Mercury contamination in the vicinity of a derelict chlor-alkali plant Part II: contamination of the aquatic and terrestrial food chain and potential risks to the local population

This study investigated the environmental impact and level of risk associated with mercury (Hg) contamination near a derelict chlor-alkali plant in Pavlodar, Northern Kazakhstan. Several species of fish were sampled from the highly polluted Lake Balkyldak and the nearby river Irtysh, to assess the extent of Hg bioaccumulation in the aquatic food chain and potential human health risks. A small number of bovine tissue samples, water samples, soil and plant samples from a nearby village were also investigated in order to make a preliminary assessment of potential impacts on the terrestrial food chain. Mercury levels in fish caught from Lake Balkyldak ranged from 0.16 to 2.2 mg kg(-1) and the majority of fish exceeded current human health criteria for Hg. Interspecies comparisons indicated that Hg is accumulated in the order dace>carp>tench. Site-specific bioaccumulation factors (BAF) were calculated for THg, and were estimated for MeHg. Fish from the river Irtysh and floodplain oxbow lakes contained between 0.075 and 0.159 mg kg(-1) of Hg and can be regarded as uncontaminated. Soils were found to be impacted by past atmospheric emissions of Hg. Cattle grazing in the surroundings of the factory are exposed to Hg from contaminated soils, plants and surface water, but the consumption of contaminated fish from the lake appears to be the main route of exposure for humans.     

Mercury contamination in the vicinity of a derelict chlor-alkali plant. Part I: sediment and water contamination of Lake Balkyldak and the River Irtysh

A mercury-cell chlor-alkali plant operated in Pavlodar, Northern Kazakhstan, for 18 years and caused widespread contamination of the surrounding environment. Untreated wastewater from the plant was discharged to Lake Balkyldak, a shallow impounded lake without an outlet. The nearby River Irtysh was also suspected to be impacted by mercury (Hg) via the transport of contaminated groundwater. We took sediment and water samples from both aquatic systems, and also sampled soils along the shoreline of the lake and in the Irtysh flood plain. Sediments from Lake Balkyldak were found to be very heavily contaminated, with Hg concentrations in the surface layer reaching up to approximately 1500 mg kg(-1) near the wastewater outfall pipe. The contaminated lake sediments are prone to wind-driven resuspension and are acting as a strong source of Hg to the water column. Unfiltered lake water samples taken in shallow areas within 10-15 m from the shoreline contained from 0.11 microg Hg L(-1) in the less contaminated northern part of the lake to 1.39 microg L(-1) near the pollutant outfall in the south (up to 7.3 microg L(-1) on windy days). Sediments from the River Irtysh were only slightly impacted, with maximum Hg concentrations of 0.046 mg kg(-1) in the old river channel and 0.36 mg kg(-1) in floodplain oxbow lakes. In water samples from the River Irtysh, Hg was generally not detected, although trace concentrations (3 to 9 ng L(-1)) were found in some samples taken from oxbow lakes. We conclude that the river is not significantly impacted by Hg, but the highly contaminated Lake Balkyldak poses a threat and is in need of remediation. Potential remediation options for the lake are reviewed and are discussed in the context of experiences made at other Hg-contaminated sites.     

T–T–T behaviour of bioactive glasses 1–98 and 13–93

In this work crystallization kinetics of bioactive glasses 1–98 and 13–93 are discussed. Within a certain temperature–time window these glasses can be hot worked into various products without interfering with crystallization. The crystallization was studied isothermally by heating glass plates at different temperatures for different times. Phases in the samples were studied through XRD and SEM analyses. The nucleation-like curves and crystallization characteristics were measured with DTA. The temperature of maximum nucleation was measured for glass 1–98 at 725 °C and for 13–93 at 700 °C. The activation energy of crystallization of both glasses was 280 kJ/mol. The Johnson–Mehl–Avrami exponent and the SEM micrographs of the samples suggested surface crystallization. The primary crystalline phase was wollastonite. The growth rate of the crystallized surface layer was 1 order of magnitude higher in the plates of 1–98 than in 13–93. The results can be utilized to optimize the parameters in hot-working of the glasses.     

Druids' Knowledge in Chemical Engineering: Analysis of the Illustrated Literature by Goscinny and Uderzo

The illustrated literature series Asterix (and Obelix) is commonly known as entertainment and distraction, but behind that mask, case studies for chemical production in small medium enterprises and the crucial role of research and development can be discovered. The series rightly puts chemistry and chemical engineering at the heart of success and prosperity. Overall, the motives exemplified are of high relevance today for chemical industry.     

New Bioactive Oxylipins Formed by Non-Enzymatic Free-Radical-Catalyzed Pathways: the Phytoprostanes

In animals and plants, fatty acids with at least three double bonds can be oxidized to prostaglandin-like compounds via enzymatic and non-enzymatic pathways. The most common fatty acid precursor in mammals is arachidonic acid (C20:4) (AA) which can be converted through the cyclooxygenase pathway to a series of prostaglandins (PG). Non-enzymatic cyclization of arachidonate yields a series of isoprostanes (IsoP) which comprises all PG (minor compounds) as well as PG isomers that cannot be formed enzymatically. In contrast, in plants, α-linolenic acid (C18:3) (ALA) is the most common substrate for the allene oxide synthase pathway leading to the jasmonate (JA) family of lipid mediators. Non-enzymatic oxidation of linolenate leads to a series of C18-IsoPs termed dinor IsoP or phytoprostanes (PP). PP structurally resemble JA but cannot be formed enzymatically. We will give an overview of the biological activity of the different classes of PP and also discuss their analytical applications and the strategies developed so far for the total synthesis of PP, depending on the synthetic approaches according to the targets and which key steps serve to access the natural products.     

Wheat bran-based biorefinery 2: Valorization of products

Wheat bran is multi-layered and consists of different cell types with different chemical compositions. The relatively high content of protein as well as the small amount of lignin is the key differentiator to other lignocellulose containing biomasses. Following the classical route of a biorefinery, bran may be disintegrated to a high extent and separated into fractions of high purity in order to build up new chemicals which serve as precursors for higher polymerized compounds. Secondly, bran contains substances that are per se valuables, but need to be further separated and purified.     

Comparison of Sampling Methods for Carbonaceous Aerosols in Ambient Air

Measurement methods for fine particle carbon were compared under field sampling conditions. Sampling methods included filtration, impaction, and adsorption-corrected filtration. Systems were operated side-by-side for nine consecutive days in the Los Angeles Basin. Analytical methods were compared separately. For organic carbon and total carbon, ambient measurements showed greater variability than could be accounted for by differences in analytical methods, and these differences are attributed to sampling methodology. The highest reported concentrations were obtained by quartz filter sampling; the lowest were from the sum of the impactor stages (excluding the quartz afterfilters). Positive artifact from the adsorption of gaseous vapors on quartz fiber filters was significant. However, correction for vapor adsorption by subtraction of the carbon value on the second of two filters in series did not completely eliminate the dependence of the apparent total aerosol carbon concentration on filter face velocity or sample duration     

Retrofitting of reinforced concrete beams using composite laminates

This paper presents the results of an experimental study to investigate the behaviour of structurally damaged full-scale reinforced concrete beams retrofitted with CFRP laminates in shear or in flexure. The main variables considered were the internal reinforcement ratio, position of retrofitting and the length of CFRP. The experimental results, generally, indicate that beams retrofitted in shear and flexure by using CFRP laminates are structurally efficient and are restored to stiffness and strength values nearly equal to or greater than those of the control beams. It was found that the efficiency of the strengthening technique by CFRP in flexure varied depending on the length. The main failure mode in the experimental work was plate debonding in retrofitted beams.     

Das Dekompositionsmodell nach Wand und Weber im Kontext der Prozessmodellierung

Whereas the benefits of decomposing process models are obvious, the question what actually characterizes a ??good?? decomposition of a business process model has been given little attention to date. In addition, the process of decomposition itself is considered as being an ??art?? in literature. Our approach for achieving a ??good?? decomposition is Wand and Weber??s decomposition model for information systems. As a first step in our investigation we aim to explore in how far the decomposition model can be adapted for business process modelling at all. The potential this model might bear for evaluating decompositions of process models has been promoted in literature quite often, while a corresponding investigation is still missing. We address this gap by the following research. In the long term, we intend to establish guidelines for decomposing business process models in a structured way.