Craig Goch Report No. 13 Invertebrate studies: Ystwyth and Rheidol

The Rivers Ystwyth and Rheidol have a history of metal pollution (Carpenter, 1924, 1925; Newton, 1944) and many reaches still receive substantial contamination from heavy metals, principally zinc and lead, although there has been considerable improvement in water quality and biological status in recent years, particularly in the r. Rheidol (Jones and Howells 1975). As a consequence of proposals to divert uncontaminated water from the headstreams of both rivers in order to provide a refill source for the enlarged Craig Goch reservoir, a surveillance programme was instituted to provide base-line data for water quality, fisheries and invertebrates. U.W.I.S.T. has implemented a programme designed to provide information on the variety, distribution and relative abundance of aquatic invertebrates: the study of other aspects has been undertaken by South West Wales River Division (1976)

Craig Goch Report No. 12 The production of two species of Ephemeropters (Ephemerella ignita PODA and Rhithrogena semicolorata CURTIS) in the upper reaches of the R. Wye, Wales

As part of a base-line ecological study of the R. Wye related to the construction of an enlarged Craig Goch, a proposed major regulating reservoir in the upper catchment which will be filled from a variety of sources, two sites (W2 and W3) in the headwaters were intensively studied during the period March 1975 – April 1976 and estimates of production made for two species of Ephemeroptera. Both study sites are typical salmon nursery areas with a substrate of cobbles and coarse gravel forming a ‘riffle’ habitat. The water, similar at both sides, is soft (mean calcium concentration = 4.1 mg/l) and low in inorganic nutrients. Samples, taken weekly during the summer and less frequently at other times, were collected from each riffle on a stratified random basis using a cylinder sampler (area, 0.05m2 ) modified after Neill (1938). Seven replicate samples were taken with weekly sampling and 14 at other sampling frequencies. The wetted area of each site was measured frequently throughout the study

Craig Goch Report No. 9 Mass mortalities of adult salmon (Salmo salar L.) in the R. Wye, 1976

The physical, biological and chemical conditions leading to a mass mortality of adult salmon (Salmo salar L.) in the lower reaches of the R. Wye are described. As a result of sunny and low flow conditions during late June, 1976, water temperatures increased to a maximum of 27.6oC and accelerated the decay of substantial plant stands, the growth of which had been enhanced by the prevailing conditions: this resulted in severe de-oxygenation of the water. It is concluded that the low oxygen concentration in the water at this time was the principal factor in causing mass mortalities of fish and was probably accentuated by high water temperatures

Craig Goch Report No. 12 The production of two species of Ephemeropters (Ephemerella ignita PODA and Rhithrogena semicolorata CURTIS) in the upper reaches of the R. Wye, Wales

As part of a base-line ecological study of the R. Wye related to the construction of an enlarged Craig Goch, a proposed major regulating reservoir in the upper catchment which will be filled from a variety of sources, two sites (W2 and W3) in the headwaters were intensively studied during the period March 1975 – April 1976 and estimates of production made for two species of Ephemeroptera. Both study sites are typical salmon nursery areas with a substrate of cobbles and coarse gravel forming a ‘riffle’ habitat. The water, similar at both sides, is soft (mean calcium concentration = 4.1 mg/l) and low in inorganic nutrients. Samples, taken weekly during the summer and less frequently at other times, were collected from each riffle on a stratified random basis using a cylinder sampler (area, 0.05m2 ) modified after Neill (1938). Seven replicate samples were taken with weekly sampling and 14 at other sampling frequencies. The wetted area of each site was measured frequently throughout the study

Microscopic Approach to Magnetism and Superconductivity of ff-Electron Systems with Filled Skutterudite Structure

In order to gain a deep insight into $f$-electron properties of filled skutterudite compounds from a microscopic viewpoint, we investigate the multiorbital Anderson model including Coulomb interactions, spin-orbit coupling, and crystalline electric field effect. For each case of $n$=1$\sim$13, where $n$ is the number of $f$ electrons per rare-earth ion, the model is analyzed by using the numerical renormalization group (NRG) method to evaluate magnetic susceptibility and entropy of $f$ electron. In order to make further step to construct a simplified model which can be treated even in a periodic system, we also analyze the Anderson model constructed based on the $j$-$j$ coupling scheme by using the NRG method. Then, we construct an orbital degenerate Hubbard model based on the $j$-$j$ coupling scheme to investigate the mechanism of superconductivity of filled skutterudites. In the 2-site model, we carefully evaluate the superconducting pair susceptibility for the case of $n$=2 and find that the susceptibility for off-site Cooper pair is clearly enhanced only in a transition region in which the singlet and triplet ground states are interchanged.Comment: 14 pages, 11 figures, Typeset with jpsj2.cl

Craig Goch Report No. 9 Mass mortalities of adult salmon (Salmo salar L.) in the R. Wye, 1976

The physical, biological and chemical conditions leading to a mass mortality of adult salmon (Salmo salar L.) in the lower reaches of the R. Wye are described. As a result of sunny and low flow conditions during late June, 1976, water temperatures increased to a maximum of 27.6oC and accelerated the decay of substantial plant stands, the growth of which had been enhanced by the prevailing conditions: this resulted in severe de-oxygenation of the water. It is concluded that the low oxygen concentration in the water at this time was the principal factor in causing mass mortalities of fish and was probably accentuated by high water temperatures

Characterization of the acidic cold seep emplaced jarositic Golden Deposit, NWT, Canada, as an analogue for jarosite deposition on Mars

Surficial deposits of the OH-bearing iron sulfate mineral jarosite have been observed in several places on Mars, such as Meridiani Planum and Mawrth Vallis. The specific depositional conditions and mechanisms are not known, but by comparing martian sites to analogous locations on Earth, the conditions of formation and, thus, the martian depositional paleoenvironments may be postulated. Located in a cold semi-arid desert ~100 km east of Norman Wells, Northwest Territories, Canada, the Golden Deposit (GD) is visible from the air as a brilliant golden-yellow patch of unvegetated soil, approximately 140 m x 50 m. The GD is underlain by permafrost and consists of yellow sediment, which is precipitating from seeps of acidic, iron-bearing groundwater. On the surface, the GD appears as a patchwork of raised polygons, with acidic waters flowing from seeps in troughs between polygonal islands. Although UV-Vis-NIR spectral analysis detects only jarosite, mineralogy, as determined by X-Ray Diffraction and Inductively Coupled Plasma Emission Spectrometry, is predominantly natrojarosite and jarosite, with hydronium jarosite, goethite, quartz, clays, and small amounts of hematite. Water pH varies significantly over short distances depending on proximity to acid seeps, from 2.3 directly above seeps, to 5.7 several m downstream from seeps within the deposit, and up to 6.5 in ponds proximal to the deposit. Visual observations of microbial filament communities and phospholipid fatty acid analyses confirm that the GD is capable of supporting life for at least part of the year. Jarositic-bearing sediments extend beneath vegetation up to 70 m out from the deposit and are mixed with plant debris and minerals presumably weathered from bedrock and glacial till. This site is of particular interest because mineralogy (natrojarosite, jarosite, hematite, and goethite) and environmental conditions (permafrost and arid conditions) at the time of deposition are conceivably analogous to jarosite deposits on Mars. Most terrestrial analogues for Mars jarosites have been identified in temperate environments, where evaporation rates are very high and jarosites form along with other sulfates due to rapid evaporation (e.g. Rio Tinto, Spain; Western Australian acidic saline lake deposits). The GD is a rare example of an analogue site where jarosite precipitates under dominant freezing processes similar to those which could have prevailed on early Mars. Thus, the GD offers a new perspective on jarosite deposition by the upwelling of acidic waters through permafrost at Meridiani Planum and Mawrth Vallis, Mars. The GD also demonstrates that martian deposits may show considerably more chemical and mineral variability than indicated by the current remote sensing data sets

Craig Goch Report No. 11 The behaviour and budgets of selected ions in the Wye Catchment

The river Wye, 250 km long and draining a predominantly rural catchment of 4183 km2, rises in mid-Wales (677m O.D.) and flows to the Severn Estuary (Fig 1). Samples for chemical analysis were obtained from sites 1 to 14 at two-week intervals over the period April 1975 to July 1976 and from site 15 at weekly intervals from 1973