Defining and detecting undesirable disturbance in the context of marine eutrophication

An understanding of undesirable disturbance to the balance of organisms is needed to diagnose marine eutrophication as defined by EU Directives and OSPAR. This review summarizes the findings of the UK Defra-funded Undesirable Disturbance Study Team, which concluded that 'an undesirable disturbance is a perturbation of a marine ecosystem that appreciably degrades the health or threatens the sustainable human use of that ecosystem'. A methodology is proposed for detecting disturbance of temperate salt-water communities dominated by phytoplanktonic or phytobenthic primary producers. It relies on monitoring indicators of ecosystem structure and vigour, which are components of health. Undesirable disturbance can be diagnosed by accumulating evidence of ecohydrodynamic type-specific changes in: (i) bulk indicators; (ii) frequency statistics; (iii) flux measurements; (iv) structural indicators; and (v) indicator species. These are exemplified by (i) chlorophyll, transparency, dissolved oxygen, and opportunistic seaweed cover; (ii) HABs frequency; (iii) primary production; (iv) benthic and planktonic 'trophic indices'; (v) seagrasses and Nephrops norvegicus. Ecological Quality Objectives are proposed for some of these. Linking the diagnosis to eutrophication requires correlation of changes with nutrient enrichment. The methodology, which requires the development of a plankton community index and emphasizes the importance of primary production as an indicator of vigour, can be harmonized with the EU Water Framework Directive and OSPAR's Strategy to Combat Eutrophication.     

Pre-treatment of feed for dry magnetic separation of fine materials

Changes in the flow properties of the feed to an induced-roll magnetic separator have been shown to have a marked effect on the efficiency of its operation. The optimisation of the feeding system and removal of the ultrafines (?10 μm) from the feed have both been found to be viable methods for achieving good dry magnetic separations of fine mineral mixtures. Series of experiments have been performed on hematite/limestone and cassiterite/wolframite separations.     

Effects of pollution on the benthos of the Firth of Forth

A long-term benthic study has been undertaken in the Firth of Forth to assess the environmental impact of a new sewage treatment scheme for the city of Edinburgh. The Sewage Scheme reduces the suspended solids content of the liquid effluent by approximately 60% and achieves a lowering of the concentration of materials in solution through more efficient dilution and dispersion. Marked changes in the intertidal benthic flora and fauna have been recorded along the Edinburgh coastal zone. These changes have been apparent as the decline and disappearance of populations of certain pollution indicator species and the appearance and establishment of several species previously unrecorded along the more polluted parts of the Edinburgh shoreline. Study of the sublittoral benthos has shown no deleterious effect arising from the new effluent outfall, although there does appear to be some enhancement of the fauna in the area.     

Water quality in the firth of forth

A long-term programme of water quality monitoring has been undertaken in the Firth of Forth to assess the environmental impact of a new sewage treatment scheme for the City of Edinburgh. The sewage scheme reduces the suspended solids content of the liquid effluent by approximately 60% and achieves a lowering of the concentration of materials in solution through more efficient dilution and dispersion. The application of a sea water quality index to water quality data has demonstrated a significant improvement along the Edinburgh coastal zone, resulting mainly from a reduction in suspended solids, biochemical oxygen demand, primary nutrients and faecal contamination. There has been no apparent change in the levels of trace metals.     

Environmental predictions for the Beagle 2 lander, based on GCM climate simulations

The Mars climate database (MCD) is a database of statistics based on output from physically consistent numerical model simulations which describe the climate and surface environment of Mars. It is used here to predict the meteorological environment of the Beagle 2 lander site. The database was constructed directly on the basis of output from multiannual integrations of two general circulation models, developed jointly at Laboratoire de Météorologie Dynamique du Centre National de la Recherche Scientifique, France, and the University of Oxford, UK. In an atmosphere with dust opacities similar to that observed by Mars Global Surveyor, the predicted surface temperature at the time of landing (L_s=322°, 13:00 local time), is , and varying between ∼186 and over the Martian day. The predicted air temperature at above the surface, the height of the fully extended Beagle 2 robot arm, is at the time of landing. The expected mean wind near the surface on landing is north-westerly in direction, becoming more southerly over the mission. An increase in mean surface pressure is expected during the mission. Heavy global dust storm predictions are discussed; conditions which may only occur in the extreme as the expected time of landing is around the end of the main dust storm period. Past observations show approximately a one in five chance of a large-scale dust storm in a whole Mars year over the landing region, Isidis Planitia. This statistic results from observations of global, encircling, regional and local dust storms but does not include any small-scale dust “events” such as dust devils.     

Catastrophic drought-induced die-off of perennial chenopod shrubs in arid Australia following intensive cattle browsing

Cover and survivorship of perennial chenopods, Atriplex vesicaria and Maireana astrotricha, declined markedly during a prolonged dry period at Roxby Downs in arid South Australia. Despite their resilience to browsing in favourable seasons, only 2% of the A. vesicaria shrubs browsed heavily by cattle survived the drought. M. astrotricha exhibited greater drought survivorship, although the post-drought cover retention in browsed shrubs was only half that of unbrowsed controls. Survivorship was highest for unbrowsed chenopods growing in moisture-enhanced run-on or dune-base environments. Maintenance of these patchy areas with reduced water-stress is hence important for the persistence of browsed chenopod shrublands. Light browsing by either European Rabbits (Oryctolagus cuniculus) or Greater Stick-nest Rats (Leporillus conditor) had no measurable impact upon chenopod survivorship.     

A comparison of empirical orthogonal decomposition methods in baroclinic flows

The relative merits of three contrasting empirical orthogonal decomposition methods in common use (namely, Proper Orthogonal Decomposition, Biorthogonal Decomposition and Multivariate Singular Systems Analysis) are considered as applied to baroclinic flow data. The regimes analysed are a steady, drifting wave, a modulated amplitude vacillating wave flow and a neighbouring multi-mode state which exhibits intermittency. The results are used to make a qualitative comparison of the methods in terms of convergence properties, variance capture and eigenfunction structure. The feasibility of using the resulting empirical orthogonal functions to transform partial differential equations to ordinary differential equations by Galerkin projection is mentioned.