ALBERT

Beschreibung: The rate of reaction of OH with CS2 to form OCS by reaction (1) has been measured through observation of O14CS following 254 nm equation image photolysis of mixtures of H2O2 with 14CS2. The OH concentrations have been monitored through simultaneous measurement in the same cell of either (a) the oxidation of CO to CO2, or (b) the removal of a hydrocarbon such as C3H8 or iso-C4H10. The upper limit for the formation of OCS based on (a) corresponds to a rate constant k1 〈 0.3 × 10−14 cm³ molecule−1 sec−1. Other chemical reactions in the system have led to the formation of both 14CO and 14CO2, indicating the existence of a complex combination of reactions such that the observed O14CS need not have been formed by (1). The rate of reaction (1) is sufficiently slow that it is neither an important atmospheric sink for CS2 nor an important source for atmospheric OCS. The reaction of OH with OCS has not been measured in these experiments, but by analogy with k1 it is probably not an important atmospheric sink for OCS nor an important source of SO2.

Beschreibung: This paper presents an event stratigraphy based on data documenting the history of vegetation cover, lake-level changes and fire frequency, as well as volcanic eruptions, over the Last Glacial–early Holocene transition from a terrestrial sediment sequence recovered at Lake Accesa in Tuscany (north-central Italy). On the basis of an age–depth model inferred from 13 radiocarbon dates and six tephra horizons, the Oldest Dryas–Bølling warming event was dated to ca. 14 560 cal. yr BP and the Younger Dryas event to ca. 12 700–11 650 cal. yr BP. Four sub-millennial scale cooling phases were recognised from pollen data at ca. 14 300–14 200, 13 900–13 700, 13 400–13 100 and 11 350–11 150 cal. yr BP. The last three may be Mediterranean equivalents to the Older Dryas (GI-1d), Intra-Allerød (GI-1b) and Preboreal Oscillation (PBO) cooling events defined from the GRIP ice-core and indicate strong climatic linkages between the North Atlantic and Mediterranean areas during the last Termination. The first may correspond to Intra-Bølling cold oscillations registered by various palaeoclimatic records in the North Atlantic region. The lake-level record shows that the sub-millennial scale climatic oscillations which punctuated the last deglaciation were associated in central Italy with different successive patterns of hydrological changes from the Bølling warming to the 8.2 ka cold reversal. Copyright © 2006 John Wiley & Sons, Ltd.

Beschreibung: Groundwater seeps are known to occur in Eckernförde Bay, Baltic Sea. Their discharge rate and dispersion were investigated with a new schlieren technique application, which is able to visualize heterogeneous water parcels with density anomalies down to Drt ¼ 0.049 on the scale of millimeters. With the use of an inverted funnel, discharged fluids can be captured and the outflow velocity can be determined. Overall, 46 stations could be categorized by three different cases: active vent sites, seep-influenced sites, and non-seep sites. New seep locations were discovered, even at shallow near-shore sites, lacking prominent sediment depression, which indicate submarine springs. The detection of numerous seeps was possible and the groundwater-influenced area was defined to be approximately 6.3 km2. Flow rates of between 0.05 and 0.71 l m)2 min)1 were measured. A single focused fluid plume, which was not disturbed by the funnel was recorded and revealed a flux of 59.6 ± 20 ml cm)2 min)1 and it was calculated that this single focused plume would be strong enough to produce a flow rate through the funnel of 1.32 ± 0.44 l m)2 min)1. The effect of different seep-meter funnel sizes is discussed.

Beschreibung: Proxy records and results of a three dimensional climate model show that European summer temperatures roughly a millennium ago were comparable to those of the last 25 years of the 20th century, supporting the existence of a summer "Medieval Warm Period" in Europe. Those two relatively mild periods were separated by a rather cold era, often referred to as the "Little Ice Age". Our modelling results suggest that the warm summer conditions during the early second millennium compared to the climate background state of the 13th–18th century are due to a large extent to the long term cooling induced by changes in land-use in Europe. During the last 200 years, the effect of increasing greenhouse gas concentrations, which was partly levelled off by that of sulphate aerosols, has dominated the climate history over Europe in summer. This induces a clear warming during the last 200 years, allowing summer temperature during the last 25 years to reach back the values simulated for the early second millennium. Volcanic and solar forcing plays a weaker role in this comparison between the last 25 years of the 20th century and the early second millennium. Our hypothesis appears consistent with proxy records but modelling results have to be weighted against the existing uncertainties in the external forcing factors, in particular related to land-use changes, and against the uncertainty of the regional climate sensitivity. Evidence for winter is more equivocal than for summer. The forced response in the model displays a clear temperature maximum at the end of the 20th century. However, the uncertainties are too large to state that this period is the warmest of the past millennium in Europe during winter.

Beschreibung: In order to get a comprehensive picture of the distribution of nitrous oxide (N2O) in the North Atlantic Ocean, measurements of dissolved nitrous oxide were made during three cruises in the tropical, subtropical and cold-temperate North Atlantic Ocean in October/November 2002, March/April 2004, and May 2002, respectively. To account for the history of atmospheric N2O, we suggest a new depth-dependent calculation of excess N2O (ΔN2O). N2O depth profiles showed supersaturation throughout the water column with a distinct increasing trend from the cold-temperate to the tropical region. Lowest nitrous oxide concentrations, near equilibrium and with an average of 11.0±1.7 nmol L−1, were found in the cold-temperate North Atlantic where the profiles showed no clear maxima. Highest values up to 37.3 nmol L−1 occurred in the tropical North Atlantic with clear maxima at approximately 400 m. A positive correlation of nitrous oxide with nitrate, as well as excess nitrous oxide with the apparent oxygen utilization (AOU), was only observed in the subtropical and tropical regions. Therefore, we conclude that the formation of nitrous oxide via nitrification occurs in the tropical region rather than in the cold-temperate region of the North Atlantic Ocean

Beschreibung: In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter called "ozone mini-hole" was caused by an elevation of tropopause height accompanied with a poleward advection of ozone-poor air from the tropics. The resultant increase in UV-radiation is of particular significance for human health. Dynamically induced low ozone episodes that happen in late spring can considerably enhance the solar UV-radiation in mid latitudes and therefore contribute to the UV-burden of people living in these regions.

Beschreibung: To commemorate the publication of the 25th Volume of the Journal of Micropalaeontology, the first issue of which came out in 1982, this celebratory review article was commissioned. Officers of each TMS Group (Ostracod, Foraminifera, Palynology, Nannofossil, Microvertebrate and Silicofossil) were requested to reflect over the last 25 years and assess the major advances and innovations in each of their disciplines. It is obvious from the presentations that all Groups report that research has moved on from the basic, but essential descriptive phase, i.e. taxonomy and establishing biostratigraphies, to the utilization of new technologies and application to issues of the day such as climate change and global warming. However, we must not lose sight of the fact that the foundation of micropalaeontology is observation and the building block for all these new and exciting innovations and developments is still good taxonomy. Briefly, the most obvious conclusion that can be drawn from this review is that micropalaeontology as a science is in relatively good health, but we have to ensure that the reported advancements will sustain and progress our discipline. There is one issue that has not really been highlighted in these contributions – we need to make sure that there are enough people being trained in micropalaeontology to maintain development. The last 25 years has seen a dramatic decrease in the number of post-graduate MSc courses in micropalaeontology. For example, in the UK, in the 1980s and early 1990s there were five specific MSc courses to choose ...

Beschreibung: We investigated the influence of atmospheric noise on the generation of interannual El Niño variability. Therefore, we perturbed a conceptual ENSO delay model with surrogate windstress data generated from tropical windspeed measurements. The effect of the additional stochastic forcing was studied for various parameter sets including periodic and chaotic regimes. The evaluation was based on a spectrum and amplitude-period relation comparison between model and measured sea surface temperature data. The additional forcing turned out to increase the variability of the model output in general. The noise-free model was unable to reproduce the observed spectral bandwidth for any choice of parameters. On the contrary, the stochastically forced model is capable of producing a realistic spectrum. The weakly nonlinear regimes of the model exhibit a proportional relation between amplitude and period matching the relation derived from measurement data. The chaotic regime, however, shows an inversely proportional relation. A stability analysis of the different regimes revealed that the spectra of the weakly nonlinear regimes are robust against slight parameter changes representing disregarded physical mechanisms, whereas the chaotic regime exhibits a very unstable realistic spectrum. We conclude that the model including stochastic forcing in a parameter range of moderate nonlinearity best matches the real conditions. This suggests that atmospheric noise plays an important role in the coupled tropical pacific ocean-atmosphere system.

Beschreibung: In late May 2005 unusual high levels of solar ultraviolet radiation were observed over central Europe. In Northern Germany the measured irradiance of erythemally effective radiation exceeded the climatological mean by more than about 20%. An extreme low ozone event for the season coincided with high solar elevation angles and high pressure induced clear sky conditions leading to the highest value of erythemal UV-radiation ever observed over this location in May since 1994. This hereafter called "ozone mini-hole" was caused by an elevation of tropopause height accompanied with a poleward advection of ozone-poor air from the tropics. The resultant increase in UV-radiation is of particular significance for human health. Dynamically induced low ozone episodes that happen in late spring can considerably enhance the solar UV-radiation in mid latitudes and therefore contribute to the UV-burden of people living in these regions.

Beschreibung: Intra‐plate volcanism in western Europe shows statistically significant episodicity during the Quaternary period. By comparing the known ages for eruptions in France and Germany, which are compiled here, with a composite oxygen isotope record, we have investigated the link between this episodic volcanism and the climate record over the last two million years. We show that increased volcanism between 415–400 ka and 17–5 ka correlates with warming phases at the end of the last Weichselian (Devensian) and earlier Elsterian (Anglian) glacial stages. The three significant caldera explosions in the eastern Eifel, Germany, are all associated with warming phases at the onset of interglacials. The growth and decay of nearby ice sheets suggest that surface changes in continental mass distribution during glacial Milankovich cycles could provide a mechanism for this correlation by means of the distal effects of flexural loading on the lithosphere.

Beschreibung: In January 2003, a major inflow of cold and oxygen-rich North Sea Water terminated an ongoing stagnation period in parts of the central Baltic Sea. In order to investigate the role of North Sea Water inflow in the production of nitrous oxide (N2O), we measured dissolved and atmospheric N〈2O at 26 stations in the southern and central Baltic Sea in October 2003. At the time of our cruise, water renewal had proceeded to the eastern Gotland Basin, whereas the western Gotland Basin was still unaffected by the inflow. The deep water renewal was detectable in the distributions of temperature, salinity, and oxygen concentrations as well as in the distribution of the N2O concentrations: Shallow stations in the Kiel Bight and Pomeranian Bight were well-ventilated with uniform N2O concentrations near equilibrium throughout the water column. In contrast, stations in the deep basins, such as the Bornholm and the Gotland Deep, showed a clear stratification with deep water affected by North Sea Water. Inflowing North Sea Water led to changed environmental conditions, especially enhanced oxygen (O2) or declining hydrogen sulphide (H2S) concentrations, thus, affecting the conditions for the production of N2O. Pattern of N2O profiles and correlations with parameters like oxygen and nitrate differed between the basins. Because of the positive correlation between ΔN2O and AOU in oxic waters the dominant production pathway seems to be nitrification rather than denitrification. Advection of N2O by North Sea Water was found to be of minor importance. A rough budget revealed a significant surplus of in situ produced N2O after the inflow. However, due to the permanent halocline, it can be assumed that the N2O produced does not reach the atmosphere. Hydrographic aspects therefore are decisive factors determining the final release of N2O produced to the atmosphere.

Beschreibung: The seasonal growth trajectories of wild Atlantic salmon Salmo salar juveniles by age group within the Margaree River, Canada, are described. Circuli counts from scales were used to infer growth rates at different ages and these were used to predict the proportions of age 2‐ and 3‐year old smolts from different portions of the watershed. In the wild Atlantic salmon juveniles from the Margaree River, there was no bimodality in fork length frequencies and no 1 year old smolts were produced. Water temperature differences during the growing season were insufficient to explain the differences in growth rates and size at age among the sites sampled. There was a positive association between the growth rate in the first year and the subsequent age at smoltification. In the Margaree River, differences in tributary specific growth rates and size at age were expected to produce important differences in the relative ages at smoltification.