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51.
The contamination and resulting degradation of water coursesby effluents from abandoned and active mines is a world-wideproblem. Traditional methods of remediating the dischargesfrom mines involve the addition of chemicals and the utilisationof artificial energy sources. Over the last 15–20 years passivetreatment systems have been developed that harness naturalchemical and biological processes to ameliorate the potentiallytoxic effects of such discharges. There are many different typesof passive system, including compost wetlands, reducing andalkalinity producing systems (RAPS), permeable reactive barriersand inorganic media passive systems. Different waste materialscan be utilised as reactive media within each of these systems,dependent upon the type of mine water and treatment technology.In many cases the reactivity of these recycled waste materialsis key to the remedial performance of these systems. The materialsused may be organic (e.g., composts) or inorganic (e.g., blast furnaceslag) and where possible are sourced locally in order to minimisetransport costs. The remediation of mine waters in itself canproduce large quantities of waste products in the form of ironoxide sludge. Potential uses of this material in the productionof pigments and in the treatment of phosphate contaminatedwaters is also currently under investigation.The exploitation of what are traditionallythought of as waste materials within treatmentsystems for polluted waters is an expandingtechnology which provides great scope for recycling. 相似文献
52.
Lewis J. Alcott Alexander J. Krause Emma U. Hammarlund Christian J. Bjerrum Florian Scholz Yijun Xiong Andrew J. Hobson Lesley Neve Benjamin J. W. Mills Christian Mrz Bernhard Schnetger Andrey Bekker Simon W. Poulton 《Geostandards and Geoanalytical Research》2020,44(3):581-591
The development and application of geochemical techniques to identify redox conditions in modern and ancient aquatic environments has intensified over recent years. Iron (Fe) speciation has emerged as one of the most widely used procedures to distinguish different redox regimes in both the water column and sediments, and is the main technique used to identify oxic, ferruginous (anoxic, Fe(II) containing) and euxinic (anoxic, sulfidic) water column conditions. However, an international sediment reference material has never been developed. This has led to concern over the consistency of results published by the many laboratories that now utilise the technique. Here, we report an interlaboratory comparison of four Fe speciation reference materials for palaeoredox analysis, which span a range of compositions and reflect deposition under different redox conditions. We provide an update of extraction techniques used in Fe speciation and assess the effects of both test portion mass, and the use of different analytical procedures, on the quantification of different Fe fractions in sedimentary rocks. While atomic absorption spectroscopy and inductively coupled plasma‐optical emission spectrometry produced comparable Fe measurements for all extraction stages, the use of ferrozine consistently underestimated Fe in the extraction step targeting mixed ferrous–ferric minerals such as magnetite. We therefore suggest that the use of ferrozine is discontinued for this Fe pool. Finally, we report the combined data of four independent Fe speciation laboratories to characterise the Fe speciation composition of the reference materials. These reference materials are available to the community to provide an essential validation of in‐house Fe speciation measurements. 相似文献
53.
正1 Introduction The primary goal of the Deep-time Digital Earth project is to develop an open collaboration and data sharing platform that enables the transition of deep-time geoscientific research to a Big Data driven paradigm.Such an open platform will require the ability to effectively and efficiently access and integrate a wide variety of digital Earth data,from remotely sensed Earth observations and geophysical data to data generated in 相似文献
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Karen Fisher Miriam Williams Stephen FitzHerbert Lesley Instone Michelle Duffy Sarah Wright Sandie Suchet‐Pearson Kate Lloyd Laklak Burarrwanga Ritjilili Ganambarr Merrkiyawuy Ganambarr‐Stubbs Banbapuy Ganambarr Djawundil Maymuru Bawaka Country 《New Zealand geographer》2015,71(1):18-33
This paper investigates the writing of situated knowledge and explores the possibilities of enacting difference by writing differently. We present a selection of research stories in which carrier bags, sounds, baskets, gardens and potatoes are interpreted less as objects of research or metaphors to aid in analysing phenomena, than as mediators of the stories. Our stories emphasise the ontological politics of engaging with and representing the relational, the messy, the spontaneous, the unpredictable, the non‐human and bodily experiences. These stories demonstrate how writing is performative and how it is integral to the production of knowledge. 相似文献
58.
Lesley K. Summers Ian R. Stevens David K. Strickland † 《Monthly notices of the Royal Astronomical Society》2001,327(2):385-396
We present ROSAT HRI X-ray data and optical imaging of the important dwarf starburst Markarian 33. We find an extended, complex, shell-like morphology in the X-ray emission, with an extent of ∼ , coincident with the bright star-forming regions at the centre of the galaxy. The physical extent of this X-ray emission from Mrk 33 is very similar to the observed H α emission, and suggests that the bulk of the X-ray emission is coming from an expanding superbubble.
We estimate the age and mass of Mrk 33's starburst to be 5.8 Myr and respectively, with the energy injection rate in the central regions of the galaxy being ∼1041 erg s−1 , while the associated mass-loss rate from the star-forming regions is estimated to be ∼0.2 M⊙ yr−1 . We suggest that the X-ray emission is predominantly powered by starburst-type activity, and argue that a blow-out in the form of a galactic wind is the most likely fate for Mrk 33, resulting in the loss of most of the galaxy's metal-enriched material and a small fraction (<1 per cent) of the ISM. 相似文献
We estimate the age and mass of Mrk 33's starburst to be 5.8 Myr and respectively, with the energy injection rate in the central regions of the galaxy being ∼10
59.
Gary L. Raines Katherine A. Connors Lesley B. Chorlton 《Natural Resources Research》2007,16(2):191-198
Geologic maps are a fundamental data source used to define mineral-resource potential tracts for the first step of a mineral
resource assessment. Further, it is generally believed that the scale of the geologic map is a critical consideration. Previously
published research has demonstrated that the U.S. Geological Survey porphyry tracts identified for the United States, which
are based on 1:500,000-scale geology and larger scale data and published at 1:1,000,000 scale, can be approximated using a
more generalized 1:2,500,000-scale geologic map. Comparison of the USGS porphyry tracts for the United States with weights-of-evidence
models made using a 1:10,000,000-scale geologic map, which was made for petroleum applications, and a 1:35,000,000-scale geologic
map, which was created as context for the distribution of porphyry deposits, demonstrates that, again, the USGS US porphyry
tracts identified are similar to tracts defined on features from these small scale maps. In fact, the results using the 1:35,000,000-scale
map show a slightly higher correlation with the USGS US tract definition, probably because the conceptual context for this
small-scale map is more appropriate for porphyry tract definition than either of the other maps. This finding demonstrates
that geologic maps are conceptual maps. The map information shown in each map is selected and generalized for the map to display
the concepts deemed important for the map maker’s purpose. Some geologic maps of small scale prove to be useful for regional
mineral-resource tract definition, despite the decrease in spatial accuracy with decreasing scale. The utility of a particular
geologic map for a particular application is critically dependent on the alignment of the intention of the map maker with
the application. 相似文献
60.
We tested the ability of pollution induced community tolerance (PICT) to detect the effects of chronic metal pollution on estuarine sediment microbial communities, along a gradient spanning two orders of magnitude in metal concentrations. In tandem, we investigated the associated microbial community structure using terminal restriction fragment length polymorphism (T-RFLP). Tolerance of microbes to Cu, measured as IC50 (inhibitory concentration 50%), was strongly correlated with pore water Cu concentration (r(2)=0.842). No strong correlation existed for other metals tested, highlighting the ability of PICT to identify the pollutant causing a toxic effect. There was no correlation between microbial community structure and community tolerance to metals tested, but analysis of community structure did provide some information on reasons for observed PICT response. PICT methodology used here provided a greater strength and consistency of association with pollutant concentration compared to microbial community structure and can be recommended as a sensitive indicator of metal pollution on estuarine sediment microbial communities. 相似文献