The distribution and relative toxic potential of organic chemicals in a PCB contaminated bay

For reliable monitoring of environmental improvement, the PCB contaminated bay Orserumsviken on Sweden's Baltic coast was investigated prior to remediation. We examined PCB congener patterns and the relative toxic potential of PCBs in extracts of three matrices: bottom sediment, settling particulate matter and the dissolved phase (obtained from semi-permeable membrane devices). Congener patterns were similar in all matrices. Three fractions were isolated from the extracts: (1) aliphatic and monocyclic aromatic compounds (MAC-fraction), (2) dicyclic aromatic compounds (DAC-fraction), including PCBs, and (3) polycyclic aromatic compounds (PAC-fraction), including PAHs. Total extracts and fractions were injected into newly fertilised rainbow trout eggs. At larval stage, hepatic EROD activities were quantified. Though high, the PCB contamination could explain only an estimated 1-5% of the total EROD induction. The order of EROD induction potential was: total extract > PAC-fraction > DAC-fraction > MAC-fraction in all matrices, suggesting that in Orserumsviken PACs made a larger contribution to the EROD induction potential than PCBs and other DACs.     

Climatically induced lake level changes during the last two millennia as reflected in sediments of Laguna Potrok Aike,southern Patagonia (Santa Cruz,Argentina)

The volcanogenic lake Laguna Potrok Aike, Santa Cruz, Argentina, reveals an unprecedented continuous high resolution climatic record for the steppe regions of southern Patagonia. With the applied multi-proxy approach rapid climatic changes before the turn of the first millennium were detected followed by medieval droughts which are intersected by moist and/or cold periods of varying durations and intensities. The total inorganic carbon content was identified as a sensitive lake level indicator. This proxy suggests that during the late Middle Ages (ca. AD 1230–1410) the lake level was rather low representing a signal of the Medieval Climate Anomaly in southeastern Patagonia. At the beginning of the Little Ice Age the lake level rose considerably staying on a high level during the whole period. Subsequently, the lake level lowered again in the course of the 20th century.     

Collisions in self-gravitating clouds of planetesimals

A theory of partially elastic collisions is constructed for frictionless planetesimals in an arbitrary gravitational field. The non-zero size of the particles and the influence of gravitational encounters are included. The equations for a self-gravitating rotationally symmetric disk or ring are written in an explicit form. Such systems turn out to be bimodal in the same sense as the Keplerian systems, i.e. there are two kinds of stable configurations which may co-exist in adjacent regions without disturbing the mechanical equilibrium. The transitions from one mode to another can also occur at essentially smaller values of the optical thickness than those previously found for Saturn's rings: in one of the numerically studied cases the transition from the dense to the rarefied mode occurred at the optical thickness 3×10^?5 while the reversed process corresponded to a higher value, 10^?2. The difference illustrates the dependence of the transition on its direction. The characteristic S shape which several authors have found for the relation between the viscosity and the optical thickness in Keplerian systems becomes more complicated if the contribution of self-gravitation increases. In some cases the stable solutions also imply a certain minimum value of the optical thickness.     

On the latitude drift of sunspot groups and solar rotation

The N-S drift of sunspot groups has been studied in a different way than previously, using positions of recurrent groups of the years 1874–1976. The existence of the meridional motions, the general shape of the drift curves, and the dissimilarity between these curves around sunspot maxima and minima, are all confirmed. In addition, also for the angular velocity of the Sun the same material gives differences around the times of sunspot maxima and minima.     

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3. Das Grundgebirge des nördlichen Teils der östlichen arabischen Wüste ägyptens

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Vertical and horizontal distribution of coccolithophores in the Caribbean Sea

Coccolithophores are one of the major, living phytoplankton groups and play important roles in geochemical cycles and climate. They are a particularly dominant group in oligotrophic waters, yet a lot more needs to be learned about their horizontal and vertical distributions. Coccolithophores were collected at different photic depths from 15 stations across the Caribbean Sea during cruise 35/1 of the RV Meteor from April to May 1996. A total of 67 species was identified, with an average of 19 species per station. Coccolithophores were encountered at nearly all stations but abundances were fairly low (10²-10³ cells 1^-1). Coccolithophore assemblages in the four oceanographical provinces identified (Granada Basin waters, Atlantic surface waters, northern Caribbean waters, and Pedro Bank waters) differed in their species composition and abundances. Abundance peaks occurred near the surface and in the deeper photic zone (140-150 m) just below the deep chlorophyll-a maximum at the top of the nitrate nutricline.