Geology of the seabed and shallow subsurface: the Irish Sea

The British Geological Survey was commissioned by the Crown Estate to assess geological conditions in the Irish Sea in relation to the possible constraints they may place on development of offshore infrastructure. The report describes the geology between 0 m and 50 m below seabed, which is the depth most relevant to current pile foundation technology. The report reviews the best available data from a variety of sources including, BGS legacy data, map sheets, and regional reports, as well as site investigations carried out for hydrocarbon and offshore renewable industries. Additional data collected for the proposed Round 3 offshore wind farm in the Irish Sea (Celtic Array) was also included. Prof. Richard Chiverrell and Dr. Katrien Van Landeghem (of Liverpool and Bangor universities), who together have extensive experience working in the Irish Sea, provided valuable advice and guidance. The report is split into four principle sections as summarised below. Section 3 summarises seabed topography, sediments and processes. The topography of the report area is split into shallow platforms and deeper troughs. Seabed sediments are subdivided into regions of soft mud- (clay and silt) rich sediment in the eastern and western Irish Sea and a central gravel belt comprising coarse sand and gravel. Small areas of bedrock outcrop at seabed are also recognised. Currents in the Irish Sea mobilise sediment to form a collection of marine bedforms ranging from ripples to very large (up to 36 m in height) solitary sediment waves and banner banks. Predicting bedform migration speeds and pathways is difficult and requires repeat surveys. Bedform migration rates of 0 m/yr to 66 m/yr, with average values around 6 m/yr have been observed. Shallow gas is expected in some areas of the Irish Sea. Where this gas is present, pockmarks or methane derived authigenic carbonate may occur. Section 4 summarises the Quaternary history of the Irish Sea and its impact on the distribution, thickness and properties of sediment. Growth and collapse of ice sheets and associated sea level fluctuations principally determine geological properties of Quaternary sediments. The stratigraphy in the report area reflects three major glacial periods with the last one having the most pronounced influence. Very stiff diamicts (glacial ‘boulder clays’ or tills) are present across most of the report area of variable thickness. In enclosed deeps, locally sediment thickness can be >100 m. Glacial landforms are preserved at the seabed and can be used to predict sediment properties. Extensive studies onshore can provide analogues to assess potential geological properties offshore. Section 5 provides a review of bedrock distribution and properties. Where Quaternary sediment cover is <50 m, bedrock will be encountered in the shallow subsurface. The predominant bedrock lithologies in the report area are Triassic and Carboniferous sandstone and mudstone. Geotechnical properties of Triassic rocks are comparable and potentially predictable. Carboniferous rock show high lateral and vertical variability. There are a number of igneous intrusions in the report area and rock properties near to the location of these igneous bodies may differ due to alteration of the host rock during intrusion. Section 6 summarises the geological constraints identified in preceding sections with reference to engineering activities and infrastructure. The report outlines the current state of knowledge of geological conditions in the Irish Sea. It is recommended for use as a guide and should not replace a detailed site investigation

Interspersed Salt-Affected and Unaffected Dryland Soils of the Lower Rio Grande Valley: I. Chemical, Physical, and Mineralogical Characteristics

The effects of soluble salts on soil productivity are global. Recent reports present information about saline soils in Spain (1), Iraq (2, 7), Canada (6), Egypt (16), and the United States (8, 10, 15, 19). Although in some areas much has been done towards reclaiming saline soils (5, 9, 17, 19), in other areas plagued by salinity problems (1, 6, 7), little or no progress is eviden

Ethylene Glycol Monoethyl Ether for Determining Surface Area of Silicate Minerals

Total surface area is a fundamental property of layer silicates, and it has been used as a criterion for identification. Early methods for determining surface area used nitrogen or ethane gas and were based on the principle that solid materials will adsorb a monomolecular layer of the gas at a particular pressure (4, 6). Dyal and Hendricks (6) introduced a method for determining surface area with ethylene glycol. Their method has been adapted to determining surface area of soils and soil minerals (2) and, although it is not an equilibrium method, much useful information has been provided by its use

Interspersed Salt Affected and Unaffected Dryland Soils of the Lower Rio Grande Valley: II. Occurrence of Salinity in Relation to Infiltration Rates and Profile Characteristics

Thirteen variables including chemical and physical characteristics, topographical features, and water table depth measurements were statistically analyzed for differences between seven saline and adjacent nonsaline soil profiles of Lower Rio Grande Valley salt-affected dryland soils. Cumulative intake and final intake rate, electrical conductivity of soil saturation extract, exchangeable sodium percentage, clay percentage, relative elevation, sand percentage, soil surface slope, and cation-exchange capacity were the variables most consistently different between saline and nonsaline soils. Profile salinity and water intake were both significantly correlated with profile sand and clay content and with soil surface elevation, In addition water infiltration was a function of profile salinity. Consideration of the effects of clay content, ground surface elevation, and soil slope on the processes of runoff and infiltration lead to the conclusion that the observed salinity pattern is due to differential infiltration of rainfall which results in differences in leaching between saline and nonsaline areas

The Ethylene Glycol Monoethyl Ether (EGME) Technique for Determining Soil-Surface Area

Total surface area is an important fundamental soil property. This property is measured to estimate the proportion of lattice expandable layer silicates in soils and to assess soil physical and chemical properties. Dyal and Hendricks (4) introduced a method for measuring surface area of layer silicates. This method was modified and adapted to soils by Bower and Gschwend (1). Subsequently, Martin (5) proposed a modification of the Dyal and Hendricks method (4) for layer silicates. His modification included a source of free ethylene glycol in the evacuated desiccator to control the vapor pressure of ethylene glycol at the mineral sorption surfaces. Bower and Goertzen (2) modified the method proposed by Martin (5) and adapted it for measuring soil surface area. This latter method is considered to be an equilibrium method (2) and is widely used today. A similar but more complex method was introduced by Sor and Kemper (7). All these methods utilize ethylene glycol, a highly polar molecule, as the absorbed phase. They all have the common disadvantage of being very time-consuming

Differences in Chemical Composition of Plant Sample Fractions Resulting from Grinding and Screening

Alfalfa, barley straw, corn leaves, peas, red clover, and wheat straw samples were ground in a Wiley mill and screened to separate particle sizes. Particle size samples were analyzed for N, P, K, Ca, Mg, Zn, Se, and SiO? The percentage comeosition of N, P, Ca, Mg, and SiO? generally increased with decreasing particle sizes of three wheat straw varieties, one baled and one hand-cut sample each of barley straw and alfalfa, corn leaves, red clover, and peas. The K concentrations were unpredictable. Selenium tended to be more concentrated in the smaller than in larger particles. The variability in chemical composition because of particle sizes points out the necessity for adequate sample grinding and mixing for obtaining representative subsamples for chemical analyses and biological experiments

Recent experimental results in sub- and near-barrier heavy ion fusion reactions

Recent advances obtained in the field of near and sub-barrier heavy-ion fusion reactions are reviewed. Emphasis is given to the results obtained in the last decade, and focus will be mainly on the experimental work performed concerning the influence of transfer channels on fusion cross sections and the hindrance phenomenon far below the barrier. Indeed, early data of sub-barrier fusion taught us that cross sections may strongly depend on the low-energy collective modes of the colliding nuclei, and, possibly, on couplings to transfer channels. The coupled-channels (CC) model has been quite successful in the interpretation of the experimental evidences. Fusion barrier distributions often yield the fingerprint of the relevant coupled channels. Recent results obtained by using radioactive beams are reported. At deep sub-barrier energies, the slope of the excitation function in a semi-logarithmic plot keeps increasing in many cases and standard CC calculations over-predict the cross sections. This was named a hindrance phenomenon, and its physical origin is still a matter of debate. Recent theoretical developments suggest that this effect, at least partially, may be a consequence of the Pauli exclusion principle. The hindrance may have far-reaching consequences in astrophysics where fusion of light systems determines stellar evolution during the carbon and oxygen burning stages, and yields important information for exotic reactions that take place in the inner crust of accreting neutron stars.Comment: 40 pages, 63 figures, review paper accepted for EPJ

The impact of neighbourhood walkability on the effectiveness of a structured education programme to increase objectively measured walking

Background: Incorporating physical activity into daily activities is key for the effectiveness of lifestyle education interventions aimed at improving health outcomes; however, consideration of the environmental context in which individuals live is not always made. Walkability is a characteristic of the physical environment, and may be a potential facilitator to changing physical activity levels.  Methods: Using data collected during the Walking Away from Diabetes randomised controlled trial, we examined the association between the walkability of the home neighbourhood and physical activity of participants. We also determined whether home neighbourhood walkability of participants was associated with the intervention effect of the education programme.  Results: Data from 706 participants were available for analysis. Neighbourhood walkability was not significantly associated with any of the physical activity measures at baseline, or at 12, 24 or 36 months following the intervention (p>0.05 for all). There was no association between walkability and change in purposeful steps/ day from baseline to 36months in the usual care or intervention arm; 25.77 (-99.04, 150.58) and 42.97 (-327.63, 413.45) respectively.  Conclusion: Neighbourhood walkability appeared to have no association with objectively-measured physical activity in this population. Furthermore, the walkability of participant’s neighbourhood did not influence the effectiveness of a lifestyle programme