The influence of sanitary and other social changes on the eutrophication of Lough Erne since 1850: Project introduction and a consideration of the potential role of metabolic wastes

Recent limnological studies of Lough Erne have suggested that the lake is highly producdve(F.B.I.u.1975.Gibsonet a1. 1980) and that the present level of productivity ig a result of increasing nutrient inputs to the llike over the past lob years or so (ila't:tarbee; 1977). It is the purpose of this project. funded by S.S.R.C. grant HR 7437. to document the deinographic. dietary and sanitary changes in the catchment since 1850 and to evalua.te the relative importance of 'domestic metabolic waste as a source of nutrient supply. This report provides an introduction to the project and considers the methods involved in estimating the minimum phosphorus output from households in the catchment ror the period 1851 - 1971

Injection of thermal and suprathermal seed particles into coronal shocks of varying obliquity

Context. Diffusive shock acceleration in the solar corona can accelerate solar energetic particles to very high energies. Acceleration efficiency is increased by entrapment through self-generated waves, which is highly dependent on the amount of accelerated particles. This, in turn, is determined by the efficiency of particle injection into the acceleration process. Aims. We present an analysis of the injection efficiency at coronal shocks of varying obliquity.We assessed injection through reflection and downstream scattering, including the effect of a cross-shock potential. Both quasi-thermal and suprathermal seed populations were analysed. We present results on the effect of cross-field diffusion downstream of the shock on the injection efficiency. Methods. Using analytical methods, we present applicable injection speed thresholds that were compared with both semi-analytical flux integration and Monte Carlo simulations, which do not resort to binary thresholds. Shock-normal angle θBn and shock-normal velocity Vs were varied to assess the injection efficiency with respect to these parameters. Results. We present evidence of a significant bias of thermal seed particle injection at small shock-normal angles. We show that downstream isotropisation methods affect the θBn-dependence of this result. We show a non-negligible effect caused by the crossshock potential, and that the effect of downstream cross-field diffusion is highly dependent on boundary definitions. Conclusions. Our results show that for Monte Carlo simulations of coronal shock acceleration a full distribution function assessment with downstream isotropisation through scatterings is necessary to realistically model particle injection. Based on our results, seed particle injection at quasi-parallel coronal shocks can result in significant acceleration efficiency, especially when combined with varying field-line geometry

The analysis of trace metals in surface waters from Scotland and Wales

188 water samples taken from Scottish and Welsh lakes in 1995/6 have been analysed for a range of trace metals, Hg, As, Se, Be, V, Cr, Co, Ni, Cu, Zn, Mo, Ag, Cd, Sb, Ba, Tl, Pb, & Bi. At all sites Hg, As, Se, Be, Bi, Pb and Ag were below limits of detection by the ICP-MS. The other elements showed various geographical distributions. In Wales, the south-central region and Anglesey appeared consistently higher and it is suggested that these are due to former mining and contemporary smelting activities respectively. In Scotland, distributions were move diverse although southern and south-west Scotland often appeared to show elevated levels as did sites on Orkney and Shetland. In general, lake sites in the north-west and Hebrides showed lower concentrations. Pnncipal Components Analysis (PCA) was used to try and determine any patterns in the data, but the results were inconclusive. The PC axes explained little of the variability within the data and clusters of sites on the bi-plots show little in common. However, only geographical location was available to be used m the PCA interpretation and it may be that other factors (lake and catchment characteristics, other water chemistry) would help explain the data more fully. The data included in this report are from smgle water samples taken over a short period of time. Therefore, althougl1 the data may show a useful 'snap-shot' of the situation, more information would be available from analyses of the sediment record (to put the data into temporal context) and other substrates where metal accumulation takes place. This would have the advantage of producing a time averaged metal value, but more importantly would mean more values above analytical detection and hence a better idea of metal distribution

Experimental Diatom Dissolution and the Quantification of Microfossil Preservation in Sediments

Four laboratory experiments on fresh, modern diatoms collected from lakes in the Northern Great Plains of North America were carried out to assess the effects of dissolution on diatom abundance and composition. Marked differences in mean dissolution susceptibility exist between species, despite sometimes significant intra- specific variation between heterovalves. Twenty-four taxa were ranked according to susceptibility to dissolution using an exponential decay model of valve abundance. This dissolution ranking was used to derive two weighted indices of sample preservation. A third index (F) was based on a simple binary classification of valve morphology into dissolved and pristine categories, as distinguished by light microscopy (LM). When compared against rank indices and a measure of species diversity, this diatom dissolution index was found to be the best predictor of the progress of dissolution as estimated by total valve abundance or biogenic silica (BiSi) loss. Strong empirical relationships between F index values and diatom abundance (r2 = 0.84, n = 32) and BiSi (r2 = 0.89, n = 32) were developed and applied to a diatom sequence from a short core from Devils Lake, North Dakota, and compared to diatom-inferred and observed salinity at this site. The F index is a simple, effective diagnostic tool to assess important aspects of diatom preservation. The index can provide insight into Si cycling and record changes in conditions pertinent to diatom dissolution, and has a role in validation of transfer functions or other inferences derived from compositional data

Heavy-ion acceleration and self-generated waves in coronal shocks

Conclusions. We suggest that understanding the acceleration of minor ions at coronal shocks requires simulations which allow us to explore trapping dynamics and acceleration timescales in detail, including evolution of the turbulent trapping boundary. We conclude that steady-state models do not adequately describe the acceleration of heavy ions in coronal shocks.</p

Holocene lake sediment core sequences from Lochnagar, Cairngorm Mts., Scotland - UK final report for CHILL-10,000

The CHILL 10,000 research objective at Lochnagar is to examine proxy data for temperature and climate conditions. Changes in lake sediment stratigraphical data can be used to reconstruct past conditions. These proxies include organic and minerogenic matter as a bulk proxy for catchment and within-lake productivity, chironomids as a proxy for air temperature, diatoms as an indicator for lake water pH, pollen as an indicator of catchment vegetation and finally biomarkers to help determine changes in proportions of organic source material within the lake mud

Particle scattering in turbulent plasmas with amplified wave modes

High-energy particles stream during coronal mass ejections or flares through the plasma of the solar wind. This causes instabilities, which lead to wave growth at specific resonant wave numbers, especially within shock regions. These amplified wave modes influence the turbulent scattering process significantly. In this paper, results of particle transport and scattering in turbulent plasmas with excited wave modes are presented. The method used is a hybrid simulation code, which treats the heliospheric turbulence by an incompressible magnetohydrodynamic approach separately from a kinetic particle description. Furthermore, a semi-analytical model using quasilinear theory (QLT) is compared to the numerical results. This paper aims at a more fundamental understanding and interpretation of the pitch-angle scattering coefficients. Our calculations show a good agreement of particle simulations and the QLT for broad-band turbulent spectra; for higher turbulence levels and particle beam driven plasmas, the QLT approximation gets worse. Especially the resonance gap at μ = 0 poses a well-known problem for QLT for steep turbulence spectra, whereas test-particle computations show no problems for the particles to scatter across this region. The reason is that the sharp resonant wave-particle interactions in QLT are an oversimplification of the broader resonances in test-particle calculations, which result from nonlinear effects not included in the QLT. We emphasise the importance of these results for both numerical simulations and analytical particle transport approaches, especially the validity of the QLT. Appendices A-D are available in electronic form at http://www.aanda.or