Sequence stratigraphy with emphasis on platform-related parasequences of the Zechstein 2 carbonate (Ca2) – the northern platform margin of the Southern Permian Basin (NE Germany)

Facies analysis combined with sequence stratigraphic interpretation of the Upper Permian carbonate (Ca2) of NE Germany (i.e. northern basin margin of the Southern Permian Basin) confirm the existence of a rimmed platform with a steep and tectonically structured slope. The karstified A1 platform is overlain by deposits of a thin transgressive systems tract (TST) and a thick highstand systems tract (HST) which shows two larger-scale regressive shallowing-upwards cycles (4th order) with typical stacking patterns of small-scale cycles (5th order). The TST consists of bitumen-rich mudstones with reworked clasts of anhydrite and early cemented wacke- to grainstones, and it shows two, probably 5th-order, deepening-upwards cycles. The first larger-scale shallowing-up cycle on the Ca2 platform (4th-order) is dominated by aggradation of the bar and shoal deposits, whereas the second one is dominated by progradation. The tops of both cycles are characterised by erosional and exposure surfaces. Various types of small-scale shallowing-upwards cycles (5th-order) are observed in the bar, in the intertidal and in the algal-dominated supratidal environment, showing pronounced transgressive boundaries. On the slope and in the basin, equally thick TST and HST are observed. These incorporate carbonate turbidites which indicate "highstand shedding" from the platform. Various orders of relative sea-level variations are discussed. Controlling factors include tectonics, climate, and eustatic processes. A combined carbonate and evaporite sequence was found on the upper Ca2 slope, which may indicate a Ca2-lowstand systems wedge.     

On the Toxicity and Biodegradation of Cationic Surfactants Über die Toxizität und den biologischen Abbau kationischer Tenside

Three ammonium halide type surfactants were tested under standard laboratory condition for biodegradability and acute toxicity to Daphnia magna and in the Microtox test with the luminescent bacterium Photobacterium phosphoreum. The tested compounds are dimethyldistearylammonium chloride (DSDMAC), cetyltrimethylammonium bromide (HTMAB) and cetylbenzyldimethylammonium chloride (HBDMAC). The results indicate DSDMAC is less toxic than the other two surfactants and that it biodegrades rapidly at both lower (2.5 mg/L) and higher (10 mg/L) concentrations.     

Impact of droughts on child mortality: a case study in Southern African countries

Natural Hazards - Natural hazards like floods and droughts affect many aspects of life. The study in particular examined the impacts of droughts on under-five mortality rate in Southern Africa,...     

Organically Bound Nutrients in Dissolved Organic Matter Fractions in Seepage and Pore Water of Weakly Developed Forest Soils

Previous field and laboratory studies showed that organically bound nutrients can contribute largely to the export of N, P, and S from soil into aquatic systems. One possible determinant for the losses of dissolved organic nutrients leaving the soil environment could be their distribution between dissolved organic matter (DOM) fractions of different mobility in soil. To elucidate the potential influence of DOM fractions under varying flow conditions on the vertical translocation of organically bound nutrients, we determined the concentrations and fluxes of dissolved organic C (DOC) and nutrients (DON, DOP, DOS) in soil water under a Scots pine (Pinus sylvestris L.) and a European beech (Fagus sylvatica L.) forest. We sampled seepage water from the organic forest floor layer and the mineral subsoil using zero‐tension lysimeters and soil pore water using tension lysimeters and suction cups. DOM in soil water was fractionated into hydrophilic and hydrophobic compounds by XAD‐8 at pH 2. We found that the organic forest floor layers were large sources for DOC, DON, DOP, and DOS. The dissolved organic nutrients were mainly concentrated in the hydrophilic DOM fraction which proved to be more mobile in mineral soil pore water than the hydrophobic one. Consequently, the concentrations and fluxes of dissolved organic nutrients decreased less with depth than those of DOC. Concentrations as well as fluxes in subsoil pore water of DOC and dissolved organic nutrients in the studied weakly developed soils were high as compared with literature data on deeply developed forest soils. Under conditions of rapid water flow through the strongly structured mineral soil at the beech site, almost no retention of DOM took place and thus the influence of the distribution of organically bound nutrients between the DOM fractions on the export of DON, DOP, and DOS was negligible.     

Demersal fishing disturbance increases predation risk for whelks (Buccinum undatum L.)

Field observations by divers indicated that a high rate of predation of whelks (Buccinum undatum) by starfish (Asterias rubens) occurred in an area disturbed by scallop dredging, although these whelks mostly appeared to be alive and externally undamaged. The ability of whelks to escape from starfish was tested in the laboratory after they were dropped or rolled to simulate direct physical contact with bottom fishing gear. Dropping whelks did not significantly affect their escape behaviour, but whelks which had been rolled took significantly longer to right themselves and were significantly less likely to perform an escape response than whelks that had not experienced this treatment. This study suggests that demersal fishing may indirectly increase whelk mortality by increasing their risk of predation.     

Sediment sequences and paleosols in the Kyichu Valley, southern Tibet (China), indicating Late Quaternary environmental changes

Abstract The Tibetan Plateau is highly sensitive to environmental changes and affects the settings of a far larger territory in Central Asia and beyond. Thus, knowledge on past environmental changes in that area is essential. Even though the Kyichu (Lhasa River) Valley and its tributaries is an easily accessible area, the Late Quaternary landscape evolution of southern Tibet is in general scarcely known. Therefore, 12 sedimentary sections in the middle and lower catchment were subjected to multidisciplinary analyses (sedimentology, paleopedology, AMS ¹⁴C and luminescence dating, and charcoal determination) aiming at results on regional paleoenvironmental changes. At the altitude studied (3600–4000 m above sealevel), no glacial relics could be detected, indicating that the valley positions have been unglaciated since the Last Interglacial. The lack of fluvial–lacustrine structures above the floodplain is due to the aggradational character of this tectonically (sub‐)active valley, which caused an alluvial burying of older valley bottoms. During the Late Pleistocene the mouth area of the Kyichu was occupied by a lake which was part of a larger dam‐lake in the superordinate Yarlung Zhangbo Valley. On the valley flanks, loesses were predominantly deposited before the Last Glacial Maximum (LGM), whereas eolian sands were predominantly deposited around and after the LGM. Paleosols of Last Interglacial, Last Glacial and Holocene ages regularly occur at terrestrial sites representing temperate to cool and humid to semiarid conditions during soil formation. Ages of colluvial sediments indicate that the widespread barren valley slopes were primarily formed by Late Pleistocene erosion followed by a secondary Holocene erosion phase. Charcoal spectra indicate a Late Holocene change from a forest environment to a pastoral environment with sparse grasses, herbs and dwarf shrubs. It is assumed that the Late Holocene environmental changes, such as loss of forests/woodlands and erosion, have at least been reinforced by humans, enhancing a regional climatic aridification and cooling trend.