BGS karst report series : C9. Karst in the Chalk of the Isle of Wight

This report documents the evidence for karst and rapid groundwater flow in the Chalk of the Isle of Wight in Southern England. It is part of the BGS karst report series on those karst aquifers in England in which cave development is limited – principally the Upper Cretaceous Chalk and the Jurassic and Permian limestones. The series is the main output of the NERC funded Knowledge Exchange fellowship “Karst knowledge exchange to improve protection of groundwater resources”. The term “karst” applies to rocks that are soluble. In classic karst there are extensive caves and large scale surface karst landforms such as dolines, shafts, stream/river sinks, and springs. In the past, the Chalk and the Jurassic and Permian limestones of England were not considered karstic because they have limited cave development, and because karst features are generally small and have not been well documented. However, permeability in these aquifers is determined by their soluble nature and groundwater flow is predominantly through small-scale karstic solutional features. These reports provide data and information on karst in each area. Karst data are compiled from the British Geological Survey databases on karst, springs, and transmissivity; reports and peer reviewed papers; from geological mapping; and through knowledge exchange with the Environment Agency, universities, water companies and consultants. This report shows that there is some evidence for karst in the Chalk of the Isle of Wight, but that karst may be less well developed than in some areas of the mainland. Overall there is more evidence for karst in the Central Chalk Downs than in the Southern Downs. Dolines and dissolution pipes appear to be less common on the Isle of Wight than in some other areas of the Chalk, but dissolution pipes can be observed in Chalk coastal cliffs, and in excavated pits inland. Two stream sinks are recorded on the Isle of Wight. Springs occur in the Chalk at the boundaries with the overlying Palaeogene deposits, and underlying Upper Greensand Formation; and springs in the Upper Greensand Formation also discharge water from the Chalk where there is connectivity between the two aquifers. There are little data on spring discharge, and discharges are likely to have been substantially reduced by groundwater abstraction, but large springs appear to be rare. Caves are exposed in the Chalk coastal cliffs, and appear to have a predominantly marine origin, but there is evidence of some karstic development in some of these caves. Smaller conduits have been observed in inland quarries. Transmissivity data for the Chalk of the Isle of Wight are limited, with two sites where higher transmissivity indicates well connected solutional networks, but other sites indicating lower transmissivity than on the mainland. Coliforms have been occasionally detected in groundwater suggesting a rapid flow component. Further work is needed to assess the extent of karstic conduit development in the Chalk of the Isle of Wight, which could include coastal surveys of conduits, consideration of karstic indicators at abstraction boreholes, investigations of spring discharges, and tracer tests

BGS karst report series : J1 karst in the Jurassic Limestone Corallian Group of Northern England

This report documents the evidence for karst and rapid groundwater flow in the Jurassic Corallian limestones of Northern England. It is part of the BGS karst report series on those karst aquifers in England in which cave development is limited – principally the Upper Cretaceous Chalk and the Jurassic and Permian limestones. This area represents something of an anomaly in the Jurassic limestones as there is evidence of extensive cave development. The series is the main output of the NERC funded Knowledge Exchange fellowship “Karst knowledge exchange to improve protection of groundwater resources”. The term “karst” applies to rocks that are soluble. In classic karst there are extensive caves and large scale surface karst landforms such as dolines, shafts, stream/river sinks, and springs. In the past, the Chalk and the Jurassic and Permian limestones of England were not considered karstic because they have limited cave development, and because karst features are usually small and have not been well documented. These reports provide data and information on karst in each area. Karst data are compiled from the British Geological Survey databases on karst, springs, and transmissivity; reports and peer reviewed papers; from geological mapping; and through knowledge exchange with the Environment Agency, universities, water companies, consultants and cavers. This report shows that the Jurassic Corallian limestones of Northern England are highly karstic. Although cave development is not as extensive as in the Carboniferous limestones of the Yorkshire Dales, the discovery of the Excalibur Pot cave system in the North York Moors in 2007 demonstrated that large and extensive caves can form in the Corallian limestones. This cave system is now more than 3.8 km long, and there are several other karstic caves recorded in the J1 Jurassic limestone area. There are many large river sinks, with eight major rivers that lose water as they cross the Corallian outcrop. The Forge Valley swallow holes on the River Derwent are particularly substantial, providing point recharge of more than 375 l.s-1. There are several hundred springs recorded in the area, but there is little information on their discharge. At least 15 have very substantial flows, many of them more than 100 l.s-1. There are no records of dolines or dissolution pipes in the area, although some surface depressions above known caves are thought to be karst dolines. Records of karst features are not well developed in this area, and it is recommended that further work be done to develop improved karst datasets. Most tracer testing studies in the area have focused on the Forge Valley swallow holes, and consequently this karst system is very well characterised, with tests demonstrating rapid groundwater flows to multiple outlets spread over a wide area to the south and west of the swallow holes (Foley et al., 2012). Groundwater velocities based on time to peak concentration ranged from 18 to 13000 m/day over distances of between 18 and 7250 m. These tests demonstrate that borehole abstractions in the area have a high degree of connectivity with the main karst systems fed by swallow holes. The groundwater supply Source Protection Zones (SPZs) in this area have been modified, with the development of a bespoke approach to SPZ delineation reflecting the highly karstic nature of the aquifer, and the results of the tracer tests from the Forge Valley swallow holes. In areas away from the River Derwent there has not been much tracer testing. Tests have been conducted to investigate the Excalibur Pot cave system fed by stream sinks on the Hutton Beck, proving velocities of thousands of metres per day; and tracer tests from boreholes have demonstrated rapid flows of hundreds of metres per day to springs at Brompton and Keld Head. Hydrogeological studies in the area provide further evidence of karst and demonstrate that the karst impacts on boreholes. Transmissivity is variable, but there are some sites with very high transmissivities and/or yields indicating connectivity with extensive karstic networks. Borehole logging studies have demonstrated that flows to boreholes are via a small number of high yielding karstic fissures. Overall, there is clear evidence of karstic systems in the Jurassic limestones in this area, which are comparable to those in highly karstic aquifers, with a high proportion of rapid recharge at some groundwater outlets. Consideration of karst is important for all aspects of hydrogeology and aquifer management in this area. Further work is recommended to develop better karst datasets and investigate local karstic networks

BGS karst report series: J2. Karst in the Jurassic limestones of central England

This report documents the evidence for karst and rapid groundwater flow in the Jurassic limestones of central England. It is part of the BGS karst report series on karst aquifers in England in which cave development is limited – the Chalk and the Jurassic and Permian limestones. The series is the main output of the NERC funded Knowledge Exchange fellowship “Karst knowledge exchange to improve protection of groundwater resources”. The term “karst” applies to rocks that are soluble. In classic karst there are extensive caves and large scale surface karst landforms such as dolines, shafts, river sinks, and springs. In the past the Chalk and the Jurassic and Permian limestones of England were not considered karstic because they have limited cave development, and because karst features are usually small and have not been well documented. However, permeability in these aquifers is determined by their soluble nature and groundwater flow is predominantly through small-scale karstic solutional features. These reports provide data and information on karst in each area. Karst data are compiled from the British Geological Survey databases on karst, springs, and transmissivity; reports and peer reviewed papers; from geological mapping; and through knowledge exchange with the Environment Agency, universities, water companies and consultants. This report shows that in the Jurassic limestones of central England there is extensive evidence for karst, with surface geomorphology, tracer tests and hydrogeological studies all highlighting the role of karstic solutional development in the aquifers. Karst is best documented in the Grantham to Stamford area, associated with the East Glen, West Glen and Witham rivers; but there is evidence for karst throughout the area. Karst is particularly developed in the Lincolnshire Limestone Formation, but there is also evidence of karst in the limestones of the Great Oolite Group. Stream sinks, dolines, dissolution pipes, and springs are all present. There are many stream sinks, and several major rivers in the area have large losses to the aquifer as they cross the limestone. Some stream sinks are very substantial with inflows of 200-300 l/s. There are also many springs, and some have large reported discharges of up to 355 l/s. Several tracer tests indicate rapid groundwater flow velocities ranging from 21 to 10000 m/day over distances of up to 11.9 km. Tracer tests demonstrate connections to multiple outlets over a wide area, suggesting that the karst comprises complex networks with divergent and convergent flow. Some tracer breakthrough curves had very long tails, with tracer discharged for more than 100 days following injection indicating high attenuation via dispersion and/or diffusion. Hydrogeological studies in the area also indicate the importance of karstic solutional development including evidence from rapid water level responses in monitoring boreholes, and powerful artesian boreholes with large discharges. Further work is needed in the area to improve understanding of karst: Data on spring discharges are very sparse, and for most springs there discharge is unknown. There is almost no information on long term variations in spring discharges or how they respond to rainfall. Further studies of dolines and stream sinks, and further tracer testing would also be useful. Indicators of karst at abstraction boreholes (e.g. conduits observed in borehole images; water quality indicators of rapid groundwater flow) have not been considered for this report, and would enable understanding of the impacts of karst on groundwater abstractions. Although karstic caves have not been identified in this area, conduits are observed in quarries and unexplored small karstic caves may be present. The Jurassic limestones of central England are karstic in nature with extensive solutional networks of conduits and fissures. Karst is an important factor that should be considered in hydrogeological studies, and which affects groundwater protection and management in this area

BGS karst report series. C7, karst in the Chalk of the South Downs.

This report documents the evidence for karst and rapid groundwater flow in the Chalk of the South Downs area in Southern England. It is part of the BGS karst report series on those karst aquifers in England in which cave development is limited – principally the Upper Cretaceous Chalk and the Jurassic and Permian limestones. The series is the main output of the NERC funded Knowledge Exchange fellowship “Karst knowledge exchange to improve protection of groundwater resources”. The term “karst” applies to rocks that are soluble. In classic karst there are extensive caves and large scale surface karst landforms such as dolines, shafts, stream/river sinks, and springs. In the past, the Chalk and the Jurassic and Permian limestones of England were not considered karstic because they have limited cave development, and because karst features are usually small and have not been well documented. However, permeability in these aquifers is determined by their soluble nature and groundwater flow is predominantly through small-scale karstic solutional features. These reports provide data and information on karst in each area. Karst data are compiled from the British Geological Survey databases on karst, springs, and transmissivity; reports and peer reviewed papers; from geological mapping, and through knowledge exchange with the Environment Agency, universities, water companies and consultants. This report shows that in the C7 karst knowledge exchange area, the South Downs area of the Chalk, there is extensive evidence for karst development with dry valleys, caves, stream sinks, dolines, dissolution pipes, and springs present. Short caves have been recorded in the area, and the longest known Chalk cave in England (~350 m) is in this area at Beachy Head. Observations of coastal cliffs have been particularly important in demonstrating that caves and conduits can occur even beneath interfluves and in the absence of obvious surface karst. Coastal sections also provide evidence for pervasive stratigraphical influence on subsurface karst with distinct stratigraphical horizons (particularly sheet and semi-tabular flints, marl seams and hardgrounds) being important for conduit development. In the Beachy Head area, the Seven Sisters Flint, the Belle Tout Marls, the Shoreham Marls, the Navigation Marl, and the Hope Gap sheet flint all host cave and conduit systems. Locally, many stream sinks occur in association with the Chalk-Palaeogene margin, particularly in the west of the area. Stream sinks are less common or absent in the eastern parts of the area where the Palaeogene cover is absent, although major rivers cross the Chalk and their contribution to point recharge via losses to the aquifer was not established during this work. Soakaways and SUDs with high infiltration rates into the Chalk have also not been identified. Dolines also occur in the area, although many recorded surface depressions are likely to be pits of anthropogenic origin. Dissolution pipes are extremely common, especially where the Chalk is overlain by thin unconsolidated superficial deposits, and in some cases can be 10s of metres deep and/or wide. There are many springs in the area, which would have formed the natural outlets for the karstic solutional networks, although little is known about the discharge of most springs and how this has changed in response to groundwater abstraction. Five large springs are identified, the largest being the Bedhampton and Havant complex with a discharge of ~ 600-1900 l.s-1. Evidence from 22 tracer test connections demonstrate very rapid groundwater flow, with velocities ranging from 0.2 to 12.3 km/day over distances of up to 6.6 km; and tracer recoveries ranging from 0.1 to 100 %. Other evidence of karst comes from hydrogeological studies including investigations of transmissivity and pumping tests, water level data from observation boreholes, downhole imaging and borehole logs, groundwater quality, inflows during tunnel construction, saline intrusion, and groundwater flooding. There is considerable evidence for karst and rapid groundwater flow at groundwater abstractions throughout the South Downs area. Karst is clearly important in enabling rapid recharge and providing some rapid flowpaths through the unsaturated zone, especially via stream sinks but also via solutional fissures with no surface expression. However, there appears to be a higher degree of protection from surface pollutants than in highly karstic aquifers, perhaps due to fewer and smaller stream sinks and the potential for more attenuation in the unsaturated zone. Saturated zone networks of solutional fissures and conduits appear to be very common, and there is evidence to suggest that they extend over distances of several kilometres suggesting that karst specific approaches to Source Protection Zone delineation are likely to be useful. Consideration of the karstic processes that result in the enhanced permeability of the aquifer through the development of solutional fissures and conduits is key to understanding the hydrogeology of this area; and improved understanding of rapid flow in both the unsaturated and saturated zones is important for groundwater protection and management of water resources. This report presents an overview of the current conceptual understanding of karst in the Chalk in the South Downs and provides a basis for further investigations of karst in this area to enable improved management and protection of groundwater resources

Synapse-specific expression of calcium-permeable AMPA receptors in neocortical layer 5

In the hippocampus, calcium‐permeable AMPA receptors have been found in a restricted subset of neuronal types that inhibit other neurons, although their localization in the neocortex is less well understood. In the present study, we looked for calcium‐permeable AMPA receptors in two distinct populations of neocortical inhibitory neurons: basket cells and Martinotti cells. We found them in the former but not in the latter. Furthermore, in basket cells, these receptors were associated with particularly fast responses. Computer modelling predicted (and experiments verified) that fast calcium‐permeable AMPA receptors enable basket cells to respond rapidly, such that they promptly inhibit neighbouring cells and shut down activity. The results obtained in the present study help our understanding of pathologies such as stroke and epilepsy that have been associated with disordered regulation of calcium‐permeable AMPA receptors

A Label-Free Proteomic and Complementary Metabolomic Analysis of Leaves of the Resurrection Plant Xerophyta schlechteri during Dehydration

Vegetative desiccation tolerance, or the ability to survive the loss of ~95% relative water content (RWC), is rare in angiosperms, with these being commonly called resurrection plants. It is a complex multigenic and multi-factorial trait, with its understanding requiring a comprehensive systems biology approach. The aim of the current study was to conduct a label-free proteomic analysis of leaves of the resurrection plant Xerophyta schlechteri in response to desiccation. A targeted metabolomics approach was validated and correlated to the proteomics, contributing the missing link in studies on this species. Three physiological stages were identified: an early response to drying, during which the leaf tissues declined from full turgor to a RWC of ~80–70%, a mid-response in which the RWC declined to 40% and a late response where the tissues declined to 10% RWC. We identified 517 distinct proteins that were differentially expressed, of which 253 proteins were upregulated and 264 were downregulated in response to the three drying stages. Metabolomics analyses, which included monitoring the levels of a selection of phytohormones, amino acids, sugars, sugar alcohols, fatty acids and organic acids in response to dehydration, correlated with some of the proteomic differences, giving insight into the biological processes apparently involved in desiccation tolerance in this species

Transient developmental imbalance of cortical interneuron subtypes presages long-term changes in behavior

Cortical GABAergic interneurons are generated in large numbers in the ganglionic eminences and migrate into the cerebral cortex during embryogenesis. At early postnatal stages, during neuronal circuit maturation, autonomous and activity-dependent mechanisms operate within the cortex to adjust cell numbers by eliminating naturally occurring neuron excess. Here, we show that when cortical interneurons are generated in aberrantly high numbers—due to a defect in precursor cell proliferation during embryogenesis—extra parvalbumin interneurons persist in the postnatal mouse cortex during critical periods of cortical network maturation. Even though cell numbers are subsequently normalized, behavioral abnormalities remain in adulthood. This suggests that timely clearance of excess cortical interneurons is critical for correct functional maturation of circuits that drive adult behavior

Dexamethasone Treatment Induces the Reprogramming of Pancreatic Acinar Cells to Hepatocytes and Ductal Cells

The pancreatic exocrine cell line AR42J-B13 can be reprogrammed to hepatocytes following treatment with dexamethasone. The question arises whether dexamethasone also has the capacity to induce ductal cells as well as hepatocytes.AR42J-B13 cells were treated with and without dexamethasone and analyzed for the expression of pancreatic exocrine, hepatocyte and ductal markers. Addition of dexamethasone inhibited pancreatic amylase expression, induced expression of the hepatocyte marker transferrin as well as markers typical of ductal cells: cytokeratin 7 and 19 and the lectin peanut agglutinin. However, the number of ductal cells was low compared to hepatocytes. The proportion of ductal cells was enhanced by culture with dexamethasone and epidermal growth factor (EGF). We established several features of the mechanism underlying the transdifferentiation of pancreatic exocrine cells to ductal cells. Using a CK19 promoter reporter, we show that a proportion of the ductal cells arise from differentiated pancreatic exocrine-like cells. We also examined whether C/EBPβ (a transcription factor important in the conversion of pancreatic cells to hepatocytes) could alter the conversion from acinar cells to a ductal phenotype. Overexpression of an activated form of C/EBPβ in dexamethasone/EGF-treated cells provoked the expression of hepatocyte markers and inhibited the expression of ductal markers. Conversely, ectopic expression of a dominant-negative form of C/EBPβ, liver inhibitory protein, inhibited hepatocyte formation in dexamethasone-treated cultures and enhanced the ductal phenotype.These results indicate that hepatocytes and ductal cells may be induced from pancreatic exocrine AR42J-B13 cells following treatment with dexamethasone. The conversion from pancreatic to hepatocyte or ductal cells is dependent upon the expression of C/EBPβ

Experimental observation of high field diamagnetic fluctuations in Niobium

We have performed a magnetic study of a bulk metallic sample of Nb with critical temperature $T_{c}=8.5$ K. Magnetization versus temperature (M {\it vs} T) data obtained for fixed magnetic fields above 1 kOe show a superconducting transition which becomes broader as the field is increased. The data are interpreted in terms of the diamagnetic lowest Landau level (LLL) fluctuation theory. The scaling analysis gives values of the superconducting transition temperature $T_{c}(H)$ consistent with $H_{c2}(T)$% . We search for universal 3D LLL behavior by comparing scaling results for Nb and YBaCuO, but obtain no evidence for universality.Comment: 5 pages, 6 figures, Accepted for publication in Phys.Rev.