Comparison of bryozoan assemblages from two contrasting Arctic shelf regions

The structure of bryozoan assemblages from two Arctic regions (East Greenland and West Spitsbergen shelf) was compared. Both areas are located at the same latitude and the samples were taken from similar depths; however, the regions differed in water temperature and oceanography. East Greenland, which has lower mean annual water temperatures, was found to be one third richer in taxa (86 species) than West Spitsbergen (59 species). Diversity (Shannon–Wiener index – H′) and abundance were also higher on average in East Greenland (e.g. H′ = 2.49) than West Spitsbergen (e.g. H′ = 2.12). However for species richness, diversity and abundance there were no significant statistical differences between means (ANOVA) from the two regions. In spite of these similarities the investigated assemblages differed to a large extent in both species composition and dominance structure. There were 55 species that occurred only in East Greenland and 28 species that were present only in West Spitsbergen. There was higher proportion of species with an Arctic distribution in East Greenland (46%) than in West Spitsbergen (24%). Observed dissimilarities were concluded to be due to different hydrological conditions between the two regions.     

Flotation study on high-hercynite ilmenite ores

Ilmenite from Polish magnetite-ilmenite ores has been floated with tall oil. Chemical and mineralogical analysis of the flotation products established that the ores containing hercynite are difficult to upgrade. For ore A (18.7% hercynite and 32.8% ilmenite) and ore B (9% hercynite and 41.3% ilmenite) poor concentrates containing much less than the required 45% TiO₂ have been obtained. It has been found that the higher concentration of hercynite in the feed, the lower the grade of concentrates in respect to TiO₂ is obtained. Ilmenite ore containing a minor amount of hercynite (ore C, 0.15% hercynite and 12.3 ilmenite) gives a good concentrate. By means of microscopic observation it was established that hercynite floats together with ilmenite in the rougher flotation but is partially depressed in the cleaning and scavenging flotation.     

Occurrence of ten metals in Mytilus edulis L. and Cardium glaucum L. from the Gdańsk Bay

The determination of Fe, Mn, Ni, Pb, Cu, Co, Zn, Cd, Ca and Mg was carried out in the soft tissues and shells of Mytilus edulis and Cardium glaucum from Gdańsk Bay. This paper reports on the influence of size (age) on the metal concentration in molluscs. Both species-dependent variability and regional variations of metal concentrations in molluscs were observed. The correlation coefficients between the concentrations of metal in the soft tissues and shells were determined. The correlation coefficients between hard and soft parts metals were calculated for Mytilus edulis.     

The statistical effects of galactic tides on the Oort cloud

This report is a comment on two papers by Matese and Whitman (1989, 1992). We discuss here the applicability of uniform probability densities for the orbital parameters of the Oort cloud comets.     

Advances in understanding calcite varve formation: new insights from a dual lake monitoring approach in the southern Baltic lowlands

We revise the conceptual model of calcite varves and present, for the first time, a dual lake monitoring study in two alkaline lakes providing new insights into the seasonal sedimentation processes forming these varves. The study lakes, Tiefer See in NE Germany and Czechowskie in N Poland, have distinct morphology and bathymetry, and therefore, they are ideal to decipher local effects on seasonal deposition. The monitoring setup in both lakes is largely identical and includes instrumental observation of (i) meteorological parameters, (ii) chemical profiling of the lake water column including water sampling, and (iii) sediment trapping at both bi-weekly and monthly intervals. We then compare our monitoring data with varve micro-facies in the sediment record. One main finding is that calcite varves form complex laminae triplets rather than simple couplets as commonly thought. Sedimentation of varve sub-layers in both lakes is largely dependent on the lake mixing dynamics and results from the same seasonality, commencing with diatom blooms in spring turning into a pulse of calcite precipitation in summer and terminating with a re-suspension layer in autumn and winter, composed of calcite patches, plant fragments and benthic diatoms. Despite the common seasonal cycle, the share of each of these depositional phases in the total annual sediment yield is different between the lakes. In Lake Tiefer See calcite sedimentation has the highest yields, whereas in Lake Czechowskie, the so far underestimated re-suspension sub-layer dominates the sediment accumulation. Even in undisturbed varved sediments, re-suspended material becomes integrated in the sediment fabric and makes up an important share of calcite varves. Thus, while the biogeochemical lake cycle defines the varves’ autochthonous components and micro-facies, the physical setting plays an important role in determining the varve sub-layers’ proportion.     

Permanence of economic potential of cities based on sector development

The paper attempts to answer the following key question: how will a city′s world rank change in the face of crisis in its main economic sector? Crisis is defined here as a decline in financial performance in the given sector, which leads to the decline of its constituent firms and corporations on the world economic scene. The World Economic Center Index(WECI) has been created in order to rank cities based on the value of their resident corporations by sector and show their level of stability upon the removal of the most important sector. This provides information on the potential of each analyzed city as well as on its advanced features or area of specialization. Research has shown that nearly half the World Economic Centers are dominated by the financial and materials sectors of the economy. Different sectors dominate different regions of the world. For example, consumer staples and materials were dominant in North America, while information technology and financials were dominant in Europe. In Asia, several sectors tend to dominate the economy. Research has shown that the ability of a principal economic sector to resist economic crisis largely depends on the strength of the command and control function of a city. Finally, a high globalization level of a city is a key determinant of its susceptibility to economic crisis.     

New fjords,new coasts,new landscapes: The geomorphology of paraglacial coasts formed after recent glacier retreat in Brepollen (Hornsund,southern Svalbard)

Changes in the properties and dynamics of tidewater glacier systems are key indicators of the state of Arctic climate and environment. Calving of tidewater glacier fronts is currently the dominant form of ice mass loss and a major contributor to global sea-level rise. An important yet under-studied aspect of this process is transformation of Arctic landscapes, where new lands and coastal systems are revealed due to the recession of marine-terminating ice masses. The evolution of those freshly exposed paraglacial coastal environments is controlled by nearshore marine, coastal and terrestrial geomorphic processes, which rework glacial-derived sediments to create new coastal paraglacial landforms and landscapes. Here, we present the first study of the paraglacial coasts of Brepollen, one of the youngest bays of Svalbard revealed by ice retreat. We describe and classify coastal systems and the variety of landforms (deltas, cliffs, tidal flats, beaches) developed along the shores of Brepollen during the last 100 years. We further discuss the main modes of sediment supply to the coast in different parts of the new bay, highlighting the fast rate of coastal transformation as a paraglacial response to rapid deglaciation in the Arctic. This study provides an exemplar of likely coastal responses to be anticipated in similar tidewater settings under future climate change. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd     

A minimum sample size required from Schmidt hammer measurements

The Schmidt hammer is a useful tool applied by geomorphologists to measure rock strength in field conditions. The essence of field application is to obtain a sufficiently large dataset of individual rebound values, which yields a meaningful numerical value of mean strength. Although there is general agreement that a certain minimum sample size is required to proceed with the statistics, the choice of size (i.e. number of individual impacts) was usually intuitive and arbitrary. In this paper we show a simple statistical method, based on the two‐sample Student's t‐test, to objectively estimate the minimum number of rebound measurements. We present the results as (1) the ‘mean’ and ‘median’ solutions, each providing a single estimate value, and (2) the empirical probability distribution of such estimates based on many field samples. Schmidt hammer data for 14 lithologies, 13–81 samples for each, with each sample consisting of 40 individual readings, have been evaluated, assuming different significance levels. The principal recommendations are: (1) the recommended minimum sample size for weak and moderately strong rock is 25; (2) a sample size of 15 is sufficient for sandstones and shales; (3) strong and coarse rocks require 30 readings at a site; (4) the minimum sample size may be reduced by one‐third if the context of research allows for higher significance level for test statistics. Interpretations based on less than 10 readings from a site should definitely be avoided. Copyright © 2009 John Wiley & Sons, Ltd.     

Seasonal and spatial changes in the zooplankton community of Kongsfjorden, Svalbard

Seasonal changes in the zooplankton composition of the glacially influenced Kongsfjorden, Svalbard (79°N, 12°E), and its adjacent shelf were studied in 2002. Samples were collected in the spring, summer and autumn in stratified hauls (according to hydrographic characteristics), by means of a 0.180-mm Multi Plankton Sampler. A strong front between the open sea and the fjord waters was observed during the spring, preventing water mass exchange, but was not observed later in the season. The considerable seasonal changes in zooplankton abundance were related to the seasonal variation in hydrographical regime. The total zooplankton abundance during the spring (40–2010 individuals m⁻³) was much lower than in the summer and autumn (410–10 560 individuals m⁻³). The main factors shaping the zooplankton community in the fjord include: the presence of a local front, advection, the flow pattern and the decreasing depth of the basin in the inner fjord. Presumably these factors regulate the gross pattern of zooplankton density and distribution, and override the importance of biological processes. This study increased our understanding of seasonal processes in fjords, particularly with regard to the strong seasonal variability in the Arctic.