Biodegradation of NOM in Rapid Sand Filters for Removing Iron and Manganese

In order to examine the Corg flow in rapid sand filter columns for the elimination of iron and manganese, reduced groundwater was treated in a pilot plant consisting of a trickling filter column (TF I) followed by a wet type filter column (WF II) and a separate wet type filter column (WF sep). Additionally the effect of filtration on BOM was studied by measuring AOC and BDOC. The biological processes in TF I and WF sep led to an elimination of iron, ammonia, and manganese. Moreover, the filtration decreased the NOM content. 21% and 23% of the TOC were eliminated in TF I and in WF sep, respectively. WF II caused no significant Corg reduction. The calculation of the Corg flow in the filter columns showed that bacteria took part in the TOC elimination. From the TOC removed, about 24% was eliminated by metabolic activities of the bacterial population whereas 86% was adsorbed onto iron sludge. Similar results were obtained for the TF I column and for the WF sep column as well. The calculated Corg flow was confirmed by the BDOC measurements. The filtration process led to a BDOC decrease. TF I and WF sep reduced appoximately 35% of the biodegradable organic carbon. In contrast there was no significant elimination by WF II. The AOC results suggest that an AOC production and an AOC elimination process exist in rapid sand filters for groundwater treatment. In the trickling filter column significant AOC production was found, whereas in the wet type filter columns AOC elimination was predominating.     

Evaluation of the Interpretation of Ceilometer Data with RASS and Radiosonde Data

Since 2006 different remote monitoring methods for determining mixing-layer height have been operated in parallel in Augsburg (Germany). One method is based on the operation of eye-safe commercial mini-lidar systems (ceilometers). The optical backscatter intensities recorded with ceilometers provide information about the range-dependent aerosol concentration; gradient minima within this profile mark the tops of mixed layers. Special software for these ceilometers provides routine retrievals of lower atmospheric layering. A second method, based on sodar observations, detects the height of a turbulent layer characterized by high acoustic backscatter intensities due to thermal fluctuations and a high variance of the vertical velocity component. This information is extended by measurements with a radio-acoustic sounding system (RASS) that directly provides the vertical temperature profile from the detection of acoustic signal propagation and thus temperature inversions that mark atmospheric layers. Ceilometer backscatter information is evaluated by comparison with parallel measurements. Data are presented from 2 years of combined ceilometer and RASS measurements at the same site and from comparison with a nearby (60 km) radiosonde for larger-scale humidity information. This evaluation is designed to ensure mixing-layer height monitoring from ceilometer data more reliable.     

COMBINED EXPERIMENTAL AND NUMERICAL INVESTIGATION OF FORMULAE FOR EROSION AND DEPOSITION OF COHESIVE SEDIMENTS

1 mTsonvCTIoxTIansport of fine cOhesive sedinds inevitably leads to the develoPment of sediment deposits inreservoirs or zones with small flow velocihes in lowland rivers. Such sediment dePosits often conshtUte aconsiderable ecological danger, as cOhesive sediInnts have the ability to bind POllutants like heavymetals, polycyclic aromatic hydrocrtons or chlorinated hydrocaIbons (F6f8iner, l989). In the case of anextreme hydraUlic event like a flood or a reservoir dePlehon, erosion of cone…     

The RHESSI Experimental Data Center

The RHESSI Experimental Data Center (HEDC) at ETH Zürich aims to facilitate the use of RHESSI data. It explores new ways to speed up browsing and selecting events such as solar flares. HEDC provides pre-processed data for on-line use and allows basic data processing remotely over the Internet. In this article, we describe the functionality and contents of HEDC, as well as first experiences by users. HEDC can be accessed at http://www.hedc.ethz.ch. Additional graphical material and color versions of most figures are available on the CD-ROM accompanying this volume. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022413302246     

Issues associated with the distinction between climatic and tectonic controls on Permian alluvial fan deposits from the Kotzen and Barnim Basins (North German Basin)

Facies analysis focussing on coarse-grained sediments has been carried out on more than 2500 m of drill cores from seven wells from southern margins of the North German Basin (NGB). The NGB forms a central element of the Southern Permian Basin (SPB). The wells exposed conglomerates and sandstones of the Rotliegend Grüneberg and Parchim Formations deposited in the Kotzen Basin and the Barnim Basin.17 lithofacies types have been grouped into six lithofacies associations. The studied successions are dominated by fluid gravity flow deposits (hyperconcentrated flows and stream flows) of alluvial fan and alluvial plain systems. Maximum particle size/bed thickness plots (MPS/BTh) support the interpretation as fluid gravity flow deposits. The MPS and BTh data have also been used to differentiate coarsening–thickening and fining–thinning trends of the fan systems.The dominance of water-rich mass flow processes together with sedimentary structures such as dewatering structures and outwashed tops suggests the presence of wet-type fans and plains under semi-humid to semi-arid seasonal climates in the central SPB. The investigated sediments show variation in clast composition subsequent to deep erosion processes on basin margins and changes of source areas. Synsedimentary normal faults and clastic dykes have been interpreted as indicators of tectonic activity of grabens itself and its frames. On a larger scale, then evolution from a half-graben to a graben is apparent for the Tuchen Sub-basin at least. The progradational/retrogradational cycles of the studied alluvial fan systems document combined local tectonic movements and influences of climatic changes. However, our data did not allow for a clear distinction between climatic and tectonic signals. Furthermore, a one-to-one correlation of fan cycles with depositional trends in the NGB basin centre would appear to be oversimplistic.     

The stratigraphic evolution of the Indus Fan and the history of sedimentation in the Arabian Sea

The Indus Fan records the erosion of the western Himalayas and Karakoram since India began to collide with Asia during the Eocene, 50 Ma. Multi-channel seismic reflection data from the northern Arabian Sea correlated to industrial well Indus Marine A-1 on the Pakistan Shelf show that sedimentation patterns are variable through time, reflecting preferential sedimentation in deep water during periods of lower sea-level (e.g., middle Miocene, Pleistocene), the diversion of sediment toward the east following uplift of the Murray Ridge, and the autocyclic switching of fan lobes. Individual channel-levee systems are estimated to have been constructed over periods of 10⁵–10⁶ yr during the Late Miocene. Sediment velocities derived from sonobuoys and multi-channel stacking velocities allow sections to be time-depth converted and then backstripped to calculate sediment budgets through time. The middle Miocene is the period of most rapid accumulation, probably reflecting surface uplift in the source regions and strengthening of the monsoon at that time. Increasing sedimentation during the Pleistocene, after a late Miocene-Pliocene minimum, is apparently caused by faster erosion during intense glaciation. The sediment-unloaded geometry of the basement under the Pakistan Shelf shows a steep gradient, similar to the continent-ocean transition seen at other rifted volcanic margins, with basement depths on the oceanward side indistinguishable from oceanic crust. Consequently we suggest that the continent-ocean transition is located close to the present shelf break, rather than >350 km to the south, as previously proposed.     

Winter synoptic-scale variability over the Mediterranean Basin under future climate conditions as simulated by the ECHAM5

Changes of the winter climate in the Mediterranean Basin (MB) for future A2 conditions are investigated for the period 2071–2100 and compared with the control period 1961–1990. The analysis is based on time-slice simulations of the latest version of the ECHAM model. First, the control simulation is evaluated with reanalysis data. The emphasis is given to synoptic and large-scale features and their variability in the MB. The model is found to be capable of reproducing the main features of the MB and southern Europe in the winter season. Second, the A2 simulation is compared with the control simulation, revealing considerable changes of the synoptic variability. Focusing on the synoptic spatio-temporal scale aims to unfold the dynamic background of the climatic changes. The Mediterranean cyclones, which are individually detected and tracked, decrease by 10% in the Western Mediterranean (WM) whereas no significant change is found in the Eastern Mediterranean. The cyclone intensity is slightly reduced in the entire region. To understand these changes, the underlying dynamical background is analyzed. It is found that changes in baroclinicity, static stability, transformation from eddy kinetic energy to kinetic energy of the mean flow and stationary wave activity are significant in particular in the WM and the coastline of North Africa. The reduction of cyclonic activity severely impacts the precipitation mainly in the southern part of the WM.     

The planet formation imager

The Planet Formation Imager (PFI, www.planetformationimager.org) is a next-generation infrared interferometer array with the primary goal of imaging the active phases of planet formation in nearby star forming regions. PFI will be sensitive to warm dust emission using mid-infrared capabilities made possible by precise fringe tracking in the near-infrared. An L/M band combiner will be especially sensitive to thermal emission from young exoplanets (and their disks) with a high spectral resolution mode to probe the kinematics of CO and H₂O gas. In this paper, we give an overview of the main science goals of PFI, define a baseline PFI architecture that can achieve those goals, point at remaining technical challenges, and suggest activities today that will help make the Planet Formation Imager facility a reality.     

Quasi-geostrophic stratified flow over isolated finite amplitude topography

The quasi-geostrophic response of a stratified stream incident upon isolated finite amplitude topography on a f-plane is examined in the limit of a Boussinesq, incompressible, inviscid fluid. Compact solutions are derived subject to the following stipulations: uniform upstream velocity and stratification, a circular obstacle and an entirely isentropic/isopycnic lower surface.It is shown that for a semi-infinite flow domain the criterion for Taylor cap formation (i.e., a region of closed streamlines) is . However, for the isentropic lower boundary condition the solutions exist (i.e., have physical validity) only if R₀F⁻¹ < 0.5. (Here R₀ and F refer to the Rossby and Froude numbers defined respectively in terms of the mountain half-width and height.) Also considered are the modifications both to the flow response and to the foregoing existence criterion that are induced by the introduction of an upstream profile comprising two layers of uniform but different stratification. In addition, the relationship of the derived solutions to the results obtained in previous studies is explored, and in particular an outline is given of the impact of adopting the ‘traditional’ simplified lower boundary condition.     

Structural evolution and strike-slip tectonics off north-western Sumatra

Based on new multi-channel seismic data, swath bathymetry, and sediment echosounder data we present a model for the interaction between strike-slip faulting and forearc basin evolution off north-western Sumatra between 2°N and 7°N. We examined seismic sequences and sea floor morphology of the Simeulue- and Aceh forearc basins and the adjacent outer arc high. We found that strike-slip faulting has controlled the forearc basin evolution since the Late Miocene. The Mentawai Fault Zone extends up to the north of Simeulue Island and was most probably connected farther northwards to the Sumatran Fault Zone until the end of the Miocene. Since then, this northern branch jumped westwards, initiating the West Andaman Fault in the Aceh area. The connection to the Mentawai Fault Zone is a left-hand step-over. In this transpressional setting the Tuba Ridge developed. We found a right-lateral strike-slip fault running from the conjunction of the West Andaman Fault and the Tuba Ridge in SSW-direction crossing the outer arc high. As a result, extrusion formed a marginal basin north of Simeulue Island which is tilted eastwards by uplift along a thrust fault in the west. The shift of strike-slip movement in the Aceh segment is accompanied by a relocation of the depocenter of the Aceh Basin to the northwest, forming one major Neogene unconformity. The Simeulue Basin bears two major Neogene unconformities, documenting that differences in subsidence evolution along the northern Sumatran margin are linked to both forearc-evolution related to subduction processes and to deformation along major strike-slip faults.