The effect of decrease in salinity on the dynamics of abundance and the cell size of <Emphasis Type="Italic">Corethron Hystrix</Emphasis> (Bacillariophyta) in laboratory culture

Effect of salinity on abundance dynamics and cell size of microalga Corethron hystrix Hensen (Bacillariophyta) were studied. C. hystrix can normally grow within a rather narrow salinity range between 32 and 28‰. The viable cells of this microalga change their morphological characters at a salinity of 24‰. This salinity level probably marks the beginning of cell division restriction, because the general number of cells by the end of the experiment was lower than in the control. The decrease of salinity to 16‰ caused pronounced irreversible morphological changes: cell height increased, chloroplasts compressed, protoplasm became granular, cytoplasm retracted, and spines shortened.     

Geochemistry and oxygen isotopic composition of olivine in kimberlites from the Arkhangelsk province: Contribution of mantle metasomatism

The paper presents data on the composition of olivine macrocrysts from two Devonian kimberlite pipes in the Arkhangelsk diamond province: the Grib pipe (whose kimberlite belongs to type I) and Pionerskaya pipe (whose kimberlite is of type II, i.e., orangeite). The dominant olivine macrocrysts in kimberlites from the two pipes significantly differ in geochemical and isotopic parameters. Olivine macrocrysts in kimberlite from the Grib pipe are dominated by magnesian (Mg# = 0.92–0.93), Ti-poor (Ti < 70 ppm) olivine possessing low Ti/Na (0.05–0.23), Zr/Nb (0.28–0.80), and Zn/Cu (3–20) ratios and low Li concentrations (1.2–2.0 ppm), and the oxygen isotopic composition of this olivine δ¹⁸O = 5.64‰ is higher than that of olivine in mantle peridotites (δ¹⁸O = 5.18 ± 0.28‰). Olivine macrocrysts in kimberlite from the Pionerskaya pipe are dominated by varieties with broadly varying Mg# = 0.90–0.93, high Ti concentrations (100–300 ppm), high ratios Ti/Na (0.90–2.39), Zr/Nb (0.31–1.96), and Zn/Cu (12–56), elevated Li concentrations (1.9–3.4 ppm), and oxygen isotopic composition δ¹⁸O = 5.34‰ corresponding to that of olivine in mantle peridotites. The geochemical and isotopic traits of low-Ti olivine macrocrysts from the Grib pipe are interpreted as evidence that the olivine interacted with carbonate-rich melts/fluids. This conclusion is consistent with the geochemical parameters of model melt in equilibrium with the low-Ti olivine that are similar to those of deep carbonatite melts. Our calculations indicate that the variations in the δ¹⁸O of the olivine relative the “mantle range” (toward both higher and lower values) can be fairly significant: from 4 to 7‰ depending on the composition of the carbonate fluid. These variations were formed at interaction with carbonate fluid, whose δ¹⁸O values do not extend outside the range typical of mantle carbonates. The geochemical parameters of high-Ti olivine macrocrysts from the Grib pipe suggest that their origin was controlled by the silicate (water–silicate) component. This olivine is characterized by a zoned Ti distribution, with the configuration of this distribution between the cores of the crystals and their outer zones showing that the zoning of the cores and outer zones is independent and was produced during two episodes of reaction interaction between the olivine and melt/fluid. The younger episode (when the outer zone was formed) likely involved interaction with kimberlite melt. The transformation of the composition of the cores during the older episode may have been of metasomatic nature, as follows from the fact that the composition varies from grain to grain. The metasomatic episode most likely occurred shortly before the kimberlite melt was emplaced and was related to the partial melting of pyroxenite source material.     

Policy discourse and biography: scripting adulthood into housing policies in comparative perspective

This article compares current Russian and Swedish policy discourses on state commitment to facilitating young adults’ access to housing by analyzing national, regional and municipal strategic documents. Both countries previously embraced the idea of housing as a commodified yet universal entitlement and exercised strong public regulation of housing redistribution, but are now establishing selective policies that support young people who comply with prescribed life-course norms. Thus, a life-course trajectory becomes integrated into the policy discourse, and a stable residential autonomy is considered a ‘crowning biographical event’, following a successful employment record and the establishment of a family unit. Notwithstanding important differences in policy formulation and realization, housing policies in Russia and Sweden are aimed to integrate emerging adults into market relations by increasing housing ownership through credit loans and stimulating individual responsibility for welfare provision.     

Sheared peridotite xenolith from the V. Grib kimberlite pipe,Arkhangelsk Diamond Province,Russia: Texture,composition, and origin

The petrography and mineral composition of a mantle-derived garnet peridotite xenolith from the V. Grib kimberlite pipe (Arkhangelsk Diamond Province, Russia) was studied. Based on petrographic characteristics, the peridotite xenolith reflects a sheared peridotite. The sheared peridotite experienced a complex evolution with formation of three main mineral assemblages: (1) a relict harzburgite assemblage consist of olivine and orthopyroxene porphyroclasts and cores of garnet grains (Gar1) with sinusoidal rare earth elements (REE) chondrite C1 normalized patterns; (2) a neoblastic olivine and orthopyroxene assemblage; (3) the last assemblage associated with the formation of clinopyroxene and garnet marginal zones (Gar2). Major and trace element compositions of olivine, orthopyroxene, clinopyroxene and garnet indicate that both the neoblast and clinopyroxene-Gar2 mineral assemblages were in equilibrium with a high Fe-Ti carbonate-silicate metasomatic agent. The nature of the metasomatic agent was estimated based on high field strength elements (HFSE) composition of olivine neoblasts, the garnet-clinopyroxene equilibrium condition and calculated by REE-composition of Gar2 and clinopyroxene. All these evidences indicate that the agent was a high temperature carbonate-silicate melt that is geochemically linked to the formation of the protokimberlite melt.     

Growth and physiological state of the microalgae <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis> Bohlin (Bacillariophyta) in the water taken from peter the Great Bay

Bioassay of water from different parts of the Peter the Great Bay using microalgae P. tricornutum revealed that water quality influences not only the growth but also the physiological state of the microalgae. There was no difference in the cell size between control and experimental cultures. Inhibition of microalgae growth was revealed in water with low phosphates concentration, for example, in the Marine Reserve. High phosphates concentration and moderate organic pollution caused the stimulation of miñroalgae growth in such sites as the Tumen, the Partizanskaya and the Vtoraya rechka rivers mouths.     

1-Hydroxypyrene as a biomarker of PAH exposure in the marine polychaete Nereis diversicolor

The possibility of using the pyrene metabolite 1-hydroxypyrene as a biomarker of polycyclic aromatic hydrocarbons (PAHs) exposure was investigated by exposure of the marine polychaete Nereis diversicolor to several PAHs in the laboratory. Animals were exposed to pyrene alone and to five different PAHs – phenanthrene, anthracene, pyrene, benzo[a]pyrene and benzo[k]flouranthene. After five days of exposure the concentrations of parent PAHs and 1-hydroxypyrene were identified using three different analytical methods, high-performance liquid chromatography with fluorescence detection (HPLC/F), synchronous fluorescence spectroscopy (SFS) and gas chromatography with mass spectrometric detection (GC/MS). The SFS measurements of 1-hydroxypyrene were validated by the more sensitive method HPLC/F. The positive correlation between total PAHs and 1-hydroxypyrene concentrations in the polychaete tissues observed in experiments, suggests the feasibility of 1-hydroxypyrene as a suitable biomarker for total PAH exposure assessment. Furthermore, the possibility of employment of the simple and rapid SFS method instead of HPLC/F for biomarker analysis has been confirmed by the positive and significant correlation between results achieved by these two analytical methods.     

Late Pleistocene Environments of the Central Ukraine

The Vyazivok loess sequence from the Dnieper Plain, Ukraine, documents regional environmental changes during the late Pleistocene and Holocene. Pedological and palynological analyses and low-field magnetic susceptibility document changes from dense temperate forest during the last interglacial maximum to open, harsh, loess–steppe during the latest Pleistocene. The Vyazivok section overlies hillwash derived from a lower Pleistocene terrace and consists of two stratified soil complexes (Kaydaky and Pryluky; marine isotope stage [MIS] 5 equivalent) separated by a layer of eolian dust (Tyasmyn silt). The lower soils in both complexes formed within forest. These soils are overlain by the Uday (MIS4) and Bug (MIS2) loess units, which are separated by boreal soils of the Vytachiv (MIS3) complex. The coldest conditions within the record occurred in the youngest loess. Holocene soils cap the Bug loess. The Vyazivok section shows remarkable similarities with other classical loess sequences in western Europe, the Czech Republic, and Austria. The Kaydaky, Pryluky, and Vytachiv deposits, correlate with the PKIII, PKII, and PKI soil complexes, respectively, of the Czech Republic. The Tyasmyn and Prylyky silt layers correspond to marker horizons from central Europe.     

Magnetic structure of polluted soil profiles from Eastern Ukraine

Our study concerned magnetic properties of soil profiles taken from polluted regions of Eastern Ukraine around the industrial centres Krivyj Rig, Mariupol and Komsomolsk. Soils represent chernozem and podzoluvisol. The low-field magnetic susceptibility shows enhancement in the topsoil caused by contamination by coarse-grain magnetite connected with industrial pollution. Magnetic mineralogy was determined by means of thermal demagnetisation of SIRM, monitoring of susceptibility changes during warming from ?196°C to room temperature and heating to 700°C, and Mössbauer analysis. Granulometry of magnetic particles was investigated by determination of hysteresis parameters, susceptibility, M _s , SIRM and ARM ratios and frequency dependence of susceptibility. The chemical parameters, namely pH, organic carbon and iron content in different pedogenic and lithogenic minerals, measured for particular horizons determined pedogenic characteristic of soil profiles. Our study showed that differences in magnetic parameters of non-polluted and polluted soil profiles are not limited to the topsoil, but reach deep layers of the parent material. Industrial pollution promotes formation of the so-called “pedogenic” SP and SD particles in these layers.     

Effect of temperature on contents of essential highly unsaturated fatty acids in freshwater zooplankton

In 11 lakes from cold and warm regions we studied the content of highly unsaturated fatty acids (HUFA) in seston (<130 μm) and crustacean zooplankton using gas chromatography–mass spectrometry. An increase of temperature correlated with a decrease of HUFA content in zooplankton. A multivariate canonical correlation analyses revealed, that the decrease of HUFA content was related with a decrease of per cent of copepods in zooplankton communities, which are known to have higher HUFA levels in their biomass, than cladocerans. This means that temperature primarily affected the HUFA levels indirectly, via changing of taxonomic structure of zooplankton community, while the homeoviscous adaptation of zooplankton individuals had comparatively lower importance. As found, water temperature was better predictor of HUFA contents of zooplankton, than the fatty acid composition of seston. Thus, it can be predicted, that a probable climate warming will decrease the content of the essential HUFA in freshwater zooplankton with possible negative consequences for animals of higher trophic levels.