Prevalence of cam and pincer-type deformities on hip MRI in an asymptomatic young Swiss female population: a cross-sectional study

OBJECTIVES Femoroacetabular impingement is proposed to cause early osteoarthritis (OA) in the non-dysplastic hip. We previously reported on the prevalence of femoral deformities in a young asymptomatic male population. The aim of this study was to determine the prevalence of both femoral and acetabular types of impingement in young females. METHODS We conducted a population-based cross-sectional study of asymptomatic young females. All participants completed a set of questionnaires and underwent clinical examination of the hip. A random sample was subsequently invited to obtain magnetic resonance images (MRI) of the hip. All MRIs were read for cam-type deformities, increased acetabular depths, labral lesions, and impingement pits. Prevalence estimates of cam-type deformities and increased acetabular depths were estimated, and relationships between deformities and signs of joint damage were examined using logistic regression models. RESULTS The study included 283 subjects, and 80 asymptomatic females with a mean age of 19.3 years attended MRI. Fifteen showed some evidence of cam-type deformities, but none were scored to be definite. The overall prevalence was therefore 0% [95% confidence interval (95% CI) 0-5%]. The prevalence of increased acetabular depth was 10% (95% CI 5-19). No association was found between increased acetabular depth and decreased internal rotation of the hip. Increased acetabular depth was not associated with signs of labral damage. CONCLUSIONS Definite cam-type deformities in women are rare compared to men, whereas the prevalence of increased acetabular depth is higher, suggesting that femoroacetabular impingement has different gender-related biomechanical mechanisms.

The Aeolian Flux of Calcium, Chloride and Nitrate to the McMurdo Dry Valleys Landscape: Evidence from Snow Pit Analysis

We have determined the flux of calcium, chloride and nitrate to the McMurdo Dry Valleys region by analysing snow pits for their chemical composition and their snow accumulation using multiple records spanning up to 48 years. The fluxes demonstrate patterns related to elevation and proximity to the ocean. In general, there is a strong relationship between the nitrate flux and snow accumulation, indicating that precipitation rates may have a great influence over the nitrogen concentrations in the soils of the valleys. Aeolian dust transport plays an important role in the deposition of some elements (e.g. C(2+)) into the McMurdo Dry Valleys' soils. Because of the antiquity of some of the soil surfaces in the McMurdo Dry Valleys regions, the accumulated atmospheric flux of salts to the soils has important ecological consequences. Although precipitation may be an important mechanism of salt deposition to the McMurdo Dry Valley surfaces, it is poorly understood because of difficulties in measurement and high losses from sublimation.

Stable-Isotope Time Series and Precipitation Origin from Firn-Core and Snow Samples, Altai Glaciers, Siberia

In the summers of 2001 and 2002, glacio-climatological research was performed at 4110-4120 m a.s.l. on the Belukha snow/firn plateau, Siberian Altai. Hundreds of samples from snow pits and a 21 m snow/firn core were collected to establish the annual/seasonal/monthly depth-accumulation scale, based on stable-isotope records, stratigraphic analyses and meteorological and synoptic data. The fluctuations of water stable-isotope records show well-preserved seasonal variations. The delta(18)O and delta D relationships in precipitation, snow pits and the snow/firn core have the same slope to the covariance as that of the global meteoric water line. The origins of precipitation nourishing the Belukha plateau were determined based on clustering analysis of delta(18)O and d-excess records and examination of synoptic atmospheric patterns. Calibration and validation of the developed clusters occurred at event and monthly timescales with about 15% uncertainty. Two distinct moisture sources were shown: oceanic sources with d-excess < 12 parts per thousand, and the Aral-Caspian closed drainage basin sources with d-excess > 12 parts per thousand. Two-thirds of the annual accumulation was from oceanic precipitation, of which more than half had isotopic ratios corresponding to moisture evaporated over the Atlantic Ocean. Precipitation from the Arctic/Pacific Ocean had the lowest deuterium excess, contributing one-tenth to annual accumulation.

Monsoonal Circulation of the McMurdo Dry Valleys, Ross Sea Region, Antarctica: Signal from the Snow Chemistry

McMurdo Dry Valleys (MDV, Ross Sea region, Antarctica) precipitation exhibits extreme seasonality in ion concentration, 3-5 orders of magnitude between summer and winter precipitation. To identify aerosol sources and investigate causes for the observed amplitude in concentration variability, four snow pits were sampled along a coast-Polar Plateau transect across the MDV. The elevation of the sites ranges from 50 to 2400 m and the distance from the coast from 8 to 93 km. Average chemistry gradients along the transect indicate that most species have either a predominant marine or terrestrial source in the MDV. Empirical orthogonal function analysis on the snow-chemistry time series shows that at least 57% of aerosol deposition occurs concurrently. A conceptual climate model, based on meteorological observations, is used to explain the strong seasonality in the MDV. Our results suggest that radiative forcing of the ice-free valleys creates a surface low-pressure cell during summer which promotes air-mass flow from the Ross Sea. The associated precipitating air mass is relatively warm, humid and contains a high concentration of aerosols. During winter, the MDV are dominated by air masses draining off the East Antarctic ice sheet, that are characterized by cold, dry and low concentrations of aerosols. The strong differences between these two air-mass sources create in the MDV a polar version of the monsoonal flow, with humid, warm summers and dry, cold winters.

Schmiede ─ Heiligtum ─ Wassermühle. Cham-Hagendorn (Kanton Zug) in römischer Zeit. Ausgrabungen 1944/45 und 2003/04

1944/1945 wurde in Cham-Hagendorn eine Wassermühle ausgegraben, die dank ihrer aussergewöhnlich guten Holzerhaltung seit langem einen prominenten Platz in der Forschung einnimmt. 2003 und 2004 konnte die Kantonsarchäologie Zug den Platz erneut archäologisch untersuchen. Dabei wurden nicht nur weitere Reste der Wassermühle, sondern auch Spuren älterer und jüngerer Anlagen geborgen: eine ältere und eine jüngere Schmiedewerkstatt (Horizont 1a/Horizont 3) sowie ein zweiphasiges Heiligtum (Horizonte 1a/1b). All diese Anlagen lassen sich nun in das in den neuen Grabungen erkannte stratigraphische Gerüst einhängen (s. Beil. 2). Dank der Holzerhaltung können die meisten Phasen dendrochronologisch datiert werden (s. Abb. 4.1/1a): Horizont 1a mit Schlagdaten zwischen 162(?)/173 und 200 n. Chr., Horizont 1b um 215/218 n. Chr. und Horizont 2 um 231 n. Chr. Ferner konnten in den neuen Grabungen Proben für mikromorphologische und archäobotanische Untersuchungen entnommen werden (Kap. 2.2; 3.11). In der vorliegenden Publikation werden der Befund und die Baustrukturen vorgelegt, (Kap. 2), desgleichen sämtliche stratifizierten Funde und eine umfassende Auswahl der 1944/1945 geborgenen Funde (Kap. 3). Dank anpassender Fragmente, sog. Passscherben, lassen sich diese zum Teil nachträglich in die Schichtenabfolge einbinden. Die mikromorphologischen und die archäobotanischen Untersuchungen (Kap. 2.2; 3.11) zeigen, dass der Fundplatz in römischer Zeit inmitten einer stark vom Wald und dem Fluss Lorze geprägten Landschaft lag. In unmittelbarer Nähe können weder eine Siedlung noch einzelne Wohnbauten gelegen haben. Die demnach nur gewerblich und sakral genutzten Anlagen standen an einem Bach, der vermutlich mit jenem Bach identisch ist, der noch heute das Groppenmoos entwässert und bei Cham-Hagendorn in die Lorze mündet (s. Abb. 2.4/1). Der antike Bach führte wiederholt Hochwasser ─ insgesamt sind fünf grössere Überschwemmungsphasen auszumachen (Kap. 2.2; 2.4). Wohl anlässlich eines Seehochstandes durch ein Überschwappen der Lorze in den Bach ausgelöst, müssen diese Überschwemmungen eine enorme Gewalt entwickelt haben, der die einzelnen Anlagen zum Opfer fielen. Wie die Untersuchung der Siedlungslandschaft römischer Zeit rund um den Zugersee wahrscheinlich macht (Kap. 6 mit Abb. 6.2/2), dürften die Anlagen von Cham-Hagendorn zu einer in Cham-Heiligkreuz vermuteten Villa gehören, einem von fünf grösseren Landgütern in diesem Gebiet. Hinweise auf Vorgängeranlagen fehlen, mit denen die vereinzelten Funde des 1. Jh. n. Chr. (Kap. 4.5) in Verbindung gebracht werden könnten. Diese dürften eher von einer der Überschwemmungen bachaufwärts weggerissen und nach Cham-Hagendorn eingeschwemmt worden sein. Die Nutzung des Fundplatzes (Horizont 1a; s. Beil. 6) setzte um 170 n. Chr. mit einer Schmiedewerkstatt ein (Kap. 2.5.1). Der Fundanfall, insbesondere die Schmiedeschlacken (Kap. 3.9) belegen, dass hier nur hin und wieder Geräte hergestellt und repariert wurden (Kap. 5.2). Diese Werkstatt war vermutlich schon aufgelassen und dem Verfall preisgegeben, als man 200 n. Chr. (Kap. 4.2.4) auf einer Insel zwischen dem Bach und einem Lorzearm ein Heiligtum errichtete (Kap. 5.3). Beleg für den sakralen Status dieser Insel ist in erster Linie mindestens ein eigens gepflanzter Pfirsichbaum, nachgewiesen mit Pollen, einem Holz und über 400 Pfirsichsteinen (Kap. 3.11). Die im Bach verlaufende Grenze zwischen dem sakralen Platz und der profanen Umgebung markierte man zusätzlich mit einer Pfahlreihe (Kap. 2.5.3). In diese war ein schmaler Langbau integriert (Kap. 2.5.2), der an die oft an Temenosmauern antiker Heiligtümer angebauten Portiken erinnert und wohl auch die gleiche Funktion wie diese gehabt hatte, nämlich das Aufbewahren von Weihegaben und Kultgerät (Kap. 5.3). Das reiche Fundmaterial, das sich in den Schichten der ersten Überschwemmung fand (s. Abb. 5./5), die um 205/210 n. Chr. dieses Heiligtum zerstört hatte, insbesondere die zahlreiche Keramik (Kap. 3.2.4), und die zum Teil auffallend wertvollen Kleinfunde (Kap. 3.3.3), dürften zum grössten Teil einst in diesem Langbau untergebracht gewesen sein. Ein als Glockenklöppel interpretiertes, stratifiziertes Objekt spricht dafür, dass die fünf grossen, 1944/1945 als Stapel aufgefundenen Eisenglocken vielleicht auch dem Heiligtum zuzuweisen sind (Kap. 3.4). In diesen Kontext passen zudem die überdurchschnittlich häufig kalzinierten Tierknochen (Kap. 3.10). Nach der Überschwemmung befestigte man für 215 n. Chr. (Kap. 4.2.4) das unterspülte Bachufer mit einer Uferverbauung (Kap. 2.6.1). Mit dem Bau eines weiteren, im Bach stehenden Langbaus (Kap. 2.6.2) stellte man 218 n. Chr. das Heiligtum auf der Insel in ähnlicher Form wieder her (Horizont 1b; s. Beil. 7). Von der Pfahlreihe, die wiederum die sakrale Insel von der profanen Umgebung abgrenzte, blieben indes nur wenige Pfähle erhalten. Dennoch ist der sakrale Charakter der Anlage gesichert. Ausser dem immer noch blühenden Pfirsichbaum ist es ein vor dem Langbau aufgestelltes Ensemble von mindestens 23 Terrakottafigurinen (s. Abb. 3.6/1), elf Veneres, zehn Matres, einem Jugendlichen in Kapuzenmantel und einem kindlichen Risus (Kap. 3.6; s. auch Kap. 2.6.3). In den Sedimenten der zweiten Überschwemmung, der diese Anlage um 225/230 n. Chr. zum Opfer gefallen war, fanden sich wiederum zahlreiche Keramikgefässe (Kap. 3.2.4) und zum Teil wertvolle Kleinfunde wie eine Glasperle mit Goldfolie (Kap. 3.8.2) und eine Fibel aus Silber (Kap. 3.3.3), die wohl ursprünglich im Langbau untergebracht waren (Kap. 5.3.2 mit Abb. 5/7). Weitere Funde mit sicherem oder möglichem sakralem Charakter finden sich unter den 1944/1945 geborgenen Funden (s. Abb. 5/8), etwa ein silberner Fingerring mit Merkurinschrift, ein silberner Lunula-Anhänger, eine silberne Kasserolle (Kap. 3.3.3), eine Glasflasche mit Schlangenfadenauflage (Kap. 3.8.2) und einige Bergkristalle (Kap. 3.8.4). Im Bereich der Terrakotten kamen ferner mehrere Münzen (Kap. 3.7) zum Vorschein, die vielleicht dort niedergelegt worden waren. Nach der zweiten Überschwemmung errichtete man um 231 n. Chr. am Bach eine Wassermühle (Horizont 2; Kap. 2.7; Beil. 8; Abb. 2.7/49). Ob das Heiligtum auf der Insel wieder aufgebaut oder aufgelassen wurde, muss mangels Hinweisen offen bleiben. Für den abgehobenen Zuflusskanal der Wassermühle verwendete man mehrere stehen gebliebene Pfähle der vorangegangenen Anlagen der Horizonte 1a und 1b. Obwohl die Wassermühle den 28 jährlichen Überschwemmungshorizonten (Kap. 2.2) und den Funden (Kap. 4.3.2; 4.4.4; 45) zufolge nur bis um 260 n. Chr., während gut einer Generation, bestand, musste sie mindestens zweimal erneuert werden – nachgewiesen sind drei Wasserräder, drei Mühlsteinpaare und vermutlich drei Podeste, auf denen jeweils das Mahlwerk ruhte. Grund für diese Umbauten war wohl der weiche, instabile Untergrund, der zu Verschiebungen geführt hatte, so dass das Zusammenspiel von Wellbaum bzw. Sternnabe und Übersetzungsrad nicht mehr funktionierte und das ganze System zerbrach. Die Analyse von Pollen aus dem Gehhorizont hat als Mahlgut Getreide vom Weizentyp nachgewiesen (Kap. 3.11.4). Das Abzeichen eines Benefiziariers (Kap. 3.3.2 mit Abb. 3.3/23,B71) könnte dafür sprechen, dass das verarbeitete Getreide zumindest zum Teil für das römische Militär bestimmt war (s. auch Kap. 6.2.3). Ein im Horizont 2 gefundener Schreibgriffel und weitere stili sowie eine Waage für das Wägen bis zu 35-40 kg schweren Waren aus dem Fundbestand von 1944/1945 könnten davon zeugen, dass das Getreide zu wägen und zu registrieren war (Kap. 3.4.2). Kurz nach 260 n. Chr. fiel die Wassermühle einem weiteren Hochwasser zum Opfer. Für den folgenden Horizont 3 (Beil. 9) brachte man einen Kiesboden ein und errichtete ein kleines Gebäude (Kap. 2.8). Hier war wohl wiederum eine Schmiede untergebracht, wie die zahlreichen Kalottenschlacken belegen (Kap. 3.9), die im Umfeld der kleinen Baus zum Vorschein kamen. Aufgrund der Funde (Kap. 4.4.4; 4.5) kann diese Werkstatt nur kurze Zeit bestanden haben, höchstens bis um 270 n. Chr., bevor sie einem weiteren Hochwasser zum Opfer fiel. Von der jüngsten Anlage, die wohl noch in römische Zeit datiert (Horizont 4; Beil. 10), war lediglich eine Konstruktion aus grossen Steinplatten zu fassen (Kap. 2.9.1). Wozu sie diente, muss offen bleiben. Auch der geringe Fundanfall spricht dafür, dass die Nutzung des Platzes, zumindest für die römische Zeit, allmählich ein Ende fand (Kap. 4.5). Zu den jüngsten Strukturen gehören mehrere Gruben (Kap. 2.9.2), die vielleicht der Lehmentnahme dienten. Mangels Funden bleibt ihre Datierung indes ungewiss. Insbesondere wissen wir nicht, ob sie noch in römische Zeit datieren oder jünger sind. Spätestens mit der fünften Überschwemmung, die zur endgültigen Verlandung führte und wohl schon in die frühe Neuzeit zu setzen ist, wurde der Platz aufgelassen und erst mit dem Bau der bestehenden Fensterfabrik Baumgartner wieder besetzt.

The Effects of Joint ENSO-Antarctic Oscillation Forcing on the McMurdo Dry Valleys, Antarctica

Stable oxygen analyses and snow accumulation rates from snow pits sampled in the McMurdo Dry Valleys have been used to reconstruct variations in summer temperature and moisture availability over the last four decades. The temperature data show a common interannual variability, with strong regional warmings occurring especially in 1984/85, 1995/96 and 1990/91 and profound coolings during 1977/78, 1983/84, 1988/89, 1993/94, and 1996/97. Annual snow accumulation shows a larger variance between sites, but the early 1970s, 1984, 1997, and to a lesser degree 1990/91 are characterized overall by wetter conditions, while the early and late 1980s show low snow accumulation values. Comparison of the reconstructed and measured summer temperatures with the Southern Oscillation Index (SOI) and the Antarctic Oscillation (AAO) yield statistically significant correlations, which improve when phaserelationships are considered. A distinct change in the phase relationship of the correlation is observed, with the SOI-AAO leading over the temperature records by one year before, and lagging by one year after 1988. These results suggest that over the last two decades summer temperatures are influenced by opposing El Niho Southern Oscillation and AAO forcings and support previous studies that identified a change in the Tropical-Antarctic teleconnection between the 1980s and 1990s.

Isotopic effects of nitrate photochemistry in snow: a field study at Dome C, Antarctica

Stable isotope ratios of nitrate preserved in deep ice cores are expected to provide unique and valuable information regarding paleoatmospheric processes. However, due to the post-depositional loss of nitrate in snow, this information may be erased or significantly modified by physical or photochemical processes before preservation in ice. We investigated the role of solar UV photolysis in the post-depositional modification of nitrate mass and stable isotoperatios at Dome C, Antarctica, during the austral summer of 2011/2012. Two 30 cm snow pits were filled with homogenized drifted snow from the vicinity of the base. One of these pits was covered with a plexiglass plate that transmits solar UV radiation, while the other was covered with a different plexiglass plate having a low UV transmittance. Samples were then collected from each pit at a 2–5 cm depth resolution and a 10-day frequency. At the end of the season, acomparable nitrate mass loss was observed in both pits for the top-level samples (0–7 cm) attributed to mixing with the surrounding snow. After excluding samples impacted by the mixing process, we derived an average apparent nitrogen isotopic fractionation (15" app/of role in driving the isotopic fractionation of nitrate in snow.We have estimated a purely photolytic nitrogen isotopic fractionation (15"photo) of -55.8 12.0 ‰ from the difference in the derived apparent isotopic ractionations of the two experimental fields, as both pits were exposed to similar physical processes except exposure to solar UV. This value is in close agreement with the 15" photo value of -47.9 6.8 ‰ derived in a laboratory experiment simulated for Dome C conditions (Berhanu et al., 2014). We have also observed an insensitivity of 15" with depth in the snowpack under the given experimental setup. This is due to the uniform attenuation of incoming solar UV by snow, as 15" is strongly dependent on the spectral distribution of the incoming light flux. Together with earlier work, the results presented here represent a strong body of evidence that solar UV photolysis is the most relevant post-depositional process modifying the stable isotope ratios of snow nitrate at low-accumulation sites, where many deep ice cores are drilled. Nevertheless, modeling the loss of nitrate in snow is still required before a robust interpretation of ice core records can be provided.

An ice-rich flow origin for the banded terrain in the Hellas basin, Mars

The interior of Hellas Basin displays a complex landscape and a variety of geomorphological domains. One of these domains, the enigmatic banded terrain covers much of the northwestern part of the basin. We use high-resolution (CTX and HiRISE) Digital Terrain Models to show that most of the complex viscous flowing behavior exhibited by the banded terrain is controlled by topography and flow-like interactions between neighboring banded terrain. Furthermore, the interior of the basin hosts several landforms suggestive of the presence of near-surface ice, which include polygonal patterns with elongated pits, scalloped depressions, isolated mounds and collapse structures. We suggest that thermal contraction cracking and sublimation of near-surface ice are responsible for the formation and the development of most of the ice-related landforms documented in Hellas. The relatively pristine form, lack of superposed craters, and strong association with the banded terrain, suggest an Amazonian (<3 Ga) age of formation for these landforms. Finally, relatively high surface pressures (above the triple point of water) expected in Hellas and summer-time temperatures often exceeding the melting point of water ice suggest that the basin may have recorded relatively “temperate” climatic conditions compared to other places on Mars. Therefore, the potentially ice-rich banded terrain may have deformed with lower viscosity and stresses compared to other locations on Mars, which may account for its unique morphology.

Insolation, erosion, and morphology of comet 67P/Churyumov-Gerasimenko

Context. The complex shape of comet 67P and its oblique rotation axis cause pronounced seasonal effects. Irradiation and hence activity vary strongly. Aims. We investigate the insolation of the cometary surface in order to predict the sublimation of water ice. The strongly varying erosion levels are correlated with the topography and morphology of the present cometary surface and its evolution. Methods. The insolation as a function of heliocentric distance and diurnal (spin dependent) variation is calculated using >10(5) facets of a detailed digital terrain model. Shading, but also illumination and thermal radiation by facets in the field of view of a specific facet are iteratively taken into account. We use a two-layer model of a thin porous dust cover above an icy surface to calculate the water sublimation, presuming steady state and a uniform surface. Our second model, which includes the history of warming and cooling due to thermal inertia, is restricted to a much simpler shape model but allows us to test various distributions of active areas. Results. Sublimation from a dirty ice surface yields maximum erosion. A thin dust cover of 50 pm yields similar rates at perihelion. Only about 6% of the surface needs to be active to match the observed water production rates at perihelion. A dust layer of 1 mm thickness suppresses the activity by a factor of 4 to 5. Erosion on the south side can reach more than 10 m per orbit at active spots. The energy input to the concave neck area (Hapi) during northern summer is enhanced by about 50% owing to self-illumination. Here surface temperatures reach maximum values along the foot of the Hathor wall. Integrated over the whole orbit this area receives the least energy input. Based on the detailed shape model, the simulations identify "hot spots" in depressions and larger pits in good correlation with observed dust activity. Three-quarters of the total sublimation is produced while the sub-solar latitude is south, resulting in a distinct dichotomy in activity and morphology. Conclusions. The northern areas display a much rougher morphology than what is seen on Imhotep, an area at the equator that will be fully illuminated when 67P is closer to the Sun. Self-illumination in concave regions enhance the energy input and hence erosion. This explains the early activity observed at Hapi. Cliffs are more prone to erosion than horizontal, often dust covered, areas, which leads to surface planation. Local activity can only persist if the forming cliff walls are eroding. Comet 67P has two lobes and also two distinct sides. Transport of material from the south to the north is probable. The morphology of the Imhotep plain should be typical for the terrains of the yet unseen southern hemisphere.

Volcanic terrain and the possible periglacial formation of "excess ice" at the mid-latitudes of Utopia Planitia, Mars

At the mid-latitudes of Utopia Planitia (UP), Mars, a suite of spatially-associated landforms exhibit geomorphological traits that, on Earth, would be consistent with periglacial processes and the possible freeze-thaw cycling of water. The suite comprises small-sized polygonally-patterned ground, polygon-junction and -margin pits, and scalloped, rimless depressions. Typically, the landforms incise a dark-toned terrain that is thought to be ice-rich. Here, we investigate the dark-toned terrain by using high resolution images from the HiRISE as well as near-infrared spectral-data from the OMEGA and CRISM. The terrain displays erosional characteristics consistent with a sedimentary nature and near-infrared spectra characterised by a blue slope similar to that of weathered basaltic-tephra. We also describe volcanic terrain that is dark-toned and periglacially-modified in the Kamchatka mountain-range of eastern Russia. The terrain is characterised by weathered tephra inter-bedded with snow, ice-wedge polygons and near-surface excess ice. The excess ice forms in the pore space of the tephra as the result of snow-melt infiltration and, subsequently, in-situ freezing. Based on this possible analogue, we construct a three-stage mechanism that explains the possible ice-enrichment of a broad expanse of dark-toned terrain at the mid-latitudes of UP: (1) the dark-toned terrain accumulates and forms via the regional deposition of sediments sourced from explosive volcanism; (2) the volcanic sediments are blanketed by atmospherically-precipitated (H2O) snow, ice or an admixture of the two, either concurrent with the volcanic-events or between discrete events; and, (3) under the influence of high obliquity or explosive volcanism, boundary conditions tolerant of thaw evolve and this, in turn, permits the migration, cycling and eventual formation of excess ice in the volcanic sediments. Over time, and through episodic iterations of this scenario, excess ice forms to decametres of depth. (C) 2015 Elsevier B.V. All rights reserved.

Hydraulic Performance of the Denitrification Bioreactor

Denitrification bioreactors, also known as woodchip bioreactors, are a new strategy for improving drainage water quality before these flows arrive at local streams, rivers, and lakes. A bioreactor is an excavated, woodchip-filled pit that is capable of supporting native microbes that convert nitrate in the drainage water to nitrogen gas. The idea of these edgeof-field treatment systems is still relatively new, meaning it is important for investigations to be made into how to design these “pits” and to determine how drainage water moves through the woodchips. Because the bioreactor at the ISU Northeast Research Farm (NERF) is one of the best monitored bioreactor sites in the state, it provided an ideal location to not only monitor bioreactor nitrate-reduction performance, but also to investigate design hydraulics.

Planktonic foraminiferal oxygen isotopes of ODP Site 143-865 samples

Cool tropical sea surface temperatures (SSTs) are reported for warm Paleogene greenhouse climates based on the d18O of planktonic foraminiferal tests. These results are difficult to reconcile with models of greenhouse gas-forced climate. It has been suggested that this "cool tropics paradox" arises from postdepositional alteration of foraminiferal calcite, yielding erroneously high d18O values. Recrystallization of foraminiferal tests is cryptic and difficult to quantify, and the compilation of robust d18O records from moderately altered material remains challenging. Scanning electron microscopy of planktonic foraminiferal chamber-wall cross sections reveals that the basal area of muricae, pustular outgrowths on the chamber walls of species belonging to the genus Morozovella, contain no mural pores and may be less susceptible to postdepositional alteration. We analyzed the d18O in muricae bases of morozovellids from the central Pacific (Ocean Drilling Program Site 865) by ion microprobe using 10 ?m pits with an analytical reproducibility of ±0.34 per mil (2 standard deviations). In situ measurements of d18O in these domains yield consistently lower values than those published for conventional multispecimen analyses. Assuming that the original d18O is largely preserved in the basal areas of muricae, this new d18O record indicates Early Paleogene (~49-56 Ma) tropical SSTs in the central Pacific were 4°-8°C higher than inferred from the previously published d18O record and that SSTs reached at least ~33°C during the Paleocene-Eocene thermal maximum. This study demonstrates the utility of ion microprobe analysis for generating more reliable paleoclimate records from moderately altered foraminiferal tests preserved in deep-sea sediments.

Utilización de material rocoso de desecho minero y enmiendas en la elaboración de sustratos edáficos para revegetar terrenos alterados

Los terrenos intervenidos por compañías mineras resultan alterados en mayor o menor grado según las actividades propias de cada una de ellas. Esta investigación hace referencia a la minera Alumbrera Ltda., que extrae el yacimiento de cobre, oro y molibdeno Bajo de la Alumbrera ubicado al noroeste de la Provincia de Catamarca. Este tipo de actividades genera grandes volúmenes de desechos de materiales rocosos extraídos de los “open pits", muchos de los cuáles pueden constituir sustratos adecuados para la revegetación de los sitios alterados por las mismas. Frente a los costos elevados de traer suelos desde sitios alejados para su uso en revegetación con especies de zonas áridas en sitios alterados por la actividad minera, se plantea el uso de los materiales rocosos inertes de desecho minero denominado Barren Core (BC) y Epidoto Clorita (ECl). Se investigan las causas del mayor éxito del ECI respecto a BC, en el establecimiento y crecimiento de las plantas, a partir del estudio de algunas propiedades hídricas (retención de agua e infiltración) y la obtención de un sustrato edáfico a partir de dichos materiales, Lombricompuesto (L) y suelo Aluvial (SAI)

Physical properties and accumulation rates in Dronning Maud Land, Antarctica

The European Programme for Ice Coring in Antarctica includes a comprehensive pre-site survey on the inland ice plateau of Dronning Maud Land, Antarctica. The German glaciological programme during the 1997/98 field season was carried out along a 1200 km traverse on Amundsenisen and involved sampling the snow cover in pits and by shallow firn cores. This paper focuses on the accumulation studies. The cores were dated by dielectric-profiling and continuous-flow analysis. Distinct volcanogenic peaks and seasonal signals in the profiles served to establish a depth time-scale. The eruptions of Krakatoa, Tambora, an unknown volcano, Kuwae and El Chichon are well-documented in the ice. Variations of the accumulation rates over different times were inferred from the depth time-scales. A composite record of accumulation rates for the last 200 years was produced by stacking 12 annually resolved records. According to this, accumulation rates decreased in the 19th century and increased in the 20th century. The recent values are by no means extraordinary, as they do not exceed the values at the beginning of the 19th century. Variations in accumulation rates are most probably linked to temperature variations indicated in d18O records from Amundsenisen.

(Table 1) Sea ice and snow characteristics and heat fluxes observed during R/V Aurora Australis cruise to East Antarctica in September/October 2007

The properties of snow on East Antarctic sea ice off Wilkes Land were examined during the Sea Ice Physics and Ecosystem Experiment (SIPEX) in late winter of 2007, focusing on the interaction with sea ice. This observation includes 11 transect lines for the measurement of ice thickness, freeboard, and snow depth, 50 snow pits on 13 ice floes, and diurnal variation of surface heat flux on three ice floes. The detailed profiling of topography along the transects and the d18O, salinity, and density datasets of snow made it possible to examine the snow-sea-ice interaction quantitatively for the first time in this area. In general, the snow displayed significant heterogeneity in types, thickness (mean: 0.14 +- 0.13 m), and density (325 +- 38 kg/m**3), as reported in other East Antarctic regions. High salinity was confined to the lowest 0.1 m. Salinity and d18O data within this layer revealed that saline water originated from the surface brine of sea ice in 20% of the total sites and from seawater in 80%. From the vertical profiles of snow density, bulk thermal conductivity of snow was estimated as 0.15 W/K/m on average, only half of the value used for numerical sea-ice models. Although the upward heat flux within snow estimated with this value was significantly lower than that within ice, it turned out that a higher value of thermal conductivity (0.3 to 0.4 W/K/m) is preferable for estimating ice growth amount in current numerical models. Diurnal measurements showed that upward conductive heat flux within the snow and net long-wave radiation at the surface seem to play important roles in the formation of snow ice from slush. The detailed surface topography allowed us to compare the air-ice drag coefficients of ice and snow surfaces under neutral conditions, and to examine the possibility of the retrieval of ice thickness distribution from satellite remote sensing. It was found that overall snow cover works to enhance the surface roughness of sea ice rather than moderate it, and increases the drag coefficient by about 10%. As for thickness retrieval, mean ice thickness had a higher correlation with ice surface roughness than mean freeboard or surface elevation, which indicates the potential usefulness of satellite L-band SAR in estimating the ice thickness distribution in the seasonal sea-ice zone.