Basic physiological biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)

By measuring a battery of basic physiological biomarkers and the concentration of SigmaDDT in adult female perch (Perca fluviatilis), an assumed aquatic pollution gradient was confirmed, with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included an upstream gradient, westwards through Lake M?laren (46 km), and a downstream gradient, eastwards through the Stockholm archipelago (84 km). The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch: retarded growth, increased frequency of sexually immature females, low gonadosomatic index, and disturbed visceral fat metabolism. SigmaDDT, measured as a pollution indicator, was 10-28 times higher than the background in perch from the Baltic Proper. Besides the main gradient other sources of pollution also influenced the response pattern of the measured biomarkers. In particular, there were strong indications of pollution coming from the Baltic Sea.     

Hyperactivity and changed diurnal activity in flounders,Platichthys flesus,exposed to DDT

Flounders (Platichthys flesus), which had been given oral doses of DDT, developed hyperactivity and abnormal diurnal activity 5–7 weeks after the dosage of DDT was terminated. For the flounder given the highest dose (12.5 mg DDT kg^?1 fresh body weight) a more than 20-fold increase in swimming activity was recorded. The levels of DDT found in various organs (axial muscle, liver and brain) are compared with levels of DDT found in wild populations of fish from the Baltic Sea. The results are also discussed in relation to results obtained in a parallel study on the physiological effects of DDT on the flounder.     

Efficiency of mixing by a turbulent jet in a stably stratified fluid

Mixing in a two-layer stably stratified fluid by a turbulent jet was studied by a laboratory experiment. A non-swirling jet was discharged vertically downwards in a confined fluid system consisting initially of a top layer of fresh water and a bottom layer of salt water. In total, 16 experimental cases were considered, where the diameter and exit velocity of the jet were varied together with the density difference between the top and bottom layer. Vertical density profiles were determined from conductivity measurements. A three-layer density structure developed in all cases with an intermediate layer that grew in size with time elapsed as fresh and salt water were mixed. The mixing efficiency, defined as the percentage of the supplied kinetic jet energy that is used for increasing the potential energy of the fluid system, was related to a densimetric Froude number based on the intermediate layer depth. Overall, the calculated jet mixing efficiency displayed higher values than comparable efficiencies for destratification with air-bubble plumes.     

The signature of ENSO in the Northern Hemisphere midlatitude seasonal mean flow and high-frequency intraseasonal variability

Summary The impact of pronounced positive and negative sea surface temperature (STT) anomalies in the tropical Pacific associated with the El Niño/Southern Oscillation (ENSO) phenomenon on the atmospheric circulation in the Northern Hemisphere extratropics during the boreal winter season is investigated. This includes both the impact on the seasonal mean flow and on the intraseasonal variability on synoptic time scales. Moreover, the interaction between the transient fluctuations on these times scales and the mean circulation is examined. Both data from an ensemble of five simulations with the ECHAM3 atmospheric general circulation model at a horizontal resolution of T42 each covering the period from 1979 through 1992 and operational analyses from ECMWF for the corresponding period are examined. In each of the simulations observed SSTs for the period of investigation are given as lower boundary forcing, but different atmospheric initial conditions are prescribed.The simulations with ECHAM3 reveal a distinct impact of the pronounced SST-anomalies in the tropical Pacific on the atmospheric circulation in the Northern Hemisphere extratropics during El Niño as well as during La Niña events. These changes in the atmospheric circulation, which are found to be highly significant in the Pacific/North American as well as in the Atlantic/European region, are consistent with the essential results obtained from the analyses. The pronounced SST-anomalies in the tropical Pacific lead to changes in the mean circulation, which are characterized by typical circulation patterns. These changes in the mean circulation are accompanied by marked variations of the activity of the transient fluctuations on synoptic time scales, that are changes in both the kinetic energy on these time scales and the atmospheric transports of momentum and heat accomplished by the short baroclinic waves. The synoptic disturbances, on the other hand, play also an important role in controlling the changes in the mean circulation associated with the ENSO phenomenon. They maintain these typical circulation patterns via barotropic, but counteract them via baroclinic processes.The hypothesis of an impact of the ENSO phenomenon in the Atlantic/European region can be supported. As the determining factor the intensification (reduction) of the Aleutian low and the simultaneous reduction (intensification) of the Icelandic low during El Niño and during La Niña events respectively, is identified. The changes in the intensity of the Aleutian low during the ENSO-events are accompanied by an alteration of the transport of momentum caused by the short baroclinic waves over the North American continent in such a way that the changes in the intensity of the Icelandic low during El Niño as well as during La Niña events are maintained.With 16 Figures     

Biomarker responses as indication of contaminant effects in blue mussel (Mytilus edulis) and female eelpout (Zoarces viviparus) from the southwestern Baltic Sea

During a field study performed in spring and autumn 2001 and 2002, blue mussels (Mytilus edulis) and female eelpout (Zoarces viviparus) were collected at three locations in the Wismar Bay (Baltic Sea), and several biomarkers of contaminant effects were analysed. Besides seasonal and inter-annual variations, biomarker signals were most pronounced at the location closest to Wismar Harbour (Wendorf) in both species. Lysosomal membrane stability (LMS) was lowest and acetylcholinesterase activity (AChE) was significantly reduced. Frequency of micronuclei (MN) was significantly higher (in blue mussels), indicating mutagenic effects. In eelpout elevated levels of DNA adducts, EROD induction and PAH-metabolites were measured. Metallothionein (MT), biomarker for trace metal exposure, showed a gradient only in spring. Organochlorine contaminant analyses (PCBs, DDTs) corresponded to the observed biomarker levels. The results obtained clearly demonstrate pollution effects in the southwestern Baltic Sea. Moreover, they show that a multibiomarker approach is also applicable in a brackish water environment.     

The Hilbert Transform on the Two-Sphere: A Spectral Characterization

The local analysis of signals arising on the sphere is a common task in earth sciences. On the real line the analytic signal turned out to be an important representation in local one-dimensional signal processing. Its generalization to two dimensions is the monogenic signal, and the properties of the analytic and the monogenic signal in the Fourier domain are well known. A generalization to the sphere is given by the Hilbert transform on the sphere known from Clifford analysis. To obtain a spectral characterization, the transform has to be decomposed into spherical harmonic functions. In this paper, we derive the spherical harmonic coefficients of the Hilbert transform on the sphere and give a series expansion. This will show that it acts as a differential operator on the spherical harmonic basis functions of the Laplace equation solution, analogously to the Riesz transform in two dimensions. This allows an interpretation of the Hilbert transform suitable for signal processing of signals naturally arising on the two-sphere. We show that the scale space naturally arising is a Poisson scale space in the unit ball. In addition, the obtained interpretation of the Hilbert transform is used for orientation analysis of plane waves. This representation is justified as a novel signal model on the sphere which can be used to construct intensity and rotation-invariant operators for local signal analysis in a scale-space concept.     

The hydrologic effects of intense groundwater pumpage in east-central Hillsborough County,Florida, U.S.A.

Well problems, water shortages, local flooding, and induced sinkholes have been periodic problems for residents in east-central Hillsborough County, Florida. This agricultural area has experienced dramatic short-term water-level declines in the Floridan aquifer from seasonal groundwater withdrawals. The sudden declines in the potentiometric surface have been caused from intense irrigation pumpage, primarily for frost and freeze protection and fruit setting. Citrus and strawberry crops are protected from occasional freezes by the application of warm groundwater to maintain minimum soil temperatures of 32°F(0°C). Local residents with inadequately constructed wells lose their source of water when the potentiometric surface is lowered to depths where their wells do not function. Some residents have lost their water supply for a week or more, and many have incurred damage to their pumps. The drawdown of the potentiometric surface in some areas has induced sinkholes causing property damage for some residents and concern for others. In addition, the high application rates for frost and freeze irrigation have created run-off problems resulting in local flooding to some residents. Fortunately, there has been no damage to resident homes from the flooding or sinkholes. This report summarizes the area's hydrogeology, and the consequences of heavy freeze irrigation. A finite-difference, numerical model is used to quantify the regional impacts to the potentiometric surface of the Floridan aquifer from estimated irrigation pumpage. Management recommendations for alleviating the problems are also discussed in the report.     

On the evaluation of temperature trends in the tropical troposphere

A series of model experiments with the coupled Max-Planck-Institute ECHAM5/OM climate model have been investigated and compared with microwave measurements from the Microwave Sounding Unit (MSU) and re-analysis data for the period 1979?C2008. The evaluation is carried out by computing the Temperature in the Lower Troposphere (TLT) and Temperature in the Middle Troposphere (TMT) using the MSU weights from both University of Alabama (UAH) and Remote Sensing Systems (RSS) and restricting the study to primarily the tropical oceans. When forced by analysed sea surface temperature the model reproduces accurately the time-evolution of the mean outgoing tropospheric microwave radiation especially over tropical oceans but with a minor bias towards higher temperatures in the upper troposphere. The latest reanalyses data from the 25?year Japanese re-analysis (JRA25) and European Center for Medium Range Weather Forecasts Interim Reanalysis are in very close agreement with the time-evolution of the MSU data with a correlation of 0.98 and 0.96, respectively. The re-analysis trends are similar to the trends obtained from UAH but smaller than the trends from RSS. Comparison of TLT, computed from observations from UAH and RSS, with Sea Surface Temperature indicates that RSS has a warm bias after 1993. In order to identify the significance of the tropospheric linear temperature trends we determined the natural variability of 30-year trends from a 500?year control integration of the coupled ECHAM5 model. The model exhibits natural unforced variations of the 30?year tropospheric trend that vary within ±0.2?K/decade for the tropical oceans. This general result is supported by similar results from the Geophysical Fluid Dynamics Laboratory (GFDL) coupled climate model. Present MSU observations from UAH for the period 1979?C2008 are well within this range but RSS is close to the upper positive limit of this variability. We have also compared the trend of the vertical lapse rate over the tropical oceans assuming that the difference between TLT and TMT is an approximate measure of the lapse rate. The TLT?CTMT trend is larger in both the measurements and in the JRA25 than in the model runs by 0.04?C0.06?K/decade. Furthermore, a calculation of all 30?year TLT?CTMT trends of the unforced 500-year integration vary between ±0.03?K/decade suggesting that the models have a minor systematic warm bias in the upper troposphere.     

High-resolution correlations between Gotland and Estonia near the base of the Wenlock

The strata of the Ireviken Event can be correlated between Gotland, Sweden and the Viki core on Saaremaa, Estonia, with a high degree of precision. Most of the ten datum planes are found with a precision of better than 0.1 m in the Lower and upper Visby Beds on Gotland and high in the Mustjala Member of the Jaani Formation on Saaremaa. Five of the latest Llandovery–early Wenlock units defined by these datum planes are between c. 0.12 and 1.77 m thick on Gotland and 0.12 and 0.67 m in Estonia. The duration of each was between a few thousand and c. 31 000 years. The stratigraphic resolution achieved in the interval of the Ireviken Event is 10,000 years. Ultimate range ends are lacking within a preceding, slightly longer interval, but the pattern of intermittent presence of some taxa agrees well with an unchanged relative rate of sedimentation. Their coeval presence in different places indicates ecological, regional or more widespread changes.