Sediment budget as a driver for sediment management at plumb beach,New York,USA: vectors of change and impacts

Persistent erosion at Plumb Beach, New York, USA, has been countered by a series of isolated actions to stabilize the shoreline. Sediment placed at the erosion site has quickly been removed and re-deposited in downdrift locations to the detriment of the existing habitats. In a renewed effort to better understand the dimensions of change at Plumb Beach, detailed spatial analysis of shoreline displacement, dune-beach profile evolution, and sediment budget has been undertaken through intensive surveying and comparisons of Digital Elevation Models. Products derived from these surveys establish that the sector of maximum erosion has shifted downdrift and that the scale of the changes is twice the volume exchange as previously estimated. Improved knowledge of the dimensions and spatial distributions of the changes is used to create a focused approach that is functioning within the scale of the local sediment budget and reducing its impacts.     

Feasibility versus sustainability in urban water management

Decision making in urban water management is exemplified by the case of Austria: Although researchers define a comprehensible concept of sustainability, practitioners emphasize feasibility and accept limitations in sustainability. Could the specification of particular methods, chosen from some decision support methodology, remedy this situation? While an integrative assessment of sustainability should not be based on prescribed or standardized criteria, or even a certain assessment method, it should force the decision makers to make their chosen premise more visible. To this end a change of the decision making process is proposed, which will allow the decision makers to adapt the decision making process to the circumstances of a specific project in a way that is accepted by the stakeholders.     

Biologische Effekte von Hexachlorbenzol (HCB) in aquatischen Modell?kosystemen

Ohne Zusammenfassung The online version of the original article can be found at     

Dose estimation and radon action level problems due to nanosize radon progeny aerosols in underground manganese ore mine

One of the essential parameters influencing of the dose conversion factor is the ratio of unattached short-lived radon progeny. This may differ from the value identified for indoor conditions when considering special workplaces such as mines. Inevitably, application of the dose conversion factors used in surface workplaces considerably reduces the reliability of dose estimation in the case of mines.This paper surveyed the concentration of radon and its short-lived radon progeny and identified the unattached fraction of short-lived radon progeny. As well equilibrium factor during the month of August was calculated simultaneously at two extraction faces in a manganese ore mine.During working hours the average radon concentrations were 220 Bq m⁻³ and 530 Bq m⁻³ at Faces 1 and 2; the average short-lived progeny concentration was 90 Bq m⁻³ and 190 Bq m⁻³, the average equilibrium factors were 0.46 and 0.36, and the average unattached fractions were 0.21 and 0.17, respectively. The calculated dose conversion factor was between 9 and 27 mSv WLM⁻¹, but higher values could also be possible.     

Marine sponges with contrasting life histories can be complementary biomonitors of heavy metal pollution in coastal ecosystems

In this study, we compared the usefulness of a long-living sponge (Hymeniacidon heliophila, Class Demospongiae) and a short-living one (Paraleucilla magna, Class Calcarea) as biomonitors of metallic pollution. The concentrations of 16 heavy metals were analyzed in both species along a gradient of decreasing pollution from the heavily polluted Guanabara Bay to the less impacted coastal islands in Rio de Janeiro, SE Brazil (SW Atlantic). The levels of most elements analyzed were higher in H. heliophila (Al, Co, Cr, Cu, Fe, Mn, Ni, Hg, Ni, and Sn) and P. magna (Ni, Cu, Mn, Al, Ti, Fe, Pb, Co, Cr, Zn, and V) collected from the heavily polluted bay when compared with the cleanest sites. Hymeniacidon heliophila accumulates 11 elements more efficiently than P. magna. This difference may be related to their skeleton composition, histological organization, symbiont bacteria and especially to their life cycle. Both species can be used as a biomonitors of metallic pollution, but while Hymeniacidon heliophila was more effective in concentrating most metals, Paraleucilla magna is more indicated to detect recent pollutant discharges due to its shorter life cycle. We suggest that the complementary use of species with contrasting life histories can be an effective monitoring strategy of heavy metals in coastal environments.     

Operating problems in anaerobic digestion plants resulting from nitrogen in MSW

Organic waste and municipal solid waste usually contain considerable amounts of different nitrogen compounds, which may inhibit anaerobic degradation processes and cause problems in the downstream and peripheral devices. This refers particularly to the different process stages of anaerobic digestion, to wastewater treatment, and to exhaust air treatment. Neither the knowledge about nitrogen problems nor the technologies for elimination of nitrogen compounds from the wastewater or the exhaust air of anaerobic digestion can be regarded as state-of-the-art. Most of the technologies in question have already been applied in other areas, but are barely tested for application in anaerobic digestion plants. The few performance data and experiences at hand were mainly derived from pilot and demonstration facilities. In this paper, the problem of nitrogen will be discussed in detail according to the separate problem fields based on the authors' experience, as well as on the basis of a review of the relevant literature. Furthermore, possible solutions will be proposed and the need for further research and development will be formulated.     

Solid-state conformations and absolute configurations of (+) and (-) alpha-, beta-, and gamma-hexabromocyclododecanes (HBCDs)

Hexabromocyclododecanes (HBCDs) are high production volume chemicals used as flame retardants for plastics and textiles. They are currently produced in quantities exceeding 20,000 t/y. Despite this fact, the correct stereochemistry of most HBCDs is still not known. Six stereocenters are formed during bromination of cyclododecatrienes, resulting in mixtures of different stereoisomers. Considering all elements of symmetry, 16 different stereoisomers including six pairs of enantiomers as well as 4 meso forms are possible theoretically. Recently, we isolated 8 of the 16 possible stereoisomers from a technical HBCD mixture and assigned their relative configurations. Herein, we report on the isolation of 6 enantiomerically pure alpha-, beta-, and gamma-HBCDs, obtained from preparative chiral-phase liquid chromatography, and we present their absolute configurations, which were determined from X-ray diffraction analysis. The absolute configuration of (-) alpha-HBCD was found to be (1R,2R,5S,6R,9R,10S), while the one of (+) beta-HBCD is assigned to (1S,2S,5S,6R,9S,10R), whereas the one of (-) gamma-HBCD corresponds to (1S,2S,5S,6R,9R,10S). The given structural information allows the unambiguous identification of the six most important HBCD stereoisomers, which typically account for more than 95% of technical HBCDs. In addition, we compared the solid-state conformations of racemic and enantiomerically pure alpha-, beta-, and gamma-HBCDs. In all cases, vicinal dibromides adopted a synclinal (sc) conformation with torsion angles of 69+/-6 degrees. A unique structural motive was common to all examined HBCD solid-state conformations. This conserved structure was described as an extended triple turn consisting of an arrangement of three pairs of synclinal and two antiperiplanar torsion angles.     

Crystal structure of δ-isobutoxypentabromo-cyclododecanes, kinetics and selectivity of their isomerization during thermal treatment of flame-proofed polystyrenes

Hexabromocyclododecanes (HBCDs) are persistent organic pollutants now ubiquitous in the environment. Technical HBCD mixtures and with it flame-proofed polystyrenes (FP-PS) also contain isobutoxypentabromocyclododecanes (iBPBCDs) as minor constituents, which are possibly released together with HBCDs. So far, eight diastereomeric pairs of enantiomers named as α-, β-, γ-, δ-, ?-, ξ-, η-, and θ-iBPBCDs with proportions of 10%, 5%, 2%, 21%, 11%, 11%, 12% and 28% were found in technical HBCD. Herein the crystal structure of racemic δ-iBPBCD, the second most prominent diastereomer, is presented and assigned to (1S)-1-isobutoxy-(2R,5R,6S,9S,10S)-2,5,6,9,10-pentabromocyclododecane and its enantiomer. During thermal treatment of FP-PS, e.g. the production of extruded polystyrenes (XPS), proportions of δ-iBPBCDs decrease and those of other stereoisomers increase. Evidence was found that δ-iBPBCDs isomerize stereo- and regioselectively to β-iBPBCDs. Based on structural and kinetic data, a transformation mechanism was proposed. Apparent first-order rate constants (k_iso) of 0.0019, 0.0050, and 0.012 min⁻¹ are found for the δ- to β-iBPBCD isomerization at 120, 130, and 140 °C, respectively, corresponding to half-lives of 360, 140, and 56 min. These transformations also occur during the production of XPS, which predominantly contain β-iBPBCDs, whereas δ-iBPBCDs dominate in materials experiencing lower thermal stress, e.g. expanded polystyrenes (EPS). The relative configurations of δ- and θ-iBPBCDs are TtCtCt, like the one of γ-HBCDs. γ-HBCDs are the kinetically and α-HBCDs with a TcCtCc configuration the thermodynamically favored products. In analogy, β-iBPBCDs are assumed to have a TcCtCc configuration like α-HBCDs because they are formed from δ-iBPBCDs under thermodynamic control. In conclusion, HBCD- and iBPBCD-patterns in flame-proofed polystyrenes vary substantially, reflecting the thermal stress these materials have experienced. When released to the environment, these patterns might further change, as observed for HBCDs.