sea, we have shown that NCP can be an important indicator of how the ecosystem is functioning
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