Inventory of aquatic contaminant flux arising from historical metal mining in England and Wales

The impact of discharges from abandoned metal and ironstone mines has been a much studied form of aquatic pollution in recent decades. Few attempts however, have been made to accurately determine the overall contaminant mass flux arising from abandoned mine sites at scales above catchment level. Such assessments are critical to determine the significance of former mining to national, regional and ultimately global trace metal flux. This paper presents the most comprehensive national survey to date across England and Wales of the total pollution burden discharged at source from abandoned non-coal mine sites. 338 discharges have been identified (from 4923 known abandoned metal mines) and while concurrent flow and contaminant concentration records are only available for around 30% of these, significant quantities of metals (and As) have been quantified to be discharged. A minimum of 193 tonnes of Zn, 18.5 tonnes of Pb, 0.64 tonnes Cd, 19.1 tonnes of Cu, 551 tonnes Fe, 72 tonnes Mn and 5.1 tonnes As are released in water discharges from abandoned non-coal mines to the surface water environment of England and Wales each year. Precautionary extrapolation of mass fluxes based on the frequency distribution of measured concentration and flow data, for discharges with absent data, suggests that the actual total mass flux for these contaminants could be up to 41% higher. The mass flux of Pb released from mines exceeds that of all currently permitted discharges (e.g. active industrial sites and wastewater treatment works) to surface waters across England and Wales, while those of As, Cd and Zn are of a similar magnitude. These data put into context the enduring legacy of historic mining on the water environment, highlighting its significance relative to more highly regulated polluting sites. Comparison of the figures with estimates of global trace metal flux suggests that the national total identified here is significant on a global scale

On the spin modulated circular polarization from the intermediate polars NY Lup and IGRJ1509-6649

We report on high time resolution, high signal/noise, photo-polarimetry of the intermediate polars NY Lup and IGRJ1509-6649. Our observations confirm the detection and colour dependence of circular polarization from NY Lup and additionally show a clear white dwarf, spin modulated signal. From our new high signal/noise photometry we have unambiguously detected wavelength dependent spin and beat periods and harmonics thereof. IGRJ1509-6649 is discovered to also have a particularly strong spin modulated circularly polarized signal. It appears double peaked through the I filter and single peaked through the B filter, consistent with cyclotron emission from a white dwarf with a relatively strong magnetic field. We discuss the implied accretion geometries in these two systems and any bearing this may have on the possible relationship with the connection between polars and soft X-ray-emitting IPs. The relatively strong magnetic fields is also suggestive of them being polar progenitors.Comment: 8 pages, 6 figures and 1 table. Accepted for publication in MNRA

Stokes imaging, Doppler mapping and Roche tomography of the AM Her system V834 Cen

We report on new simultaneous phase resolved spectroscopic and polarimetric observations of the polar (AM Herculis star) V834 Cen during a high state of accretion. Strong emission lines and high levels of variable circular and linear polarization are observed over the orbital period. The polarization data is modelled using the Stokes imaging technique of Potter et al. The spectroscopic emission lines are investigated using the Doppler tomography technique of Marsh and Horne and the Roche tomography technique of Dhillon and Watson. Up to now all three techniques have been used separately to investigate the geometry and accretion dynamics in Cataclysmic Variables. For the first time, we apply all three techniques to simultaneous data for a single system. This allows us to compare and test each of the techniques against each other and hence derive a better understanding of the geometry, dynamics and system parameters of V834 Cen.Comment: 10 pages, 8 figures; Accepted for publication in MNRA

Computational studies of light acceptance and propagation in straight and curved multimodal active fibres

A Monte Carlo simulation has been performed to track light rays in cylindrical multimode fibres by ray optics. The trapping efficiencies for skew and meridional rays in active fibres and distributions of characteristic quantities for all trapped light rays have been calculated. The simulation provides new results for curved fibres, where the analytical expressions are too complex to be solved. The light losses due to sharp bending of fibres are presented as a function of the ratio of curvature to fibre radius and bending angle. It is shown that a radius of curvature to fibre radius ratio of greater than 65 results in a light loss of less than 10% with the loss occurring in a transition region at bending angles of pi/8 rad.Comment: 21 pages, 13 figure