Neutral aldoses as source indicators for marine snow

The chemical characteristics of aggregating material in the marine environment are largely unknown. We investigated neutral aldose (NA) abundance and composition in aggregation of marine snow and other organic matter (OM) size fractions in the field. Four sample sets were fractionated using membrane filtration and ultrafiltration into the following size fractions: particulate material, high-molecular-weight (HMW) material, and low-molecular-weight (LMW) material. We also collected three sample sets of marine-snow aggregates. Each sample set contained small, medium, and large aggregate size fractions and each size fraction consisted of 25–50 aggregates. For 7 marine-snow samples and for each water-sample size fraction, we determined monomeric and polymeric NA concentration, NA yield (amount of NA-C normalized to organic carbon), and composition; total organic carbon (TOC) concentration; transparent exopolymer particles (TEP) concentration, and TEP propensity (TEP concentration after inducing TEP formation in filtered samples). This is the first study to include compound-specific NA determinations on these four marine OM size fractions.The mass balances of organic carbon and NA indicated that there were no serious contamination or loss problems. Concentrations, yields, and NA mol fractions in water samples were similar to results from other studies. Glucose and galactose had the highest relative abundance in all size fractions. The NA yield increased with increasing molecular weight or particle size for all fractions except marine snow. The NA yield increased in the order: LMW< marine snow< HMW< particles. Marine snow had a higher average NA yield than the LMW fraction, but lower than particle and HMW-fractions. This indicates that OM in marine snow could have been diagenetically derived from particulate and HMW-fractions, that is, marine snow may include material from the particulate and the colloidal phase.TEP concentration or TEP propensity was positively correlated with concentrations of all individual NAs as well as the sum NA concentrations, indicating that TEP contains neutral sugars in addition to the acidic polysaccharides stained in the determination of TEP concentrations.Despite the relatively low NA yield in marine snow, marine snow was enriched in NA when compared with seawater, with enrichment factors of 34–225 (average 125). By combining data from this study with data from other studies, we estimate that < 10% of carbohydrates in marine snow comprise NAs.There was no clear correlation between marine-snow aggregate size and NA yield, that is, there appears to be no general age difference between small and large marine-snow aggregates. NA composition was similar among different marine-snow size fracions collected during the same day, indicating that aggregation/disaggregation reactions resulted in homogenizing NA composition in marine-snow aggregates of all sizes. The NA composition of marine snow was different from that of other OM size fractions, indicating either that bacterial degradation has modified the composition of marine snow to a larger extent than other OM size fractions or that marine snow is formed through the aggregation of selected subcomponents of OM.     

Water quality assessment of Wei River, China using fuzzy synthetic evaluation

Wei River is the major source of water for the urban residents, industrial production and agricultural activities in the central Shaanxi plain of China. Water quality of the Wei River was determined by collecting water samples from 25 locations along the Baoji Xi’an reach and analyzing for pH, EC, BOD₅, DO, COD, F, Se, As, and Hg. Fuzzy synthetic evaluation with the entropy method for weight determination was used to assess the water quality of the river. Results indicate that the water quality of 23 sampling sites fall into the fifth grade (bad level), whereas two sampling sites are in the fourth grade (poor level). The comparison of this method with the typical fuzzy synthetic evaluation shows that it is effective in water quality assessment. The assessment results indicate that the Wei River is heavily polluted at most of the sampling locations, with mercury as the major pollutant. Strict enforcement of the regulations for domestic and industrial wastewater discharges is vital to avoid damage to the water environment and to protect human and ecological health.     

Radiological hazards of coal and ash samples collected from Xi’an coal-fired power plants of China

The natural radiological characteristics and their respective annual effective dose (AED) rates, produced by ²²⁶Ra, ²³²Th and ⁴⁰K in coal, fly ash and bottom ash from two large coal-fired power plants (CFPPs) of Xi’an were determined by means of γ-ray spectrometry. The average activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in all ash samples (fly ash and bottom ash samples) from the two CFPPs were 67.6, 74.3 and 225.3 Bq kg⁻¹, respectively. The results are compared with data from other locations. To evaluate the radiological hazards of the natural radioactivity, the radium equivalent activity (Ra_eq), air absorbed dose rate (D), AED and external hazard index (H _ex) are compared with internationally accepted values. Ra_eq and H _ex of all samples except three fly ash samples were less than the limits of 370 Bq kg⁻¹ and unity, respectively. The average D and AED for ash samples were 86.8 nGy h⁻¹ and 0.11 mSv y⁻¹, respectively, which exceed the world average and Xi’an average values.     

Critical geography and the opening up of the academy: lessons from 'real life' attempts

Summary Two 'real' attempts that have been made to engage geography with everyday struggles are considered in the light of the critical geography movement. First, my experiences of an anti-gentrification workshop at the Inaugural International Conference on Critical Geography in Vancouver, Canada. Second, my experiences in speaking about a research project 'outside' the academy, through the media. These attempts illustrate that geographers may be overestimating the particular expertise and experience that we bring to the table. Stepping out of our so-called 'ivory towers' is but the first step in what can only be called an educational journey.     

Rough evaluation of the water-inflow discharge in abandoned mining tunnels using a simplified water balance model: the case of the Cogne iron mine (Aosta Valley, NW Italy)

One of the most complex hydrogeological problems in the design and maintenance of drainage systems in abandoned mining sites is quantifying the maximum water infiltration and, therefore, the amount that is potentially drainable by the tunnels. This problem is compounded when water-inflow data are limited or lacking. The aim of the study was to present a single but reliable model for making this evaluation; this model was applied to the case history of the abandoned Cogne iron ore mining complex (Western Alps, Aosta Valley Region, NW Italy). The study focused on quantifying the amount of water infiltrating into the mine drifts, using a water balance model in a Geographic Information System (GIS) environment. In the model, five different infiltration scenarios were calculated, including a detailed analysis of rainfall data, snow density and thickness (Snow Water Equivalent calculation), and melting periods. The maximum water discharge that could affect the mine tunnels was, therefore, determined under several scenarios of normal precipitation conditions and during heavy rainfall, including the case of the Cogne valley flood in October 2000, used as a reference for the limit conditions. Taking into account the various approximations considered, the results can be considered a good indication of the magnitude of the total amount of water that should be drained out through abandoned mine drifts and in the drainage network during implementation of final closure of the mine.     

Cassiopeia A: dust factory revealed via submillimetre polarimetry

If Type II supernovae – the evolutionary end points of short-lived, massive stars – produce a significant quantity of dust  (>0.1 M_⊙)  then they can explain the rest-frame far-infrared emission seen in galaxies and quasars in the first Gyr of the Universe. Submillimetre (submm) observations of the Galactic supernova remnant, Cas A, provided the first observational evidence for the formation of significant quantities of dust in Type II supernovae. In this paper, we present new data which show that the submm emission from Cas A is polarized at a level significantly higher than that of its synchrotron emission. The orientation is consistent with that of the magnetic field in Cas A, implying that the polarized submm emission is associated with the remnant. No known mechanism would vary the synchrotron polarization in this way and so we attribute the excess polarized submm flux to cold dust within the remnant, providing fresh evidence that cosmic dust can form rapidly. This is supported by the presence of both polarized and unpolarized dust emission in the north of the remnant where there is no contamination from foreground molecular clouds. The inferred dust polarization fraction is unprecedented  ( f _pol∼ 30 per cent)  which, coupled with the brief time-scale available for grain alignment (<300 yr), suggests that supernova dust differs from that seen in other Galactic sources (where   f _pol= 2−7  per cent) or that a highly efficient grain alignment process must operate in the environment of a supernova remnant.     

Quantitative measures of textural anisotropy resulting from magmatic compaction illustrated by a sample from the Palisades sill, New Jersey

Early in the crystallization of many tholeiitic basaltic magmas, plagioclase crystals cluster together into a 3-D cellular network, which forms a passive marker capable of recording the deformation that accompanies compaction of crystal mush. Although irregular in detail, the overall network is initially isotropic and only becomes anisotropic as a result of compaction. We have developed four independent methods to quantify the 3-D textural anisotropy of a basalt sample using at least three non-parallel thin sections. Three of the methods are based on the geometrical properties of digitized maps of the feldspar chain networks. One approach focuses on the angular variation of the mean intercept along parallel traverses through the network, another examines the orientation and size distribution of individual links, and the third considers the average shape of interstitial regions outlined by the plagioclase network. The fourth technique approximates the textural anisotropy by the variogram anisotropy of a scanned thin section image. We illustrate the methods using five oriented non-parallel thin sections from a sample of diabase 146 m above the base of the 300-m-thick Palisades sill of New Jersey. Compaction of crystal mush in this sill has previously been postulated on the basis of chemical evidence. The 3-D feldspar network anisotropy based on the first three approaches suggests nearly uniaxial compaction on the order of 8.6% in a direction within 3° of the intersection of the columnar joints at the sample site. A rigorous statistical test based on the statistics of elliptically contoured non-normal multivariate distributions documents that the link-vector distribution in vertical sections are statistically anisotropic at a 95% confidence level and that the overall compaction is 7.9±2.6%. The orientation and magnitude of the 3-D textural anisotropy determined by the image variogram of the non-opaque minerals is almost identical to the mean feldspar network anisotropy; 8.5% compaction in a direction 10° from the columnar joint intersections. The major silicate textural and feldspar network anisotropy axes both plunge almost directly down dip of the sill. On the other hand, the major axis of the variogram anisotropy of the opaque minerals is approximately parallel to the strike of the sill and to the major axis of the anisotropic magnetic susceptibility. The anisotropy of the silicate mineral fabric may reflect down-dip flow of a deformable melt-rich crystal mush, whereas the AMS and opaque textural anisotropy reflects the influence of gravitational stresses during the growth of magnetite in the final stages of melt crystallization. Evidently the Palisades sill was not originally horizontal but was intruded in an orientation close to its present attitude.     

Evaluation of the Johnson and Ettinger Model for Prediction of Indoor Air Quality

Screening level models are now commonly used to estimate vapor intrusion for subsurface volatile organic compounds (VOCs). Significant uncertainty is associated with processes and models and, to date, there has been only limited field-based evaluation of models for this pathway. To address these limitations, a comprehensive evaluation of the Johnson and Ettinger (J&E) model is provided through sensitivity analysis, comparisons of model-predicted to measured vapor intrusion for 11 petroleum hydrocarbon and chlorinated solvent sites, and review of radon and flux chamber studies. Significant intrusion was measured at five of 12 sites with measured vapor attenuation ratios (α_m's) (indoor air/source vapor) ranging from ∼1 × 10⁻⁶ to 1 × 10⁻⁴. Higher attenuation ratios were measured for studies using radon, inert tracers, and flux chambers; however, these ratios are conservative owing to boundary conditions and tracer properties that are different than those at most VOC-contaminated sites. Reasonable predictions were obtained using the J&E model with comparisons indicating that model-predicted vapor attenuation ratios (α_p's) were on the same order, or less than the α_m's. For several sites, the (m were approximately two orders of magnitude less than the a 's indicating that the J&E model is conservative in these cases. The model comparisons highlight the importance in using appropriate input parameters for the J&E model. The regulatory implications associated with use of the J&E model to derive screening criteria are also discussed.     

Driving environmental certification: its impact on the furniture and timber products value chain in South Africa

In this new globalised era there is an increasing demand in the developed world for environmental certification (Forestry Stewardship Council) of furniture and timber products. The imposition of this requirement has major implications for producers in developing countries. This paper examines this issue from a value chain perspective, exploring how certification requirements are driven through the links of the global furniture value chain. It does so by focusing on the dynamic underlying the spread of FSC certification through the furniture and timber industry in South Africa, and investigates the role of the various organisational ‘drivers’ of the system. In doing so it explores how developing country firms relate to these opportunities and pressures, drawing out the logistical implications, the costs and benefits, as well as the future for FSC certification. It concludes with a discussion of the role of buyers, agents, certification agencies and manufacturers in driving FSC certification through the wood products value chain in South Africa.     

The experimental oceanographic satellite Seasat-A

A Seasat-A Project was conceived and is being implemented to establish the utility of an array of microwave instruments in space for oceanic research and marine technology. The instruments include: a short-pulse radar altimeter, a wind-field scatterometer, an experimental synthetic-aperture imaging radar, a scanning multifrequency microwave radiometer, and a supporting visual and infrared radiometer. All weather, day-night measurements of sea-surface temperature, surface wind speed and direction, sea state and directional wave spectra will be made, the latter over limited areas and times because of operational limitations on the synthetic-aperture-radar instrument. Highly precise (&<0.1 m) range information from the radar altimeter, in combination with an accurate satellite emphemeris, will be used to infer dynamic departures of sea level from the marine geoid produced by tides, currents, and storm surges. Sea ice will be observed by the synthetic-aperture radar, radar altimeter and the scanning multifrequency microwave radiometer, with particular emphasis on demonstrating their capability to determine polar ice coverage, dynamics and navigability.The satellite will be launched into a high-inclination (108 °), non-sun-synchronous, nearly-circular 800 km orbit in May of 1978. The orbit is such that a dense network traced out by the subsatellite point (18.5-km equatorial separation of ascending orbits) will be obtained in 152 days for geodesy. The satellite is designed for a minimum lifetime of one year; with expendables, including orbit adjust capability, for three.All data, except those obtained from the synthetic-aperture radar, will be collected globally, and returned, as measured, first by a 25 kbps data stream, and then after playback at a rate of 800 kbps from the on-board tape recorder. Synthetic-aperture radar data will be returned in real time only, over a 20-MHz analog telemetry link. We expect that satellite data will be distributed through the National Oceanic and Atmospheric Administrations Environmental Data Service. Processed data are expected to be generally available through this agency within a very few months of launch, following preliminary assessment of instrument operation and evaluation of performance.