Diodenlaser-gestützter In-situ-Nachweis von O 2 und Alkaliatomen zur Optimierung der Hochtemperaturkohlenstaub- und Sondermüllverbrennung sowie der Brandbekämpfung

Direkte Absorptionsspektroskopie mit abstimmbaren Diodenlasern (TDLAS) diente dem kalibrationsfreien quantitativen Analyse gasförmiger Stoffe, deren Nachweis mit extraktiven Methoden nicht oder nur eingeschränkt möglich ist. Verschiedene Diodenlasertypen (Fabry-Pérot (FPDL), Distributed Feedback (DFB), External Cavity (ECDL) und Vertical Cavity Surface Emitting Laser (VCSEL)) wurden eingesetzt, charakterisiert und verglichen. Die In-situ-Meßtechnik wurde für drei Anwendungsbereiche optimiert: (1.) Für die Bewertung der Wirksamkeit verschiedener Feuerlöschsysteme wurde in Zusammenarbeit mit dem Naval Research Laboratory (Washington, DC, USA) ein Spektrometer im Multireflex-Freistrahl-Aufbau (Herriott-Design: 1,8 m Absorptionsweg, 30 cm Basislänge) zur Ermittlung des In-situ-Sauerstoffgehalts bei Feuerlöschübungen im Realmaßstab entwickelt. Ein DFB-Diodenlaser (761 nm) erlaubte auch zum Zeitpunkt der Wassernebelfreisetzung mit starken Transmissionsschwankungen eine Meßgenauigkeit von besser als 1 vol\%. Im Vergleich mit extraktiven Sensoren konnte die Verdrängung von Sauerstoff durch Wasserdampf quantifiziert werden. (2.) Für die Entwicklung eines Kalium-Schwellwertsensors wurden hochreaktive freie Kaliumatome, die unter den Bedingungen der Kohlestaubverbrennung in geringen Mengen aus den im Brennstoff enthaltenen Verbindungen freigesetzt werden, empfindlich (10 ppt) in situ unter industriellen Bedingungen nachgewiesen. Bei der Druckkohlenstaubverbrennung herrschten bis zu 1600 K, 12 bar, starke thermische Strahlung sowie schnelle und große breitbandige Transmissionsschwankungen vor. Durch Ausnutzung der schnellen und weiten Abstimmbarkeit (>15 Wellenzahlen) der VCSEL konnten die stark druckverbreiterten D-Linien von Kalium (767 nm, 770 nm) vollständig erfaßt und charakterisiert werden. Die erreichte Nachweisgrenze bei einer Absorptionsstrecke von 14 cm lag bei 10 ng/m³ i.N. und Konzentrationen bis zu 10 mg/m³ i.N. wurden beobachtet. Die Abhängigkeit der Kaliumatom-Konzentration von den Anlagenparametern, besonders der Temperatur, dem Sauerstoffgehalt und der korrosionsfördernden Kaliumverbindungs-Konzentration wurde untersucht. Dazu wurde simultan die Sauerstoffkonzentration in situ mittels Time Domain Multiplexing oder extraktiv bestimmt. (3.) Der Alkaliatomnachweis anhand der D-Linien wurde auf Lithium, Rubidium und Cäsium ausgedehnt und damit - in Zusammenarbeit mit dem Forschungszentrum Karlsruhe - eine neue Methode zur Ermittlung von Verweilzeiten in Hochtemperaturprozessen erfunden. In einem halbtechnischen Drehrohrofen (THERESA, 3\/~MW) wurden geringe Mengen gelöste Alkalisalze (~100 mg) eingedüst und die Konzentration der freien Alkaliatome (Dissoziationsrate 1 bis 100ppm) bei einer Zeitauflösung von 0,4 s verfolgt. Aus den Verweilzeitverteilungen wurden je nach Betrieb und Anlagenabschnitt mittlere Verweilzeiten von 6 s bis 16 s erfolgreich bestimmt

Hydrogen peroxide in deep waters from the Mediterranean Sea, South Atlantic and South Pacific Oceans

Hydrogen peroxide (H2O2) is present ubiquitously in marine surface waters where it is a reactive intermediate in the cycling of many trace elements. Photochemical processes are considered the dominant natural H2O2 source, yet cannot explain nanomolar H2O2 concentrations below the photic zone. Here, we determined the concentration of H2O2 in full depth profiles across three ocean basins (Mediterranean Sea, South Atlantic and South Pacific Oceans). To determine the accuracy of H2O2 measurements in the deep ocean we also re-assessed the contribution of interfering species to ‘apparent H2O2’, as analysed by the luminol based chemiluminescence technique. Within the vicinity of coastal oxygen minimum zones, accurate measurement of H2O2 was not possible due to interference from Fe(II). Offshore, in deep (>1000 m) waters H2O2 concentrations ranged from 0.25 ± 0.27 nM (Mediterranean, Balearics-Algeria) to 2.9 ± 2.2 nM (Mediterranean, Corsica-France). Our results indicate that a dark, pelagic H2O2 production mechanism must occur throughout the deep ocean. A bacterial source of H2O2 is the most likely origin and we show that this source is likely sufficient to account for all of the observed H2O2 in the deep ocean

Influence of ocean acidification on the organic complexation of iron and copper in Northwest European shelf seas; a combined observational and model study

The pH of aqueous solutions is known to impact the chemical speciation of trace metals. In this study we conducted titrations of coastal seawaters with iron and copper at pH 7.91, 7.37 and 6.99 (expressed on the total pH scale). Changes in the concentration of iron and copper that complexed with the added ligands 1-nitroso-2-napthol and salicylaldoxime respectively were determined by adsorptive cathodic stripping voltammetry - competitive ligand equilibrium (AdCSV-CLE). Interpretation of the results, assuming complexation by a low concentration of discrete ligands, showed that conditional stability constants for iron complexes increased relative to inorganic iron complexation as pH decreased by approximately 1 log unit per pH unit, whilst those for copper did not change. No trend was observed for concentrations of iron and copper complexing ligands over the pH range examined. We also interpreted our titration data by describing chemical binding and polyelectrolytic effects using non-ideal competitive adsorption in Donnan-like gels (NICA-Donnan model) in a proof of concept study. The NICA-Donnan approach allows for the development of a set of model parameters that are independent of ionic strength and pH, and thus calculation of metal speciation can be undertaken at ambient sample pH or the pH of a future, more acidic ocean. There is currently a lack of basic NICA-Donnan parameters applicable to marine dissolved organic matter (DOM) so we assumed that the measured marine dissolved organic carbon could be characterized as terrestrial fulvic acids. Generic NICA-Donnan parameters were applied within the framework of the software program visual MINTEQ and the metal –added ligand concentrations [MeAL] calculated for the AdCSV-CLE conditions. For copper, calculated [MeAL] using the NICA-Donnan model for DOM were consistent with measured [MeAL], but for iron an inert fraction with kinetically inhibited dissolution was required in addition to the NICA-Donnan model in order to approximate the trends observed in measured [MeAL]. We calculated iron and copper speciation in Northwest European shelf water samples at ambient alkalinity and projected increased pCO2 concentrations as a demonstration of the potential of the approach

OSUL 2013 Implementation Phase Final Report

The University Archives has determined that this item is of continuing value to OSU's history.OSUL 2013 overview; Implementation Team and Community; Projects; Long-term plan for OSUL; Proposal for next 2013 grou

Spread, Behavior, and Ecosystem Consequences of Conventional Munitions Compounds in Coastal Marine Waters

Coastal marine environments are contaminated globally with a vast quantity of unexploded ordnance and munitions from intentional disposal. These munitions contain organic explosive compounds as well as a variety of metals, and represent point sources of chemical pollution to marine waters. Most underwater munitions originate from World Wars at the beginning of the twentieth century, and metal munitions housings have been impacted by extensive corrosion over the course of the following decades. As a result, the risk of munitions-related contaminant release to the water column is increasing. The behavior of munitions compounds is well-characterized in terrestrial systems and groundwater, but is only poorly understood in marine systems. Organic explosive compounds, primarily nitroaromatics and nitramines, can be degraded or transformed by a variety of biotic and abiotic mechanisms. These reaction products exhibit a range in biogeochemical characteristics such as sorption by particles and sediments, and variable environmental behavior as a result. The reaction products often exhibit increased toxicity to biological receptors and geochemical controls like sorption can limit this exposure. Environmental samples typically show low concentrations of munitions compounds in water and sediments (on the order of ng/L and μg/kg, respectively), and ecological risk appears generally low. Nonetheless, recent work demonstrates the possibility of sub-lethal genetic and metabolic effects. This review evaluates the state of knowledge on the occurrence, fate, and effect of munition-related chemical contaminants in the marine environment. There remain a number of knowledge gaps that limit our understanding of munitions-related contaminant spread and effect, and the need for additional work is made all the more urgent by increasing risk of release to the environment

: Preoperative Patient-centric Predictors of Postoperative Outcomes in Patients Undergoing Arthroscopic Meniscectomy

The Patient-Reported Outcomes Measurement Information System (PROMIS) is a valid and efficient means of collecting patient outcomes in patients with meniscal tears. The studies purpose was to define the minimally clinical important difference (MCID) for PROMIS domains following meniscectomy procedures. Secondary aims included determining the role of pre-operative PROMIS computer adaptive test (CAT) scores in predicting achievement of MCID following meniscectomy. Patients undergoing arthroscopic meniscectomy who completed PROMIS CAT forms for physical function (PROMIS-PF), pain interference (PROMIS-PI), and depression (PROMIS-D), from July 2017 to July 2019, at a single institution were utilized. MCID was calculated according to the distribution methodology, and receiver operating characteristics (ROC) were utilized to determine if pre-operative scores were predictive of post-operative outcomes. A total of 135 patients met inclusion criteria. Postoperative PROMIS-PF (45.6), PROMIS-PI (54.6), and PROMIS-D (44.1) significantly improved 3 months after surgery (

El Niño‐driven oxygenation impacts Peruvian shelf iron supply to the South Pacific Ocean

Upwelling ocean currents associated with oxygen minimum zones (OMZs) supply nutrients fuelling intense marine productivity. Perturbations in the extent and intensity of OMZs are projected in the future, but it is currently uncertain how this will impact fluxes of redox‐sensitive trace metal micronutrients to the surface ocean. Here we report seawater concentrations of Fe, Mn, Co, Cd, and Ni alongside the redox indicator iodide/iodate in the Peruvian OMZ during the 2015 El Niño event. The El Niño drove atypical upwelling of oxygen‐enriched water over the Peruvian Shelf, resulting in oxidized iodine and strongly depleted Fe (II), total dissolved Fe, and reactive particulate Fe concentrations relative to non‐El Niño conditions. Observations of Fe were matched by the redox‐sensitive micronutrients Co and Mn, but not by non‐redox‐sensitive Cd and Ni. These observations demonstrate that oxygenation of OMZs significantly reduces water column inventories of redox‐sensitive micronutrients, with potential impacts on ocean productivity. Plain Language Summary Some trace metals, including iron, are essential micronutrients for phytoplankton growth. However, the solubility of iron is very low under oxygenated conditions. Consequently, restricted iron availability in oxygen‐rich seawater can limit phytoplankton growth in the ocean, including in the Eastern Tropical South Pacific. Under typical conditions, depleted oxygen on the South American continental shelf is generally thought to enhance iron supply to the ocean, fuelling phytoplankton productivity in overlying waters. However, the impact of changes in oxygenation, which are predicted to occur in the future, are not known. The 2015 El Niño event led to unusually high oxygen on the Peruvian shelf, offering a system‐scale test on how oxygen influences seawater iron concentrations. We show that El Niño‐driven oxygenation resulted in marked decreases in iron and other metals sensitive to oxygen (cobalt and manganese), whilst metals not sensitive to oxygen (cadmium and nickel) were unaffected. The measured reductions in iron may have led to decreased phytoplankton productivity

In situ measurements of explosive compound dissolution fluxes from exposed munition material in the Baltic Sea

Underwater munitions containing millions of tons of toxic explosives are present worldwide in coastal marine waters as a result of unexploded ordnance and intentional dumping. Dissolution flux of solid explosives following corrosion of metal munition housings controls exposure of biological receptors to toxic munition compounds (MC; including TNT: 2,4,6-Trinitrotoluene, RDX: 1,3,5-Trinitro-1,3,5-triazinane, and DNB: 1,3-Dinitrobenzene). Very little is known about the dissolution behavior of MC in the marine environment. In this work, we exploit a unique marine study site in the Baltic Sea with exposed solid explosives to quantify in situ MC dissolution fluxes using dissolved MC gradients near the exposed explosive surface, as well as benthic chamber incubations. The gradient method gave dissolution fluxes that ranged between 0.001 and 3.2, 0.0001 and 0.04, and 0.003 and 1.7 mg cm-2 d-1 for TNT, RDX, and DNB, respectively. Benthic chamber incubations indicated dissolution fluxes of 0.0047-0.277, 0-0.11, and 0.00047-1.45 mg cm-2 d-1 for TNT, RDX, and DNB, respectively. In situ dissolution fluxes estimated in the current study were lower than most dissolution rates reported for laboratory experiments, but clearly demonstrated that MC are released from underwater munitions to the water column in the Baltic Sea