Assessing risk to groundwater quality using an integrated risk framework

Source-water protection strategies are ideally focused where the greatest amount of harm reduction can occur. This process of risk management requires an assessment of the spatial variability of risk to water. The assessment methodology presented herein combines aquifer susceptibility with a hazard threat inventory and an analysis of the consequence of contamination to assess the risk to water quality. Aquifer susceptibility combines the intrinsic susceptibility of the physical system with anthropogenic features that locally increase susceptibility. Hazard threats are assessed based on the properties of the chemicals (toxicity and environmental fate), the potential magnitude (extent and quantity of release) and the likelihood of release. The consequence is herein considered as the financial costs of the loss of the resource, including the replacement of a water source and the economic loss where water intensive businesses are lost. A second scenario is included that analyses health issues related to pathogen sources as well as the financial impact to the community where people fall ill and present a financial burden to the public health care system. The risk assessment methodology is applied to the Township of Langley, in southwestern British Columbia, Canada. The results outline the most vulnerable areas as those where susceptible aquifers coexist with potential chemical and biological threats. The risk is greatest where these vulnerable areas coincide with those with the greatest potential for financial loss: within the capture zones of major municipal production wells and where private wells serve agricultural operations with high annual farm sales.     

Replacing carbon lost from forests: an assessment of insurance,reserves, and expiring credits

Abstract

Concern over the “non-permanence” or reversibility of carbon sequestration projects has been prominent in discussions over how to develop guidelines for forest project investments under the Clean Development Mechanism (CDM) of the UNFCCC Kyoto Protocol. Accordingly, a number of approaches have been proposed that aim to help ensure that parties do not receive credit for carbon that is lost before project obligations are fulfilled. These approaches include forest carbon insurance, land reserves, and issuance of expiring credits. The potential costs of each of these different approaches are evaluated using a range of assumptions about project length, risk and discount rate, and a comparison of costs is ventured based on the estimated reduction in value of these credits compared with uninsured, and permanent credits. Obstacles to participation in the different approaches are discussed related to problems of long-term commitments, project scale, rising replacement costs, and low credit value. It is concluded that a system of expiring credits, which could be coupled with insurance or reserves, could guarantee obligations that span time-scales longer than that of conventional insurance policies while maintaining incentives for long-term sequestration.     

The origin of crystalline residues in Stardust Al foils: Surviving cometary dust or crystallized impact melts?

Abstract– Samples returned by the Stardust mission from comet 81P/Wild 2 provide an unequaled opportunity to investigate cometary formation and evolution. Crystalline silicates have been identified in impact craters in Stardust Al foil, yet their origin is ambiguous. They may be original cometary components, or they may have grown from melt generated by impact. We have now studied experimental impacts of the calcium silicate mineral wollastonite, using scanning and transmission electron microscopy to document the relationship between impact feature shape and crystal lattice orientation in impact residue. Wollastonite can have a characteristic acicular habit, forming crater shapes that indicate crystal orientation upon impact. From extracted impact residue, we determined the lattice orientation of crystalline material for comparison with the whole particle orientation. We assume that crystallization from melt, without surviving seed nuclei, should result in randomly oriented crystallite growth, with no preferred direction for individual crystals. However, we find that the majority of crystalline material in the residue retains b‐axis orientation parallel to the long axis of the crater form. This, together with impact parameter calculations and lack of Al incorporation by the residue (suggesting melting did not occur), indicates that these crystals and, by analogy, the majority of Al‐free crystalline silicates in Stardust foil, are surviving remnants of the impactor. Furthermore, amorphous wollastonite residue probably did not form via melting and subsequent quenching, but instead by high‐pressure amorphization or degradation of unquenchable phases. Finally, one crystal studied appears to be a new high‐pressure/temperature polymorph of CaSiO₃, indicating that such polymorphs may be observed in Stardust residues in craters.     

GRAVITAS: general relativistic astrophysics via timing and spectroscopy

GRAVITAS is an X-ray observatory, designed and optimised to address the ESA Cosmic Vision theme of ??Matter under extreme conditions??. It was submitted as a response to the call for M3 mission proposals. The concept centres around an X-ray telescope of unprecedented effective area, which will focus radiation emitted from close to the event horizon of black holes or the surface of neutron stars. To reveal the nature and behaviour of matter in the most extreme astrophysical environments, GRAVITAS targets a key feature in the X-ray spectra of compact objects: the iron K?? line at ~6.5?keV. The energy, profile, and variability of this emission line, and the properties of the surrounding continuum emission, shaped by General Relativity (GR) effects, provide a unique probe of gravity in its strong field limit. Among its prime targets are hundreds of supermassive black holes in bright Active Galactic Nuclei (AGN), which form the perfect laboratory to help understand the physical processes behind black hole growth. Accretion plays a fundamental role in the shaping of galaxies throughout cosmic time, via the process of feedback. Modest (~sub-arcmin) spatial resolution would deliver the necessary sensitivity to extend high quality X-ray spectroscopy of AGN to cosmologically-relevant distances. Closer to home, ultra-high count rate capabilities and sub-millisecond time resolution enable the study of GR effects and the equation of state of dense matter in the brightest X-ray binaries in our own Galaxy, using multiple probes, such as the broad iron line, the shape of the disk continuum emission, quasi-periodic oscillations, reverberation mapping, and X-ray burst oscillations. The enormous advance in spectral and timing capability compared to current or planned X-ray observatories would enable a vast array of additional scientific investigations, spanning the entire range of contemporary astrophysics from stars to distant galaxy clusters. Despite its breakthrough capabilities, all enabling technologies for GRAVITAS are already in a high state of readiness. It is based on ultra light-weight X-ray optics and a focal plane detector using silicon technology. The baseline launcher would be a Soyuz?CFregat to place GRAVITAS into a zero inclination, low-earth orbit, providing low and relatively stable background.     

A growth agenda without growth: English spatial policy,sustainable communities,and the death of the neo-liberal project?

The rapid onset of the recession in the UK in 2009 is likely to have profound implications for English spatial policy. The neo-liberal emphasis on supporting, and catering for, the expansion of the globally competitive London and the South East region is coming under strain as growth falters. The future of spatial policy seems uncertain as does the emphasis on what has been termed sustainable community-building. This paper explores and assesses the politics of assumption-building that have underpinned spatial policy practices and thinking in England under the Labour government. It examines and highlights some of the key challenges and difficulties that now face policy-makers and explores the possibility that we are witnessing the emergence of new forms of neo-Keynesianism. It shows that as the core assumptions of the 1990s and 2000s break down, so new opportunities are opened up for alternative, less growth-oriented agendas. The paper concludes by highlighting areas for further research and sketching out possible futures for the sustainable communities agenda.     

The mineralogy and mineral associations of platinum group elements and gold in the Platreef at Zwartfontein, Akanani Project, Northern Bushveld Complex, South Africa

The mineralogy of the platinum-group elements (PGE), and gold, in the Platreef of the Bushveld Complex, was investigated using an FEI Mineral Liberation Analyser. Polished sections were prepared from 171 samples collected from two boreholes, for the in-situ examination of platinum group minerals (PGM). PGM and gold minerals encountered include maslovite (PtBiTe, 32 area% of total PGM), kotulskite (Pd(BiTe), 17?%), isoferroplatinum (Pt₃Fe, 15?%), sperrylite (PtAs₂, 11?%), cooperite (PtS, 5?%), moncheite (PtTe₂; 5?%), electrum (AuAg; 5?%), michenerite (PdBiTe; 3?%), Pd alloys (Pd, Sb, Sn; 3?%), hollingworthite ((Rh,Pt)AsS; 2?%), as well as minor (all <1 area% of total PGM) merenskyite (PdBiTe₂), laurite (RuS₂), rustenburgite (Pt_0.4Pd_0.4Sn_0.2), froodite (PdBi₂), atokite (Pd_0.5Pt_0.3Sn_0.2), stumpflite (PtSb), plumbopalladinite (Pd₃Pb₂), and zvyagintsevite (Pd₃Pb). An observed association of all PGM with base metal sulfides (BMS), and a pronounced association of PGE tellurides, arsenides and Pd&Pt alloys with secondary silicates, is consistent with the remobilisation and recrystallisation of some of the PGM’s during hydrothermal alteration and serpentinisation subsequent to their initial (primary) crystallisation from BMS (e.g. Godel et al. J Petrol 48:1569–1604, 2007; Hutchinson and McDonald Appl Earth Sci (Trans Inst Min Metall B) 114:B208–224, 2008).     

Palaeomagnetic results from Mounts Gambier and Schank,South Australia

Palaeomagnetic results are presented for two young volcanoes in southeastern Australia. Directions for the basalt and lava spatter, erupted near the beginning and end of activity at Mt Gambier respectively, are identical and suggest there was no long break in activity. The direction for basalt at Mt Schank differs from that of Mt Gambier by several degrees, and indicates that the two volcanoes differ in age, probably by three centuries or more. Directions for both volcanoes are much shallower than the present‐day geomagnetic direction at the locality. Palaeomagnetic field strength estimates, from baked ash at Mt Gambier and baked sand at Mt Schank, are higher than the present‐day field strength. Comparisons with other late Pleistocene and Holocene results suggest that ages for Mts Gambier and Schank are either greater than 7000 years or between 5000 and 1000 years. These conclusions are consistent with published radiocarbon ages from charcoal in fossil soil horizons sealed beneath ash deposits.     

Explosion craters associated with shallow submarine gas venting off Panarea island, Italy

Explosions of hot water, steam, and gas are common periodic events of subaerial geothermal systems. These highly destructive events may cause loss of life and substantial damage to infrastructure, especially in densely populated areas and where geothermal systems are actively exploited for energy. We report on the occurrence of a large number of explosion craters associated with the offshore venting of gas and thermal waters at the volcanic island of Panarea, Italy, demonstrating that violent explosions similar to those observed on land also are common in the shallow submarine environment. With diameters ranging from 5 to over 100?m, the observed circular seafloor depressions record a history of major gas explosions caused by frequent perturbation of the submarine geothermal system over the past 10,000?years. Estimates of the total gas flux indicate that the Panarea geothermal system released over 70?Mt of CO₂ over this period of time, suggesting that CO₂ venting at submerged arc volcanoes contributes significantly to the global atmospheric budget of this greenhouse gas. The findings at Panarea highlight that shallow submarine gas explosions represent a previously unrecognized volcanic hazard around populated volcanic islands that needs to be taken into account in the development of risk management strategies.