Zur Bewertung der Analytik und Interpretation des Gruppenparameters “Extrahierbares organisch gebundenes Halogen” von Wässern

Organohalogen compounds are gaining in importance in the control of surface and drinking water due to their unwholesome properties. An accumulation of the organohalogen compounds, occurring mostly at low concentrations, is possible in different ways. The author discusses the possibility and problems of the extractability from waters with the aid of organic solvents. The group parameter EOX that can be determined does not allow any statement concerning components of individual substances, but gives some clues to the state of surface and drinking waters which are mostly anthropogenically polluted. Results of practical examples as well as theoretical considerations indicate the importance of the different distribution coefficients in the solvent/water extraction system. The degree of extraction can be considerably increased by the application of suitable mixtures of solvents. In waters with a known composition, the probably detectable EOX-quantity can be calculated by means of theoretical degrees of extraction.     

Polybrominated diphenyl ethers and their hydroxylated/methoxylated analogs: environmental sources, metabolic relationships, and relative toxicities

Brominated compounds are ubiquitous in the aquatic environment. The polybrominated diphenyl ether (PBDE) flame retardants are anthropogenic compounds of concern. Studies suggest that PBDEs can be biotransformed to hydroxylated brominated diphenyl ethers (OH-BDE). However, the rate of OH-BDE formation observed has been extremely small. OH-BDEs have also been identified as natural compounds produced by some marine invertebrates. Another class of compounds, the methoxylated BDEs (MeO-BDEs), has also been identified as natural compounds in the marine environment. Both the OH-BDEs and MeO-BDEs bioaccumulate in higher marine organisms. Recent studies have demonstrated that MeO-BDEs can be biotransformed to OH-BDEs and this generates greater amounts of OH-BDEs than could be generated from PBDEs. Consequently, MeO-BDEs likely represent the primary source of metabolically derived OH-BDEs. Given that for some endpoints OH-BDEs often exhibit greater toxicity compared to PBDEs, it is prudent to consider OH-BDEs as chemicals of concern, despite their seemingly "natural" origins.     

Polybrominated diphenyl ethers and their hydroxylated/methoxylated analogs: Environmental sources,metabolic relationships,and relative toxicities

Brominated compounds are ubiquitous in the aquatic environment. The polybrominated diphenyl ether (PBDE) flame retardants are anthropogenic compounds of concern. Studies suggest that PBDEs can be biotransformed to hydroxylated brominated diphenyl ethers (OH-BDE). However, the rate of OH-BDE formation observed has been extremely small. OH-BDEs have also been identified as natural compounds produced by some marine invertebrates. Another class of compounds, the methoxylated BDEs (MeO-BDEs), has also been identified as natural compounds in the marine environment. Both the OH-BDEs and MeO-BDEs bioaccumulate in higher marine organisms. Recent studies have demonstrated that MeO-BDEs can be biotransformed to OH-BDEs and this generates greater amounts of OH-BDEs than could be generated from PBDEs. Consequently, MeO-BDEs likely represent the primary source of metabolically derived OH-BDEs. Given that for some endpoints OH-BDEs often exhibit greater toxicity compared to PBDEs, it is prudent to consider OH-BDEs as chemicals of concern, despite their seemingly “natural” origins.     

Size distribution of the number of lithospheric plates

To describe the cumulative distribution of the number of lithospheric plates over areas S, the dependence N(≥S) ～ S ^?0.33 was proposed by Bird [2003]. Based on dimension considerations, the dependence N(≥S) ～ (?/S)^1/3, where ? is the generation rate of kinetic energy of convection in the mantle estimated at 10^?11 m²/s³, is proposed. The analogy of plate formation with developed hydrodynamic turbulence and other processes involving an energy input into the system and its dissipation is considered. Simple experiments on random partitioning of a surface into polygons gave their cumulative distributions over areas resembling those observed for lithospheric plates. This has led to the conclusion that the plate distribution pattern is characteristic of the random partitioning of surfaces.     

The relationship between methylated chromans and maturity of organic matter in the source rocks from Jianghan hypersaline basin

The distribution, the relative composition, and their variation of methylated chromans (MTTC) with maturation of organic matter in the source rocks from Mingjia 1 well, Jianghan hypersaline basin, have been analyzed and studied. There is a close relationship between the distribution of methylatd chromans and paleosalinity of depositional environment. In the Eq ₁–Eq ₃ source rocks deposited under hypersaline environment with lower Pr/Ph ratio, higher gammacerane index and abundant organic sulfur-containing compounds, methyl MTTC and dimethyl MTTC are main components, but in the Eq ₄ source rocks deposited non-hypersaline environment with relatively higher Pr/Ph ratio, lower gammacerane index and organic sulfur-containing compounds, trimethyl MTTC is a major compound in methylate chromans. Obviously, the distributions and the compositions of methylated chromans in the source rocks are in harmony with biomarker indicators indicating the paleaosalinity and redox of depositional environment. The relationship between the ratio of 5,8-dimethyl MTTC to 7,8-dimethyl MTTC (dimethyl MTTC ratio) and the maturity of organic matter in the source rocks from Mingjia 1 well has been discussed. The results show that dimethyl MTTC ratio increased with the burial depth and the maturation of organic matter in the source rocks, especially in immature level. It is noteworthy that this ratio is very susceptible to small variation in the maturity of organic matter in the source rocks when vitrinite reflectance R _o is less than 0.65%. It may imply that this ratio is a good and susceptible aromatic maturity indicator for the relative maturity of organic matter in immature source rocks.     

On computation of second derivatives from gravity data

Summary Second derivative formulae ofElkins andRosenbach are developed from a unified approach and their merits and demerits are discussed. Some new formulae are suggested, which, from theoretical considerations it is felt, will prove more efficient.     

Shear wave velocity-based evaluation and design of stone column improved ground for liquefaction mitigation

The evaluation and design of stone column improvement ground for liquefaction mitigation is a challenging issue for the state of practice. In this paper, a shear wave velocity-based approach is proposed based on the well-defined correlations of liquefaction resistance (CRR)-shear wave velocity (V _s)-void ratio (e) of sandy soils, and the values of parameters in this approach are recommended for preliminary design purpose when site specific values are not available. The detailed procedures of pre- and post-improvement liquefaction evaluations and stone column design are given. According to this approach, the required level of ground improvement will be met once the target V _s of soil is raised high enough (i.e., no less than the critical velocity) to resist the given earthquake loading according to the CRR-V _s relationship, and then this requirement is transferred to the control of target void ratio (i.e., the critical e) according to the V _s-e relationship. As this approach relies on the densification of the surrounding soil instead of the whole improved ground and is conservative by nature, specific considerations of the densification mechanism and effect are given, and the effects of drainage and reinforcement of stone columns are also discussed. A case study of a thermal power plant in Indonesia is introduced, where the effectiveness of stone column improved ground was evaluated by the proposed V _s-based method and compared with the SPT-based evaluation. This improved ground performed well and experienced no liquefaction during subsequent strong earthquakes.     

Synthesis of Sulfonated Naphthalene-Formaldehyde Condensates and their Trace-analytical Determination in Wastewater and River Water

Naphthalenesulfonates and their condensates with formaldehyde (SNFC) are widely used in industrial processes, e.g. as plasticizers for concrete or as tanning agents. Based on their high aqueous solubility these compounds are expected to be eliminated incompletely in mechanical-biological treatment plants and to end up in the aquatic environment. Due to the lack of reference compounds the identification and quantification of these condensates in the aquatic environment was impossible in the past. This paper describes the synthesis of several condensates of 2-naphthalenesulfonate with formaldehyde. With the synthesized products as reference compounds it was possible for the first time to detect and quantify some sulfonated naphthalene-formaldehyde condensates in the aquatic environment. For this purpose characteristic peaks in the HPLC screening of wastewater and river water samples were compared with the corresponding peaks of a technical SNFC product. Three out of several paths on which these compounds enter the aquatic environment were identified. The identified compounds in the analyzed wastewater samples have concentrations between 0.14 and 110 μg/L.     

On the question of coronal holes as sources of geomagnetic disturbances

Summary Using a more detailed geomagnetic activity Kp index, the finding in [3] that geomagnetic activity increases after the CMP of coronal holes, was verified; it was shown using individual activity patterns, that coronal holes apparently do not form a homogeneous class of phenomena, which must be respect in considerations of emissions of fast solar wind streams.     

Using blood samples to estimate persistent organic pollutants and metals in green sea turtles (Chelonia mydas)

Persistent organic pollutants (POPs) and heavy metals have been reported in a number of green turtle (Chelonia mydas) populations worldwide. However, due to ethical considerations, these studies have generally been on tissues from deceased and stranded animals. The purpose of this study was to investigate the use of blood samples to estimate the tissue contamination of live C. mydas populations. This study analysed 125 POP compounds and eight heavy metals in the blood, liver, kidney and muscle of 16 C. mydas from the Sea World Sea Turtle Rehabilitation Program, Gold Coast, Australia. Strong correlations were observed between blood and tissue concentrations for a number of POPs and metals. Furthermore, these correlations were observed over large ranges of turtle size, sex and condition. These results indicate that blood samples are a reliable non-lethal method for predicting chemical contamination in C. mydas.     

Generic and parsimonious stochastic modelling for hydrology and beyond

ABSTRACT

The old principle of parsimonious modelling of natural processes has regained its importance in the last few years. The inevitability of uncertainty and risk, and the value of stochastic modelling in dealing with them, are also again appreciated, after a period of growing hopes for radical reduction of uncertainty. Yet, in stochastic modelling of natural processes several families of models are used that are often non-parsimonious, unnatural or artificial, theoretically unjustified and, eventually, unnecessary. Here we develop a general methodology for more theoretically justified stochastic processes, which evolve in continuous time and stem from maximum entropy production considerations. The discrete-time properties thereof are theoretically derived from the continuous-time ones and a general simulation methodology in discrete time is built, which explicitly handles the effects of discretization and truncation. Some additional modelling issues are discussed with a focus on model identification and fitting, which are often made using inappropriate methods.

EDITOR Z.W. Kundzewicz ASSOCIATE EDITOR S. Grimaldi     

Long-term prediction of the Earth Orientation Parameters by the artificial neural network technique

There are increasing demands for EOP predictions in science, deep space navigation, etc. Based on previous research on short-term prediction of Earth Orientation Parameters (EOP) by artificial neural networks (ANN), we extend our attempt to long-term predictions of EOPs, i.e. predictions with a lead time up to 360 days. The basic theory and some special considerations for the ANN forecast of EOPs are presented, and finally our preliminary results and their accuracy estimates are shown and compared with those obtained by other authors.     

Complex site effects and building codes: Making the leap

The engineering community is aware of the importance of site effects, but it lags behind seismological studies when it comes to incorporating site effect considerations in design spectra for seismic norms. This lag is reflected in the conspicuous fact that current building codes make allowance for 1D site effects but ignore complex site effects. The purpose of this paper is to explore a way for including complex site effects in a building code environment. We take as example Eurocode 8, which is a modern code that exemplifies the current approach to site effect consideration. We examine the restrictions that we have imposed to make the problem of a feasible size and discuss the approach we have taken. We propose a strategy to incorporate a class of complex site effects in a design elastic spectrum.     

Geomagnetotail dynamics: Different types of equilibriums and transitions between them

Two time scales are distinguished in the geomagnetotail dynamics. The small scale (T ₁) corresponds to disturbances propagating in the tail lobes, which have a relatively strong magnetic field and low plasma density. The larger scale (T ₂) corresponds to plasma motions in the plasma sheet and has a relatively weak magnetic field and a relatively higher density. A disturbance, which is initiated by a localized burst of magnetic reconnection and appears in the geomagnetotail on the time scale T ₁, generates the upset of equilibrium in the plasma sheet zones with intermediate spatial dimensions (about R _E). The theoretical considerations and numerical simulation indicate that the relaxation process, which subsequently proceeds on the larger time scale (T ₂), results in the appearance of extremely thin embedded current sheets and in the generation of fast plasma flows. This process gives an effective mechanism by which the magnetic energy stored in the geomagnetotail is transformed into the plasma flow kinetic energy. Such fast flows can also generate eddy plasma motions on smaller spatial scales. On the one hand, fast MHD components of this process carry a disturbance in other plasma sheet zones, where new magnetic reconnection bursts can originate at a large distance from the zone of an initial nonlinear disturbance. As a result, new recurrent processes of relaxation originate on the T ₂ time scale. Alternation originating in such a way is apparently the characteristic feature of eddy disturbances actually observed in the plasma sheet.     

Biogene und nichtbiogene organische Schmutzstoffe

Analytical methods and their application on the river Rhine for the identification and determination of refractory organic compounds are reported. 18 hydrocarbons, 32 chlorinated hydrocarbons, 13 organic nitro compounds, 14 ethers, 4 alcohols, 9 phenols, 6 esters and 21 other organic compounds have been identified. In view of the tedious methods which have to be applied, a technique for determining the ratio of persistent to biodegradable organic compounds has to be found. Requirements and perspectives of microbiological assays are discussed and rules for the survey of waste discharges are proposed.     

Behaviour of hexachlorocyclohexane isomers and Zn,Cu and Cd in the freshwater-seawater mixing area

Dissolved and suspended concentrations of hexachlorocyclohexane isomers, α, γ and δ HCH, and Zn, Cu and Cd have been measured in the Napostá Grande stream, located in the Blance Bay area, Argentina, for the purpose of studying the behaviour of these compounds in the freshwater-seawater mixing zone. The aim was to establish the mobilization processes, according to their distribution over the dissolved and suspended forms, in order to obtain a better understanding of their impact on organochlorine and heavy metal levels in the marine environment. It is concluded that the compounds studied are removed from solution by suspended matter which is afterwards precipitated during the freshwater-seawater mixing process. Seawater and surface sediment concentrations of these pollutants for two sampling sites in Blanca Bay, Argentina, are also reported.     

Microbial D-amino acids and marine carbon storage

In nature, there are two conformational types of amino acids: L- and D-isomers. The L-amino acids are the predominant form and are used mainly for protein synthesis, while the D-amino acids are few in quantity but more diverse in terms of their biological functions. D-amino acids are produced by many marine microbes, which are important players in carbon and energy cycles in the ocean. As the major constituent of the marine organic carbon pool, D-amino acids can persist in the water column for a long time before being further transformed by chemical or biological processes or transported through physical processes (such as absorption and aggregation). This article reviews the microbial synthesis of D-amino acids, their physiological function and metabolism in microbes, and the contribution of D-amino acids as a carbon source to the oceanic carbon reservoir.     

考虑自退磁影响的三维复杂形体磁场正反演研究进展与展望

忽视自退磁效应的影响,会导致磁异常反演结果的误差,影响地质解释的效果,这使得人们在实际应用中不得不考虑退磁的影响.本文对考虑自退磁影响的三维复杂形体磁场正演和反演方法进行了系统总结,论述了各种方法的特点和实际应用中的困难,提出了考虑自退磁影响的三维复杂形体磁场正反演研究的发展方向.     

Aliphatic and polyaromatic hydrocarbons in bottom sediments of offshore mouth area of the Volga

Data on the concentration and composition of aliphatic and polyaromatic hydrocarbons in the surface layer and the body of bottom sediments in Volga delta and on the northern Caspian shelf are given. Volga delta sediments are shown to contain large concentrations of organic compounds. It is established that the concentrations of organic compounds is largely dependent on the dispersiveness of sediments. Anthropogenic hydrocarbons, both oil and pyrogenic, fail to pass the marginal filter of the Volga River and do not reach the open part of the sea. Therefore, the hydrocarbons contained in the bottom sediments on the Caspian Sea shelf are mostly of natural genesis. The distribution of organic compounds in the bottom sediment strata has a complex character. In some cases, their concentration increases because of the higher flux of hydrocarbons (especially, polyarenes in the 1950s).