Sekundäre Prozesse in Bergbauhalden und Aufbereitungsabgängen - Steuerung von Stoffmobilität und Krustenbildung

Aufbereitungsabgänge aus dem Abbau sulfidischer Erze verursachen diverse Umweltprobleme, wie Sauerwasserbildung und Staubemissionen. Diesen Gefahren kann durch Unterstützung der Krustenbildung entgegengesteuert werden. Krusten stellen passive in-situ Behandlungsmethoden dar. Sie können den Austrag von Schwermetallen nachhaltig reduzieren. Stoffmobilitäts- und Krustenbildungsprozesse sind materialabhängig und klimatisch gesteuert. In dieser Arbeit wurden ihre steuernden Parameter untersucht. Von wesentlicher Bedeutung ist der Wasserhaushalt in einer Halde. Bei hoher Durchlässigkeit der Aufbereitungsabgänge und starken Niederschlägen ist der Flüssigkeitstransport abwärts gerichtet und es kann zur Ausschwemmung von Schadstoffen mit dem Sickerwasser kommen. Bei verdunstungsbetonten Bedingungen findet jedoch vornehmlich ein kapillarer Aufstieg von Lösungen statt, die im Oberflächenbereich der Halden verdunsten und sekundäre Phasen abscheiden. Zur Untersuchung der stattfindenden Prozesse wurde der Internbau von zwei 40 Jahre alten Halden im Freiberger Bergbaurevier (Erzgebirge) erkundet. Verschiedene Spuren und Schwermetalle sind im Oberflächenbereich der Halden angereichert worden. Als Maß für die Stärke der Krustenbildungsprozesse diente ein aus der spezifischen Oberfläche der Komponenten berechneter Oberflächen-Rauhigkeitsfaktor. Thiobacillen (T. ferrooxidans und thiooxidans) steigern die Mobilität von Zink und Kupfer, verringern durch die beschleunigte Oxidation allerdings die von Eisen. Infolgedessen können diese Bakterien zur Krustenbildung beitragen, obwohl die von ihnen etablierten pH-Bedingungen niedriger sind. Durch Einkapselung von Komponenten in neugebildeten Präzipitaten, also einer Verringerung ihrer Zugänglichkeit, kommt es faktisch zur Immobilisierung von Spuren und Schwermetallen. Im Labormaßstab wurden die in Halden herrschenden Bedingungen simuliert. Die dazu verwendeten Aufbereitungsabgänge wurden mit verschiedenen Elutionsverfahren charakterisiert. Noch besser zur Charakterisierung von Aufbereitungsabgängen sind neu entwickelte Säulenversuche geeignet. Durch Verdunstung an den offenen Säulenoberflächen wurde ein kapillarer Flüssigkeitstransport von unten nach oben erzeugt, der natürliche Verhältnisse nachbilden konnte. Es wurden Versuche zur Reproduzierbarkeit, zur Dynamik der Prozesse, zur Mobilität von sulfidischen Erzkonzentraten und zum Krustenbildungspotential verschiedener Aufbereitungsabgänge angestellt. Besondere Aufmerksamkeit wurde dem Einfluß klimatischer Parameter auf die Krustenbildung zuteil. Die Abhängigkeit der Krustenstärke von ihrer Position auf einer Halde ist eine Folge der unterschiedlichen ‚Angriffsflächen‘, die klimatischen Größen, wie Luftbewegungen, geboten werden. Bei Erhöhung der Windstärke konnte in Säulenversuchen bis zu einem bestimmtem Grad eine Steigerung der Krustenbildung erzielt werden. Diese Steigerung war limitiert, da bei zu hoher Windstärke die Verdunstungsrate derart anwuchs, daß der kapillare Transport abriß. Auch durch erhöhte Temperatur wurde die Verdunstung verstärkt, was wiederum den kapillaren Flüssigkeitstransport bis zu dem Punkt steigerte, an welchem die Säulenoberfläche austrocknete, weil die Transportkapazität der Kapillaren nicht mehr den Flüssigkeitsbedarf decken konnte. Neben der absoluten Menge an Niederschlag ist seine zeitliche Verteilung für Stoffmobilität und Krustenbildung ausschlaggebend. Bei kontinuierlicher Beregnung kommt es nicht zur oberflächlichen Krustenbildung, da eine abwärts gerichtete Flüssigkeitsbewegung etabliert wird. Alternieren Niederschlagsereignisse jedoch mit Trockenzeiten kommt es zu einem Wechsel von abwärts gerichteter Flüssigkeitsbewegung und aufwärts gerichtetem kapillarem Transport, da die Verdunstung zeitweise das dominierende Element ist und die Bildung einer Kruste ermöglicht. Die Tiefenlage einer Krustenbildung wird neben Neutralisations- und Redoxreaktionen von der Verdunstungsrate bestimmt. Bei zu starker Verdunstung kommt es zum Abriß der Kapillaren und mobile Stoffe werden nicht mehr zur Oberfläche einer Halde transportiert. Stattdessen scheiden sich sekundäre Phasen in einer tiefer gelegenen Zone ab, die noch vom aufwärts gerichteten Flüssigkeitsstrom erreicht wird. Neben evaporitischen Mineralen haben sich in den Krusten der Säulenversuche verschiedenste, teilweise metastabile sulfatische Phasen gebildet. Neben dem Transport von mobilen Stoffen in echten Lösungen kommt dem kolloidalen Transport von Spuren und Schwermetallen Bedeutung zu, dem eine rein thermodynamische Beschreibung nicht gerecht wird. Im Porenwasser wurden nicht nur oxidierte Stoffe transportiert, sondern auch reduzierte bzw. nicht völlig aufoxidierte Schwermetalle. Bergbauhalden können aufgrund ihrer durch Krustenbildung bedingten stofflichen Differenzierung und Anreicherung bestimmter Metalle selbst wieder Lagerstättencharakter haben

DESIGN, CONSTRUCTION AND FIELD DEMONSTRATION OF EXPLORER: A LONG-RANGE UNTETHERED LIVE GASLINE INSPECTION ROBOT SYSTEM

This program is undertaken in order to construct and field-demonstrate EXPLORER, a modular, remotely controllable, self-powered, untethered robot system for the inspection of live gas distribution 150 mm (6-inch) to 200 mm (8-inch) diameter mains. The modular design of the system allows it to accommodate various components intended to accomplish different inspection, repair, sample retrieval, and other in-pipe tasks. The prototype system being built under this project will include all the basic modules needed, i.e. the locomotor, power storage, wireless communication, and camera. The camera, a solid-state fisheye-type, is used to transmit real-time video to the operator that allows for the live inspection of gas distribution pipes. This module, which incorporates technology developed by NASA, has already been designed, constructed and tested, having exceeded performance expectations. The full prototype system will be comprehensively tested in the laboratory followed by two field demonstrations in real applications in NGA member utilities' pipes. The system under development significantly advances the state of the art in inspection systems for gas distribution mains, which presently consist of tethered systems of limited range (about 500 ft form the point of launch) and limited inspection views. Also current inspection systems have no ability to incorporate additional modules to expand their functionality. The present report summarizes the accomplishments of the project during its third six-month period. The project has in general achieved its goals for this period as outlined in the report. The fabrication of the prototype is complete and is now been tested in the laboratory mainly focusing on the last system integration issues and on software development for the turning and launching routines. Testing of the prototype in the lab is expected to be completed by Summer 2003, to be followed by two field demonstrations in early Fall 2003

DESIGN, CONSTRUCTION AND FIELD DEMONSTRATION OF EXPLORER: A LONG-RANGE UNTETHERED LIVE GASLINE INSPECTION ROBOT SYSTEM

This program is undertaken in order to construct and field-demonstrate EXPLORER, a modular, remotely controllable, self-powered, untethered robot system for the inspection of live gas distribution 150 mm (6- inch) to 200 mm (8-inch) diameter mains. The modular design of the system allows it to accommodate various components intended to accomplish different inspection, repair, sample retrieval, and other in-pipe tasks. The prototype system being built under this project will include all the basic modules needed, i.e. the locomotor, power storage, wireless communication, and camera. The camera, a solid-state fisheye-type, is used to transmit real-time video to the operator that allows for the live inspection of gas distribution pipes. This module, which incorporates technology developed by NASA, has already been designed, constructed and tested, having exceeded performance expectations. The full prototype system will be comprehensively tested in the laboratory followed by two field demonstrations in real applications in NYGAS member utilities' pipes. The system under development significantly advances the state of the art in inspection systems for gas distribution mains, which presently consist of tethered systems of limited range (about 500 ft form the point of launch) and limited inspection views. Also current inspection systems have no ability to incorporate additional modules to expand their functionality. This development program is a joint effort among the New York Gas Group (NYGAS; a trade association of the publicly owned gas utilities in New York State), the Jet Propulsion Laboratory (JPL), the Johnson Space Center (JSC), Carnegie Mellon University's (CMU) National Robotics Engineering Consortium (NREC), and the US Department of Energy (DOE) through the National Energy Technology Laboratory (NETL). The DOE's contribution to this current phase of the project is $499,023 out of a total of$780,735 (not including NASA's contribution). The present report summarizes the accomplishments of the project during its second six months. The project has achieved its goals for this period as outlined in the report. Currently the fabrication of the prototype is nearing completion. Testing of the prototype in the lab is expected to be completed by Spring 2003, to be followed by two field demonstrations in Summer 2003

Coupling virtual watersheds with ecosystem services assessment: A 21st century platform to support river research and management

The demand for freshwater is projected to increase worldwide over the coming decades, resulting in severe water stress and threats to riverine biodiversity, ecosystem functioning and services. A major societal challenge is to determine where environmental changes will have the greatest impacts on riverine ecosystem services and where resilience can be incorporated into adaptive resource planning. Both water managers and scientists need new integrative tools to guide them towards the best solutions that meet the demands of a growing human population but also ensure riverine biodiversity and ecosystem integrity. Resource planners and scientists could better address a growing set of riverine management and risk mitigation issues by (1) using a “Virtual Watersheds” approach based on improved digital river networks and better connections to terrestrial systems; (2) integrating Virtual Watersheds with ecosystem services technology (ARtificial Intelligence for Ecosystem Services: ARIES), and (3) incorporating the role of riverine biotic interactions in shaping ecological responses. This integrative platform can support both interdisciplinary scientific analyses of pressing societal issues and effective dissemination of findings across river research and management communities. It should also provide new integrative tools to identify the best solutions and trade-offs to ensure the conservation of riverine biodiversity and ecosystem services

Three-Body Halo States in Effective Field Theory: Renormalization and Three-Body Interactions in the Helium-6 System

In this paper we study the renormalization of Halo effective field theory applied to the Helium-6 halo nucleus seen as an alpha-neutron-neutron three-body state. We include the 0(+) dineutron channel together with both the 3/2(-) and 1/2(-) neutron-alpha channels into the field theory and study all of the six lowest-order three-body interactions that are present. Furthermore, we discuss three different prescriptions to handle the unphysical poles in the P-wave two-body sector. In the simpler field theory without the 1/2(-) channel present we find that the bound-state spectrum of the field theory is renormalized by the inclusion of a single three-body interaction. However, in the field theory with both the 3/2(-) and 1/2(-) included, the system can not be renormalized by only one three-body operator

The relationship between sensory sensitivity and autistic traits in the general population.

Individuals with Autism Spectrum Disorders (ASDs) tend to have sensory processing difficulties (Baranek et al. in J Child Psychol Psychiatry 47:591–601, 2006). These difficulties include over- and under-responsiveness to sensory stimuli, and problems modulating sensory input (Ben-Sasson et al. in J Autism Dev Disorders 39:1–11, 2009). As those with ASD exist at the extreme end of a continuum of autistic traits that is also evident in the general population, we investigated the link between ASD and sensory sensitivity in the general population by administering two questionnaires online to 212 adult participants. Results showed a highly significant positive correlation (r = .775, p < .001) between number of autistic traits and the frequency of sensory processing problems. These data suggest a strong link between sensory processing and autistic traits in the general population, which in turn potentially implicates sensory processing problems in social interaction difficulties

Microbiota-directed fibre activates both targeted and secondary metabolic shifts in the distal gut

Beneficial modulation of the gut microbiome has high-impact implications not only in humans, but also in livestock that sustain our current societal needs. In this context, we have tailored an acetylated galactoglucomannan (AcGGM) fibre to match unique enzymatic capabilities of Roseburia and Faecalibacterium species, both renowned butyrate-producing gut commensals. Here, we test the accuracy of AcGGM within the complex endogenous gut microbiome of pigs, wherein we resolve 355 metagenome-assembled genomes together with quantitative metaproteomes. In AcGGM-fed pigs, both target populations differentially express AcGGM-specific polysaccharide utilization loci, including novel, mannan-specific esterases that are critical to its deconstruction. However, AcGGM-inclusion also manifests a “butterfly effect”, whereby numerous metabolic changes and interdependent cross-feeding pathways occur in neighboring non-mannanolytic populations that produce short-chain fatty acids. Our findings show how intricate structural features and acetylation patterns of dietary fibre can be customized to specific bacterial populations, with potential to create greater modulatory effects at large

Laparoscopic fistula excision and omentoplasty for high rectovaginal fistulas: a prospective study of 40 patients

AIM: The aim of this study is to prospectively evaluate 40 patients with a high rectovaginal fistula treated by a laparoscopic fistula division and closure, followed by an omentoplasty. PATIENTS AND METHODS: Forty patients with a rectovaginal fistula, between the middle third of the rectum and the posterior vaginal fornix, resulting from different causes (IBD, iatrogenic and birth trauma) were treated by a laparoscopic excision of the fistula and insertion of an omentoplasty in the rectovaginal septum. The patients completed the gastrointestinal quality of life index questionnaire (GIQLI) and the Cleveland Clinic incontinence score (CCIS). All tests were performed at regular intervals after treatment. RESULTS: In 38 (95%) patients with a median age of 53 years (range 33-72), the surgical procedure was feasible. In two patients, the fistula was closed without an omentoplasty, and a diverting stoma was performed. The median follow-up was 28 months (range 10-35). Two patients (5%) developed a recurrent fistula. In one patient, the interposed omentum became necrotic and was successfully treated laparoscopically. In another patient, an abscess developed, which needed drainage procedures. The mean CCIS was 9 (range 7-10) before treatment and 10 (range 7-13) after treatment (p = 0.5 Wilcoxon). The median GIQLI score was 85 (range 34-129) before treatment and 120 (range75-142) after treatment (p = 0.0001, Wilcoxon). CONCLUSIONS: Laparoscopic fistula excision combined with omentoplasty is a good treatment modality with a high healing rate for high rectovaginal fistulas and an acceptable complication rate