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.     

Effects of cadmium, zinc and nitrogen status on non-protein thiols in the macroalgae Enteromorpha spp. from the Scheldt Estuary (SW Netherlands, Belgium) and Thermaikos Gulf (N Aegean Sea, Greece)

Enteromorpha prolifera (Scheldt Estuary) and E. linza (Thermaikos Gulf) were incubated at three salinities with 100 and 200microgL(-1)Cd and Zn. The objective was to measure effects of Cd, Zn and nitrogen (N) status on the pools of metal-binding non-protein thiols: glutathione and phytochelatins, (gamma-glutamyl-cysteinyl)(n)-glycine (PC). In E. linza, ammonium pools were higher, but amino acid pools, total N and protein contents were lower than in E. prolifera. Reduced glutathione (GSH) pools were positively correlated with free glutamate and protein contents. In E. linza GSH pools increased and the ratio of reduced to oxidized glutathione (GSH:(GSH+0.5GSSG)), an indicator of oxidative stress, decreased with Cd contents, indicating Cd-induced glutathione oxidation. Total glutathione pools (reduced plus oxidized) ranged from 16nmolSgdwt(-1) in controls (at 0.5micromolCdgdwt(-1)) to 179nmolSgdwt(-1) (at 1.9micromolCdgdwt(-1)) at the highest cadmium dosage. Cadmium stimulated PC synthesis in E. prolifera which suggests that in N-rich algae, glutathione pools were high enough for PC synthesis. In both species GSH and protein increased with Zn contents, whereas GSH:(GSH+0.5GSSG) decreased, which would indicate Zn-induced oxidative stress; in E. linza, at the highest salinity the glutathione redox ratio decreased from 0.61 (at 2.9micromolZngdwt(-1)) to 0.26 (at 4.9nmolSgdwt(-1)) (at 0.5molCdgdwt(-1)). PCs were not synthesized in response to Zn, which may have resulted in Zn-induced GSH oxidation. The presence of both oxidative effects (Cd, Zn) and detoxification (Cd) could be identified by observing the responses of glutathione and PC pools to metal stress.     

Evaluation of the Presence of Methane in Złoczew Lignite: Comparison with Other Lignite Deposits in Poland

Natural Resources Research - Catastrophic cases of methane explosion during exploratory drilling within the Be?chatów ortholignite deposit have led to testing for methane in other Polish...     

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.     

Economic gains of liberalising access to fishing quotas within the European Union

This paper analyses the extent to which specialisation gains can be achieved by liberalising access to fishing quotas within the European Union (EU). Fishing quotas are today exchanged between EU member states at a rate of 4% of total turnover in EU fisheries. Germany, Belgium, Denmark and the Netherlands are the most active. Only one fourth of these exchanges are permanent. With the management systems in EU fisheries differing among countries, comparative advantages in fisheries exist in member states with the best management practices. Hence, although positive but small specialisation gains exist in EU fisheries today, these gains might potentially be increased by liberalising access to fishing quotas and allowing transferability of quotas between individuals from different countries on a permanent basis. Increasing the gains might, however, affect relative stability.     

Joint modelling of wave spectral parameters for extreme sea states

Characterising the dependence between extremes of wave spectral parameters such as significant wave height (H_S) and spectral peak period (T_P) is important in understanding extreme ocean environments and in the design and assessment of marine structures. For example, it is known that mean values of wave periods tend to increase with increasing storm intensity. Here we seek to characterise joint dependence in a straightforward manner, accessible to the ocean engineering community, using a statistically sound approach.Many methods of multivariate extreme value analyses are based on models which assume implicitly that in some joint tail region each parameter is either independent of or asymptotically dependent on other parameters; yet in reality the dependence structure in general is neither of these. The underpinning assumption of multivariate regular variation restricts these methods to estimation of joint regions in which all parameters are extreme; but regions where only a subset of parameters are extreme can be equally important for design. The conditional approach of Heffernan and Tawn (2004), similar in spirit to that of Haver (1985) but with better theoretical foundation, overcomes these difficulties.We use the conditional approach to characterise the dependence structure of H_S and T_P. The key elements of the procedure are: (1) marginal modelling for all parameters, (2) transformation of data to a common standard Gumbel marginal form, (3) modelling dependence between data for extremes of pairs of parameters using a form of regression, (4) simulation of long return periods to estimate joint extremes. We demonstrate the approach in application to measured and hindcast data from the Northern North Sea, the Gulf of Mexico and the North West Shelf of Australia. We also illustrate the use of data re-sampling techniques such as bootstrapping to estimate the uncertainty in marginal and dependence models and accommodate this uncertainty in extreme quantile estimation.We discuss the current approach in the context of other approaches to multivariate extreme value estimation popular in the ocean engineering community.     

A model for the emplacement of the eastern compartment of the bushveld complex

The stratigraphy and geological position of the eastern compartment of the Bushveld Complex are described. A mechanical model for the initiation and growth of the eastern compartment of the Bushveld intrusion has been developed using thin elastic plate theory, assuming linked conical magma chambers. It is shown that the contribution to the pressure at the base of a cell by the restitutional force exerted by the roof of Rooiberg felsites is 10⁴ times as great as that of the layers of host in the cone. Both are minimal compared to the lithostatic pressure exerted by the magma pile. Roof deformation is therefore seen to be a more important process than sagging of the floor during intrusion—a feature which probably occurred during cooling, solidification and isostatic readjustment of the area.A stratigraphie model is proposed in which the intrusion of basic rocks into the Transvaal sequence is discussed in the light of continuous basin subsidence. Early submarine sedimentation in an irregularly-floored basin some 620 km in diameter situated on the Archaean craton gave rise to a 7.7 km thick sedimentary pile, to which was added some 7 km of subaerial basalts and felsites. Depression of the floor of the basin into the regime of maximum horizontal compression induced favourable conditions for the intrusion of a total of 2.5 km of diabase sills which further assisted the subsidence. The 9 km thick Bushveld Complex was intruded into the basal sections at points along a 010° trend in a regime characterised by shear failure. Early magma influxes gave rise to a laminated marginal zone forming a shallow cone, with associated sill activity, whilst continued later influxes filled the conical cell, transgressed the floor and uparched the roof. Partial melting in the regions beneath the Complex, exacerbated by continued crustal depression, gave rise to the late Bushveld granites.