Surface Geophysical Methods used to Verify the Karst Geological Structure in the Built-up Area: A Case Study of Specific Engineering-Geological Conditions

This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaská near Banská Bystrica in Slovakia. The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material. Its maximum thickness is 3 m. Another specificific condition of the study area is its location in the built-up area, due to which the applicability of geophysical methods was limited. The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill, which complicates the identification of cave spaces. The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.     

Seagrass as the main food source of Neaxius acanthus (Thalassinidea: Strahlaxiidae), its burrow associates, and of Corallianassa coutierei (Thalassinidea: Callianassidae)

Burrows of the thalassinidean shrimps Neaxius acanthus and Corallianassa coutierei are striking aspects in tropical seagrass beds of the Spermonde Archipelago, Indonesia. Burrow construction, behaviour, burrow type and associated commensal community were investigated to clarify the ecological role and food requirements of these shrimps and their commensals. Gut content analysis and stable-isotope data were used to unravel the food sources and the trophic interactions among the commensal community.Individuals of Neaxius acanthus were caught on Bone Batang Island. In narrow aquaria filled with sediment they constructed burrows resembling those found in the field. During burrow construction and maintenance only little sediment was brought to the surface, most was sorted and compacted to create a distinct lining. Maintenance work by single shrimps typically took about 5 min, after which the shrimp walked up to the entrance and rested for a similar period of time. There were no differences in behaviour between day and night. Intrasexual encounters inside the burrow were characterised by a high level of aggression and all resulted in one participant being driven out of the burrow. Intersexual encounters led to coexistence with both animals taking turns in burrow maintenance and guarding the entrance. Offered seagrass leaves were pulled underground, cut into pieces and eventually integrated into the lining. Burrows of Corallianassa coutierei resembled a deep U-shape. Chambers branching off halfway down and at the deepest point contained seagrass fragments. All steep parts of the burrow were lined similar to burrows of N. acanthus.No commensals were found associated with Corallianassa coutierei. However, burrows of Neaxius acanthus in the field typically contained a pair of shrimps, up to 8 individuals of the commensal bivalve Barrimysia cumingii and large numbers of gammarid amphipods. Other animals found associated with the burrow were the goby Austrolethops wardi, a palaemonid shrimp species and two species of tube-building polychaetes, one of which was also found as an epibiont on N. acanthus.Stable-isotope and gut content analyses indicate that the diet of Neaxius acanthus, its commensal Austrolethops wardi, and Corallianassa coutierei is mainly derived from detrital seagrass leaves, with a potential contribution of sediment organic matter and seagrass epiphytes. In contrast the isotopic signature of Barrimysia cumingii suggests the presence of symbiotic sulphide metabolism bacteria. This study underlines that, besides their interactions with the surrounding ecosystem, thalassinid shrimp burrows play an important role as a sub-habitat with a unique associated fauna.     

The bivalve Lembulus bicuspidatus may enhance denitrification in shelf sediment at the Angola–Benguela Frontal Zone

We collected living individuals of the bivalve Lembulus bicuspidatus, which shows an unusual preference for the oxygen-deficient habitat found at the Angola–Benguela Frontal Zone of the southeastern Atlantic. With a series of incubation experiments with ¹⁵N-labelled nitrate as a tracer in combination with membrane-inlet mass spectrometry, we studied the potential contribution of L. bicuspidatus to nitrate reduction in the upper sediment layer. Our preliminary results suggest that L. bicuspidatus enhances nitrate reduction if the oxygen concentration is sufficiently low. The Lembulus-mediated nitrate reduction rate is then similar to the rate of microbial nitrate reduction in the surrounding sediment.     

Error Analysis for the Astrometric Determination of Absolute Proper Motions by means of a Monte Carlo Simulation

Bei der Ermittlung von Positionen und Eigenbewegungen von Himmelsobjekten wurden bisher nur Korrektionen instrumenteller und atmosphärischer Fehler durchgeführt. Meßfehler als zufällige Fehler wurden nicht berücksichtigt. Deshalb wurde eine Monte-Carlo-Simulation der Fortpflanzung dieser zufälligen Fehler bei der Berechnung der sog. mittleren Meßkoordinaten und der Eigenbewegungen vorgenommen. Als markante Größe wurde die jeweilige Standardabweichung geschäzt und ihre Abhängigkeit von auftretenden Parametern studiert. Bei dieser Methode sin die wahren Werte der betrachteten Größen bekannt (simulativ erzeugt), so daß die Fehler der berechneten Größen direkt bestimmt werden können. Es werden Rückschlüsse auf die Genauigkeit einer Einzelmessung vorgenommen.     

The occurrence of nocturnal low‐level jets In new England and the Canadian maritimes

Abstract

Detailed low‐level wind data collected in southern New Brunswick each summer since 1973 have revealed the existence of a significant low‐level jet during the evening on many occasions. The major contributing factor is considered to be an opposing thermal wind generated by the land/sea surface temperature difference when the low‐level airflow parallels the coastline. The maximum wind is characteristically located between 300 and 500 m above msl. Intensities have been found as great as 15 m s^‐1 in excess of the 1000‐m wind speed. A detailed study is presented for a well‐documented case on 8 July 1975, using hourly information from three stations near Fredericton, N.B., and Doppler measurements of the drift of a specially equipped research aircraft. There is clear evidence of an undulation in the altitude of the “nose” of the low‐level jet and of a progressive increase in intensity from early evening until midnight.     

Spatial patterns of groundwater‐lake exchange – implications for acid neutralization processes in an acid mine lake

Exchange of groundwater and lake water with typically quite different chemical composition is an important driver for biogeochemical processes at the groundwater‐lake interface, which can affect the water quality of lakes. This is of particular relevance in mine lakes where anoxic and slightly acidic groundwater mixes with oxic and acidic lake water (pH < 3). To identify links between groundwater‐lake exchange rates and acid neutralization processes in the sediments, exchange rates were quantified and related to pore‐water pH, sulfate and iron concentrations as well as sulfate reduction rates within the sediment. Seepage rates measured with seepage meters (?2.5 to 5.8 L m^‐2 d^‐1) were in reasonable agreement with rates inverted from modeled chloride profiles (?1.8 to 8.1 L m^‐2 d^‐1). Large‐scale exchange patterns were defined by the (hydro)geologic setting but superimposed by smaller scale variations caused by variability in sediment texture. Sites characterized by groundwater upwelling (flow into the lake) and sites where flow alternated between upwelling and downwelling were identified. Observed chloride profiles at the alternating sites reflected the transient flow regime. Seepage direction, as well as seepage rate, were found to influence pH, sulfate and iron profiles and the associated sulfate reduction rates. Under alternating conditions proton‐consuming processes, for example, sulfate reduction, were slowed. In the uppermost layer of the sediment (max. 5 cm), sulfate reduction rates were significantly higher at upwelling (>330 nmol g^‐1 d^‐1) compared to alternating sites (<220 nmol g^‐1 d^‐1). Although differences in sulfate reduction rates could not be explained solely by different flux rates, they were clearly related to the prevailing groundwater‐lake exchange patterns and the associated pH conditions. Our findings strongly suggest that groundwater‐lake exchange has significant effects on the biogeochemical processes that are coupled to sulfate reduction such as acidity retention and precipitation of iron sulfides. Copyright © 2012 John Wiley & Sons, Ltd.     

On the enhanced smoothing over topography in some mesometeorological models

An equation is derived for the components of the horizontal (turbulent) frictional force in the -coordinate system with special attention to mesometeorological flow models. The starting point is the horizontal equation of motion in its flux-form in the -system in which we replace (following Reynolds' procedure) the velocity components u,v and % MathType!MTEF!2!1!+- % feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafq4WdmNbai % aaaaa!37B8! \[ \dot \sigma \] aswell as other relevant quantities by terms of the form u = + u,..., = ± + % MathType!MTEF!2!1!+- % feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGafq4WdmNbai % Gbauaaaaa!37C3! \[ \dot \sigma ' \] , etc. ( = time average of u; u = fluctuating part of u.) Next, the equation is averaged with respect to time and terms which we believe are small in mesometeorological flows, are neglected. On expressing by an appropriate expression that involves w, the result shows the appearance of two new terms which, have not been considered previously in the published literature. While the expression earlier used in the literature involved the -derivative of % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaaceWG3bGbauaaaaaaaa!380B!\[\overline {u'w'} \] alone, the new terms add the -derivatives of % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaadaahaaWcbeqaaiaaikdaaaaaaaaa!37EC!\[\overline {u'^2 } \] and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaaceWG2bGbauaaaaaaaa!380A!\[\overline {u'v'} \] for the x-component of the force, and the -derivatives of % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG2bGbauaadaahaaWcbeqaaiaaikdaaaaaaaaa!37ED!\[\overline {v'^2 } \]} and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWaa0aaaeaace% WG1bGbauaaceWG2bGbauaaaaaaaa!380A!\[\overline {u'v'} \] for the y-component, where and are the slopes of the -surfaces in the x- and y-directions, respectively. Further, a few numerical simulations of the sea-breeze over topography are carried out with and without the correction terms. It is shown that when corrections terms are not included the effective smoothing is stronger above the sloping regions and may amount to as high as 50 percent of the convergence with slopes of ~.04. The ìnclusìon of the new terms does not lead to any special computational difficulties and for that reason there is no compelling reason to neglect them, all the more so because, as is shown, the addition of the new terms results in a consistent apportioning of the degree of horizontal diffusion.On leave from CIMMS, Norman, OK.Now visiting Dept. of Met., Helsinki, Finland.     

Organic geochemistry and pore water chemistry of sediments from Mangrove Lake,Bermuda

Mangrove Lake, Bermuda, is a small coastal, brackish-water lake that has accumulated 14 m of banded, gelatinous, sapropelic sediments in less than 10⁴ yr. Stratigraphic evidence indicates that Mangrove Lake's sedimentary environment has undergone three major depositional changes (peat, freshwater gel, brackish-water gel) as a result of sea level changes. The deposits were examined geochemically in an effort to delineate sedimentological and diagenetic changes. Gas and pore water studies include measurements of sulfides, ammonia, methane, nitrogen gas, calcium, magnesium, chloride, alkalinity, and pH. Results indicate that sulfate reduction is complete, and some evidence is presented for bacterial denitrification and metal sulfide precipitation. The organic-rich sapropel is predominantly algal in origin, composed mostly of carbohydrates and insoluble macromolecular organic matter called humin with minor amounts of proteins, lipids, and humic acids. Carbohydrates and proteins undergo hydrolysis with depth in the marine sapropel but tend to be preserved in the freshwater sapropel. The humin, which has a predominantly aliphatic structure, increases linearly with depth and composes the greatest fraction of the organic matter. Humic acids are minor components and are more like polysaccharides than typical marine humic acids. Fatty acid distributions reveal that the lipids are of an algal and/or terrestrial plant source. Normal alkanes with a total concentration of 75 ppm exhibit two distribution maxima. One is centered about n-C₂₂ with no odd/even predominance, suggestive of a degraded algal source. The other is centered at n-C₃₁ with a distinct odd/even predominance indicative of a vascular plant origin. Stratigraphic changes in the sediment correlate to observed changes in the gas and pore water chemistry and the organic geochemistry.     

Dissolution of secondary copper sulphides using complex-forming agents (EDTA,EDA). Part I: Covellite dissolution in EDTA and EDA

Problems of dissolution of the so-called secondary copper sulphides are very important for dynamic as well as percolation leaching of ores. This paper deals with dissolution kinetics of sulphides in an alkaline medium, using complex-forming agents in connection with possibility to leach basic, partially oxidized ores. Natural minerals and their polydispersions were investigated and the so-called geometrical model was used for evaluation. Basic dependences of the dissolution rate on the reagent concentration and pH value of the leaching solution were found and an attempt at their mathematical expression and physical interpretation was made. The first part of this work refers to the systems of covellite-ethylene diamine tetra-acetic acid (EDTA) and covellite-ethylene diamine (EDA). The established dependences are not only of theoretical but also of practical importance.